Analytical Chemist

www.flowinjectiontutorial.com

2013-12-10T08:37:00.006+00:00

www.flowinjectiontutorial.com

The 5^th edition of The Tutorial, now accessible on line comprises:

Preface, discussing revolution taking place in scientific publishing
Introduction, reviews development of methods of flow analysis, beginning with air segmented systems, focuses on flow programming, and concludes with high throughput Sequential Injection technique.
Theory deals with mixing by dispersion in flow system, emphasizing the essential role of the turbulent flow.
Methods section deals with Flow Injection, Sequential Injection, Bead Injection and Sequential Injection Chromatography, illustrated by examples of work from world leaders in the field.
FIA Story is collection of contributions written by those, who participated in inventing, advancing and commercialization of Flow Injection and related techniques. This multicolor quilt of stories is the heritage from which much is to be learned about science, discovery and commerce.
Database contains over 22000 instantly searchable references.
News section comprises announcements of forthcoming meetings and publications from the field of analytical chemistry.

Contributions related to flow analysis and instrumentation are cordially invited, and will be published free of charge, with the exception of commercials. The website is financially supported by the author.

2014 Bunsen-Kirchhoff Award for Analytical Spectroscopy

2013-11-20T15:37:00.001+00:00

Annoucement

The DASp – German Working group for Applied Spectroscopy - regularly awards the "Bunsen-Kirchhoff-Preis für analytische Spektroskopie" to honour preferably the work of young scientists from universities, research institutes or industry who made excellent contributions to analytical spectroscopy. Especially preferred is an oeuvre in new areas like spectroscopy in nano compartments, spectroscopy of biomolecules a.s.o. The Award consists of an award-document and an amount of € 2.500,00 sponsored by Perkin Elmer and the DASp seeks nominations for the 2014 Bunsen-Kirchhoff Award for Analytical Spectroscopy. The Award will be presented at the Analytica in April 2014 in Munich (Germany).

A nomination (in electronic form) should include:

1. letter with the candidate´s accomplishments

2. list of publications or recent work,

3. scientific curriculum vitae stating the age of the candidate; the candidate´s address, phone fax and e-mail.

Nominations can be made by members of DASp but eligibility is open for any scientist meeting the requirements. Self-nomination is excluded. The decision as to whom the prize is to be awarded shall be made by a jury consisting of the current members of the board of DASp.

Further information is available at:

https://www.gdch.de/netzwerk-strukturen/fachstrukturen/analytische-chemie/arbeitskreise/ak-dasp.html

All documents should be sent not later than 15 December 2013 to: Prof. Dr. Detlef Günther, President of the Jury for the Bunsen-Kirchhoff Award 2014, ETH Zürich, Laboratorium für Anorganische Chemie, Wolfgang-pauli-Str. 10, HCI G113, CH-8093 Zürich (Schweiz)

E-Mail: Secretary, Ms Nicole Bachmann (nbachmann@inorg.chem.ethz.ch

Just Published: Sensors & Actuators B: Chemical

2013-11-20T08:17:00.001+00:00

A new issue of this journal has just been published. To see abstracts of the papers it contains (with links through to the full papers) click here:

Sensors & Actuators B: Chemical
http://rss.sciencedirect.com/publication/science/5283

Selected papers from the latest issue:

A novel way for detection of eugenol via poly (diallyldimethylammonium chloride) functionalized graphene-MoS2 nano-flower fabricated electrochemical sensor

20 November 2013, 08:11:22

Publication date: 1 March 2014
Source:Sensors and Actuators B: Chemical, Volume 192
Author(s): Qingliang Feng , Kaiyue Duan , Xiaoliang Ye , Daban Lu , Yongling Du , Chunming Wang
Poly (diallyldimethylammonium chloride) functionalized graphene-MoS2 nano-flower materials (PDDA-G-MoS2) were successfully synthesized, in which the addition of MoS2 wrinkling the graphene further increased the specific surface area. Then, the gold nanoparticles (AuNPs) were assembled on the surface of PDDA-G-MoS2 via electrostatic attractive force and function of AuS bond. The obtained Au/PDDA-G-MoS2 nanomaterial was used to modify glassy carbon electrode (Au/PDDA-G-MoS2/GCE) and determine sensitively eugenol. The oxidation peak currents increased distinctly on the proposed electrochemical sensor by cyclic voltammetry (CV) in 0.10molL⁻¹ NaAc-HAc buffer solution (pH=5.50), indicating that the material shows excellent electrochemical properties. The reaction kinetics was studied and the experimental conditions were optimized. The oxidation peak current of eugenol increased linearly with addition of concentration in the range from 0.1 to 440μmolL⁻¹ with a low detection limit of 0.036μmolL⁻¹ (S/N =3). This sensor exhibited high sensitivity, good stability and fast responses, and also has been applied to determination of eugenol in real samples with satisfactory results. The novel PDDA functionalization graphene-MoS2 nanoflower shows excellent electrocatalysis for determination of eugenol and satisfactory dispersity in water than graphene; these would show its potential application in analysis, medical science and nanodevice field via combining graphene with graphene-like materials (MoS2) for its novel properties.

Graphical abstract

Dual signaling of azide ions by deprotection of a dichlorofluorescein chloroacetate

20 November 2013, 08:11:22

Publication date: 1 March 2014
Source:Sensors and Actuators B: Chemical, Volume 192
Author(s): Jung Woo Lee , Ho Won Kim , Hyun Gyu Im , Hong Yeong Kim , Suk-Kyu Chang
We investigated the dual optical signaling of azide ions by the selective cleavage of fluorescein acetates. The chloroacetate derivative of 2′,7′-dichlorofluorescein showed prominent colorimetric and fluorogenic signaling behaviors toward azide ions in aqueous acetonitrile solution. Fluorescein analogs also showed a selective response, but the signaling speed was unfavorably slow. The detection of azide ions was not affected by the presence of commonly encountered anions. In particular, significant interference from sulfide ions in the azide-selective signaling of the probe was readily suppressed by using a Hg(II)–N,N,N′,N′-tetrakis(2-pyridylmethyl)ethylenediamine (TPEN) complex as a masking agent. The detection limit for the determination of azide ions by the chloroacetate of 2′,7′-dichlorofluorescein in 10% aqueous acetonitrile was 4.0×10⁻⁷ M (17ppb). The signaling of azide ions in real samples using tap water and simulated wastewater was also tested.

Graphical abstract

Characterization of a new fluorescence-enhancing substrate for microarrays with femtomolar sensitivity

20 November 2013, 08:11:22

Publication date: 1 March 2014
Source:Sensors and Actuators B: Chemical, Volume 192
Author(s): Marina Cretich , Clelia Galati , Lucio Renna , Guglielmo Guido Condorelli , Paola Gagni , Marcella Chiari
The demand for high sensitivity in microarray technology has stimulated the research of new labeling strategies, new substrates with increased loading capacity and new approaches to amplify the fluorescence signals. Although these methods improve the sensitivity, they are based on non-routine procedures which limit their widespread usage. A simple way to achieve fluorescence enhancement is the optical interference (OI) coating technology based on the use of substrates with films of well-defined thickness that maximize photoabsorption of the dye molecules in the vicinity of the surface and reflect the emitted light toward the detector. Here we introduce a new substrate for fluorescence enhancement composed of a thin aluminum mirror and a single quarter wave silicon oxide as a dielectric layer. The use of such material allows the development of a substrate suited for parallel production in conventional IC (Integrated Circuit's) technology, which produces a 20-fold enhancement of fluorescence compared to glass, which is the most common material used in microarrays. The new substrate was coated with a copolymer of N,N-dimethylacrylamide, N-acryloyloxysuccinimide, and 3-(trimethoxysilyl)propyl methacrylate, copoly(DMA-NAS-MAPS), which forms, by a simple and robust procedure, a functional nanometric film that covalently binds bio-probes on the surface and efficiently suppresses non-specific adsorption. The performance of the new fluorescence-enhancing substrate in microarray technology was demonstrated for the detection of a panel of inflammation biomarkers pushing detection limits into the femtomolar range.

Measurement of the evolution of rigid and viscoelastic mass contributions from fibrin network formation during plasma coagulation using quartz crystal microbalance

20 November 2013, 08:11:22

Publication date: 1 March 2014
Source:Sensors and Actuators B: Chemical, Volume 192
Author(s): Ramji S. Lakshmanan , Vitaly Efremov , Sinéad M. Cullen , Anthony J. Killard
The coagulation of blood plasma and the effect of fibrinogen concentration were studied with a quartz crystal microbalance (QCM), where frequency and half-width at half-maximum (bandwidth) values measured from the conductance spectrum near resonant frequency were used. Bandwidth change is an indicator of energy dissipation, allowing for an understanding of qualitative changes occurring during fibrin clot formation. Both frequency shift (Δf) and bandwidth shift (ΔΓ) were dependent on the concentration of fibrinogen in plasma. We defined a sum of squares function α (=Δf ²/1000+ΔΓ ²/1000) that measures absolute changes in QCM resonant characteristics to semi-quantitatively include an overall contribution of adsorbed mass and elastic modulus components and a function β (=1−ΔΓ/Δf) that indicates qualitatively the nature of response based on its deviation from ideal Newtonian behaviour. Increasing concentration of fibrinogen resulted in an increase in the value of α, showing that a larger amount of fibrinogen results in larger amount of coupled viscoelastic mass. Changes in β indicated that the nature of changes occurring was very similar to Newtonian and that coupling of rigid-mass dominates the overall response in the early stage of coagulation and in the later stage growing elastic mass compensates some of the response.

A novel BODIPY-based colorimetric and fluorometric dual-mode chemosensor for Hg2+ and Cu2+

20 November 2013, 08:11:22

Publication date: 1 March 2014
Source:Sensors and Actuators B: Chemical, Volume 192
Author(s): Xingxing He , Jing Zhang , Xungao Liu , Lin Dong , Di Li , Huayu Qiu , Shouchun Yin
A novel BODIPY-based colorimetric fluorescent sensor with bis[2-(phenylseleno)ethyl]amine as binding site (Se-1) for Hg²⁺ and Cu²⁺ has been developed. Se-1 shows high selectivity and sensitivity toward Hg²⁺ and Cu²⁺ over alkali and transition metal ions. Se-1shows a significant red-shift in the absorption spectra from 525 to 571nm for Hg²⁺ and 590nm for Cu²⁺, which induces color changes from pink to purple and blue. Upon excitation at 570nm, Se-1 upon interaction with Hg²⁺ ions displays a 5-fold fluorescence enhancement with a 2nm blue-shift, while Se-1 with Cu²⁺ exhibits a 13-fold fluorescence enhancement and red-shifts from 595 to 610nm. The binding mode of Se-1 with Hg²⁺ or Cu²⁺ has been investigated by Job's plot, ESI and ¹H NMR experiments. The absorption and fluorescence of the Se-1–Hg²⁺ complex can be reversibly restored to that of the uncomplexed ligand by using EDTA or cysteine, however, the sensing processing of Se-1 in response to Cu²⁺ ions cannot.

A microfluidic device for the hydrodynamic immobilisation of living fission yeast cells for super-resolution imaging

20 November 2013, 08:11:22

Publication date: 1 March 2014
Source:Sensors and Actuators B: Chemical, Volume 192
Author(s): Laurence Bell , Ashwin Seshia , David Lando , Ernest Laue , Matthieu Palayret , Steven F. Lee , David Klenerman
We describe a microfluidic device designed specifically for the reversible immobilisation of Schizosaccharomyces pombe (Fission Yeast) cells to facilitate live cell super-resolution microscopy. Photo-Activation Localisation Microscopy (PALM) is used to create detailed super-resolution images within living cells with a modal accuracy of >25nm in the lateral dimensions. The novel flow design captures and holds cells in a well-defined array with minimal effect on the normal growth kinetics. Cells are held over several hours and can continue to grow and divide within the device during fluorescence imaging.

Synthesis of Ag-MoS2/chitosan nanocomposite and its application for catalytic oxidation of tryptophan

20 November 2013, 08:11:22

Publication date: 1 March 2014
Source:Sensors and Actuators B: Chemical, Volume 192
Author(s): Xiaohong Xia , Zhixiang Zheng , Yan Zhang , Xiaojuan Zhao , Chunming Wang
A convenient and low-cost synthesis approach is proposed for the development of a simple and novel electrochemical sensor for the determination of tryptophan (Try). In this synthesis process, graphene-like molybdenum sulfide was successfully obtained, and silver nanoflakes (AgNFs) were directly synthesized on the surface of molybdenum sulfide (MoS2) films, in this process chitosan (CS) and ascorbic acid (AA) acted as the stabilizer and reducing agent, respectively. This nanocomposite was characterized by transmission electron microscopy (TEM) and X-ray diffraction (XRD). Electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV) and differential pulse voltammetry (DPV) were employed to evaluate the electrochemical property of Ag-MoS2/CS toward the oxidation of tryptophan. Under the optimized experimental conditions, the oxidation peak currents are proportional to the concentrations of tryptophan over the range of 0.5μM to 120μM, and the detection limit is 0.05μM (S/N=3). Moreover, the proposed method is free of interference from other amino acid to other coexisting species.

Polymeric optodes based on upconverting nanorods for fluorescence measurements of Pb2+ in complex samples

20 November 2013, 08:11:22

Publication date: 1 March 2014
Source:Sensors and Actuators B: Chemical, Volume 192
Author(s): Jing Wu , Yu Qin
We reported here a lead ion selective optode incorporating NaYF4: Er,Yb upconverting nanorods, chromoionophore ETH 5418, and lead ionophore together in hydrophobic polymer matrixes. The absorption spectra of protonated and unprotonated ETH 5418 overlap the two emission peaks of the upconverting material, respectively, which allows the fluorescent ion sensing based on the inner filter effect. The proposed optodes exhibited highly selective and reproducible sensing property for measuring lead ions in the range of 10⁻⁶–10⁻² M at pH 5. Because the excitation source is 980nm and the emission wavelength lies in the near-infrared region, the sensors have been successfully used in complex samples for example plasma with minimized background absorption and sample autofluorescence. The lead levels in sheep plasma and artificial industry wastewater samples obtained by the optode were comparable with the known addition amounts of Pb(NO3)2, providing a new method for testing Pb²⁺ in the industry wastewater.

GADH screen-printed biosensor for gluconic acid determination in wine samples

20 November 2013, 08:11:22

Publication date: 1 March 2014
Source:Sensors and Actuators B: Chemical, Volume 192
Author(s): Lorena del Torno-de Román , M. Asunción Alonso-Lomillo , Olga Domínguez-Renedo , Arrate Jaureguibeitia , M. Julia Arcos-Martínez
Gluconate dehydrogenase (GADH) biosensors have been developed for the satisfactory determination of gluconic acid in wine samples, without any pretreatment. The biosensors have been fabricated by cross-linking immobilization of GADH onto screen-printed carbon electrodes, containing the mediator tetrathiafulvalene (TTF). Chronoamperograms have been registered at +100mV vs. screen-printed Ag/AgCl electrode by successive additions of a gluconic acid solution in the concentration range from 9.0 to 131.4μM. This method shows a reproducibility of 8.1% (n =3) related to the slopes of these calibration curves and a repeatability of 3.2% (n =5). The procedure has shown an average capability of detection of 9.0μM for a probability of false positive and negative of 0.05. Wine samples have been analyzed with these biosensors, obtaining satisfactory results.

Volume-doped cobalt titanates for ethanol sensing: An impedance and X-ray absorption spectroscopy study

20 November 2013, 08:11:22

Publication date: 1 March 2014
Source:Sensors and Actuators B: Chemical, Volume 192
Author(s): Clemens J. Belle , Günter E. Wesch , Stefan Neumeier , M. Janeth Lozano-Rodríguez , Andreas C. Scheinost , Ulrich Simon
The dynamic C2H5OH sensitivity of ilmenite-type cobalt titanates volume-doped by 2at% Li, Na, K, Sb, La, Sm, Gd, Ho and Pb was systematically studied with respect to exhaust monitoring. Therefore, the p-type semiconducting CoTiO3 materials were characterized as resistive gas sensors via high-throughput impedance spectroscopy toward 5–200ppm C2H5OH at 300–500°C. The best performing materials were tested further by time-resolved and long-term measurements whereby the CoTiO3 volume-doped with K exhibited an outstanding overall performance. X-ray absorption spectroscopy on this particular material gave evidence that the local structure around Co and Ti remains unaffected by the doping despite of a slight increase in static disorder. Hence, the effect of K doping does not originate from alteration in the metal-to-oxygen interaction as expected from previous findings.

Validation of wavelength modulation spectroscopy techniques for oxygen concentration measurement

20 November 2013, 08:11:22

Publication date: 1 March 2014
Source:Sensors and Actuators B: Chemical, Volume 192
Author(s): S. Neethu , R. Verma , S.S. Kamble , J.K. Radhakrishnan , P.P. Krishnapur , V.C. Padaki
Tunable Diode Laser Absorption Spectroscopy (TDLAS) based gas sensing technology, has widespread applications, ranging from use in biomedical industry to aerospace applications. An experimental set-up was established to measure concentration of oxygen gas in the range 0–100% using TDLAS technique. The oxygen absorption at 760.241nm was scanned with a tunable DFB laser, and wavelength modulation spectroscopy was used to obtain the harmonics (1f, 2f, 3f & 4f) of the oxygen absorption signal. The modulation parameters such as the modulation voltage, modulation frequency, reference phase, time constant of lock in amplifier, the tuning voltage, and the tuning frequency were optimized to obtain the harmonics of high amplitude and narrow half width. Keeping the experimental parameters constant, the oxygen concentration measurements were obtained by the following three methodologies, viz, (i) using only the 2nd harmonic, (ii) using the 2nd and 4th harmonics and, (iii) using the 1st and 2nd harmonics. The results of these measurements were compared and the merits and drawbacks of these methods are discussed.

Colorimetric determination of DNA concentration and mismatches using hybridization-mediated growth of gold nanoparticle probes

20 November 2013, 08:11:22

Publication date: 1 March 2014
Source:Sensors and Actuators B: Chemical, Volume 192
Author(s): Wei-Feng Fang , Wen-Jone Chen , Jing-Tang Yang
A novel colorimetric approach to sense DNA samples was demonstrated successfully based on a concept of hybridization-mediated growth of gold nanoparticles probes (AuNP probes). The growth size and conformation of the probes are dominated by DNA samples that hybridize with the probes. The growth probes serve as nanoparticle biosensors that can be utilized to analyze concentrations of DNA samples or to discriminate mismatches of DNA samples to the probes (complementarity of DNA) in terms of size- and shape-dependence optical properties. By means of the proposed method, not only the semi-quantitation of target DNA but also the differentiation of DNA mismatches can be readily achieved with a naked eye or simple spectrophotometer. This method features small consumption of reagents, a satisfactory detection limit (about 60nM), a small duration of assay (a couple of minutes), and a simple procedure without thermal control.

Improving Overall Growth & Performance of Primary Neurons

2013-11-20T08:14:00.000+00:00

Developed as an alternative to B27® * - GS21 from AMSBIO is a next generation serum-free neural media supplement, based on the formulation of NS21 Supplement, designed to improve the overall growth and performance of primary neurons.

GS21 has been specifically optimized for the maturation and long-term viability of primary rat and mouse neurons in culture, without the need for co-culture with astrocyte feeder cells. In experimental tests, GS21 has been shown to significantly improve long-term viability of rat and mouse primary neurons in vitro, as well as enhance neurite outgrowth of primary neurons in culture. Beneficially, GS21 also supports growth and maintenance of primary neurons at low or high cell density plating.

AMSBIO is a leading provider of innovative products and services to support all stages of stem cell and neurobiology research from source to storage. Regardless of the application, AMSBIO offers products and services to accelerate basic, translational and clinical research. For further information on GS21 neural supplement please visit http://www.amsbio.com/B-27.aspx or contact AMSBIO now on +44-1235-828200 / +1-949-768-8365 or email info@amsbio.com.

Founded in 1987, AMS Biotechnology (AMSBIO) is recognized today as a leading company contributing to the acceleration of discovery through the provision of cutting-edge life science technology products and services for research and development in the medical, nutrition, cosmetics and energy industries. The AMSBIO range includes specialist antibodies, peptides and recombinant proteins. In addition the company is able to draw upon in-depth expertise in extracellular matrices to provide elegant solutions for studying cell motility, migration, invasion and proliferation. Widely acknowledged as experts in cell culture, AMSBIO partners with clients in tailoring cell systems to enhance screening outcomes and eventual prognosis. With a range of molecular detection reagents, and a significant Biorepository the company can also provide tissue DNA, RNA, protein and microarray products. Key research areas for these products include: Oncology, Regenerative Medicine, Environmental Analysis, Cytotoxicity Screening, Glycomics and Stem Cell Biology.

Hold the front page!

2013-11-19T16:20:00.005+00:00

A paper entitled, Determination of selected biogenic amines in Acacia rigidulaplant materials and dietary supplements using LC–MS/MS methods published in the Journal of Pharmaceutical & Biomedical Analysis has made the front page of national newspaper, USA Today (see this link http://www.usatoday.com/story/news/nation/2013/11/18/fda-scientists-find-amphetamine-like-compound-in-dietary-supplements/3627963/).

The paper was published in Volume 88, 25 January 2014, Pages 457–466 and can be found here:

http://www.sciencedirect.com/science/article/pii/S0731708513004378

Just Published: Sensors & Actuators A: Physical

2013-11-19T09:48:00.001+00:00

A new issue of this journal has just been published. To see abstracts of the papers it contains (with links through to the full papers) click here:

Sensors & Actuators A: Physical
http://rss.sciencedirect.com/publication/science/5282

Selected papers from the latest issue:

Self-writing smart labels for humidity monitoring

19 November 2013, 09:42:19

Publication date: 1 January 2014
Source:Sensors and Actuators A: Physical, Volume 205
Author(s): Christian Schoo , Meinhard Knoll
Lateral anodic oxidation is a recent display technique with potential usage in self-writing smart labels and switching applications, which have the ability to operate with established RFID units. This process requires water to operate, which is harvested by a hygroscopic electrolyte layer from the ambient atmosphere. This precondition enables the realization of a humidity monitoring functionality. We develop smart labels displaying the maximum relative humidity during a period of time by the usage of halides providing different hygroscopicity in the electrolyte layer. Therefore we investigate the behavior of the humidity monitoring smart labels under test conditions with diverse relative humidity.

Color sensing ability of an amorphous silicon position sensitive detector array system

19 November 2013, 09:42:19

Publication date: 1 January 2014
Source:Sensors and Actuators A: Physical, Volume 205
Author(s): Javier Contreras , Rodrigo Martins , Pawel Wojcik , Sergej Filonovich , Hugo Aguas , Luis Gomes , Elvira Fortunato , Isabel Ferreira
The color sensing ability of a data acquisition prototype system integrating a 32 linear array of 1D amorphous silicon position sensitive detectors (PSD) was analyzed. Besides being used to reproduce a 3D profile of highly reflective surfaces, here we show that it can also differentiate primary red, green, blue (RGB) and derived colors. This was realized by using an incident beam with a RGB color combination and adequate integration times taking into account that a color surface mostly reflects its corresponding color. A mean colorimetric error of 25.7 was obtained. Overall, we show that color detection is possible via the use of this sensor array system, composed by a simpler amorphous silicon pin junction.

Investigation of guided surface acoustic wave sensors by analytical modeling and perturbation analysis

19 November 2013, 09:42:19

Publication date: 1 January 2014
Source:Sensors and Actuators A: Physical, Volume 205
Author(s): Onursal Onen , Rasim Guldiken
In this paper, shear horizontal polarized guided surface acoustic wave propagation was investigated with analytical modeling and perturbation analysis for biosensing applications. The model was also verified experimentally. The analytical model was developed for multilayer systems taking viscoelasticity into consideration. Detailed parametric investigation of dispersion curves was conducted using various substrate materials and guiding layers. The effects of frequency and degree of viscoelasticity were also studied. Perturbation equations were developed with first order approximations by relating the dispersion curve slopes to sensitivity. Among the guiding layers investigated, Parylene C showed the highest sensitivity followed by gold, chrome and silicon dioxide. The perturbation investigations were also extended to protein layers for immunosensing applications. It was observed that viscous behavior resulted in slightly higher sensitivity, and protein layers showed almost identical sensitivity similar to polymers investigated (SU-8, Parylene, etc.). The optimum configuration is found to be Parylene-C guiding layer on a ST-cut quartz substrate for protein layer sensing and this configuration has 40 times the sensitivity of gold guiding layer on quartz substrate. Our results indicate that chrome and silicon dioxide have low sensitivity when used as guiding layers. Also, lithium tantalate substrate with gold and Parylene-C guiding layers results in ∼10% lower sensitivity as compared to quartz substrate.

MEMS based normally closed silicon microregulator for gas and water

19 November 2013, 09:42:19

Publication date: 1 January 2014
Source:Sensors and Actuators A: Physical, Volume 205
Author(s): B. Pramanick , S. Das , T.K. Bhattacharyya
This paper presents the design, fabrication and performance evaluation of a normally closed piezoelectrically actuated silicon microregulator. The microregulator is realized using two wafers process and is designed for the maximum operating pressure 5bar and it is found to be leak proof (1×10⁻⁴ sccm of helium gas).This paper also reports the development of precision fixturing, assembling and testing of the valve. One of the potential areas for application of microregulators is in satellite propulsion using ion thrusters. Ion thrusters require feed systems with very precise propellant gas flow rate and it makes microregulator a suitable candidate. Another application of the microregulator is liquid propellant flow control in micropropulsion. The water flow measurement of the same microregulator is discussed here. The hysteresis measurement of the silicon membrane using inductive probe and the cyclic test of the microregulator are also described here.

A novel compliant micropositioning stage with dual ranges and resolutions

19 November 2013, 09:42:19

Publication date: 1 January 2014
Source:Sensors and Actuators A: Physical, Volume 205
Author(s): Qingsong Xu
Dual-range stages are demanded in precision positioning applications that call for fine resolution in a smaller motion range and coarse resolution in a larger range. Traditional dual-range stages are realized using two actuators, which complicates the mechanism and control design procedures. This paper presents the design and testing of a novel dual-range, dual-resolution precision positioning stage driven by a single linear actuator. The stage structure is devised with leaf flexures to achieve a large stroke. Strain sensors are employed to provide different resolutions in the two motion ranges. To quantify the design of the motion ranges and fine/coarse resolution ratio, analytical models are established and verified through finite element analysis simulations. A proof-of-concept prototype is fabricated for experimental investigations and the experimental results validate the effectiveness of the proposed design. The reported ideas can also be extended to the design of multi-axis micropositioning stages.

Design and analysis of a 2D broadband vibration energy harvester for wireless sensors

19 November 2013, 09:42:19

Publication date: 1 January 2014
Source:Sensors and Actuators A: Physical, Volume 205
Author(s): Jin Yang , Xihai Yue , Yumei Wen , Ping Li , Qiangmo Yu , Xiaoling Bai
This paper presents a design for a novel vibration energy harvester using a magnetoelectric (ME) transducer, which is efficiently applicable in two-dimensional (2D) motion and over a range of vibration frequencies. This harvester adopts a circular cross-section cantilever rod to extract the ambient vibration energy because of its ability to host accelerations in arbitrary motion directions. Moreover, the magnetic interactions between the magnets and the ME transducer will lead to the nonlinear oscillation of the rod with increased frequency bandwidth. The influences of the nonlinear vibration factor and magnetic field distribution on the electrical output and bandwidth of the harvester are investigated to achieve optimal vibration energy harvesting performances. The experimental results showed that, the harvester was sensitive to the vibration with arbitrary in-plane directions. With an acceleration of 0.6g (where g =9.8ms⁻²), it had the working bandwidths of 4.2Hz, 2.6Hz, 2.3Hz, 2.5Hz and 3.2Hz, and the output powers of 0.6mW, 0.49mW, 0.33mW, 0.5mW and 0.56mW at the in-plane excitation angles of−90°, −45°, 0°, 45° and 90°, respectively.

Design and evaluation of a skin-like sensor with high stretchability for contact pressure measurement

19 November 2013, 09:42:19

Publication date: 15 December 2013
Source:Sensors and Actuators A: Physical, Volume 204
Author(s): Debao Zhou , Haopeng Wang
This paper presents the development of a new type of skin-like tactile pressure sensor array. The sensor array is scalable, flexible and stretchable and can measure pressure up to 250kPa within 30% stretching rate without damaging its mechanical structure. It can also conform to irregular three-dimensional surfaces. The sensor array consists of three layers. The top and bottom layers are formed by the array of parallel conductive strips made of silver nanowires (AgNWs) embedded in polydimethylsiloxane (PDMS) thin films. The AgNWs/PDMS conductor strips are used as stretchable interconnections to transmit electrical signals. The middle layer is made of PDMS. This film is pre-molded with holes filling with cylinder-shaped conductive elastomer for pressure measurement. In this paper, the characteristic of the AgNWs/PDMS conductor strips as stretchable interconnections is studied. The piezoresistive properties of the sensels (one sensing element is called a sensel) were measured and discussed. The performance of the tactile sensor array under stretching was also tested. With the associated scanning power-supply circuit and data acquisition system, it is demonstrated that the system can successfully capture the tactile images induced by objects of different shapes. Such sensor system could be applied on curved or non-planar surfaces in robots or medical devices for force detection and feedback.

Improvement of the off-diagonal magnetoimpedance sensor white noise

19 November 2013, 09:42:19

Publication date: 15 December 2013
Source:Sensors and Actuators A: Physical, Volume 204
Author(s): M. Malatek , B. Dufay , S. Saez , C. Dolabdjian
This work deals with the analysis of noise sources of the off-diagonal magneto-impedance sensor with stress-annealed amorphous ribbon. This experimental analysis shows that the equivalent magnetic noise spectral density is mostly due to the electronic conditioning circuitry that operates the sensor. The electronic noise was then reduced with employment of an improved excitation-detection technique for our sensor and an equivalent magnetic noise spectral density below 1 pT / Hz in white noise region has been reached. Indeed, the equivalent magnetic white noise level of the output signal decreased from 5 pT / Hz to 560 fT / Hz . Nevertheless, this noise level is still limited by the electronic conditioning, leaving room for further improvement.

Laser-unzipped carbon nanotube based glucose sensor for separated structure of enzyme modified field effect transistor

19 November 2013, 09:42:19

Publication date: 15 December 2013
Source:Sensors and Actuators A: Physical, Volume 204
Author(s): Wan-Lin Tsai , Yun-Shan Chien , Po-Yu Yang , I-Che Lee , Kuang-Yu Wang , Huang-Chung Cheng
A glucose sensing film composed of unzipped multiwalled carbon nanotubes (MWCNTs) via continuous-wave laser irradiation is investigated. Some structural defects decorate on MWCNTs after an acid treatment, and the MWCNTs are unzipped into sheet-shaped layers initiated from these defects after the laser irradiation. The laser-irradiated carbon nanotube thin films (CNTFs) possess higher conductance owing to larger contact area, and the side edges of unzipped CNTs could act as sensing sites for hydrogen ions. Thus the laser-irradiated CNTF as a glucose sensing film could achieve a higher sensitivity of 0.302mV(mg/dl)⁻¹, equal to 7.55mV(mg/dl)⁻¹ per centimeter square, and a larger linearity of 0.9947 than the as-sprayed one. Moreover, the fully low-temperature processes of this work also reveal the potentials for flexible and disposable biosensors.

Highly enhanced piezoelectric properties of PLZT/PVDF composite by tailoring the ceramic Curie temperature, particle size and volume fraction

19 November 2013, 09:42:19

Publication date: 15 December 2013
Source:Sensors and Actuators A: Physical, Volume 204
Author(s): Peng Han , Shengli Pang , Jingbo Fan , Xiangqian Shen , Tiezheng Pan
Piezoelectric oxides Pb1−x La x (Zr y Ti1−y )1−x/4O3 (PLZT) were synthesized by the solid-state reaction process and Pb0.96La0.04(Zr0.54Ti0.46)0.99O3/polyvinylidene fluoride (PL0.04ZT/PVDF), Pb0.92La0.07(Zr0.555Ti0.445)0.9825O3/PVDF (PL0.07ZT/PVDF) composites with various particle sizes and contents (50–90vol.%) of the ceramic phase were prepared by the hot-press process. The Curie temperature (T c ) of PLZT decreases monotonously from 312°C to 98°C with La content (x) increasing from 0.02 to 0.09. The polarizability of PLZT/PVDF composites increases from 39.5% (PL0.04ZT/PVDF) to 56.7% (PL0.07ZT/PVDF) when poled at 125°C (at the vicinity of T c of PL0.07ZT). As a result, the electrical property improvement with d 33 (ɛ r ) from 53pC/N (159) to 76pC/N (222) proves that tailoring T c of the piezoelectric ceramic to the poling temperature is a useful way to enhance the piezoelectric and dielectric properties of the ceramic/polymer composite. To further investigate the electrical properties of the 0–3 type PLZT/PVDF composite, the particle size and volume fraction of PLZT are also optimized.

Nanometer scale active ground motion isolator

19 November 2013, 09:42:19

Publication date: 15 December 2013
Source:Sensors and Actuators A: Physical, Volume 204
Author(s): R. Le Breton , G. Deleglise , J. Allibe , A. Badel , G. Balik , B. Caron , A. Jeremie , J. Lottin , S. Vilalte
Vibration isolation is a critical issue in various precision engineering fields. A new design of an active isolation system operating heavy loads (up to 50kg) is presented in this work. This system provides state of the art vibration isolation at the nanometer scale for magnets of a future particle accelerator and is more compact than other studies in this field. The choice of sensors and actuators, the mechanical design and the acquisition electronics are investigated in order to reject ground motion efficiently. A dynamic experimental characterization is performed. Based on the identified model, a specific controller, giving an attenuation between 10Hz and 100Hz was designed and experimentally qualified.

Development of an auto-calibrated interfacing circuit for thick film multi-gas sensor

19 November 2013, 09:42:19

Publication date: 15 December 2013
Source:Sensors and Actuators A: Physical, Volume 204
Author(s): R. Khakpour , M.N. Hamidon , G.A.E. Vandenbosch
A simple, cheap, and integrated architecture is introduced to measure gases with a thick film gas sensor. The temperatures of the sensors are stabilized by controlling the heaters of the sensors. The heaters’ temperatures are measured by sampling the heaters resistance through the use of a voltage divider and ADCs. A microcontroller accordingly adjusts the output of DACs in order to apply the appropriate steering voltage to the heaters. The method employed to measure the gases is to sample the voltage drop over the resistances of the sensors, which are depending on the gases, by ADCs. The innovation lies in the simplicity of the design and the use of different simple methods and commercially available technologies to fabricate the circuit. Also, a single microcontroller is used to drive and control the heaters’ temperature, to compensate ambient temperature of the heaters, to measure and monitor the amount of gases detected by sensors and finally, to select the sensors. This opens the possibility to use these gas sensors for monitoring purposes at a large scale, for example in alarms and computers.

Development of piezoelectric coaxial filament sensors P(VDF-TrFE)/copper for textile structure instrumentation

19 November 2013, 09:42:19

Publication date: 15 December 2013
Source:Sensors and Actuators A: Physical, Volume 204
Author(s): M.B. Kechiche , F. Bauer , O. Harzallah , J.-Y. Drean
Coaxial filaments based on Poly (vinylidene fluoride-co-trifluoroethylene) and copper filament was developed, their mechanical properties characterized. They were then instrumented in textile structure and their detection capabilities were observed. P(VDF-TrFE)/copper coaxial filaments were obtained by a melt spinning process, the mechanical drawing applied at the end of spinning process enabled the increasing of the crystalline β phase from 43% for the copolymer in pellet shape to 52% for the developed coaxial filament of 250μm in diameter. Coaxial filaments surfaces and sections have been analyzed with a scanning electron microscope. The mechanical properties have been quantified by tensile analyses. Coaxial filaments were polarized by the ISL process in order to correlate the level of the polarization with the piezoelectric activity. The textile instrumentation was tested by the integration of some samples in the weft direction of a weaving structure using an industrial weaving machine (Muller NCE 10). An example of electrical signal delivered by integrated filament in textile when subjected to strain and stress actions is shown.

A multi-frequency vibration-based MEMS electromagnetic energy harvesting device

19 November 2013, 09:42:19

Publication date: 15 December 2013
Source:Sensors and Actuators A: Physical, Volume 204
Author(s): Huicong Liu , You Qian , Chengkuo Lee
A multi-frequency vibration-based MEMS electromagnetic energy harvesting (EH) device has been presented, fabricated and characterized in this paper. It consists of a permanent magnet and a circular suspension structure on a MEMS EH chip. By emulating the magnetic field of a cylinder magnet, the gap distance between the magnet and EH chip is optimized to be zero for achieving larger magnetic flux change and higher output performance. From the experimental results, the vibration energy can be harvested at three excitation frequencies of 840, 1070 and 1490Hz, which corresponds to the out-of-plane (mode I), torsion (mode II/III) and in-plane (mode IV/V) vibrations of the EH device, respectively. The maximum power densities at these three frequencies are 0.157, 0.014 and 0.117μW/cm³, respectively, for a matched load resistance of 626Ω and an input acceleration of 1.0g. The feasibility study results show promising application potentials for harvesting energy from vibrations of multi-frequency.

Starter Kit for SPE Sample Preparation

2013-11-19T09:45:00.001+00:00

Porvair Sciences has announced the Microlute SPE sample preparation starter kit.

This kit contains everything needed to begin productive SPE sample preparation in a 96 well plate format, including two development filter plates and a popular C18 sorbent filter plate, 2ml collection plates, disposable waste trays and, most importantly, the Microlute Acrylic Vacuum Manifold.

The new starter kit offers all the advantages of SPE sample preparation in a convenient microplate format, capable of rapidly processing 96 samples in one run, repeatedly and precisely. All that is required for full operation is a suitable laboratory vacuum connection or pump.

Handling samples as small as 150µl - the Microlute™ SPE starter kit helps to increase analytical sensitivity by providing pre-injection clean-up and concentration. Two ‘Development Microlute’ plates in the kit are pre-loaded with eight different sorbents to aid method development. Once the most suitable sorbent has been identified, whole plates containing the chosen material can be ordered for use with the Microlute system. Standard 2ml sample collection plates are supplied, but dedicated plates with well volumes of 350 ul and 1ml may also be used to optimally match your sample preparation requirements. The supplied disposable polycarbonate waste trays simplify waste solvent handling during sample clean up.

Constructed from a single piece of moulded ultra-pure polypropylene, the Microlute™ plate will not bend or distort, unlike individual SPE cartridges which have to be repeatedly plugged in and out. Using a proprietary technique, Porvair has eliminated the channelling effects that often limit the performance of SPE columns. Each well on a Microlute™ plate has an individual drain spout ensuring 100% sample transfer and zero crossover contamination. To recover dried or concentrated sample the Microlute™ SPE sample preparation starter kit may be coupled to a Porvair MiniVap sample concentrator.

For further information please visit www.porvair-sciences.com/en/services-menu/solid-phase-extraction/spe-starter-pack/ or contact Porvair Sciences on +44-1978-666240 / int.sales@porvair-sciences.com.

Just Published: Microchemical Journal

2013-11-18T10:35:00.000+00:00

A new issue of this journal has just been published. To see abstracts of the papers it contains (with links through to the full papers) click here:

Microchemical Journal
http://rss.sciencedirect.com/publication/science/6599

Selected papers from the latest issue:

Laboratory controlled study of the uptake and release of vanadium by oysters (Crassostrea virginica)

17 November 2013, 20:10:18

Publication date: March 2014
Source:Microchemical Journal, Volume 113
Author(s): Joel C. Richert , Carey J. Hardaway , Joseph Sneddon
Preliminary investigation of the uptake and removal of vanadium by oysters in a controlled laboratory environment showed that this occurs although the extent was difficult to quantify due to losses attributed to possible precipitation and the oyster shells impacting on the results. Nevertheless results did indicate that oysters can be affected (uptake) but can also purge (remove) vanadium in solution.

Classification of edible vegetable oil using digital image and pattern recognition techniques

17 November 2013, 20:10:18

Publication date: March 2014
Source:Microchemical Journal, Volume 113
Author(s): Karla Danielle Tavares Melo Milanez , Márcio José Coelho Pontes
This work presents a simple and non-expensive method based on digital image and pattern recognition techniques for the classification of edible vegetable oils with respect to the type (soybean, canola, sunflower and corn) and the conservation state (expired and non-expired shelf life). For this purpose, vegetable oil sample images were obtained from a webcam and the frequency distribution of color indexes in the red–green–blue (RGB), hue (H), saturation (S), intensity (I), and grayscale channels were obtained. Linear discriminant analysis (LDA) was employed in order to build classification models on the basis of a reduced subset of variables. For the purpose of variable selection, two techniques were utilized, namely the successive projection algorithm (SPA) and stepwise (SW) formulation. For the study evolving the classification with respect to oil type, LDA/SPA and LDA/SW models achieved a correct classification rate (CCR) of 95% and 90% respectively. For the identification of expired and non-expired samples, LDA/SPA models were found to be the best method for classifying sunflower, soybean and canola oils, achieving a CCR in the overall data set of 97%, 94% and 93%, respectively, while the LDA/SW correctly classified at 100% for corn oil data. These results suggest that the proposed method is a promising alternative for the inspection of authenticity and the conservation state of edible vegetable oils. As advantages, the method does not use reagents to carry out the analysis and laborious procedures for chemical characterization of the samples are not required.

Determination of reduced glutathione, cystein and total thiols in pine pollen powder by in situ derivatization

17 November 2013, 20:10:18

Publication date: January 2014
Source:Microchemical Journal, Volume 112
Author(s): Xiao-Yong Zhang , Yu-Lian Piao , Sheng-Yun Cui , Yong-Ill Lee
Glutathione (GSH), cystein (CySH) and total thiols in pine pollen powder were determined by spectrometric, fluorometric and high performance liquid chromatographic (HPLC) assays utilizing 5,5′-dithio-bis(2-nitrobenzoic acid) (DTNB, Ellman's reagent) and o-phthaldehyde (OPA) as derivatizing agents. The pollen samples were extracted with phosphate buffer solutions (PBS) containing excess derivatizing agents concomitant with ultrasonic cell rupture. In this way, thiol groups in the samples could be effectively blocked by in situ formation of relatively stable derivatizing products just after the pollen cell ruptured, thereby effectively preventing thiol groups from oxidation during sample preparation and making it possible to perform sensitive and accurate detections. Using a precolumn derivatization method, DTNB, GSH and CySH, as well as other thiol compounds can be determined or estimated by the HPLC method. Total thiols in the samples were determined by the spectrometric method using DTNB as the derivatizing agent. GSH was also selectively determined by the fluorometric method using OPA as the derivatizing agent. The detection results indicated that abundant thiol compounds, such as GSH, CySH and thiol protein, existed in pine pollen powder with measured amounts of 0.50–0.53μmol∙g⁻¹ of GSH, 0.41μmol∙g⁻¹ of CySH and 4.15μmol∙g⁻¹ of total thiols.

Flow injection hydride generation for on-atomizer trapping: Highly sensitive determination of cadmium by tungsten coil atomic absorption spectrometry

17 November 2013, 20:10:18

Publication date: January 2014
Source:Microchemical Journal, Volume 112
Author(s): Piaopiao Chen , Yujia Deng , Kuncheng Guo , Xiaoming Jiang , Chengbin Zheng , Xiandeng Hou
Here we report the use of the tungsten-coil atomizer of a portable atomic absorption spectrometer as an on-atomizer trapping device and atomizer for the determination of trace cadmium, with flow injection hydride generation for production of volatile cadmium species from sample solutions. By mixing acidic analyte solution with tetrahydroborate solution, volatile cadmium species is produced and separated from the solution, and then transported and impacted onto the surface of the atomizer with a heating current set at 2.3A. Subsequent atomic absorption measurement was accomplished with in situ atomization at 8.5A. Compared to conventional direct injection, the sensitivity and the limit of detection were improved by 58- and 66-fold, respectively, based on 5.0mL sampling volume. In addition, use of flow injection significantly improved sample throughput. The proposed method was used for the analysis of several real water samples with good spiked recoveries.

Emerging issues on degradation by-products deriving from personal care products and pharmaceuticals during disinfection processes of water used in swimming pools

17 November 2013, 20:10:18

Publication date: January 2014
Source:Microchemical Journal, Volume 112
Author(s): Paola Bottoni , Lucia Bonadonna , Mattea Chirico , Sergio Caroli , Gyula Záray
The use of disinfection substances in the sanitation and disinfection processes of artificial water used for sports amenities and swimming pools has recently raised some serious concerns. Recreational Water Illnesses (RWIs) can put at serious risk the health of bathers and swimmers due to adverse effects caused by the use of disinfection chemicals, such as chlorine, chloramine, ozone and UV radiation, as well as their by-products. Remarkable documented evidence is available on the impact of Disinfection By-Products (DBPs), such as chloroform and other trihalomethanes, haloacetic acids and chlorophenols, deriving from the oxidation of common organic pollutants dissolved in raw, drinking, waste and artificial waters. Appropriate countermeasures, aimed at avoiding bathers' exposures to these chemicals, have been developed and adopted in public and private structures, also through important scientific contributions and technical provisions issued by the WHO and some national health authorities. On the other hand, it has been demonstrated that high reactive disinfection agents may transform other undesirable chemicals released by bathers, namely pharmaceuticals, sunscreens and other Pharmaceuticals and Personal Care Products (PPCPs) into chlorinated and oxidized compounds and nitrosamine precursors. The first symptoms of potentially adverse health effects on human subjects of these largely unknown by-products should be adequately taken into consideration and investigated.

Single-step procedure for trace element determination in synovial fluid by dynamic reaction cell-inductively coupled plasma mass spectrometry

17 November 2013, 20:10:1

Publication date: January 2014
Source:Microchemical Journal, Volume 112
Author(s): Franco Moyano , Ernesto Verni , Héctor Tamashiro , Silvia Digenaro , Luis D. Martinez , Raúl A. Gil
A fast and single-step procedure for the dissolution of human synovial fluid in formic acid and further determination by dynamic reaction cell-inductively coupled plasma mass spectrometry (DRC-ICPMS) with a high-efficiency sample introduction system was developed. The samples were collected, treated and analyzed in the same screw-capped tubes. In order to overcome the effect of considerable carbon content, the sample introduction, nebulization and ICP operating conditions were carefully optimized. Furthermore, DRC technology with CH4 as reaction gas was used for the elimination of spectral interferences due to polyatomic ions. The effect of the sample matrix was evaluated and mitigated through comparison of direct calibration against aqueous standards, direct calibration in formic acid media and analyte addition calibration. The recommended procedure involved low dilution and low detection limits (from 0.003μgL⁻¹ for U to 13.3μgL⁻¹ for Ti) with adequate precision (from 0.6% for Co to 6.6% for Ti). The proposed method was successfully applied to determine 16 trace elements in concentrations from 0.03μgL⁻¹ (Cd) to 88.2μgL⁻¹ (Cu) in human synovial fluid samples.

Modeling of second-order spectrophotometric data generated by a pH-gradient flow injection technique for the determination of doxorubicin in human plasma

17 November 2013, 20:10:18

Publication date: January 2014
Source:Microchemical Journal, Volume 112
Author(s): Mirta R. Alcaráz , Agustina V. Schenone , María J. Culzoni , Héctor C. Goicoechea
In this paper, the development of a pH-gradient flow-injection method with diode-array spectrophotometric detection combined with extended multivariate curve resolution–alternating least-squares (MCR–ALS) to quantitate doxorubicin in the presence of rifampicin in plasma samples is presented. Quantitation of doxorubicin was based on acid–base and spectral differences between its species and those for the interference. Overlapped profiles among the analyte and the interference were mathematically solved by data modeling with the well-known extended MCR–ALS algorithm. The method, which involves a simple sample pretreatment consisting in the addition of trichloroacetic acid followed by centrifugation, was applied to resolve validation mixtures composed of human plasma spiked with doxorubicin. Acceptable analytical figures of merit were obtained, i.e. recoveries from 96 to 107%, coefficients of variation between 0.2% and 7.8%, and limits of detection and quantification of 0.77 and 2.32μgL⁻¹, respectively.

Graphical abstract

Effects of UV-dechloramination of swimming pool water on the formation of disinfection by-products: A lab-scale study

17 November 2013, 20:10:18

Publication date: January 2014
Source:Microchemical Journal, Volume 112
Author(s): Nicolas Cimetiere , Joseph De Laat
UV dechloramination has become a very popular process for reducing the concentration of chloramines in public swimming pool water. As the effects of this process on the formation of disinfection by-products (DBPs) remain a controversial issue, a bench-scale study has been undertaken to examine the impact of UV dechloramination on the formation of various DBPs. Four pool water samples were exposed to UV radiation at 254nm in the presence of free chlorine ([Cl2]0 =3mgL⁻¹) and then chlorinated in the dark for 24h ([Cl2]0 =3mgL⁻¹). High UV doses (up to 47kJm⁻²) were used to simulate cumulative UV doses received by real pool waters. The data showed that UV irradiation led to a 90% photodecay of free chlorine for UV doses ranging from 13 to 20kJm⁻², to the formation of chlorate ion (0.05–0.11mol of chlorate/mole of free chlorine decomposed) and to a significant increase in the chlorine demand of pool water during the post-chlorination step. UV exposure followed by post-chlorination did not significantly affect the formation of haloacetic acids, led to a small increase in the concentrations of adsorbable organic halogen (AOX) and of chloral hydrate and markedly increased the formation of trihalomethanes (chloroform, bromodichloromethane, chlorodibromomethane), dichloroacetonitrile, 1,1,1-trichloropropanone and chloropicrin.

Preconcentration of toxic elements in artificial saliva extract of different smokeless tobacco products by dual-cloud point extraction

17 November 2013, 20:10:18

Publication date: January 2014
Source:Microchemical Journal, Volume 112
Author(s): Sadaf Sadia Arain , Tasneem Gul Kazi , Jamshed Bashir Arain , Hassan Imran Afridi , Kapil Dev Brahman , Naeemullah
Smokeless tobacco (SLT) has been associated with oral cancer. In present study, the total and artificial saliva extracted toxic elements (TEs), arsenic (As), cadmium (Cd), nickel (Ni) and lead (Pb) were estimated in SLT products (gutkha, green and brown snuff). Dual-cloud point extraction has been used for the preconcentration of As, Cd, Ni and Pb in artificial saliva extract, using complexing reagent, ammonium pyrrolidinedithiocarbamate. The dual-cloud point extraction procedure was based on forming complexes of elemental ions with complexing reagent and subsequent entrapping of the complexes in nonionic surfactant. Then the surfactant rich phase containing the complexes was treated with nitric acid, and detected ions were back extracted again into aqueous phase at the second cloud point extraction stage, and finally determined by electrothermal atomic absorption spectrometry. The validity of methodology was tested by simultaneously analyzing certified reference material and spike recovery test. The experimental enhancement factors of As, Cd, Ni and Pb were found to be 52, 58, 48 and 44, respectively. The concentration of As, Cd, Ni and Pb in artificial saliva extracts corresponds to 18–24, 45–75, 30–55, and 20–30%, respectively, of the total contents of TE in different types of SLT products (gutkha, brown and green snuff). It was estimated that 10g intake of SLT products (gutkha, brown and green snuff) could contribute 2.2–13, 21–69, 3.4–48 and 10–75% of the provisional maximum tolerable daily intake of As, Cd, Ni and Pb, respectively for adults ~60kg.

Determination of aluminum in botanical samples by adsorptive cathodic stripping voltammetry as Al-8-hydroxyquinoline complex

17 November 2013, 20:10:18

Publication date: January 2014
Source:Microchemical Journal, Volume 112
Author(s): Lídia B. Santos , Maisa T.F. de Souza , Alexandre T. Paulino , Edivaldo E. Garcia , Eurica M. Nogami , Juliana C. Garcia , Nilson E. de Souza
A fast and sensitive new procedure for the determination of total aluminum by adsorptive cathodic stripping voltammetry (AdCSV) in plant samples consumed for dietary and/or medicinal purposes was described. The Al(III)-8-hydroxyquinoline (Al-8HQ) complex was adsorbed on a hanging mercury dropping electrode (HMDE) at 0.300V versus Ag/AgCl electrode during a 30s accumulation time. An electrochemical cell containing 0.024molL⁻¹ ammonia–ammonium acetate buffer (pH6.80) as supporting electrolyte and 7.43mgL⁻¹ 8-hydroxyquinoline (8-HQ) as ligand for aluminum were employed. A linear response was observed over the 8.54×10⁻⁸ to 2.35×10⁻⁷ molL⁻¹ range with a limit of detection (LOD) of 8.54×10⁻⁸ molL⁻¹ and a relative standard deviation (RSD; n=3) of 1.86% for 8.54×10⁻⁸ molL⁻¹ aluminum solution. Aluminum contents in green tea (Camellia sinensis), carqueja (Baccharis genistelloides), cascara sagrada (Rhamnus purshiana) and senna (Cassia acutifolia) were 502.5±14.1, 195.6±21.0, 309.1±11.7, 205.6±16.1μg aluminum per g of dry tea, respectively. The accuracy of the developed method was evaluated by flame atomic absorption spectrometry (FAAS) and all of the results were similar. It indicates that AdCSV could be efficiently applied in the determination of aluminum as 8-HQ complex in real food samples.

Arsenic metabolites in human serum and urine after seafood (Anemonia sulcata) consumption and bioaccessibility assessment using liquid chromatography coupled to inorganic and organic mass spectrometry

17 November 2013, 20:10:18

Publication date: January 2014
Source:Microchemical Journal, Volume 112
Author(s): M. Contreras-Acuña , T. García-Barrera , M.A. García-Sevillano , J.L. Gómez-Ariza
The present paper reports for the first time the bioaccessibility of arsenic species in Anemonia sulcata and its metabolization in the human body after the ingestion of this seafood, a delicacy highly appreciated in the south of Spain. Speciation in tissue extracts and human fluids was carried out by anion/cation exchange chromatography with inductively coupled plasma mass spectrometry ((IC)-ICP-MS). Results obtained show that about 54% of the arsenic present in the anemones is lost after cooking, around 95% of total arsenic in cooked anemones is bioaccessible and 85% of the amount ingested is eliminated from the body by urine in 90h. The relative abundance of As in urine varies along the time, but after the first 10h follows the order arsenobetaine (AB)≈DMA^V (dimethylarsinate)>arsenocholine (AsC)>tetra-methyl-arsonium (TETRA)>trimethyl-arsine oxide (TMAO)>MA^V (monomethylarsonate)>iAs^V >dimethylarsenoethanol (DMAE), while the major species in cooked anemones is AB followed by DMA^V >dimethylmonothioarsinic acid (DMAS^V)>AsC>TETRA>TMAO>iAs^V >glycerylphosphorylarsenocholine(GPAsC)>MA^V >DMA. After 30min from the ingestion, DMA^V is the most abundant in human serum, followed by AB, MA^V and AsC. Finally, the use of organic mass spectrometry allowed the standardless identification of AsC, GPAsC, DMAS^V and DMAE.

Legionella spp. survival after different disinfection procedures: Comparison between conventional culture, qPCR and EMA–qPCR

17 November 2013, 20:10:18

Publication date: January 2014
Source:Microchemical Journal, Volume 112
Author(s): A. Mansi , I. Amori , I. Marchesi , A.M. Marcelloni , A.R. Proietto , G. Ferranti , V. Magini , F. Valeriani , P. Borella
The development of rapid and sensitive methods for the detection and quantification of Legionella viable cells is essential for monitoring water quality and preventing legionellosis. The aim of this study was to verify the applicability of a quantitative PCR (qPCR) method used in combination with ethidium monoazide (EMA) to the quantification of Legionella spp. in samples collected from swimming pools, water recirculation systems and hot water systems in two fitness clubs. This molecular technique (EMA–qPCR) allows the amplification of target DNA from culturable and viable cells, but prevents the amplification of DNA from non-viable cells. The effectiveness of this new method able to detect alive legionellae was also compared with conventional qPCR and culture method. Our results confirm that EMA–qPCR allows to discriminate the non-viable cells from those viable and that it is particularly indicated for monitoring the effectiveness of thermal treatments for the Legionella contamination control in water environments, also providing information about the presence of Viable But Non-Culturable (VBNC) cells. Other Gram-negative bacteria typically associated with biofilm were identified in samples taken from swimming pools and balance tanks, suggesting that also the presence of biofilm should be monitored for a more general view of water contamination.

The molecular enrichment approach for the identification of microbiological indicators in recreational waters

17 November 2013, 20:10:18

Publication date: January 2014
Source:Microchemical Journal, Volume 112
Author(s): F. Valeriani , S. Giampaoli , V. Romano Spica
The identification of rapid methods for the surveillance of recreational waters and aquatic environments is necessary to provide adequate levels of health safety and quality standards. Molecular techniques have been proposed in recent years as a valuable alternative to traditional microbiological cultural methods, having numerous advantages (speed, specificity and sensibility). We have previously described a method for the detection of Staphylococcus aureus in recreational waters by a molecular enrichment approach, based on a two steps PCR performed on 23S rDNA. The approach has been now expanded to other microbiological indicators, Enterococcus faecalis, Pseudomonas aeruginosa, Escherichia coli. This methodological extension to other prokaryotic genomes has required a partial primer re-design and protocol optimization, in order to improve the assay. The usage of native not recombinant Taq-polymerases for detection of E. coli eliminated the background probably due to traces of the bacterial genome in many commercially available reagents. The obtained results clearly underline the feasibility of a fast and integrated molecular approach to quantify the standard biological indicators for assessment of safety and quality in recreational waters.

Identification of starch and determination of its botanical source in ancient manuscripts by MEKC–DAD and LDA

17 November 2013, 20:10:18

Publication date: January 2014
Source:Microchemical Journal, Volume 112
Author(s): M.E. Castillo-Valdivia , A. López-Montes , T. Espejo , J.L. Vílchez , R. Blanc
A simple and rapid Micellar Electrokinetic Capillary Chromatography method with UV diode-array detection (MEKC–DAD) has been developed for the identification of the two starch polysaccharides, amylopectin and amylose, in ancient manuscripts. Moreover, a linear discriminant analysis (LDA) has been used in order to determine the botanical source of the starch (wheat, maize or rice). The reason to develop this method is that starch has been used throughout history in paper manufacture as glue and sizing agent. The LDA was applied to the amylopectin/amylose ratio using the area and height data recorded. The separation was performed in an extended path-length fused-silica capillary (‘bubble capillary’) of 36cm in length and 50μm i.d.. The running buffer was composed of 20mM sodium acetate, 1.2mM I2, 7.2mM KI, and 50mM sodium dodecyl sulphate (SDS) at pH6. The potential applied was 22kV in positive polarity, the temperature was 25°C, and the detection was performed at 560nm. Injection of the samples was performed at 20mbar for 2s. An artificial ageing test was carried out in the three types of starch in order to determine the effect of the temperature, relative humidity and irradiance on this compound. The procedure was performed in an ageing chamber according to the ISO 5630-3:1996 and 11341:2004 standards. The methods were applied to samples from manuscripts preserved in the Historic Archive of the University of Granada and the Royal Chancellery Archive of Granada (Spain).

CALL FOR NOMINATIONS:

2013-11-15T16:42:00.000+00:00

2014 Chemometrics and Intelligent Laboratory Systems Award

The 2014 Chemometrics and Intelligent Laboratory Systems Award will be presented in 2014 to a chemometrician, not older than 40 years of age, who has contributed significantly to the development of chemometrics in the last 5 years. This prestigious award was established to stimulate the careers of young scientists by recognizing noteworthy accomplishments in the field. This is the sixth time that this award is given and it will be delivered during the celebration of the Chemometrics in Analytical Chemistry meeting (in Richmond, VA USA, 9-13 June, 2014, See: http://www.cac2014.vcu.edu)

The winner chosen by a selected committee of leading international scientists

in the field of chemometrics, will receive 2000 Eu, and a framed certificate. The

awardee is selected by the committee based mainly on one or more outstanding

scientific papers, but contributions to the field of chemometrics in another form will

also be considered.

There are no restrictions of nationality or professional affiliation. The application deadline for the 2014 award is March 1st 2014. Nominations can be made by sending a nomination letter and a complete résumé of the nominee to the Chemometrics Committee by e-mail: chemometrics@elsevier.com

Romà Tauler, Editor in Chief Chemometrics and Intelligent Laboratory Systems

Beata Walczak, Editor Chemometrics and Intelligent Laboratory Systems

Phil Hopke, Editor Chemometrics and Intelligent Laboratory Systems

Yizeng Liang, Editor Chemometrics and Intelligent Laboratory Systems

Lutgarde Buydens, Editor Analytica Chimica Acta

Sarah Rutan, CAC 2014 Organizing Committee Chair

Dave Sleeman, Publishing Editor Elsevier

Just Published: Journal of Pharmaceutical and Biomedical Analysis

2013-11-14T09:40:00.002+00:00

A new issue of this journal has just been published. To see abstracts of the papers it contains (with links through to the full papers) click here:

Journal of Pharmaceutical and Biomedical Analysis
http://rss.sciencedirect.com/publication/science/5266

Selected papers from the latest issue:

Improving the efficiency of quantitative 1H NMR: An innovative external standard–internal reference approach

13 November 2013, 23:32:30

Publication date: 25 January 2014
Source:Journal of Pharmaceutical and Biomedical Analysis, Volume 88
Author(s): Yande Huang , Bao-Ning Su , Qingmei Ye , Venkatapuram A. Palaniswamy , Mark S. Bolgar , Thomas V. Raglione
The classical internal standard quantitative NMR (qNMR) method determines the purity of an analyte by the determination of a solution containing the analyte and a standard. Therefore, the standard must meet the requirements of chemical compatibility and lack of resonance interference with the analyte as well as a known purity. The identification of such a standard can be time consuming and must be repeated for each analyte. In contrast, the external standard qNMR method utilizes a standard with a known purity to calibrate the NMR instrument. The external standard and the analyte are measured separately, thereby eliminating the matter of chemical compatibility and resonance interference between the standard and the analyte. However, the instrumental factors, including the quality of NMR tubes, must be kept the same. Any deviations will compromise the accuracy of the results. An innovative qNMR method reported herein utilizes an internal reference substance along with an external standard to assume the role of the standard used in the traditional internal standard qNMR method. In this new method, the internal reference substance must only be chemically compatible and be free of resonance-interference with the analyte or external standard whereas the external standard must only be of a known purity. The exact purity or concentration of the internal reference substance is not required as long as the same quantity is added to the external standard and the analyte. The new method reduces the burden of searching for an appropriate standard for each analyte significantly. Therefore the efficiency of the qNMR purity assay increases while the precision of the internal standard method is retained.

Graphical abstract

Combined HPLC-DAD–MS, HPLC–MSn and NMR spectroscopy for quality control of plant extracts: The case of a commercial blend sold as dietary supplement

13 November 2013, 23:32:30

Publication date: 25 January 2014
Source:Journal of Pharmaceutical and Biomedical Analysis, Volume 88
Author(s): A. Karioti , E. Giocaliere , C. Guccione , G. Pieraccini , E. Gallo , A. Vannacci , A.R. Bilia
The efficiency of 1D and 2D NMR spectroscopy along with HPLC-DAD–MS analyses in characterising the content of a dietary supplement is demonstrated. Experiments directly performed on a lyophilised sample of a commercial product gave details on the quality control of the product. The lack of the marker constituents of some of the declared plant species (Crataegus oxyacantha, Olea europea, Capsella bursa-pastoris and Fumaria officinalis) and the presence of banned adulterants, responsible for the strong antihypertensive effect of the supplement were established. The analyses proved the presence of indole alkaloids belonging to the group of Rauwolfia sp., such as ajmaline, reserpine and yohimbine. Quantitative HPLC analysis showed that the content of reserpine in the product was in the therapeutic range and therefore responsible for the collapses of the patients.

Graphical abstract

Determination of pKa values of a triptolide derivative and its impurities by pressure-assisted capillary electrophoresis

13 November 2013, 23:32:30

Publication date: 25 January 2014
Source:Journal of Pharmaceutical and Biomedical Analysis, Volume 88
Author(s): Jian-Ling Wang , Xue-Jiao Xu , Dong-Ying Chen
A pressure-assisted capillary zone electrophoresis method was developed to determine the pK a values of a triptolide derivative (LLDT-246) and its impurities. The method was performed in an uncoated fused-silica capillary under the electric voltage of 18kV and 50mbar of external pressure applied simultaneously. A series of running electrolyte buffers were used with pH ranging between 2.2 and 10.0 with the constant ionic strength of 0.05M. The values of pK a of LLDT-246 and two impurities were calculated based on the pH dependence of effective mobilities (μ eff). The pK a value of LLDT-246 was in good agreement with that of determined by potentiometric titration method.

Improved detection of variants in recombinant human interferon alpha-2a products by reverse-phase high-performance liquid chromatography on a core–shell stationary phase

13 November 2013, 23:32:30

Publication date: 25 January 2014
Source:Journal of Pharmaceutical and Biomedical Analysis, Volume 88
Author(s): Yonghong Li , Chunming Rao , Lei Tao , Junzhi Wang , Barry Lorbetskie , Michel Girard
The detection of variants is one of the important aspects in quality control of recombinant DNA drugs. In this study, a gradient reverse-phase high-performance liquid chromatography (RP-HPLC) method with fluorescence detection is described for the separation of interferon alpha-2a (rhIFN α-2a) from several product related variants. The methodology employed a core–shell C18 column with a linear gradient elution of 0.2% (v/v) trifluoroacetic acid (TFA)-acetonitrile (ACN) at 1.0mL/min, and the temperature of the column was maintained at 60°C. The method was validated in terms of linearity, sensitivity, intra- and inter-day variations. Compared to the European Pharmacopeia RP-HPLC method of rhIFN α-2a analysis, this new method can separate N-methionylated variant in both drug substance and finished product, and analyze the variants in untreated, oxidized sample and slightly degraded samples more efficiently. In conclusion the method has an improved capability to detect variants in rhIFN α-2a products.

Graphical abstract

A novel sample preparation and on-line HPLC–DAD–MS/MS–BCD analysis for rapid screening and characterization of specific enzyme inhibitors in herbal extracts: Case study of α-glucosidase

13 November 2013, 23:32:30

Publication date: 25 January 2014
Source:Journal of Pharmaceutical and Biomedical Analysis, Volume 88
Author(s): D.Q. Li , J. Zhao , J. Xie , S.P. Li
Drug discovery from complex mixture like Chinese herbs is a challenge and extensive false positives make the obtainment of specific bioactive compounds difficult. In the present study, a novel sample preparation method was proposed to rapidly reveal the specific bioactive compounds from complex mixtures using α-glucosidase as a case. Firstly, aqueous and methanol extracts of 500 traditional Chinese medicines were carried out with the aim of finding new sources of α-glucosidase inhibitors. As a result, the extracts of fruit of Terminalia chebula (FTC), flowers of Rosa rugosa (FRR) and Eugenia caryophyllata (FEC) as well as husk of Punica granatum (HPG) showed high inhibition on α-glucosidase. On-line liquid chromatography–diode array detection–tandem mass spectrometry and biochemical detection (HPLC–DAD–MS/MS–BCD) was performed to rapidly screen and characterize α-glucosidase inhibitors in these four extracts. After tentative identification, most of compounds with inhibitory activity in the investigated crude extracts were found to be tannins commonly recognized as non-specific enzyme inhibitors in vitro. Subsequently, the four extracts were treated with gelatin to improve specificity of the on-line system. Finally, two compounds with specific α-glucosidase inhibition were identified as corilagin and ellagic acid. The developed method could discover specific α-glucosidase inhibitors in complex mixtures such as plant extracts, which could also be used for discovery of specific inhibitors of other enzymes.

Graphical abstract

Screening for multiple weight loss and related drugs in dietary supplement materials by flow injection tandem mass spectrometry and their confirmation by liquid chromatography tandem mass spectrometry

13 November 2013, 23:32:30

Publication date: 25 January 2014
Source:Journal of Pharmaceutical and Biomedical Analysis, Volume 88
Author(s): Fenhong Song , Douglas Monroe , Aref El-Demerdash , Cynthia Palmer
A new method has been developed using flow injection tandem mass spectrometry to semi-quantitatively screen for weight loss drugs, including sibutramine, N-desmethylsibutramine, N-didesmethylsibutramine, and phenolphthalein in dietary supplements. Positive identification of these drugs in samples was further confirmed and quantified by liquid chromatography tandem mass spectrometry. The degradation products of sibutramine were observed and identified by LC–MS/MS which include N-desmethylsibutramine, N-didesmethylsibutramine, N-formyldesmethylsibutramine, and N-formyldidesmethylsibutramine.

Graphical abstract

Phase quantification of antihypertensive drugs – Chlorthalidone, Hydrochlorothiazide, Losartan and combinations, Losartan/Chlorthalidone and Losartan/Hydrochlorothiazide – by the Rietveld method

13 November 2013, 23:32:30

Publication date: 25 January 2014
Source:Journal of Pharmaceutical and Biomedical Analysis, Volume 88
Author(s): Weberton Reis do Carmo , Fabio Furlan Ferreira , Renata Diniz
The identification and quantification of crystalline phases of antihypertensive drugs – Losartan potassium (LOS-K), Hydrochlorothiazide (HCTZ) and Chlorthalidone (CTD) were carried out by means of X-ray powder diffraction data and the Rietveld method. Quantitative phase analyses of Losartan potassium/Chlorthalidone (LOS-K/CTD) and Losartan potassium/Hydrochlorothiazide (LOS-K/HCTZ) combinations were also evaluated. The results indicated that for diuretics (HCTZ and CTD) only one crystalline phase was found in samples, and for LOS-K the crystal structure showed similarity between the Bragg peaks to the phase described as monoclinic and space group P21/c. After one year storage, the orthorhombic one was also observed in this sample.

Graphical abstract

Comparison of (bio-)transformation methods for the generation of metabolite-like compound libraries of p38α MAP kinase inhibitors using high-resolution screening

13 November 2013, 23:32:30

Publication date: 25 January 2014
Source:Journal of Pharmaceutical and Biomedical Analysis, Volume 88
Author(s): David Falck , Fatie Rahimi Pirkolachachi , Martin Giera , Maarten Honing , Jeroen Kool , Wilfried M.A. Niessen
Four hydrophobic p38α mitogen-activated protein kinase inhibitors were refluxed with 7.5% hydrogen peroxide at 80°C and irradiated with visible light in order to generate more hydrophilic conversion products. The resulting mixtures were analyzed in a high-resolution screening (HRS) platform, featuring liquid chromatographic separation coupled in parallel with a fluorescence enhancement based continuous-flow affinity bioassay towards the p38α mitogen-activated protein kinase and with high-resolution (tandem) mass spectrometry on an ion-trap-time-of-flight hybrid instrument. The results were compared with similar data where chemical diversity was achieved by means of electrochemical conversion or incubation with either human liver microsomes or cytochrome P450s from Bacillus megaterium (BM3s). In total, more than 50 conversion products were identified. The metabolite-like compound libraries studied are discussed in terms of the reactions enabled, the retention of affinity, and the change in hydrophilicity by modification, in summary the ability to generate bioactive, more hydrophilic potential lead compounds. In this context, HRS is demonstrated to be an effective tool as it reduces the effort directed towards laborious synthesis and purification schemes.

Graphical abstract

Quantitative determination of phenolic compounds by UHPLC-UV–MS and use of partial least-square discriminant analysis to differentiate chemo-types of Chamomile/Chrysanthemum flower heads

13 November 2013, 23:32:30

Publication date: 25 January 2014
Source:Journal of Pharmaceutical and Biomedical Analysis, Volume 88
Author(s): Bharathi Avula , Yan-Hong Wang , Mei Wang , Cristina Avonto , Jianping Zhao , Troy J. Smillie , Diego Rua , Ikhlas A. Khan
A new rapid UHPLC-UV-QTOF/MS method has been developed for the simultaneous analysis of nine phenolic compounds [(Z)-2-β-d-glucopyranosyloxy-4-methoxycinnamic acid (cis-GMCA), chlorogenic acid, (E)-2-β-d-glucopyranosyloxy-4-methoxycinnamic acid (trans-GMCA), quercetagetin-7-O-β-d-glucopyranoside, luteolin-7-O-β-d-glucoside, apigenin-7-O-β-d-glucoside, chamaemeloside, apigenin 7-O-(6″-O-acetyl-β-d-glucopyranoside), apigenin] and one polyacetylene (tonghaosu) from the flower heads of Chamomile/Chrysanthemum samples. The chromatographic separation was achieved using a reversed phase C18 column with a mobile phase of water and acetonitrile, both containing 0.05% formic acid. The ten compounds were completely separated within 15min at a flow rate of 0.25mL/min with a 2μL injection volume. The different chemo-types of Chamomiles/Chrysanthemum displayed variations in the presence of chemical constituents. German Chamomile samples confirmed the presence of cis-GMCA, trans-GMCA, apigenin-7-O-β-d-glucoside and tonghaosu as major constituents whereas Roman chamomile samples confirmed the presence of chamamaeloside and apigenin as major compounds. The Chrysanthemum morifolium samples showed the presence of luteolin-7-O-β-d-glucose as the major compound. The method was applied for the analysis of various commercial products including capsules, tea bags, body and hair care products. LC-mass spectrometry with electrospray ionization (ESI) interface method is described for the evaluation of ten compounds in plant samples and commercial products. This method involved the detection of [M+Na]⁺ and [M+H]⁺ ions in the positive mode. Partial least squares discriminant analysis (PLS-DA) was used to visualize commercial samples quality and may be of value for discriminating between chamomile types and Chrysanthemum with regards to the relative content of individual constituents. The results indicated that the method is suitable as a quality control test for various Chamomile/Chrysanthemum samples and market products.

Graphical abstract

Batch-to-batch reproducibility of Transferon™

13 November 2013, 23:32:30

Publication date: 25 January 2014
Source:Journal of Pharmaceutical and Biomedical Analysis, Volume 88
Author(s): Emilio Medina-Rivero , Giovanna Merchand-Reyes , Lenin Pavón , Said Vázquez-Leyva , Gilberto Pérez-Sánchez , Nohemí Salinas-Jazmín , Sergio Estrada-Parra , Marco Velasco-Velázquez , Sonia Mayra Pérez-Tapia
Human dialyzable leukocyte extracts (DLEs) are heterogeneous mixtures of low-molecular-weight peptides that modulate immune responses in various diseases. Due their complexity, standardized methods to identify their physicochemical properties and determine that production batches are biologically active must be established. We aimed to develop and validate a size exclusion ultra performance chromatographic (SE-UPLC) method to characterize Transferon™, a DLE that is produced under good manufacturing practices (GMPs). We analyzed an internal human DLE standard and 10 representative batches of Transferon™, all of which had a chromatographic profile characterized by 8 main peaks and a molecular weight range between 17.0 and 0.2kDa. There was high homogeneity between batches with regard to retention times and area percentages, varying by less than 0.2% and 30%, respectively, and the control chart was within 3 standard deviations. To analyze the biological activity of the batches, we studied the ability of Transferon™ to stimulate IFN-γ production in vitro. Transferon™ consistently induced IFN-γ production in Jurkat cells, demonstrating that this method can be included as a quality control step in releasing Transferon™ batches. Because all analyzed batches complied with the quality attributes that were evaluated, we conclude that the DLE Transferon™ is produced with high homogeneity.

Graphical abstract

Easy Concentration of Large Sample Volumes

2013-11-14T09:38:00.000+00:00

SampleGenie 3 is the latest version of Genevac’s unique SampleGenie technology.

SampleGenie 3 technology used in conjunction with the Genevac ROCKET Evaporator enables large sample volumes to be dried directly into vials, eliminating a number of time consuming sample handling steps and the attendant risk of errors. The new third generation SampleGenie enhances the exceptional capabilities of this unique sample concentration methodology through improved ease of use, enhanced evaporation performance and reduced operational costs.

Traditionally protocols for concentration of chromatographic fractions has involved drying multiple fractions in an evaporator, re-suspending pooled fractions into a single vial and then re-drying before storage and analysis. Even with modern centrifugal evaporators such processes typically take 2-3 days to complete. The development of SampleGenie™ technology has been shown to enable samples in Genevac evaporators to be concentrated, without loss of volatile components, directly into a single GC or HPLC vial eliminating the need for reformatting of samples after drying. This, and the automation offered by Genevac evaporators simplifies the protocol to a single overnight drying step before storage and analysis. Not only does SampleGenie remove time consuming manual steps - it lowers labour costs and improves data reliability.

For further information about SampleGenie 3 please visit www.evaporatorinfo.com/info13_e.html or contact Genevac on +44-1473-240000 / +1-845-687-5000 / email salesinfo@genevac.co.uk

Just Published: Journal of Chromatography B

2013-11-13T09:44:00.001+00:00

A new issue of this journal has just been published. To see abstracts of the papers it contains (with links through to the full papers) click here:

Journal of Chromatography B
http://rss.sciencedirect.com/publication/science/7220

Selected papers from the latest issue:

Determination of trichothecenes A (T-2 toxin, HT-2 toxin, and diacetoxyscirpenol) in the tissues of broilers using liquid chromatography coupled to tandem mass spectrometry

13 November 2013, 09:24:38

Publication date: 30 December 2013
Source:Journal of Chromatography B, Volumes 942–943
Author(s): Lingchen Yang , Zhiyong Zhao , Aibo Wu , Yifeng Deng , Zhenlei Zhou , Jianpeng Zhang , Jiafa Hou
A stable and sensitive method has been developed for use in food and livestock product safety for the detection of mycotoxins. This newly developed method allows for the determination of T-2 toxin, HT-2 toxin and diacetoxyscirpenol (DAS) in heart, liver, spleen, lung, kidney, Glandular stomach, muscular stomach, small intestine, muscle, bone and brain samples from broilers using liquid chromatography coupled to tandem mass spectrometry (LC–MS/MS). The samples were initially extracted with ethyl acetate before being filtered through a 0.22μm nylon syringe filter and subjected to chromatographic separation on a reversed-phase C18 (50×2.1mm, 3μm) column. A mobile phase composed of 0.1% acetic acid and 10mM ammonium acetate in methanol and water was used in an assay of the levels of T-2 toxin, HT-2 toxin and DAS. For the analysis of the target compounds, the mass spectrometer was operated under positive electrospray ionization conditions in the selected reaction monitoring mode. The limit of detection was in the range of 0.02–0.05ng/g, whereas the limit of quantification was in the range of 0.08–0.15ng/g. The extraction recoveries of spiked samples from the high, intermediate and low levels ranged from 58.5% to 110.5%, and the relative standard deviation (RSD (%)) values were less than 17.0%. The results of inter- and intra-day precision (RSD (%)) were within 14.7%. The results revealed that the present method could be successfully applied to the analysis of T-2 toxin, HT-2 toxin and DAS in the real samples

Pharmacokinetics, tissue distribution and excretion study of dictamnine, a major bioactive component from the root bark of Dictamnus dasycarpus Turcz. (Rutaceae)

13 November 2013, 09:24:38

Publication date: 30 December 2013
Source:Journal of Chromatography B, Volumes 942–943
Author(s): Pei Wang , Jianbo Sun , Jingyao Xu , Qin Yan , Enze Gao , Wei Qu , Yunli Zhao , Zhiguo Yu
Dictamnine is an herbal ingredient isolated from the root bark of Dictamnus dasycarpus Turcz. (Rutaceae). The present study was aimed at the development of an ultra-high performance liquid chromatography–tandem mass spectrometry method to quantify the concentration of dictamnine in rat plasma and tissues for the in vivo pharmacokinetics, tissue distribution and excretion study. Biological samples were processed with protein precipitation. Skimmianine was chosen as internal standard. The chromatographic separation was carried out on a Thermo Syncronis C18 column (2.1mm×50mm, 1.7μm) with an isocratic mobile phase consisting of methanol and 0.1% formic acid water (75:25, v/v). The detection was accomplished by using positive ion electrospray ionization in multiple reaction monitoring (MRM) mode. The MS/MS ion transitions were monitored at m/z 200.0→129.0 for dictamnine and 260.3→227.1 for IS, respectively. An excellent linearity was observed over the concentration range from 0.5 to 250ng/mL. The lower limit of quantification (LLOQ) was 0.5ng/mL for dictamnine. The developed method was rapid, accurate, and highly sensitive and selective. It was successfully applied to the in vivo pharmacokinetics, tissue distribution and excretion study of dictamnine in rats after oral or intravenous administration of dictamnine.

Novel superparamagnetic sanoparticles for trypsin immobilization and the application for efficient proteolysis

13 November 2013, 09:24:38

Publication date: 30 December 2013
Source:Journal of Chromatography B, Volumes 942–943
Author(s): Jun Sun , Kunya Hu , Yuntao Liu , Yuting Pan , Yanjun Yang
Immobilization of trypsin onto the superparamagnetic carboxymethyl chitosan (Fe3O4 (PEG+CM-CTS)) nanoparticles was studied. FTIR and fluorescence spectroscopy data demonstrated that the Fe3O4 (PEG+CM-CTS) nanoparticles were capable of preventing the trypsin unfolding. Due to the large specific surface area and excellent dispersibility, the adsorption equilibrium of trypsin onto the nanoparticles was achieved quickly within 30min. The results of kinetic parameters (Michaelis constant, Km) with regards to the free trypsin (FT) and immobilized trypsin (IT) were 23.1 and 24.1mg/mL separately, implying that IT has less affinity to the BAEE used as the substrate. However, the MALDI-TOF MS analysis indicated that, IT could be used for fast and efficient Bovine Serum Albumin (BSA) digestion under very facile processes, thanks to the easy manipulation of the magnetic nanoparticles (MNs), as well as the greatly reduced digestion time (from 12h to 15min). IT exhibited a sound stability after re-uses for six times, with 76.3% of the initial activity thereof still retained, thus making it more attractive in the application fields. These results are expected to open up a great potential use of such Fe3O4 (PEG+CM-CTS) nanoparticles as a superior nanosupport for trypsin immobilization.

Simple segmental hair analysis for α-pyrrolidinophenone-type designer drugs by MonoSpin extraction for evaluation of abuse history

13 November 2013, 09:24:38

Publication date: 30 December 2013
Source:Journal of Chromatography B, Volumes 942–943
Author(s): Akira Namera , Kyohei Konuma , Takeshi Saito , Shigenori Ota , Hiroshi Oikawa , Shota Miyazaki , Shumari Urabe , Hiroaki Shiraishi , Masataka Nagao
For detection of a history of drug abused, we developed a simple method for extracting pyrrolidinophenone-type designer drugs in human hair by using a MonoSpin^® C18 column. Target drugs were extracted from a single alkaline-digested hair segment (length, 10mm; weight, ca 0.1mg). The analytes extracted were then analyzed by high-performance liquid chromatography–mass spectrometry without evaporation of the eluent after MonoSpin extraction. Linearity from 0.5 to 500ng/mg was observed for all the tested drugs using an internal standard method (correlation coefficients >0.998) and the limit of detection was 0.2ng/mg. The recoveries were between 0.7 and 11.1%. The coefficients for intraday and interday variations at 4, 40, 200, and 400ng/mg in hair were between 0.7 and 11.1%. This method was successfully applied to the identification of these designer drugs in segmented human hair from drug abusers and indicated their history of drug abuse. The results were consistent with the patients’ statements, indicating that this rapid method can be used to detect a history of drug abuse.

Capillary electrophoresis–mass spectrometry for direct determination of urinary modified nucleosides. Evaluation of synthetic urine as a surrogate matrix for quantitative analysis

13 November 2013, 09:24:38

Publication date: 30 December 2013
Source:Journal of Chromatography B, Volumes 942–943
Author(s): Encarnación Rodríguez-Gonzalo , Raquel Hernández-Prieto , Diego García-Gómez , Rita Carabias-Martínez
This work describes the development of a fast and reliable method based on capillary zone electrophoresis coupled with electrospray ionization–mass spectrometry (CZE–ESI–MS) for the determination of modified nucleosides in untreated human urine. The target compounds were guanine, 1-methyl-guanine, 7-methyl-guanine, 9-methyl-guanine, adenosine, 1-methyl-adenosine, cytidine, guanosine, 7-methyl-guanosine. As internal standards, ribose-2-¹³C-adenosine and 8-¹³C-guanine were used. The CZE separation was carried out in acidic medium (pH 2.5). MS detection with a single quadrupole, with ESI operating in positive-ion mode, was optimized. For the analysis of urine samples, owing to the endogenous character of these analytes different quantification strategies were explored. The standard additions method, matrix-matched calibration in synthetic urine and calibration in pure aqueous medium were compared in order to evaluate the endogenous levels of these compounds in human urine. The results obtained showed that calibration in synthetic urine as a surrogate matrix was an appropriate alternative to the method of standard additions for the accurate quantitation of compounds such as guanine, 1-methyl-guanine, 7-methyl-guanine, adenosine, 1-methyl-adenosine and cytidine by CE–ESI–MS directly in the urine matrix; values in the range 0.1μg/mL for cytidine and 6.4μg/mL for 7mGua, as the lowest and the highest level, were found in untreated urine from healthy volunteers. These results were confirmed by LC–MS/MS detection. It can be concluded that the electrophoretic CZE–ESI–MS methodology offers a valid and reliable alternative for the determination of urinary nucleosides at naturally occurring levels in healthy individuals.

A simple sample preparation approach based on hydrophilic solid-phase extraction coupled with liquid chromatography–tandem mass spectrometry for determination of endogenous cytokinins

13 November 2013, 09:24:38

Publication date: 30 December 2013
Source:Journal of Chromatography B, Volumes 942–943
Author(s): Bao-Dong Cai , Jiu-Xia Zhu , Zhi-Guo Shi , Bi-Feng Yuan , Yu-Qi Feng
Cytokinins (CKs), a vital family of phytohormones, play important roles in the regulation of shoot and root development. However, the quantification of CKs in plant samples is frequently affected by the complex plant matrix. In the current study, we developed a simple, rapid and efficient hydrophilic interaction chromatography-solid phase extraction (HILIC–SPE) method for CKs purification. CKs were extracted by acetonitrile (ACN) followed by HILIC–SPE (silica as sorbents) purification. The extraction solution of plant samples could be directly applied to HILIC–SPE without solvent evaporation step, which simplified the analysis process. Moreover, with HILIC chromatographic retention mechanism, the hydrophobic co-extracted impurities were efficiently removed. Subsequently, CKs were separated by RPLC, orthogonal to the HILIC pretreatment process, and detected by tandem mass spectrometry. The method exhibits high specificity and recovery yield (>77.0%). Good linearities were obtained for all eight CKs ranging from 0.002 to 100ngmL⁻¹ with correlation coefficients (r) higher than 0.9927. The limits of detection (LODs, signal/noise=5) for the CKs were between 1.0 and 12.4pgmL⁻¹. Reproducibility of the method was evaluated by intra-day and inter-day measurements and the results showed that relative standard deviations (RSDs) were less than 10.5%. Employing this method, we successfully quantified six CKs in 20mg Oryza sativa leaves and the method was also successfully applied to Brassica napus (flower and leaves).

Activity-guided identification of acetogenins as novel lipophilic antioxidants present in avocado pulp (Persea americana)

13 November 2013, 09:24:38

Publication date: 30 December 2013
Source:Journal of Chromatography B, Volumes 942–943
Author(s): Dariana Rodríguez-Sánchez , Christian Silva-Platas , Rocío P. Rojo , Noemí García , Luis Cisneros-Zevallos , Gerardo García-Rivas , Carmen Hernández-Brenes
Avocado fruit is a rich source of health-related lipophilic phytochemicals such as monounsaturated fatty acids, tocopherols, carotenes, acetogenins and sterols. However, limited information is available on the contribution of specific phytochemicals to the overall antioxidant capacity (AOC) of the fruit. Centrifugal partition chromatography was used as fractionation tool, guided by an in vitro chemical assay of oxygen radical absorbance capacity (ORAC). Subsequent experiments focused on isolation and characterization of the chemical nature of the main contributors to lipophilic AOC of avocado pulp. ORAC values obtained for acetogenins were contrasted with results from an isolated kidney mitochondria membrane lipid peroxidation bioassay. The present study established that lipophilic AOC of the pulp was significantly higher than its hydrophilic AOC. Our results confirmed the presence of acetogenins in the fractions with highest lipophilic AOC, and for the first time linked them as contributors to lipophilic-ORAC values. Further HPLC-PDA/MS-TOF analysis led to structural elucidation of two novel acetogenins, not previously reported as present in avocado pulp, along with five already known related-compounds. Antioxidant properties observed for avocado pulp acetogenins by the ORAC assay suggested that, in the presence of an emulsifying agent, acetogenins could serve as novel lipophilic antioxidants in a food matrix. Results from isolated mitochondria lipid peroxidation bioassay, indicated that L-ORAC values which may have relevance for food matrix applications, should not be interpreted to have a direct relevance in health-related claims, compounds need to be evaluated considering the complexity of biological systems.

Simultaneous determination of eight illegal dyes in chili products by liquid chromatography–tandem mass spectrometry

13 November 2013, 09:24:38

Publication date: 30 December 2013
Source:Journal of Chromatography B, Volumes 942–943
Author(s): Juan Li , Xiao-Ming Ding , Dan-Dan Liu , Fei Guo , Yu Chen , Yan-Bing Zhang , Hong-Min Liu
A sensitive and accurate method based on the use of liquid chromatography–tandem mass spectrometry (LC–MS/MS) was developed for the simultaneous determination of eight illegal synthetic dyes (Sudan (I–IV), Para Red, Rhodamine B, Chrysoidin and Auramine O) in chili products. A simple sample treatment procedure entailing the use of an extraction step with acetonitrile/H2O (9/1) without further cleanup was developed. HPLC was performed on a C18 column using a multistep gradient elution with 5mM ammonium acetate (pH 3.0 with formic acid) and methanol as the mobile phase. Mass spectral acquisition was done in multiple reaction monitoring (MRM) mode using positive electrospray ionization (ESI). Linear calibrations were obtained with correlation coefficients R ² >0.99. Limit of detection (LOD) and limit of quantification (LOQ) for the studied dyes were in the ranges of 0.05–0.6μgkg⁻¹ and 0.3–3.0μgkg⁻¹ depending on matrices, respectively. The recoveries of the eight synthetic dyes in five matrices ranged from 70.5% to 119.2%. The intra- and inter-day precisions (RSDs) were between 2.3–15.8% and 5.7–15.6%, respectively. The applicability of the method to the determination of eight banned dyes in chili products was demonstrated.

The profile of bile acids and their sulfate metabolites in human urine and serum

13 November 2013, 09:24:38

Publication date: 30 December 2013
Source:Journal of Chromatography B, Volumes 942–943
Author(s): Sai Praneeth R. Bathena , Sandeep Mukherjee , Marco Olivera , Yazen Alnouti
The role of sulfation in ameliorating the hepatotoxicity of bile acids (BAs) in humans remains unknown due to the lack of proper analytical methods to quantify individual BAs and their sulfate metabolites in biological tissues and fluids. To this end, a simple and sensitive liquid chromatography–tandem mass spectrometry (LC–MS/MS) method was developed and validated to characterize the detailed BA profile in human urine and serum. The limit of quantification was 1ng/mL and baseline separation of all analytes was achieved within in a run time of 32min. The method was validated over the dynamic range of 1–1000ng/mL. The LC–MS/MS method was more accurate, precise, and selective than the commercially available kits for the quantification of sulfated and unsulfated BAs, and the indirect quantification of individual sulfated BAs after solvolysis. The LC–MS/MS method was applied to characterize the BA profile in urine and serum of healthy subjects. Thirty three percent of serum BAs were sulfated, whereas 89% of urinary BAs existed in the sulfate form, indicating the role of sulfation in enhancing the urinary excretion of BAs. The percentage of sulfation of individual BAs increased with the decrease in the number of hydroxyl groups indicating the role of sulfation in the detoxification of the more hydrophobic and toxic BA species. Eighty percent of urinary BAs and 55% of serum BAs were present in the glycine-amidated form, whereas 8% of urinary BAs and 13% of serum BAs existed in the taurine-amidated form.

Simultaneous detection of 22 toxic plant alkaloids (aconitum alkaloids, solanaceous tropane alkaloids, sophora alkaloids, strychnos alkaloids and colchicine) in human urine and herbal samples using liquid chromatography–tandem mass spectrometry

13 November 2013, 09:24:38

Publication date: 30 December 2013
Source:Journal of Chromatography B, Volumes 942–943
Author(s): Sau Wah Ng , Chor Kwan Ching , Albert Yan Wo Chan , Tony Wing Lai Mak
A liquid chromatography–tandem mass spectrometry method for simultaneous detection of 22 toxic plant alkaloids, including aconitum alkaloids and their hydrolyzed products (aconitine, hypaconitine, mesaconitine, yunaconitine, crassicauline A, benzoylaconine, benzoylmesaconine, benzoylhypaconine, deacetylyunaconitine, deacetylcrassicauline A), solanaceous tropane alkaloids (atropine, anisodamine, scopolamine, anisodine), sophora alkaloids (matrine, sophoridine, oxymatrine, cytisine, N-methylcytisine), strychnos alkaloids (brucine, strychnine) and colchicine, in herbal and urine samples was developed and validated. Following sample preparation by liquid–liquid extraction, chromatographic separation was achieved on Eclipse XDB C8 column. Identification was based on two multiple reaction monitoring transitions and the relative ion intensity. Method selectivity was demonstrated. The limits of detection were 5ng/mL for all analytes, except 50ng/mL for cytisine. The herbal matrix effects ranged from 89% to 118%, whereas the urine matrix effects were between 91% and 109% for all analytes except cytisine (57%) and N-methylcytisine (67%). The urine extraction recovery ranged from 74% to 110% for all analytes, except cytisine (15%) and oxymatrine (30%). With the good extraction efficiency of the other major sophora alkaloids, the relatively low extraction recovery of the minor sophora alkaloids cytisine and oxymatrine did not affect identification of sophora alkaloids as a group. Carry-over was minimal at less than 0.1%. The method was successfully applied in analysis of 170 cases of suspected herbal poisoning, with aconitum alkaloids, sophora alkaloids, solanaceous tropane alkaloids, and strychnos alkaloids being detected in 53, 42, 18, and 6 cases, respectively.

Preclinical pharmacokinetics, tissue distribution and excretion studies of a potential analgesics – corydaline using an ultra performance liquid chromatography–tandem mass spectrometry

13 November 2013, 09:24:38

Publication date: 30 December 2013
Source:Journal of Chromatography B, Volumes 942–943
Author(s): Jianfeng Wang , Lishuang Liang , Qiongyu Zhang , Xingang Li , Zhijian Fu
A rapid resolution ultra performance liquid chromatography (UPLC) coupled with electrospray ionization (ESI) mass spectrometry method was developed and validated for the quantitative analysis of corydaline in rats’ plasma and various tissues for pharmacokinetic, tissue distribution and excretion studies of corydaline. The analytes were separated on an Acquity UPLC BEH C18 column (2.1mm×100mm, 1.7μm) and detected with a triple quadrupole mass spectrometer using positive ion ESI in the multiple reaction monitoring (MRM) mode. The MS/MS ion transitions monitored were m/z 370.0→192.0 for corydaline and 354.1→188.0 for IS, respectively. Calibration curves (1/x ² weighted) offered satisfactory linearity (r ² >0.9984) within 1–1000ng/mL. The accuracy and precision ranged from −7.4% to 8.5% and 3.4% to 12.8%, respectively. The absolute matrix effect (94.2–119.2%), relative matrix effect (1.7–9.6%) and recoveries (81.4–93.7%) were satisfactory in all the biological matrices examined. The assay was successfully applied to the plasma pharmacokinetics, tissue distribution and excretion studies of corydaline in rats. The pharmacokinetic parameters such as half-life (t 1/2), mean residence time (MRT) and maximum concentration (C max) were determined. These preclinical data of corydaline would be useful for the clinical reference.

Pharmacokinetics and tissue distribution of a novel marine fibrinolytic compound in Wistar rat following intravenous administrations

13 November 2013, 09:24:38

Publication date: 30 December 2013
Source:Journal of Chromatography B, Volumes 942–943
Author(s): Tongwei Su , Wenhui Wu , Ting Yan , Chaoyan Zhang , Quangang Zhu , Bin Bao
We investigated a novel marine fibrinolytic compound for use in thrombolytic therapy. Pharmacokinetics and the tissue distribution of this novel marine fibrinolytic compound, FGFC1 ² 2 FGFC1: Fungi fibrinolytic compound 1,2,5-bis-[8-(4,8-dimethyl-nona-3,7-dienyl)-5,7-dihydroxy-8-methyl-3-keto-1,2,7,8-tertahydro-6H-pyran[a]isoindol-2-yl]-pentanoic acid, a novel pyran-isoindolone derivative with bioactivity isolated from marine microorganism in our laboratory. (fungi fibrinolytic compound 1), were investigated in Wistar rats after intravenous (IV) bolus administration of two concentrations (10 and 20mg/kg). Plasma FGFC1 and tissue extracts were measured using HPLC with UV detection. FGFC1 was detected using a C18 column with a gradient eluted mobile phase of acetonitrile–water (0.1% trifluoroacetic acid), 1.0mL/min. Chromatograms were monitored at 265nm (column temperature: 40°C). Pharmacokinetic data indicate that FGFC1 fitted well to a two-compartment model. Elimination half-lives (t 1/2) of FGFC1 were 21.51±2.17 and 23.22±2.11min for 10 and 20mg/kg, respectively. AUC0 - t were 412.19±19.09, 899.09±35.86μg/mLmin, systemic clearance (CL) was 0.023±0.002, 0.022±0.002 ((mg/kg)/(μg/mL)/min) and the mean residence time (MRT) was 10.15±0.97, 9.65±1.40min at 10 and 20mg/kg, respectively. No significant differences were observed in the systemic clearance and mean residence time at the tested doses, suggesting linear pharmacokinetics in rats. Tissue distribution data reveal that FGFC1 distributed rapidly in most tissues except the brain and that the highest concentration of the drug was in the liver. In the small intestine, FGFC1 initially increased and then declined, but remained comparatively high 60min after administration, suggesting that enterohepatic circulation may exist

Determination of naloxone-3-glucuronide in human plasma and urine by HILIC–MS/MS

13 November 2013, 09:24:38

Publication date: 30 December 2013
Source:Journal of Chromatography B, Volumes 942–943
Author(s): Ji Dong , Shuaibing Liu , Hua Zhang , Qianli Hua , Xuegang Zhao , Liyan Miao
A hydrophilic interaction chromatography–tandem mass spectrometric (HILIC–MS/MS) method was developed for the direct determination of naloxone-3-glucuronide (N3G) in human plasma and urine. After a straightforward sample preparation by protein precipitation, N3G was analyzed directly without the need for hydrolysis. Chromatographic separation was performed on a HILIC column. The mobile phase was composed of acetonitrile–10mmol/L ammonium formate (86:14, v/v), with a flow rate of 0.4mL/min. The detection was performed on a triple quadrupole tandem mass spectrometer by multiple reaction monitoring (MRM) mode via positive electrospray ionisation (ESI+) source. The linear calibration range was 0.5 to 200ng/mL in plasma and 10 to 5000ng/mL in urine (r ² >0.99). The intra- and inter-day precision (relative standard deviation, RSD) values were below 15% and the accuracies (relative error, RE) were −7.1% to 2.8% in plasma and −1.3% to 10.3% in urine at three quality control levels. In human subjects receiving 100mg tilidine and 8mg naloxone, mean AUC0–24 of N3G was 160.93±52.77ng/mLh and mean C max was 75.33±25.27ng/mL. In 24-h urine samples, 8.0% of the dose was excreted in the form of N3G in urine. These results demonstrated a new method suitable for in vivo pharmacokinetic studies of N3G.

Analysis of neutral lipids from microalgae by HPLC-ELSD and APCI-MS/MS

13 November 2013, 09:24:38

Publication date: 30 December 2013
Source:Journal of Chromatography B, Volumes 942–943
Author(s): F. Donot , G. Cazals , Z. Gunata , D. Egron , J. Malinge , C. Strub , A. Fontana , S. Schorr-Galindo
A method was developed to analyze neutral lipids through the use of three triglycerides, four free fatty acids, six di- and four mono-glycerides standards by high performance liquid chromatography (HPLC) normal phase coupled with either with evaporative light scattering detector (ELSD) or with mass spectrometry (MS) operating in atmospheric pressure chemical ionization (APCI) mode. The method was applied to the determination of the neutral lipid fraction from a Botryococcus braunii race A (B. braunii) culture. This method led us to identify neutral lipids synthesized by B. braunii in a single analysis within 45min through HPLC–APCI-MS/MS technique.

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2013-11-13T09:41:00.002+00:00

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Just Published: Journal of Chromatography A

2013-11-07T09:34:00.000+00:00

A new issue of this journal has just been published. To see abstracts of the papers it contains (with links through to the full papers) click here:

Journal of Chromatography A

http://rss.sciencedirect.com/publication/science/5248

Selected papers from the latest issue:

High concentration capacity sample preparation techniques to improve the informative potential of two-dimensional comprehensive gas chromatography–mass spectrometry: Application to sensomics

07 November 2013, 09:10:03

Publication date: 29 November 2013
Source:Journal of Chromatography A, Volume 1318
Author(s): Chiara Cordero , Cecilia Cagliero , Erica Liberto , Luca Nicolotti , Patrizia Rubiolo , Barbara Sgorbini , Carlo Bicchi
This study reports and critically discusses the results of a systematic investigation on the effectiveness of different and complementary sampling approaches, based on either sorption and adsorption, treated as a further dimension of a two-dimensional comprehensive gas chromatography–mass spectrometry analytical platform for sensomics. The focus is on the potentials of a group of high concentration capacity (HCC) sample preparation (Solid Phase Microextraction, SPME, Stir Bar Sorptive Extraction, SBSE and Headspace Sorptive Extraction, HSSE) and Dynamic Headspace (D-HS) techniques investigated to provide information useful for fingerprinting and profiling studies of food aroma. Volatiles and semi-volatiles contributing to define whole and nonfat dry milk aroma have been successfully characterized thanks to the combination of effective and selective sampling by HCC and D-HS techniques, high separation and detection power of GC×GC–MS and suitable data elaboration (i.e., Comprehensive Template Matching Fingerprinting – CTMF). Out of the sample preparation techniques investigated, HSSE and SBSE have shown to be really effective for sensomics studies because of their high concentration factors, providing highly representative profiles as well as analyte recovery suitable for GC-Olfactometry even with high odor threshold (OT) markers or potent odorants in sub-trace amounts.

A new strategy to eliminate sample mixing during in-tube solid phase microextraction

07 November 2013, 09:10:03

Publication date: 29 November 2013
Source:Journal of Chromatography A, Volume 1318
Author(s): Yang Yang , Heather Lord , Janusz Pawliszyn
During in-tube solid phase microextraction, sample mixing with mobile phase contained in the autosampler tubing during extraction may result in some amount of sample becoming entrained in the mobile phase rather than returning to the sample vial or being directed to waste after extraction. In cases where target analytes have relatively low affinity for the sorbent on the wall of the capillary, mixing can impact data quality. Where the sample contains components that may interfere with either the separation (e.g. proteins) or detection (e.g. ions with MS detection), additional difficulties can arise. In the current research, the magnitude of the sample mixing effect was illustrated by analyzing ranitidine and a series of polycyclic aromatic hydrocarbons (PAH). The sample volume equivalent of mixing was calculated as 37μL for ranitidine and 20μL for PAHs using the same inner diameter of capillary. To address this issue, a novel approach involving adding a switching valve located between the metering pump and the capillary was developed. Capillary flush conditions, draw/eject speed and extraction time were optimized for ranitidine with the result that in the final method, no mixing of sample with mobile phase was apparent in the detected amounts. To provide information on a compound class with intermediate polarity, two β-blockers were also extracted using the optimized washing conditions respectively. The results indicated that the issue of sample mixing had been resolved for these as well. Finally, in-tube SPME calibration of these three analyte classes was shown to be highly linear, providing further indication that sample mixing was not impacting data quality. Available literature on the subject was surveyed, and a discussion on the rational selection of conditions to guide method development was also provided.

Trace analysis of biocidal oligoguanidines in environmental water samples

07 November 2013, 09:10:03

Publication date: 29 November 2013
Source:Journal of Chromatography A, Volume 1318
Author(s): Tamara Buchberger , Markus Himmelsbach , Wolfgang Buchberger
This paper demonstrates the determination of residues of biocidal oligoguanidines manufactured by polycondensation of guanidine hydrochloride and 2,2′-(ethylenedioxy)bis(ethylamine) in environmental water samples. The analytes were preconcentrated from samples adjusted to pH 4 by solid-phase extraction using a mixed-mode sorbent with weak cation exchange functionalities. Elution from the sorbent was achieved by 2M hydrochloric acid in methanol. After evaporation and reconstitution in water, the extract was analyzed by reversed-phase high performance liquid chromatography combined with quadrupole/time-of-flight or triple quadrupole mass spectrometry employing electrospray ionization. A preconcentration factor of 10,000 could be achieved and detection limits were in the sub-μgL⁻¹ range. This method looks promising to monitor the fate of these biocides released into the aquatic environment during different applications.

Graphene oxide: An adsorbent for the extraction and quantification of aflatoxins in peanuts by high-performance liquid chromatography

07 November 2013, 09:10:03

Publication date: 29 November 2013
Source:Journal of Chromatography A, Volume 1318
Author(s): Li Yu , Peiwu Li , Qi Zhang , Wen Zhang , Xiaoxia Ding , Xiupin Wang
In this paper, graphene oxide (GO) was synthesized and specifically selected by centrifugation to extract four aflatoxins (B1, B2, G1, and G2) as an effective adsorbent. Then, the amount of aflatoxins was quantitatively measured by high-performance liquid chromatography (HPLC). The GO was characterized by X-ray diffraction (XRD), atomic force microscopy (AFM), and ultraviolet (UV) spectrophotometer. Several parameters that could affect the extraction efficiency, including the GO amount, methanol concentration in the extraction solvent, spiked amount, extraction time, and elution cycle, were also investigated and optimized in this work. Under optimal conditions, good linear relationships were achieved with the correlation coefficient (r) ranging from 0.99217 to 0.99995. The detection limit of this method for the four aflatoxins ranged from 0.08 to 0.65ng/g. Finally, the proposed method has been successfully applied to determine aflatoxins in peanut samples. The results show that the recoveries of the four aflatoxins range from 85.1% to 100.8% with the relative standard deviations between 2.1% and 7.9%.

In situ derivatization coupled to microextraction by packed sorbent and gas chromatography for the automated determination of haloacetic acids in chlorinated water

07 November 2013, 09:10:03

Publication date: 29 November 2013
Source:Journal of Chromatography A, Volume 1318
Author(s): Ana María Casas Ferreira , María Esther Fernández Laespada , José Luis Pérez Pavón , Bernardo Moreno Cordero
A novel analytical method is reported for the determination of monochloroacetic acid, dichloroacetic acid, trichloroacetic acid, monobromoacetic acid, and dibromoacetic acid. These are the five haloacetic acids (HAAs) for which the U.S. Environmental Protection Agency (US EPA) has regulated a maximum contamination level (MCL) of 0.060mgL⁻¹ for the sum of their concentrations in drinking waters. The method uses in situ aqueous derivatization, followed by microextraction by packed sorbent (MEPS) prior to gas chromatography–mass spectrometry (GC–MS). The parameters affecting derivatization and extraction were optimized with a view to obtaining maximum sensitivity. The HAAs were derivatized with 2,2,2-trifluroethylamine (TFEA), using N-ethyl-N′-(3-dimethylaminopropyl) carbodiimide (EDC) as a condensation agent. The reaction occurred in aqueous medium and was carried out in 10min in the vial of an autosampler used to perform microextraction by packed sorbent. The whole process, from the mixing of the reagents for the derivatization, was automated. Precision values varied from 4.2 to 9.8% (as intra-day relative standard deviation, RSD) and 9.4 to 14% (as inter-day RSD). The recoveries from spiked concentrations ranged from 83 to 117%, revealing the accuracy of the method. The detection limits ranged from 0.36 to 1.2μgL⁻¹, such that it is possible to measure the US EPA MCL in drinking waters. The method developed was applied to the analysis of HAAs in drinking and swimming pool water from Salamanca (North West of Spain).

In-tube solid-phase microextraction with molecularly imprinted polymer to determine interferon alpha 2a in plasma sample by high performance liquid chromatography

07 November 2013, 09:10:03

Publication date: 29 November 2013
Source:Journal of Chromatography A, Volume 1318
Author(s): Andréa Rodrigues Chaves , Maria Eugênia Costa Queiroz
A molecularly imprinted sol–gel polymer (MIP) based on protein (biopharmaceutical) template with a mild template removal condition using protease was synthetized and evaluated as stationary phase for in-tube solid phase microextraction (in-tube SPME) of the interferon alpha 2a from plasma samples, followed by high performance liquid chromatography analysis with fluorescence detection (HPLC-FD). The developed MIP exhibited high selectivity for the analyte in a complex matrix. The in-tube SPME variables such as draw/eject cycles, draw/eject volume, and desorption conditions were optimized to establish the equilibrium conditions in a short time. The MIP in-tube SPME/HPLC-FD method presented linear response over a dynamic range of 8–300ngmL⁻¹, with a correlation coefficient of 0.997. The inter-assay precision presented coefficient of variation lower than 9.2%, and accuracy values between 92% and 98%. The developed MIP performed as well as other selective interferon alpha 2a stationary phases (e.g., immunosorbent and restricted access material), with the advantage that it is robust, easy to handle and cheap to synthesize, in a addition to requiring smaller sample volume (50μL). Based on the analytical validation results, the proposed method (MIP in-tube SPME/HPLC-FD) can be a useful tool to determine interferon alpha 2a in plasma samples from patients receiving therapeutic dosages.

Stir bar sorptive extraction combined with high performance liquid chromatography-ultraviolet/inductively coupled plasma mass spectrometry for analysis of thyroxine in urine samples

07 November 2013, 09:10:03

Publication date: 29 November 2013
Source:Journal of Chromatography A, Volume 1318
Author(s): Wenying Fan , Xiangju Mao , Man He , Beibei Chen , Bin Hu
In this work, polyethyleneglycol (PEG)/hydroxyl polydimethylsiloxane (OH-PDMS)/γ-mercaptopropyl trimethoxysilane (γ-MPTS) coated stir bar was prepared by sol–gel process and its extraction performance for the extraction of amphoteric thyroxines (3,3′,5,5′-tetraiodothyronin, T4; 3,3′,5-triiodothyronine, T3; reversed-3,3′,5-triiodothyronine, rT3) and their metabolite (3,5-diiodothyronine, T2) was studied. The preparation reproducibility of PEG/OH-PDMS/γ-MPTS coated stir bar was investigated, and the relative standard deviations (RSDs) in the same batch and among different batches were 3.3–14.3% (n =5) and 7.7–16.6% (n =3), respectively. The prepared PEG/OH-PDMS/γ-MPTS coated stir bar could be reused for more than 20 times. Based on this fact, a novel method of stir bar sorptive extraction (SBSE) combined with high performance liquid chromatography (HPLC)-ultraviolet (UV) and HPLC-inductively coupled plasma mass spectrometry (ICP-MS) for the analysis of target thyroxines in human urine samples was developed. The influencing factors of SBSE, such as sample pH, extraction time, stirring rate, salt effect, desorption solution and desorption time, were studied in detail, and the analytical performance of the proposed method was evaluated under the optimized conditions. The enrichment factors (EFs) of the developed method for four target thyroxines were in the range of 14.9–70.4 (theoretical enrichment factor was 100). The RSDs were ranging from 4.0% to 13.8% for SBSE-HPLC-UV (c =25μg/L, n =6) and from 3.7% to 6.1% for SBSE-HPLC-ICP-MS (c =0.5μg/L, n =5). The linear range obtained by SBSE-HPLC-UV was 2–500μg/L for T2 and 5–500μg/L for rT3, T3 and T4, with correlation coefficients (r) ranging from 0.9957 to 0.9998, respectively, while the linear range obtained by SBSE-HPLC-ICP-MS was 0.05–500μg/L for T2 and rT3, 0.10–200μg/L for T3 and 0.05–200μg/L for T4 with r ranging from 0.9979 to 0.9998, respectively. The limits of detection (LODs) for the target thyroxines were 0.60–2.20μg/L for SBSE-HPLC-UV and 0.0071–0.0355μg/L SBSE-HPLC-ICP-MS, respectively. The developed method was applied for the determination of target thyroxines in urine samples, and the recovery for the spiking samples obtained by SBSE-HPLC-UV was in the range of 81.6–137.6% for human urine, while the recovery for the spiking urine samples obtained by SBSE-HPLC-ICP-MS were in the range of 72.0–121.5%.

Grafting the sol–gel based sorbents by diazonium salts: A novel approach toward unbreakable capillary microextraction

07 November 2013, 09:10:03

Publication date: 29 November 2013
Source:Journal of Chromatography A, Volume 1318
Author(s): Habib Bagheri , Parisa Bayat , Hamed Piri-Moghadam
The present work deals with a novel approach for grafting a sol–gel based sorbent, using diazonium salts for preparation of an unbreakable capillary microextraction (CME) device in on-line combination with high performance liquid chromatography (HPLC). The use of diazonium salts modifier allowed all types of metallic and non-metallic substrates to be used without any limitation. Substrates including copper, brass, stainless steel and polytetrafluoroethylene (PTFE) were chosen to be functionalized by chemical or electrochemical reduction of 4-amino phenyl acetic acid. Then, 3-(trimethoxysilyl)propylamine (3TMSPA) was selected as the precursor and the only reagent for preparation of the desired surface chemical bonded sorbent. The presence of chemical bond between substrate, diazonium salts and 3TMSPA is more probably responsible for thermal and solvent stability and long lifetime of the prepared sorbent. Characterization of the aryl group formation on the various substrates along with the prepared sorbents was thoroughly investigated by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR) and thermogravimetry analysis (TGA). Typically, one of the prepared sorbents, deposited on the inner surface of the copper tube, was selected for assessing the developed method. The CME device was used for on-line extraction of atrazine, ametryn and terbutryn, as model compounds, from the aquatic media. After extraction, the HPLC mobile phase was used for on-line desorption and elution of the extracted analytes from the CME loop, containing the grafted sol–gel based sorbent, through the HPLC column. Figures of merit of the developed method were also obtained in which the linearity for the analytes was in the range of 30–1000μgL⁻¹. The value of LOD (S/N=3) for all analytes was 10μgL⁻¹ and the RSD% values (n =5) were all below 9.4% at the 500μgL⁻¹ level. Applicability of the developed method was examined by analyzing some real water samples in which the relative recovery percentage ranged from 75 to 95%.

Semiautomated solid-phase extraction followed by derivatisation and gas chromatography–mass spectrometry for determination of perfluoroalkyl acids in water

07 November 2013, 09:10:03

Publication date: 29 November 2013
Source:Journal of Chromatography A, Volume 1318
Author(s): Beatriz Jurado-Sánchez , Evaristo Ballesteros , Mercedes Gallego
This paper describes a sensitive approach for the determination of 6 perfluoroalkyl carboxylic acids and perfluorooctane sulfonic acid in water. Samples were preconcentrated using an automatic solid-phase extraction module and then manually derivatised and determined by gas chromatography–mass spectrometry. The analytes were derivatised with a isobutyl chloroformate/isobutanol mixture, using 3% N,N-dicyclohexylcarbodiimide in pyridine as the catalyst. From a systematic comparison of several reversed-phase and anion-exchange sorbent materials for the retention of perfluoroalkyl acids, the highest retention efficiencies (∼100%) were achieved with LiChrolut EN and Discovery DSC-SAX columns. LiChrolut EN was the sorbent selected due to several advantages (sample pH ∼1; sample flow rate, 5.5mL/min; breakthrough volume, 300mL) over Discovery DSC-SAX (sample pH ∼6; sample flow rate, 3.0mL/min; breakthrough volume, 45mL), for the retention of the studied compounds. Detection and quantification limits within the range of 0.1–0.5ng/L and 0.4–1.7ng/L, respectively, were obtained for a sorbent column of 70mg of LiChrolut EN and 250mL of sample, the relative standard deviation being lower than 7%. The method was applied both to the analysis of water collected at the intake (raw) and at the exit (treated) of two drinking water treatment plants, as well as to various types of water. Few samples were positive for perfluoroalkyl acids and only one acid (perfluoroheptanoic or perfluorooctanoic) was found in each treatment plant. The highest number and concentration of analytes (perfluoroheptanoic, perfluorooctanoic and perfluorodecanoic acid) were found in one wastewater.

Adsorption of cations onto positively charged surface mesopores

07 November 2013, 09:10:03

Publication date: 29 November 2013
Source:Journal of Chromatography A, Volume 1318
Author(s): Uwe Neue , Pamela Iraneta , Fabrice Gritti , Georges Guiochon
Uwe Neue developed a theoretical treatment to account for the adsorption of ions on mesopores of packing materials the walls of which are bonded to ionic ligands but left this work unfinished. We elaborated upon this treatment and refined it, based on the equivalence that he suggested between charged surface particles and a membrane that separates two ionic solutions but is impermeable to one specification. He had written that the electro-chemical potentials in both ionic solutions are equal (Donnan equilibrium). The equilibrium between the surface and the pore concentrations is accounted for by an homogeneous electrostatically modified Langmuir (EML) isotherm model. The theoretical results are presented for four different charge surface concentrations σ 0 =0, 0.001, 0.002, and 0.003C/m², using a phosphate buffer ( W S pH = 2.65 ) of ionic strength I =10mM. The average pore size, the specific surface area, and the specific pore volume of the stationary phase were D p =140Å, S p =182m²/g, and V p =0.70cm³/g, respectively. The theoretical results provide the quantitative difference between the ionic strength, the pH, and the concentrations of all the ions in the pores and in the bulk eluent. The theory predicts (1) that the retention times of cations under linear conditions is lower and (2) that their band widths under overloaded conditions for a given retention factor shrinks when the surface charge density σ 0 is increased. These theoretical results are in good agreement with experimental results published previously and explain them.

A high-throughput 2D-analytical technique to obtain single protein parameters from complex cell lysates for in silico process development of ion exchange chromatography

07 November 2013, 09:10:03

Publication date: 29 November 2013
Source:Journal of Chromatography A, Volume 1318
Author(s): Frieder Kröner , Dennis Elsäßer , Jürgen Hubbuch
The accelerating growth of the market for biopharmaceutical proteins, the market entry of biosimilars and the growing interest in new, more complex molecules constantly pose new challenges for bioseparation process development. In the presented work we demonstrate the application of a multidimensional, analytical separation approach to obtain the relevant physicochemical parameters of single proteins in a complex mixture for in silico chromatographic process development. A complete cell lysate containing a low titre target protein was first fractionated by multiple linear salt gradient anion exchange chromatography (AEC) with varying gradient length. The collected fractions were subsequently analysed by high-throughput capillary gel electrophoresis (HT-CGE) after being desalted and concentrated. From the obtained data of the 2D-separation the retention-volumes and the concentration of the single proteins were determined. The retention-volumes of the single proteins were used to calculate the related steric-mass action model parameters. In a final evaluation experiment the received parameters were successfully applied to predict the retention behaviour of the single proteins in salt gradient AEC.

Reversed-phase liquid chromatography with octadecylsilyl, immobilized artificial membrane and cholesterol columns in correlation studies with in silico biological descriptors of newly synthesized antiproliferative and analgesic active compounds

07 November 2013, 09:10:03

Publication date: 29 November 2013
Source:Journal of Chromatography A, Volume 1318
Author(s): Małgorzata Janicka , Małgorzata Sztanke , Krzysztof Sztanke
Reversed-phase liquid chromatography (RPLC) with different stationary phases, i.e., octadecylsilyl, immobilized artificial membrane and immobilized cholesterol, was used to study lipophilicity of 56 newly-designed 7,8-dihydroimidazo[2,1-c][1,2,4]triazin-4(6H)-ones and 2,6,7,8-tetrahydroimidazo[2,1-c][1,2,4]triazine-3,4-diones with potential anti-proliferative, anti-metastatic and analgesic activities. Extrapolated retention parameters that correspond to pure buffer as the mobile phase, i.e., log k w values are used as chromatographic lipophilicities. The lipophilic properties of compounds also are characterized by computed log P values and basic pharmacokinetic descriptors calculated in silico with the use of ACD/Percepta software according to Abraham's linear solvation energy relationship. Chromatographic and partitioning parameters are compared with biological descriptors using principal component analysis (PCA), and similarities and dissimilarities between variables and compounds are described. Highly significant, predictive relationships between biological descriptors and chromatographic parameters are obtained. Reversed parabolic relationships, which have very good statistical quality between various biological descriptors, i.e., log K sc , log K p , log BB, and log K hsa , and the log k w values, indicate the advantages of a cholesterol column in comparison with immobilized artificial membrane and octadecylsilyl stationary phase.

Evaluation between ultrahigh pressure liquid chromatography and high-performance liquid chromatography analytical methods for characterizing natural dyestuffs

07 November 2013, 09:10:03

Publication date: 29 November 2013
Source:Journal of Chromatography A, Volume 1318
Author(s): Ana Serrano , Maarten van Bommel , Jessica Hallett
An evaluation was undertaken of ultrahigh pressure liquid chromatography (UHPLC) in comparison to high-performance liquid chromatography (HPLC) for characterizing natural dyes in cultural heritage objects. A new UHPLC method was optimized by testing several analytical parameters adapted from prior UHPLC studies developed in diverse fields of research. Different gradient elution programs were tested on seven UHPLC columns with different dimensions and stationary phase compositions by applying several mobile phases, flow rates, temperatures, and runtimes. The UHPLC method successfully provided more improved data than that achieved by the HPLC method. Indeed, even though carminic acid has shown circa 146% higher resolution with HPLC, UHPLC resulted in an increase of 41–61% resolution and a decrease of 91–422% limit of detection, depending on the dye compound. The optimized method was subsequently assigned to analyse 59 natural reference materials, in which 85 different components were ascribed with different physicochemical properties, in order to create a spectral database for future characterization of dyes in cultural heritage objects. The majority of these reference samples could be successfully distinguished with one single method through the examination of these compounds’ retention times and their spectra acquired with a photodiode array detector. These results demonstrate that UHPLC analyses are extremely valuable for the acquisition of more precise chromatographic information concerning natural dyes with complex mixtures of different and/or closely related physicochemical properties, essential for distinguishing similar species of plants and animals used to colour cultural heritage objects.

Effect of pressure on secondary structure of proteins under ultra high pressure liquid chromatographic conditions

07 November 2013, 09:10:03

Publication date: 29 November 2013
Source:Journal of Chromatography A, Volume 1318
Author(s): Alexey Makarov , Rosario LoBrutto , Paul Karpinski
There are several spectroscopic techniques such as IR and CD, that allow for analyzing protein secondary structure in solution. However, a majority of these techniques require using purified protein, concentrated enough in the solution, to produce a relevant spectrum. Fundamental principles for the usage of reversed-phase ultra high pressure liquid chromatography (UHPLC) as an alternative technique to study protein secondary structures in solution were investigated. Several “model” proteins, as well as several small ionizable and neutral molecules, were used for these studies. The studies were conducted with UHPLC in isocratic mode, using premixed mobile phases at constant flow rate and temperature. The pressure was modified by a backpressure regulator from about 6000psi to about 12,000psi. It was found that when using a mobile phase composition at which proteins were fully denatured (loss of alpha-helix secondary structure), the retention factors of the proteins increased upon pressure increase in the same manner as non-proteins. When using a mobile phase composition in which proteins were not fully denatured, it was observed that the retention factors of the proteins displayed a much steeper (by one order of magnitude) increase in retention upon pressure increase. It was concluded that in a mobile phase in which the protein is not initially fully denatured, the increase of pressure may facilitate the folding back of the protein to its native state (alpha-helix secondary structure). The impact of different mobile phase compositions on the denaturation of the proteins was studied using CD (Circular Dichroism). Moreover, the effect of flow rate on retention of proteins and small molecules was studied at constant pressure on the different pore size silicas and the impact of internal frictional heating was evaluated.

Fast gradient separation by very high pressure liquid chromatography: Reproducibility of analytical data and influence of delay between successive runs

07 November 2013, 09:10:03

Publication date: 29 November 2013
Source:Journal of Chromatography A, Volume 1318
Author(s): Joseph J. Stankovich , Fabrice Gritti , Lois Ann Beaver , Paul G. Stevenson , Georges Guiochon
Five methods were used to implement fast gradient separations: constant flow rate, constant column-wall temperature, constant inlet pressure at moderate and high pressures (controlled by a pressure controller), and programmed flow constant pressure. For programmed flow constant pressure, the flow rates and gradient compositions are controlled using input into the method instead of the pressure controller. Minor fluctuations in the inlet pressure do not affect the mobile phase flow rate in programmed flow. The reproducibilities of the retention times, the response factors, and the eluted band width of six successive separations of the same sample (9 components) were measured with different equilibration times between 0 and 15min. The influence of the length of the equilibration time on these reproducibilities is discussed. The results show that the average column temperature may increase from one separation to the next and that this contributes to fluctuation of the results.

Determination of egg yolk xanthophylls by isocratic high-performance liquid chromatography

07 November 2013, 09:10:03

Publication date: 29 November 2013
Source:Journal of Chromatography A, Volume 1318
Author(s): Lučka Brulc , Breda Simonovska , Irena Vovk , Vesna Glavnik
An isocratic HPLC method was developed for the determination of eight xanthophylls (lutein, capsanthin, zeaxanthin, canthaxanthin, β-apo-8′-carotenal, ethyl-8′-apo-β-carotene-8′-oate, citranaxanthin and β-cryptoxanthin; registered as additives in poultry feeding) in egg yolks. Optimum separation of all-E-isomers of these xanthophylls was achieved in less than 18min on a ProntoSIL C30 column at 27°C using acetone–methanol–0.5M triethylammonium acetate buffer pH 7 14:5:1 (v/v) as the mobile phase with a flow rate of 1mL/min using spectrophotometric detection at 450nm. Other mobile phases were also found suitable, including acetone–water 93:7 (v/v) and acetone–methanol 1:4 (v/v) and the influences of column temperature on the separation and addition of triethylammonium acetate buffer pH 7 to the mobile phase on enhancement of the peak areas were evaluated. Preparation of test solution from yolks included a short vortexing of 0.5g of yolk in 10mL of acetone, followed by 15min magnetic stirring under nitrogen and centrifugation. The method was validated for 5 analytes. The calibration range was between 0.04 and 2μg/mL and the mean recovery of the analytes (95%) and the intra-day precision of the method (RSD less than 5%) on three levels in triplicates were obtained. Analyses of eggs from four husbandry classes showed the presence of up to four xanthophylls (lutein, zeaxanthin, canthaxanthin and ethyl-8′-apo-β-carotene-8′-oate) and traces of β-cryptoxanthin.

Synchronized gradient elution in capillary liquid chromatography

07 November 2013, 09:10:03

Publication date: 29 November 2013
Source:Journal of Chromatography A, Volume 1318
Author(s): Enrique Javier Carrasco-Correa , Agustín Acquaviva , José Manuel Herrero-Martínez , Guillermo Ramis-Ramos
The synchronization of injection valve operation and gradient elution in capillary liquid chromatography (cHPLC) is studied. Focus is placed on the cHPLC systems which rely on the splitting of a primary flow to provide the much smaller secondary flow required at the injection device and analytical column. Owing to the tiny secondary flow rates, synchronization is necessary to achieve proper optimization of gradient elution methods. Otherwise, there is a risk of having the analytes totally or partially eluted in the initial isocratic conditions, and there is no control on the actual gradient profile reaching the column. Synchronization is first achieved by switching back the valve to bypass after injection. This is important to save time, and to avoid the gradient slope to be reduced by mixing within the internal volume of the injector (a 47% of slope reduction, in the conditions used in this work). Valve switching to bypass should be produced immediately after the arrival of the end of the sample plug to the valve (t V ). Fine system synchronization is further achieved by starting the gradient at the match time (t M ), which is the time required to match the arrival of both the gradient front and the end of the sample plug to the valve, and therefore also to the column inlet. Synchronization of these two events requires starting the gradient either before or even after the injection, thus to prevent a late or an early arrival of the gradient front to the injection valve, respectively. Owing to their dependence with the backpressure, both t V and t M should be measured in the presence of the column at the initial gradient conditions. Simple experiments designed to measure t V and t M are described. With synchronization according to the techniques described in this work, control on the real gradient elution conditions at the column location is maintained, the analysis time is reduced and efficiency improves. The effects of synchronization are illustrated by injecting a mixture of alkylbenzenes. At 1μL min⁻¹, valve switching to bypass reduced analysis time from ca. 36 to 12min (butylbenzene), and improved peak symmetry (from 2.00 to 0.94 for methylbenzene) and efficiency (the average apparent plate count increased approximately 60%). Synchronization according to the match time further improved efficiency (approximately, up to 120%).

‘Bringing the Nanoworld Together’ (BTNT), an initiative from Oxford Instruments to share expertise with Nanotechnology

2013-11-07T09:30:00.000+00:00

Following the great success of Oxford Instruments’ seminar in Bangalore last December, the company has planned two more seminars to be held this year in India. BTNT 2013 will be held at Mohali (29th November) in association with "Indian Institute of Science Education and Research Mohali", "Institute of Nano Science and Technology”, and at Mumbai (2^nd & 3^rd December) in association with "Indian Institute of Technology Bombay'. The seminars will focus on cutting edge nanotechnology tools and their use in multiple fields.

At both events, two parallel sessions will focus on thin film processing, & materials characterisation, surface science and cryogenic environments and a wide range of topics will be covered within each technical area. These sessions will include guest international speakers from renowned research institutions, speakers from the host institutes, and technical experts from Oxford Instruments. This will also present an excellent opportunity for networking between all participants.

The thin film processing sessions will review latest etch and deposition technological advances, including: ALD, Magnetron Sputtering, ICP PECVD, Nanoscale Etch, MEMS, MBE and more.

Materials characterisation, Surface Science and Cryogenic Environment sessions will cover multiple topics and technologies including: Ultra high vacuum SPM, Cryo free low temperature solutions, XPS/ESCA, an introduction to atomic force microscopy (AFM) and applications such as nanomechanics, In-situ heating and tensile characterisation using EBSD, Measuring Layer thicknesses and compositions using EDS, Nanomanipulation and fabrication within the SEM / FIB.

The host of last year’s seminar Prof. Rudra Pratap, Chairperson at the Centre for Nano Science and Engineering, Indian Institute of Science, IISC Bangalore commented, “This seminar has been extremely well organised with competent speakers covering a variety of processes and tools for nano fabrication. It is great to have practitioners of the art give talks and provide tips and solutions based on their experience, something that cannot be found in text books.”

“As a leading provider of high technology solutions, we actively listen and engage with our customers for mutual success, and hope to build long term relationships based on trust and respect”, comments Mark Sefton, Sector Head of Oxford Instruments Nanotechnology Tools, “By providing these educational events in addition to our high technology tools and superior service, we are proving our commitment to our customers, encouraging discussion and cross dissemination of ideas that will benefit all those attending.”

This seminar is free of charge but prior booking is essential. Bookings may be made at: www.oxinst.com/btnt2013

Just Published: Journal of Analytical and Applied Pyrolysis

2013-11-06T10:16:00.001+00:00

A new issue of this journal has just been published. To see abstracts of the papers it contains (with links through to the full papers) click here:

Journal of Analytical and Applied Pyrolysis
http://rss.sciencedirect.com/publication/science/5247

Selected papers from the latest issue:

A study of lignocellulosic biomass pyrolysis via the pyrolysis of cellulose, hemicellulose and lignin

06 November 2013, 01:53:33

Publication date: Available online 5 November 2013
Source:Journal of Analytical and Applied Pyrolysis
Author(s): Stylianos D. Stefanidis , Konstantinos G. Kalogiannis , Eleni F. Iliopoulou , Chrysoula M. Michailof , Petros A. Pilavachi , Angelos A. Lappas
In this study, thermogravimetric (TG) analyses, along with thermal and catalytic fast pyrolysis experiments of cellulose, hemicellulose, lignin and their mixtures were carried out in order to investigate their pyrolysis products and whether the prediction of the pyrolysis behavior of a certain lignocellulosic biomass feedstock is possible, when its content in these three constituents is known. We were able to accurately predict the final solid residue of mixed component samples in the TG analyses but the differential thermogravimetric (DTG) curves indicated limited heat transfer when more than one component was present in the pyrolyzed sample. The limited heat transfer did not have a significant effect on the TG curves but it affected the product distribution in the fast pyrolysis experiments, which resulted in inaccurate calculation of the product yields, when using a simple additive law. In addition, the pyrolysis products of each biomass constituent were characterized in order to study their contribution to the yield and composition of the products from whole biomass pyrolysis. An investigation into the pyrolysis reaction pathways of each component was also carried out, using the bio-oil characterization data from this study and data found in the literature.

Use of Py-GC/MS and PCFC to characterize the surface modification of flax fibers

06 November 2013, 01:53:33

Publication date: Available online 4 November 2013
Source:Journal of Analytical and Applied Pyrolysis
Author(s): G. Dorez , B. Otazaghine , A. Taguet , L. Ferry , J.M. Lopez-Cuesta
Surface modification of flax fibers with a phosphorous agent in a solvent process have been originally evaluated through thermal degradation using Pyrolysis Combustion Flow Calorimeter and Pyrolysis-Gas Chromatography/Mass Spectrometry. It has been highlighted that these techniques are particularly sensitive to the presence of the phosphonated grafting agent on natural fibers. After treatment, octadecylphosphonic acid (ODPA) was found to be covalently grafted on the flax fibers at a rate of almost 5%. For a better comprehension of the interactions between the phosphonic group and flax, the reactivity of the phosphonic acid function of ODPA with the main components of fibers was assessed. The results showed that ODPA reacts strongly with lignin and at a lower degree with xylan (model for hemicellulose) whereas no reaction with cellulose was evidenced.

KOH activation of HyperCoal to develop activated carbons for electric double-layer capacitors

06 November 2013, 01:53:33

Publication date: Available online 27 October 2013
Source:Journal of Analytical and Applied Pyrolysis
Author(s): Xiaoyan Zhao , Shanshan Huang , Jingpei Cao , Shaochen Xi , Xianyong Wei , Junpei Kamamoto , Takayuki Takarada
A series of activated carbons (ACs) was prepared from HyperCoal by conventional and direct KOH activation methods, and was used as electrodes in electric double-layer capacitors (EDLC) using 0.5M TEABF4/PC as the electrolytic solution. The effects of carbonization temperature (CT), activation temperature (AT) and KOH/sample ratio on BET surface area, average pore size and capacitance of ACs were investigated in this study. Nitrogen adsorption isotherms of all ACs indicated that the pores in ACs were mainly micropores. The BET surface area and capacitance decreased with raising CT from 500 to 900°C, while the highest BET surface area of 2540m² g⁻¹ and maximum capacitance of 46.0Fg⁻¹ were achieved at CT of 500°C and AT of 800°C in conventional activation. On the contrary, in the direct activation, the BET surface area and the capacitance increased with the increase of AT and KOH/sample ratio, getting the maximum value of 2440m² g⁻¹ and 44.4Fg⁻¹, which is comparable with that of conventional method, at AT of 800°C and KOH/sample ratio of 4.0. Such a procedure provides a cost-effective approach to preparation of high performance activated carbons from HyperCoal for EDLC.

Microwave pyrolysis of cellulose at low temperature

06 November 2013, 01:53:33

Publication date: Available online 25 October 2013
Source:Journal of Analytical and Applied Pyrolysis
Author(s): Ahmad Al Shra’ah , Robert Helleur
Microwave pyrolysis of cellulose was successfully achieved at low temperature (200 to 280°C) using a lab-scale microwave synthesis system. Both closed and open microwave setups were developed to measure yields of pyrolysis products and to characterize the bio-oil. The effect of temperature, type of cellulose (crystalline and amorphous), and microwave absorber were examined. Microwave-derived bio-oil compositions were compared to conventional pyrolysis (microfurnace pyrolyzer- GC/MS) under similar heating rates. Maximum bio-oil yield (45%) was obtained from amorphous cellulose at 260°C using an open system. Addition of water significantly increased the bio-oil yield to 52% (amorphous) and to 47% (crystalline) while addition of activated carbon had the effect of increasing gaseous products. Microwave-derived bio-oil products varied in chemical nature and abundance depending on cellulose crystallinity and between open or closed microwave pyrolysis and showed significant differences from conventional pyrolysis bio-oil. High yields of levoglucosan were obtained from amorphous cellulose at 260°C while conventional pyrolysis required a much higher temperature (400°C).

Characterization of the products from the pyrolysis of sewage sludge in 1kg/h rotating cylinder reactor

06 November 2013, 01:53:33

Publication date: Available online 24 October 2013
Source:Journal of Analytical and Applied Pyrolysis
Author(s): M.M. Pedroza , J.F. Sousa , G.E.G. Vieira , M.B.D. Bezerra
The objectives of this study were to produce and characterize bio-fuels through the thermal treatment of sewage sludge in an 1kg/h. rotating cylinder reactor. The experimental procedure was divided into three parts: (a) initial test using the temperatures of 450, 500, 550, 600 and 650°C while the nitrogen flow, the centrifuge rotation and biomass flow were kept constant, (b) 2^4–1 fractional experimental design and (c) experiments exclusively for the characterization of gaseous fraction, using the temperatures of 500, 550 and 600°C. The maximum liquid yield was 10.5% obtained at the temperature of 500°C, inert gas of 200mL/min, biomass flow of 22g/min and centrifuge rotation of 20Hz. The maximum char yield was 61.9%, obtained at 500°C, inert gas of 100mL/min, biomass flow of 4g/min and centrifuge rotation frequency of 20Hz. The highest phase gas yield was 23.3%, obtained at 600°C, inert flow rate of 200mL/min, biomass flow rate of 22g/min and rotation frequency of 30Hz. The bio-oil had the following characteristics: pH between 6.80 and 6.84, density between 1.05 and 1.09g/mL, viscosity between 2.5 and 3.1 cSt and High Heating Value between 16.91 and 17.85MJ/kg. Non-oxygenated aliphatic (55%) and aliphatic oxygenated hydrocarbons (27%) were found in the bio-oil. The main components detected in the gas phase were H2, CO, CO2 and CH4. Hydrogen was the main constituent, with a yield of 46.2% at 600°C. Among the hydrocarbons formed, methane was predominant (16.6%) at 500°C. The results show that increasing the temperature from 500 to 600°C favors the increase in the gaseous phase and reduction of solid and liquid fractions.

Preparation, characterization and analyses of carbons with natural and induced calcium compounds for the adsorption of fluoride

06 November 2013, 01:53:33

Publication date: Available online 24 October 2013
Source:Journal of Analytical and Applied Pyrolysis
Author(s): L.A. Ramírez-Montoya , V. Hernández-Montoya , A. Bonilla-Petriciolet , Miguel A. Montes-Morán , R. Tovar-Gómez , M.R. Moreno-Virgen
A comparative study of fluoride removal has been made using samples of carbons obtained from single carbonization from pecan nut shells and plum kernels and carbons obtained by impregnation of these wastes, prior to their carbonization, with a calcium acetate solution. The impregnation step was determinant for increasing the ability of carbons to remove fluoride anions from water of carbons prepared from both precursors. The intrinsic calcium content of the precursors left a footprint in the process, with carbons prepared from the higher calcium content precursor (i.e., pecan nut shells) always performing better than the plum kernel carbon counterpart. Outstanding fluoride retention abilities (from 0.5 to 2.5mg of fluoride adsorbed per gram of carbon) were obtained if pecan nut shells are impregnated with a calcium solution of 3151mg/L and carbonized at 800°C (sample denominated IC-PN-25). These results can be associated with the calcium compounds founded in IC-PN-25 which are CaO and CaCO3, according with the X-ray results. Furthermore, dynamic adsorption studies were carried out using beds of carbon denominated IC-PN-25. Reasonably high (0.4) filter usage ratios were obtained in such on-column adsorption studies. Finally, different models were used to fit batch and dynamic adsorption data, with Sips and Yan models fitting better the equilibrium isotherm and breaktrough curve data, respectively, than others.

Synthetic Fuel Production From Cottonseed: Fast Pyrolysis And A Tga/Ft-Ir/Ms Study

06 November 2013, 01:53:33

Publication date: Available online 24 October 2013
Source:Journal of Analytical and Applied Pyrolysis
Author(s): ESİN Apaydin-Varol , BAŞAK BURCU Uzun , EYLEM Önal , AYŞE E. Pütün
This study investigates the thermal decomposition behavior of cotton seed via TGA/FT-IR/MS and the quantification/characterization of liquid products from fast pyrolysis. Thermal degradation of the biomass sample has occurred in four steps, corresponding to the removal of moisture, decomposition of cellulose, hemicellulose and lignin and it was completed at about 700°C. The main gaseous products evolved were CO2, light hydrocarbons and H2O. For the fast pyrolysis experiments, particular investigated process variables were temperature (400-700°C), heating rate (5–700°Cmin⁻¹) and nitrogen gas flow rate (100–800 cm³min⁻¹). Maximum oil yield was attained at 500°C with a yield of 49.5% under 200 cm³min⁻¹ nitrogen flow rate and at a heating rate of 300°Cmin⁻¹. Bio-oil obtained at optimum conditions are separated into its fractions by column chromatography. The oil and its sub-fractions were characterized by elemental analysis, FT-IR, and GC/MS. The char was characterized with elemental analysis and FT-IR techniques. The aliphatic sub-fraction of the obtained bio-oil contains predominantly straight chain of n-alkanes and alkenes. According to the chemical characterization, the bio-oil can be utilized as conventional liquid fuels.

Terpenoid composition and chemotaxonomic aspects of Miocene amber from the Koroglu Mountains, Turkey

06 November 2013, 01:53:33

Publication date: Available online 24 October 2013
Source:Journal of Analytical and Applied Pyrolysis
Author(s): Oluwadayo O. Sonibare , Ru-Jin Huang , Dorrit E. Jacob , Yunyun Nie , Eike Kleine-Benne , Thorsten Hoffmann , Stephen F. Foley
A recently discovered fossil resin from Koroglu Mountain in Turkey has been analyzed by gas chromatography-mass spectrometry and pyrolysis gas chromatography-mass spectrometry to determine its structural class and botanical origin. The sesqui- and diterpenoids contained in the amber extract were used as chemosystematic markers when compared with terpenoids in extant conifers. The pyrolysis products were dominated by labdanoid derived bicyclic products together with succinic acid indicating Class Ia type amber. The biomarker compositions of the resin comprise mainly sesqui- and diterpenoids, and lack triterpenoids. This distribution suggests a gymnosperm, and more specifically a conifer source. The exclusive presence of abietane- and labdane- type diterpenoids together with the absence of phenolic diterpenoids strongly suggest that the resin was derived from Pinaceae. However, the presence of methyl-16,17-dinor callitrisate in the pyrolysate also suggests that Cupressaceae cannot be excluded as a possible source for the amber.

Review of analytical strategies in the production and upgrading of bio-oils derived from lignocellulosic biomass

06 November 2013, 01:53:33

Publication date: Available online 20 October 2013
Source:Journal of Analytical and Applied Pyrolysis
Author(s): Pankaj K. Kanaujia , Y.K. Sharma , M.O. Garg , Deependra Tripathi , Raghuvir Singh
Lignocellulosic biomass is a promising source of renewable energy and valuable chemicals. It is abundant in several forms which may be pyrolyzed to give gases, condensates and char. The condensed liquid obtained through pyrolysis is popularly called bio-oil from which valuable chemicals may be derived in a well defined manner. Chemically, this liquid is a complex mixture of simple organic, inorganic and macromolecular compounds formed through thermo-chemical breakdown of lignocellulosic biomass. High oxygen content is responsible for its low gross calorific value which renders it useless for fuel applications however; upgrading processes aimed at reducing oxygenates potentially increase its usage at par with fossil fuels. Fast and efficient analytical methods have revealed huge amount of informations from biomass and pyrolysis liquids hence a key component in organizing research in this area. Owing to the high compositional complexity and diversity in bio-oils originating from different sources, generalized analytical procedures are very difficult to formulate. However, tools of analytical chemistry have helped in understanding the underlying mechanisms involved in production and upgrading of bio-oils at molecular levels. With the possibility of commercial large scale production plants coming up in Europe, concerns with bio-oil quality, stability and upgrading rely strongly on analytical approaches. With this review we have tried to present outcomes of important research related to chemical analysis of bio-oils. The discussion is intended to summarize role of prominent analytical techniques in the chemical characterization of bio-oils. On this basis, optimum sample preparation strategies have also been proposed along with the rationale behind analysis with conclusions.

Mechanism studies on β-d-glucopyranose pyrolysis by density functional theory methods

06 November 2013, 01:53:33

Publication date: Available online 19 October 2013
Source:Journal of Analytical and Applied Pyrolysis
Author(s): Yayun Zhang , Chao Liu , Hui Xie
In order to understand the pyrolysis mechanism of cellulose, the pyrolysis of β-d-glucopyranose as cellulose unit model compound was investigated by employing density function theory methods at B3LYP level with 6-31G(d,p) basis set. Two series of pyrolytic reactions containing seven possible pathways were proposed after several pathways were analyzed in detail. All the reactants, transition states, intermediates and products were optimized, also the standard thermodynamic and kinetic parameters in each reaction pathway were calculated. The calculation results indicate that the reactions of pathways 1–5 are endothermic, but ones of pathways 6–7 are exothermic. All the pathways can occur spontaneously above 400K and 1atm. We also obtain five better reaction pathways from two modes of reaction pathways. Among these five pathways, hydroxyacetaldehyde (HAA), acetol, formic acid, acetic acid and furfural are generated in pathway 2, 4, 7, 6 and 3 with the activation energy of 258.9, 291.1, 295.7, 321.5 and 360.6kJ/mol, respectively. Both thermodynamic and kinetic analyses support reaction pathways 2 and 4 as major reaction channels. It can be inferred that HAA, acetol and 5-hydroxymethylfurfural are the main products among small molecular products during cellulose pyrolysis. The formation of formic acid, acetic acid and furfural are difficult than that of former main products. The above results are in accordance with the related experimental results.

From new simple aliphatic to aromatic heterocycles built from 2-chloroethylisocyanate

06 November 2013, 01:53:33

Publication date: Available online 19 October 2013
Source:Journal of Analytical and Applied Pyrolysis
Author(s): Ana Julieta Pepino , Walter José Peláez , Gustavo Alejandro Argüello
New routes for gas phase thermal reactions of 2-chloroethylisocyanate are presented. They can be tuned by simply changing the material of the reactor and the temperature. Many interesting products are formed, including pyrazines and novel imidazolidine-2-ones. A comprehensive analysis that included high level ab-initio calculations has been carried out. Beyond the general agreement found with experimental results, the most relevant information is that, irrespective of the material of the reactor, all the products can be explained through a common unique key intermediate.

Characterisation of gas evolution and char structural change during pyrolysis of waste CDs

06 November 2013, 01:53:33

Publication date: Available online 18 October 2013
Source:Journal of Analytical and Applied Pyrolysis
Author(s): Ravindra Rajarao , Irshad Mansuri , Renu Dhunna , Rita Khanna , Veena Sahajwalla
The purpose of this study is to determine the characteristics of gas evolution and char structural change during pyrolysis of waste compact disc (CD). A combination of Thermogravimtetry-Fourier Transform Infrared spectroscopy (TG-FTIR) and Thermogravimtetry-Gas Chromatography/Mass Spectrometry (TG-GCMS) techniques are employed for this study. The thermal characteristics, temperature trend of evolving gas species and gas characteristics are investigated by TG-FTIR and TG-GCMS techniques. From the results, the waste CD degradation is divided into three stages (a) main gaseous compounds in first stage (<500°C) are CO2, CO, CH4 and H2O (b) organic species including aromatic hydrocarbons, phenols and its derivatives are evolved between 500 and 600°C. (c) Temperature above 600°C, carbonisation and char formation occurred. The char chemical structure and physical characteristics are investigated by Scanning Electron Microscopy, FTIR spectroscopy, Raman spectroscopy and X-ray diffraction techniques. This fundamental study provides basic insight of waste CD pyrolysis and also indicates that very high valuable carbon product (90% carbon in residue) with good crystallinity is achievable.

Thermal analysis and products distribution of dried sewage sludge pyrolysis

06 November 2013, 01:53:33

Publication date: Available online 16 October 2013
Source:Journal of Analytical and Applied Pyrolysis
Author(s): Ningbo Gao , Juanjuan Li , Benyu Qi , Aimin Li , Yue Duan , Ze Wang
Pyrolysis behavior of dried sewage sludge was studied by thermogravimetric–Fourier transforms infrared analysis (TG–FTIR) and differential scanning calorimetry (DSC) to investigate thermal decomposition and kinetics analysis. A tubular pyrolyzer was used to explore the production distribution of dried sewage sludge pyrolysis under different runs. The results showed that two weight loss peaks were presented in pyrolysis reaction in the ranges of 186–296°C and 296–518°C, and the activation energy of each stage was 82.284kJmol⁻¹ and 48.342kJmol⁻¹, respectively. The main gases identified by FTIR analysis were CH4, CO2, CO and organic volatile compounds such as aldehydes, acids, alcohols and phenols. Under fast pyrolysis of dried sewage sludge, the maximum tar yield obtained was 46.14% at the temperature of 550°C. The concentrations of all gases increased steadily with increasing pyrolysis temperature from 450°C to 650°C except for CO2.

The new Olympus high-speed, high- precision deep-imaging multiphoton system FVMPE-RS

2013-11-06T10:06:00.000+00:00

The new Olympus FluoView FVMPE-RS, a dedicated multiphoton microscope system, enables high-precision, ultra-fast scanning and stimulation, allowing researchers to see deep within specimens, take measurements at the highest speeds, and capture images, even when working under the most demanding conditions.

With its high speed and precision performance, the FVMPE-RS is designed for electrophysiology and optogenetics studies. It is also a good match for applications such as high-speed calcium and in vivo imaging, peristalsis and blood flow studies, mosaic imaging, connectomics and functional brain imaging, stem cell research, and any field that requires precise colocalisation, uncaging, simultaneous imaging/stimulation, extensive real-time signal processing, or multipoint mapping. Its design offers ready adaptability for researchers who design their own custom-built systems as well.

The precision timing on the system allows for microsecond repeatability and control of multiple imaging and stimulation protocols, as well as millisecond repeatability over days of time-lapse imaging. Complex multi-position imaging or optogenetic stimulation protocols can be accomplished using the advanced stage control and sequence manager.

The new system offers unmatched speed. The FVMPE-RS captures 438 frames per second (fps) at 512x32, the fastest rate commercially available. It also captures full-frame, 512x512 images at 30 fps without any reduction of the field of view, a critical feature for many functional imaging studies. Its scanner unit combines a newly designed resonance scanner with a galvanometer scanner to provide both speed and excellent definition. The resonance scanner offers an exclusive non-linear sampling method for smooth imaging without jitter. An optional third galvanometer scanner is also available for imaging with simultaneous 3D stimulation or uncaging. The system’s multipoint mapping capability allows ultra-high-speed measurement of rapid fluctuations in groups of cells for functional imaging studies, 3D intensity measurement or mapping with high signal-to-noise performance.

In addition to speed, the FVMPE-RS offers optimal performance when imaging live cells and tissues. It provides multicolour, multiphoton excitation and imaging with a choice of lasers, along with an industry-first four-axis auto-alignment capability for precise colocalisation and coalignment without pixel shift. With its multiple-laser-line performance, researchers can work with two IR laser lines simultaneously while stimulating the sample with visible light. The system delivers sharp images with clear separation of fluorescence proteins for analysis.

The high-sensitivity system offers high efficiency multiphoton excitation at wavelengths of 1300nm, with the ability to support wavelengths of up to 1600nm. Objectives that offer working distances of 2, 4 or 8mm deliver super-deep imaging. Light collection efficiency is further improved by the system’s optimised light path. In Deep Focus Mode, researchers can tune lasers precisely for deep-tissue imaging to achieve signal improvements of 20 percent or more over comparable systems. An optional high-sensitivity cooled gallium arsenide phosphide (GaAsP) detector unit further enhances sensitivity while minimising electrical noise, making the most out of the system’s high-speed capabilities.

The new system’s multichannel analogue box for triggering, synchronisation and signal input provides additional support for advanced electrophysiology studies and other applications requiring external device triggering. The advanced optional nosepiece piezo drive provides greater rigidity and faster z-plane stabilisation to ensure accurate and repeatable high-speed focus performance.

The FVMPE-RS is designed to be simple to use and require minimal alignment, thanks to its robust auto-alignment system and easy touch-panel control. Enhanced temperature stability and a highly rigid frame make it an ideal foundation for live cell experiments.

A dedicated multiphoton system, the FVMPE-RS is compatible with Olympus’ industry-leading range of multiphoton specialty objectives, including the multi-award-winning 4mm and 8mm SCALEVIEW objectives and Olympus’ high-performance, 25x dedicated multiphoton objectives.

The system will be sold as part of the full line of Olympus advanced imaging microscope systems, including the FV1200 and FV1200MPE family of microscope systems. For more information on the Olympus FVMPE-RS multiphoton system, visit www.microscopy.olympus.eu

Jus Published: Chemometrics and Intelligent Laboratory Systems

2013-11-05T09:22:00.003+00:00

A new issue of this journal has just been published. To see abstracts of the papers it contains (with links through to the full papers) click here:

Chemometrics and Intelligent Laboratory Systems
http://rss.sciencedirect.com/publication/science/5232

Selected papers from the latest issue:

Modeling and correction of Raman and Rayleigh scatter in fluorescence landscapes

05 November 2013, 09:21:02

Publication date: 15 January 2014
Source:Chemometrics and Intelligent Laboratory Systems, Volume 130
Author(s): Paul H.C. Eilers , Pieter M. Kroonenberg
Rayleigh and Raman scatter in fluorescence (excitation–emission) landscapes are a nuisance in two-way and three-way data modeling. We provide a method to clean individual emission spectra. The scatter can be represented accurately by Gaussian peaks, characterized by location, width and height. The analytic signal of interest effectively acts as a background to the scatter peaks. Modeling it locally as a smooth curve, using penalized least squares, allows accurate estimation of the parameters of scatter peaks. Once the peaks are modeled, they can be subtracted from the spectrum, almost completely removing the artifacts. Apart from local smoothness, no assumptions are made about the fluorescence spectra.

Dimensionality choice in principal components analysis via cross-validatory methods

05 November 2013, 09:21:02

Publication date: 15 January 2014
Source:Chemometrics and Intelligent Laboratory Systems, Volume 130
Author(s): Peyman Eshghi
This paper considers cross-validation based approaches to automatically determine the appropriate number of dimensions to retain in a Principal Components Analysis (PCA). Three approaches based on a mixture of leaving groups of observations and variables out are described. They are compared through simulation across a range of datasets of differing sizes and differing levels of missingness using the NIPALS algorithm to carry out the PCA. Also included in the paper is an explicit description of how the NIPALS algorithm is implemented to deal with missing data. Finally we provide suggestions as to which approach offers a better compromise between reliability in choosing the optimal number of components, and the computational burden.

Support vector regression in sum space for multivariate calibration

05 November 2013, 09:21:02

Publication date: 15 January 2014
Source:Chemometrics and Intelligent Laboratory Systems, Volume 130
Author(s): Jiangtao Peng , Luoqing Li
In this paper, a support vector regression algorithm in the sum of reproducing kernel Hilbert spaces (SVRSS) is proposed for multivariate calibration. In SVRSS, the target regression function is represented as the sum of several single kernel decision functions, where each single kernel function with specific scale can approximate certain component of the target function. For sum spaces with two Gaussian kernels, the proposed method is compared, in terms of RMSEP, to traditional chemometric PLS calibration methods and recent promising SVR, GPR and ELM methods on a simulated data set and four real spectroscopic data sets. Experimental results demonstrate that SVR methods outperform PLS methods for spectroscopy regression problems. Moreover, SVRSS method with multi-scale kernels improves the single kernel SVR method and shows superiority over GPR and ELM methods.

Statistical process monitoring based on a multi-manifold projection algorithm

05 November 2013, 09:21:02

Publication date: 15 January 2014
Source:Chemometrics and Intelligent Laboratory Systems, Volume 130
Author(s): Chudong Tong , Xuefeng Yan
Considering that the global and local structures of process data would probably be changed in some abnormal states, a multi-manifold projection (MMP) algorithm for process monitoring and fault diagnosis is proposed under the graph embedded learning framework. To exploit the underlying geometrical structure that contains both global and local information of sampled data, the global graph and local graph are designed to characterize the global and local structures, respectively. A unified optimization framework, i.e. global graph maximum and local graph minimum, is then constructed to extract meaningful low-dimensional representations for high-dimensional process data. In the proposed MMP, the neighborhood embedding is used in both global and local graphs and the extracted features are faithful representations of the original data. The feasibility and validity of the MMP-based process monitoring scheme are investigated through two case studies: a simple simulation process and the Tennessee Eastman process. The experimental results demonstrate that the whole performance of MMP is better than those of some traditional preserving global or local or global and local feature methods.

Two-level PLS model for quality prediction of multiphase batch processes

05 November 2013, 09:21:02

Publication date: 15 January 2014
Source:Chemometrics and Intelligent Laboratory Systems, Volume 130
Author(s): Zhiqiang Ge , Zhihuan Song , Luping Zhao , Furong Gao
Statistical quality prediction methods for multiphase batch processes have gained much attention in recent years. While most methods are focused on the data information inside each phase, the relationships among different phases have rarely been explored and used for quality prediction, although it may have significant impacts on prediction of the final quality. In this paper, a two-level partial least squares (PLS) model is proposed, in which the relationships among different single phases are modeled and incorporated for quality prediction. In the first level of this method, a representative intraphase-PLS model is built for each single phase, while in the second level, a series of interphase-PLS models are constructed to capture the relationships among different phases. With the incorporation of the additional interphase information, the multiphase quality prediction performance can be improved, which is evaluated through an industrial case study.

Radial basis function network-based transformation for nonlinear partial least-squares as optimized by particle swarm optimization: Application to QSAR studies

05 November 2013, 09:21:02

Publication date: 15 January 2014
Source:Chemometrics and Intelligent Laboratory Systems, Volume 130
Author(s): Jing-Jing Xing , Rui-Min Luo , Hai-Li Guo , Ya-Qiong Li , Hai-Yan Fu , Tian-Ming Yang , Yan-Ping Zhou
This study presented a new version of the nonlinear partial least-squares method on the optimized radial basis function network transformation by particle swarm optimization (PSORBFPLS). This algorithm firstly transformed the training inputs into the hidden outputs using the nonlinear transformation carried by a radial basis function network (RBFN), and then employed linear partial least-squares (PLS) to relate the outputs of the hidden layer to the bioactivities. The widths and centers involved in RBF transformation were optimized by particle swarm optimization (PSO) with the minimized model error via PLS modeling as the criterion. The number of latent variables associated with PLS modeling was automatically identified by F-statistic. Two QSAR data sets were used to evaluate the performance of the newly proposed PSORBFPLS. Results of these two data sets demonstrated that PSORBFPLS offers substantially enhanced capacities in modeling nonlinearity while circumvents overfitting frequently encountered in nonlinear modeling.

A consensus PLS method based on diverse wavelength variables models for analysis of near-infrared spectra

05 November 2013, 09:21:02

Publication date: 15 January 2014
Source:Chemometrics and Intelligent Laboratory Systems, Volume 130
Author(s): Yankun Li , Jing Jing
A new method named as diverse variables-consensus partial least squares (DV-CPLS) is proposed based on consensus (ensemble) strategy combined with uninformative variable elimination (UVE) technique. In the approach, UVE-PLS is used to construct member models with different numbers of variables (wavelengths) instead of altering training subset in conventional consensus method, and then prediction results of multiple member models are combined by a new weighted averaging way to give ensemble results. DV-CPLS is applied for building quantitative model between diesel near-infrared (NIR) spectra and cetane number (CN), and the results show fine prediction capability in terms of accuracy and robustness. When DV-CPLS was further combined with wavelet transform (WT) method, a more parsimonious model was obtained. The proposed method improves the performance of conventional PLS linear modeling in determination of diesel CN by NIR spectra. So it is hoped that it will help further investigations of consensus modeling and variable selection technique, and as well as applications in the sphere of NIR and even other spectral analysis of sophisticated systems.

Metabolomics research on time-selected combination of Liuwei Dihuang and Jinkui Shenqi pills in treating kidney deficiency and aging by chemometric methods

05 November 2013, 09:21:02

Publication date: 15 January 2014
Source:Chemometrics and Intelligent Laboratory Systems, Volume 130
Author(s): Liangxiao Zhang , Xiaofei Han , Zhan Li , Renhui Liu , Wenjuan Xu , Chunlan Tang , Xiujuan Wang , Hongbin Xiao
Jinkui Shenqi pill (JKSQ) and Liuwei Dihuang (LWDH) pills are ancient traditional Chinese medicines (TCMs), which are usually used for the treatment of kidney deficiency for thousands of years in China. Time-selected combination of LWDH and JKSQ pills in treating kidney deficiency and aging is one of the features of traditional Chinese medicines (TCMs). However, the molecular mechanisms of time-selected combination remain unclear. In this work, UHPLC–QTOF/MS based metabolomics research was conducted to evaluate the therapeutic effect of LWDH, JKSQ pills and their combinations on kidney deficiency in Sprague–Dawley rats induced by d-galactose and Dexamethasone. Based on peak areas of serum extracts, analysis of variance (ANOVA) and graphical index of separation (GIOS) were employed to select the significant variables for kidney deficiency and aging and principal component projection (PCP) was subsequently applied to evaluate the influence of drugs on endogenous metabolites. 10 endogenous metabolites from 22 important ions were identified via database search. The score plot of PCA shows that nourishing Yang–nourishing Yin group shows the strongest rehabilitation for metabolic disorder induced by kidney deficiency and aging, which is consistent with the classic theories of traditional Chinese medicine. Moreover, metabolic pathway function analysis indicates that kidney deficiency and aging might possess closed relationships with lipid metabolism and energy metabolism. In this work, the change trends of potential biomarkers after administration provide molecular evidence for combined administration of Jinkui Shenqi pill in the morning and Liuwei Dihuang pill at night for the patients with kidney deficiency. The method proposed in this study may provide inspiration for evaluation of the therapeutic effect of Chinese medicines by comparing the rehabilitation of potential biomarkers.

Graphical abstract

Oxford Instruments wins etch system order from SITP Shanghai

2013-11-05T09:21:00.000+00:00

Leading provider of etch and deposition systems to the global semiconductor research market, Oxford Instruments, has just won an order for its PlasmaPro 100 etch system from the prestigious multi-disciplinary Shanghai Institute of Technical Physics of the Chinese Academy of Sciences (SITP-CAS). This leading institute will use the advanced plasma etch system for its semiconductor research.

Mr. Heliang Xu from the SIPT commented, "SITP has PECVD and RIE systems installed that are mainly focused on non-metal films, which have been applied to light sensitive devices, passivation and multi-layer metal layout isolation with excellent results. Our recently purchased PlasmaPro 100 ICP system will be used for thick dielectric etch where good results have already been obtained good results with the CMOS image sensor devices.”

Mr Xu continued, “We have been using Oxford Instruments systems for over 30 years, and are impressed with the service support, prompt reaction to customer needs and the wide range of application capabilities. We are happy to work with Oxford Instruments on research and development.”

“PlasmaPro 100 process modules are built on 200mm platforms, with single wafer and multi-wafer batch capability. The systems offer excellent uniformity and high throughput processes on a range of applications.” said Jeffery Seah, Business Manager Asia for Oxford Instruments. “We are delighted to have won this order from such a prominent and innovative research centre as SITP, in the rapidly growing Chinese market. This versatile etch system is backed by our exclusive library of over 6,000 process recipes, and a global customer support network, made it the system of choice for this research environment.”

Just Published: Biosensors & Bioelectronics

2013-11-04T09:17:00.004+00:00

A new issue of this journal has just been published. To see abstracts of the papers it contains (with links through to the full papers) click here:

Biosensors & Bioelectronics
http://rss.sciencedirect.com/publication/science/5223

Selected papers from the latest issue:

Synthesis of surface molecularly imprinted nanoparticles for recognition of lysozyme using a metal coordination monomer

03 November 2013, 19:39:14

Publication date: 15 March 2014
Source:Biosensors and Bioelectronics, Volume 53
Author(s): Huachang Chen , Juan Kong , Dongying Yuan , Guoqi Fu
Molecularly imprinted polymers against proteins are regarded as promising substitutes for natural antibodies, but have been frustrated with the problems including reduced interaction between functional monomers and protein template in the aqueous media required during their synthesis and restricted mass transfer across the resulting crosslinked polymer matrixes. For addressing these issues, herein we proposed a strategy for imprinting of a protein on the surface of nanoparticles using a metal chelating monomer. With lysozyme as a model protein template and Cu²⁺ chelating N-(4-vinyl)-benzyl iminodiacetic acid as the coordination monomer along with other monomers, protein imprinted polymer nanoshells were formed over vinyl-modified silica nanoparticles via surface polymerization in high-dilution monomer solution. The feed concentration of the crosslinking monomer was optimized toward achieving the best imprinting effect. Compared with the related imprinted materials reported previously, the resultant core–shell imprinted particles showed greatly faster binding kinetics, elevated rebinding capacity and selectivity. More importantly, noticeably high binding affinity was achieved with an estimated dissociation constant of 4.1×10⁻⁸ M which is comparable to that of conventional antibodies

Label-free electrochemical biosensor using home-made 10-methyl-3-nitro-acridone as indicator for picomolar detection of nuclear factor kappa B

03 November 2013, 19:39:14

Publication date: 15 March 2014
Source:Biosensors and Bioelectronics, Volume 53
Author(s): Jing Hua Chen , Xi Zhang , Shuxian Cai , Dongzhi Wu , Jia Lin , Chunyan Li , Jing Zhang
A new acridone derivative 10-methyl-3-nitro-acridone (MNA) with excellent electrochemical activity was synthesized in this paper. Using it as an electrochemical indicator, a signal-on and label-free electrochemical biosensor was developed for picomolar determination of nuclear factor kappa B (NF-κB) in serum. Initially, linear double-stranded DNA (dsDNA) probes, which contain a protein-binding site specific to NF-κB, were self-assembled on the surface of a glass carbon electrode (GCE). If the NF-κB was absent, the dsDNA probes were cut into ss-DNA fragments by the digestion of ExoIII, resulting in a low electrochemical signal of MNA due to the weak binding affinity of MNA to ss-DNA. On the contrary, in the presence of NF-κB, it could bind with the dsDNA probes at the specific site and hinder the digestion of ExoIII, resulting in a significant increase of electrochemical response due to the intercalation of MNA into the dsDNA probes. By employing the above strategy, this sensor could detect as low as 40pM NF-κB with high specificity. To the best of our knowledge, the proposed sensor is the first attempt to use acridone derivative as an electrochemical indicator for NF-κB detection, which may represent a promising path toward clinical diagnosis and drug developments.

Cell-based high-throughput odorant screening system through visualization on a microwell array

03 November 2013, 19:39:14

Publication date: 15 March 2014
Source:Biosensors and Bioelectronics, Volume 53
Author(s): Eun Hae Oh , Seung Hwan Lee , Sang Hun Lee , Hwi Jin Ko , Tai Hyun Park
The development of a cell-based high-throughput screening system has attracted much attention from researchers who study drug screening mechanisms and characterization of G-protein coupled receptors (GPCRs). Although olfactory receptors (ORs) constitute the largest group of GPCRs that play a critical role recognizing and discriminating odorants, only a few ORs have been characterized, and most remain orphan. The conventional cell-based assay system for characterizing GPCRs, including ORs, is very laborious, time consuming, and requires an expensive assay system. In this study, we developed a simple, low-cost miniaturized odorant screening method by combining Micro-Electro-Mechanical system (MEMs) technique and visualization technique for detecting an odorant response. We fabricated PEG microwell from a photocrosslinkable polyethylene glycol diacrylate (PEGDA) solution and applied it to cell culture and a reverse transfection platform for cell-based high-throughput screening. For the first time, the olfactory receptors were expressed on the microwell platform using reverse transfection technique. The various olfactory receptors can be expressed simultaneously using this technique and the microwell spotted with olfactory receptor genes can be used as a high-throughput screening platform. The odorant response was detected via fluorescence analysis on the microwell using a cAMP response element (CRE) reporter assay. We tested this platform using four de-orphaned ORs. This new cell-based screening method not only reduced numerous time-consuming steps but also allowed for simple, efficient, and quantitative screening and patterning of large numbers of GPCRs including ORs, which can help to visualize the OR response to odorants on a microwell.

Lipase-nanoporous gold biocomposite modified electrode for reliable detection of triglycerides

03 November 2013, 19:39:14

Publication date: 15 March 2014
Source:Biosensors and Bioelectronics, Volume 53
Author(s): Chao Wu , Xueying Liu , Yufei Li , Xiaoyu Du , Xia Wang , Ping Xu
For triglycerides biosensor design, protein immobilization is necessary to create the interface between the enzyme and the electrode. In this study, a glassy carbon electrode (GCE) was modified with lipase-nanoporous gold (NPG) biocomposite (denoted as lipase/NPG/GCE). Due to highly conductive, porous, and biocompatible three-dimensional structure, NPG is suitable for enzyme immobilization. In cyclic voltammetry experiments, the lipase/NPG/GCE bioelectrode displayed surface-confined reaction in a phosphate buffer solution. Linear responses were obtained for tributyrin concentrations ranging from 50 to 250mgdl⁻¹ and olive oil concentrations ranging from 10 to 200mgdl⁻¹. The value of apparent Michaelis–Menten constant for tributyrin was 10.67mgdl⁻¹ and the detection limit was 2.68mgdl⁻¹. Further, the lipase/NPG/GCE bioelectrode had strong anti-interference ability against urea, glucose, cholesterol, and uric acid as well as a long shelf-life. For the detection of triglycerides in human serum, the values given by the lipase/NPG/GCE bioelectrode were in good agreement with those of an automatic biochemical analyzer. These properties along with a long self-life make the lipase/NPG/GCE bioelectrode an excellent choice for the construction of triglycerides biosensor.

Black silicon SERS substrate: Effect of surface morphology on SERS detection and application of single algal cell analysis

03 November 2013, 19:39:14

Publication date: 15 March 2014
Source:Biosensors and Bioelectronics, Volume 53
Author(s): Yu-Luen Deng , Yi-Je Juang
In this study, we have investigated the effect of the surface morphology of the black silicon substrate on surface enhanced Raman spectroscopy (SERS) and explored its application of single algal cell detection. By adjusting the O2 and SF6 flow rates in the cryogenic plasma etching process, different surface morphologies of the black silicon substrate was produced without performing the lithographic process. It was found the Raman signals were better enhanced as the tip density of the black silicon substrate increased. In addition, as the thickness of the deposited gold layer increased, the SERS effect increased as well, which could be owing to the generation of more hot spots by bridging individual silicon tips through deposition of gold layer. For the black silicon substrate with tip density of 30tips/μm² and covered by 400nm deposited gold layer, the detection limit of 10fM R6G solution concentration with uniform SERS effect across the substrate was achieved. Furthermore, detection of individual algal cell (Chlorella vulgaris) was performed at the SERS substrate as fabricated and the Raman signals of carotenoid and lipid were substantially enhanced.

Assessment of genotoxicity of catecholics using impedimetric DNA-biosensor

03 November 2013, 19:39:14

Publication date: 15 March 2014
Source:Biosensors and Bioelectronics, Volume 53
Author(s): Ali A. Ensafi , Maryam Amini , B. Rezaei
The potential toxicity of catecholics is a big concern, because the catechol-derived semiquinone radical after the oxidation of catechol (CA) can donate an H-atom to generate quinone, and during this process a superoxide anion radical may be produced. Considering the fact that catecholics are highly consumed in our daily life and some drugs also contain one or more CA moieties, we speculate that CA's toxicity might not be insurmountable. Therefore, finding approaches to investigate catecholics potential toxicity is of great significance. Here in, an electrochemical protocol for direct monitoring of genotoxicity of catecholics is described. CA encapsulated on MWCNTs (CA@MWCNT) through continuous cyclic voltammetric on the surface of pencil graphite electrode (PGE). Subsequently, a DNA functionalized biosensor (DNA/CA@MWCNT/PGE) was prepared and characterized for the detection and the investigation of DNA damage induced by radicals generated from catecholics. The change in the charge transfer resistance (R ct ) after the incubation of the DNA biosensor in the damaging solution for a certain time was used as an indicator for DNA damage. Incubation of DNA-modified electrode with CA solution containing Cu(II), Cr(VI) and Fe(III) has been shown to result in oxidative damage to the DNA and change in the electrochemical properties. It was found that the presence of Cu(II), Cr(VI) and Fe(III) in solution caused damage to DNA. The inhibitory effect of glutathione and plumbagin on the CA-mediated DNA damage has also been investigated using the biosensor. The minimum concentration of the metal ions for CA induced DNA damage was investigated. Recognition of suitable matrixes for CA-mediated DNA damage can be assessed using proposed DNA biosensor. Such direct monitoring of the DNA damage holds great promise for designing new biosensors with modification of the biosensor with different damaging agents.

Polymers effects on synthesis of AuNPs, and Au/Ag nanoalloys: Indirectly generated AuNPs and versatile sensing applications including anti-leukemic agent

03 November 2013, 19:39:14

Publication date: 15 March 2014
Source:Biosensors and Bioelectronics, Volume 53
Author(s): Shanaz Jahan , Farrukh Mansoor , Shamsa Kanwal
Polymers either serve as shielding or capping agents to restrict the nanoparticle size. This study demonstrates the polymer depositions and their effects in synthesis and sharp stabilization of gold nanoparticles (AuNPs) and to develop gold/silver nanoalloys (Au/Ag nanoalloys). Effects of different polymers are tested to justify their role in synthesis and stability of phloroglucinol (PG) coated AuNPs and Au/Ag nanoalloys. Cationic and anionic i.e. [Polydiallyldimethylammonium]⁺ (PDDA), [Polyethyleneimine]⁺ (PEI), [Polystyrene sulfonate]²⁻ (PSS) and neutral polymer Polychlorotriflouroethylene (PCTFE) produce praiseworthy stable AuNPs and Au/Ag nanoalloy. To prove polymer effects characterization protocols including UV–vis, Fluorescence (PL), IR and AFM imaging are performed to fully investigate the mechanism and size characteristics of these nanoparticles/nanoalloys. In this study sharp size controlling/sheilding effects were observed particularly with cationic polymers simply through the favorable electrostatic interactions with the terminal ends of PG Potent/significant detection of doxorubicin (DOX, an antileukemic agent) via fluorescence resonance energy transfer (FRET) between PEI shielded AuNPs (AuNPEI) and DOX was achieved upto 10pM level, while PDDA protected AuNPs facilitated the detection of ascorbic acid based on fluorescence enhancement effects in wide range (10–200nM) and with detection limit of 200pM. Similarly sensing performance of PEI stabilized Au/Ag nanoalloys on addition of halides (Cl⁻, Br^-, I⁻) is evaluated through red shifted SPR along with continuous increase in absorbance and also through AFM. Moreover the addition of halide ions also helped the regeneration of AuNPs by taking away silver from the Au/Ag nanoalloys enabling their detections upto subnanomolar levels.

An aptamer based wall-less LSPR array chip for label-free and high throughput detection of biomolecules

03 November 2013, 19:39:14

Publication date: 15 March 2014
Source:Biosensors and Bioelectronics, Volume 53
Author(s): Liping Xie , Xiaojun Yan , Yanan Du
Despite recent progress in localized surface plasmon resonance (LSPR) based bio-sensing, it remains challenging to achieve sensitive and high throughput LSPR detection with facilities available in common laboratories. Here we developed a wall-less LSPR array chip for facile, label-free and high throughput detection of biomolecules using a normal microplate reader. The wall-less LSPR array chip was fabricated by immobilizing plasmonic nanoparticles (NPs) on a hydrophilic–hydrophobic patterned glass slide, enabling high throughput detection. The wall-less configuration simplifies chip fabrication and sample processing, and enables miniaturization to significantly reduce sample and reagent consumption. A double-gold NPs enhanced system comprising of 13-nm-gold NPs conjugated to aptamer modified 39-nm-gold NPs on glass substrate was adopted to constitute competitive replacement assay for signal amplification in small molecule (i.e. ATP) detection. Upon enhancement, the detection sensitivity of ATP was augmented by 5 orders of magnitude from 0.01µM to 100µM measured by the laboratory microplate reader. The wall-less LSPR sensor chip can be widely applied for miniaturized and high throughput detection of a variety of targets in biomedical applications and environmental monitoring using facilities available in common laboratories.

Graphical abstract

Fast & Precise Biomass Analysis Tool

2013-11-04T09:15:00.001+00:00

Exeter Analytical reports that its Model 440 Elemental Analyser provides a fast and precise analytical tool for the biomass industry.

Identifying a particular tree, crop, grass, or algae with the chemical composition to make it an optimal biofuel candidate has traditionally been laborious and painstaking. The Exeter Analytical Model 440 Elemental Analyser can analyse a sample in as little as 6 minutes to provide precise percentage Carbon (C), Hydrogen (H) and Nitrogen (N) data. Using the percentage Hydrogen data enables easy calculation of the biomass sample gross or net calorific value. With increasing global interest in 'Carbon Trading' the determination of percentage carbon provides accurate data to enable organisations (or countries) to buy and sell carbon permits as part of a programme to reduce carbon emissions. The determination of the Nitrogen content of biomass samples using a Model 440 saves considerable time and cost with no diminishment of data quality compared with the traditional Kjeldahl nitrogen determination method.

The Model 440 is a static combustion CHN Elemental Analyser, with a unique horizontal furnace design, which enables easy removal of sample residue between each biomass analysis. Consequently one combustion tube will analyse in excess of 1000 biomass samples without the need for removal and cleaning. By comparison other elemental analysers, employing vertical furnace designs, will require cleaning after as little as 20 samples. The gas flow characteristics of the Model 440 analyser are superior to other elemental analysers due to the effective elimination of troublesome residue build-up. This thereby provides longer-term calibration stability as well as enhanced accuracy and precision for measured biomass sample data.

In addition, as the Model 440 provides complete control over combustion parameters it is able to reproducibly achieve 100% combustion with the widest range of biomass samples. Proprietary Nitrogen analysis software uniquely enables accurate measurement of low Nitrogen levels (in the 0.1-0.2% range) with a high degree of accuracy.

For further information on Biomass analysis please contact Exeter Analytical on tel. +44 (0)2476 323 223 or email info@exeteranalytical.co.uk

Just Published: Analytica Chimica Acta

2013-11-01T09:35:00.000+00:00

A new issue of this journal has just been published. To see abstracts of the papers it contains (with links through to the full papers) click here:

Analytica Chimica Acta
http://rss.sciencedirect.com/publication/science/5216

Selected papers from the latest issue:

Metabolomics, peptidomics and proteomics applications of capillary electrophoresis-mass spectrometry in Foodomics: A review

31 October 2013, 13:29:59

Publication date: 13 November 2013
Source:Analytica Chimica Acta, Volume 802
Author(s): Clara Ibáñez , Carolina Simó , Virginia García-Cañas , Alejandro Cifuentes , María Castro-Puyana
In the current post-genomic era, Foodomics has been defined as a discipline that studies food and nutrition through the application of advanced omics approaches. Foodomics involves the use of genomics, transcriptomics, epigenetics, proteomics, peptidomics, and/or metabolomics to investigate food quality, safety, traceability and bioactivity. In this context, capillary electrophoresis-mass spectrometry (CE-MS) has been applied mainly in food proteomics, peptidomics and metabolomics. The aim of this review work is to present an overview of the most recent developments and applications of CE-MS as analytical platform for Foodomics, covering the relevant works published from 2008 to 2012. The review provides also information about the integration of several omics approaches in the new Foodomics field.

Graphical abstract

Activated sludge characterization through microscopy: A review on quantitative image analysis and chemometric techniques

31 October 2013, 13:29:59

Publication date: 13 November 2013
Source:Analytica Chimica Acta, Volume 802
Author(s): Daniela P. Mesquita , A. Luís Amaral , Eugénio C. Ferreira
In wastewater treatment processes, and particularly in activated sludge systems, efficiency is quite dependent on the operating conditions, and a number of problems may arise due to sludge structure and proliferation of specific microorganisms. In fact, bacterial communities and protozoa identification by microscopy inspection is already routinely employed in a considerable number of cases. Furthermore, quantitative image analysis techniques have been increasingly used throughout the years for the assessment of aggregates and filamentous bacteria properties. These procedures are able to provide an ever growing amount of data for wastewater treatment processes in which chemometric techniques can be a valuable tool. However, the determination of microbial communities’ properties remains a current challenge in spite of the great diversity of microscopy techniques applied. In this review, activated sludge characterization is discussed highlighting the aggregates structure and filamentous bacteria determination by image analysis on bright-field, phase-contrast, and fluorescence microscopy. An in-depth analysis is performed to summarize the many new findings that have been obtained, and future developments for these biological processes are further discussed.

Graphical abstract

Handling large datasets of hyperspectral images: Reducing data size without loss of useful information

31 October 2013, 13:29:59

Publication date: 13 November 2013
Source:Analytica Chimica Acta, Volume 802
Author(s): Carlotta Ferrari , Giorgia Foca , Alessandro Ulrici
Hyperspectral Imaging (HSI) is gaining increasing interest in the field of analytical chemistry, since this fast and non-destructive technique allows one to easily acquire a large amount of spectral and spatial information on a wide number of samples in very short times. However, the large size of hyperspectral image data often limits the possible uses of this technique, due to the difficulty of evaluating many samples altogether, for example when one needs to consider a representative number of samples for the implementation of on-line applications. In order to solve this problem, we propose a novel chemometric strategy aimed to significantly reduce the dataset size, which allows to analyze in a completely automated way from tens up to hundreds of hyperspectral images altogether, without losing neither spectral nor spatial information. The approach essentially consists in compressing each hyperspectral image into a signal, named hyperspectrogram, which is created by combining several quantities obtained by applying PCA to each single hyperspectral image. Hyperspectrograms can then be used as a compact set of descriptors and subjected to blind analysis techniques. Moreover, a further improvement of both data compression and calibration/classification performances can be achieved by applying proper variable selection methods to the hyperspectrograms. A visual evaluation of the correctness of the choices made by the algorithm can be obtained by representing the selected features back into the original image domain. Likewise, the interpretation of the chemical information underlying the selected regions of the hyperspectrograms related to the loadings is enabled by projecting them in the original spectral domain. Examples of applications of the hyperspectrogram-based approach to hyperspectral images of food samples in the NIR range (1000–1700nm) and in the vis–NIR range (400–1000nm), facing a calibration and a defect detection issue respectively, demonstrate the effectiveness of the proposed approach.

Graphical abstract

Vapor-phase testing of the memory-effects in benzene- and toluene-imprinted polymers conditioned at elevated temperature

31 October 2013, 13:29:59

Publication date: 13 November 2013
Source:Analytica Chimica Acta, Volume 802
Author(s): Manuel Azenha , Eric Schillinger , Esther Sanmartin , M. Teresa Regueiras , Fernando Silva , Börje Sellergren
The preparation of polymers imprinted with common aromatic solvents such as benzene and toluene is an under-exploited subject of research. The present study was aimed at the understanding of whether true solvent memory effects can be achieved by molecular imprinting, as well as if they are stable at elevated temperature. A set of copolymers, comprising low and high cross-linking levels, was prepared from four different combinations of functional monomer and cross-linker, namely methacrylic acid (MAA)/ethylene glycol dimethacrylate (EGDMA), methyl methacrylate (MMA)/EGDMA, MAA/divinyl benzene (DVB) and MMA/DVB. Each possible combination was prepared separately in benzene, toluene and acetonitrile. The obtained materials were applied as coatings onto nickel–titanium (Ni–Ti) alloy wires which were incorporated into solid-phase microextraction devices and finally tested for their ability to competitively adsorb vapors from the headspace of an aqueous solution containing a few volatile organic compounds. Porosity analysis showed that, regardless of the solvent used, only a high cross-linking level permitted the preparation of mesoporous copolymers (BJH radius typically in the range 13–15nm), a requirement for providing accessibility to the targeted nanoscale-imprinted cavities. A noticeable exception was, however, observed for the MMA/DVB copolymers which exhibited much diminished BJH radius. The porosity data correlated well with the extraction profiles found, which suggested the presence of benzene-imprinted sites in all the highly cross-linked copolymers prepared in benzene, except for the MMA/DVB copolymers. Concerning the effect of an elevated conditioning temperature on the memory-effects created by the imprinting process, the results were clearly indicative that the tested copolymers, including the more robust highly cross-linked ones, are not suitable for high temperature applications such as solid-phase microextraction coupled to gas chromatography.

Graphical abstract

Molecular evaluation of soil organic matter characteristics in three agricultural soils by improved off-line thermochemolysis: The effect of hydrofluoric acid demineralisation treatment

31 October 2013, 13:29:59

Publication date: 13 November 2013
Source:Analytica Chimica Acta, Volume 802
Author(s): Riccardo Spaccini , XiangYun Song , Vincenza Cozzolino , Alessandro Piccolo
The molecular composition of soil organic matter (SOM) in three agricultural fields under different managements, was evaluated by off-line thermochemolysis followed by gas chromatography mass spectrometry analysis (THM-GC-MS). While this technique enabled the characterization of SOM components in coarse textured soil, its efficiency in heavy textured soils was seriously affected by the interference of clay minerals, which catalyzed the formation of secondary artifacts in pyrolysates. Soil demineralization with hydrofluoric acid (HF) solutions effectively improved the reliable characterization of organic compounds in clayey soils by thermochemolysis, while did not alter significantly the results of coarse textured soil. A wide range of lignin monomers and lipids molecules, of plant and microbial origin, were identified in the pyrograms of HF treated soils, thereby revealing interesting molecular differences between SOM management practices. Our results indicated that clay removal provided by HF pretreatment enhanced the capacity of thermochemolysis to be a valuable and accurate technique to study the SOM dynamics also in heavy-textured and OC-depleted cultivated soils.

Graphical abstract

Steroid and steroid glucuronide profiles in urine during pregnancy determined by liquid chromatography–electrospray ionization-tandem mass spectrometry

31 October 2013, 13:29:59

Publication date: 13 November 2013
Source:Analytica Chimica Acta, Volume 802
Author(s): Sirkku E. Jäntti , Minna Hartonen , Mika Hilvo , Heli Nygren , Tuulia Hyötyläinen , Raimo A. Ketola , Risto Kostiainen
An ultra performance liquid chromatography–electrospray ionization-tandem mass spectrometry (UPLC–MS/MS) method was developed for the analysis of steroids and their glucuronides in urine samples. The method provides high sensitivity and fast analysis, as both steroids and their glucuronides can be analyzed directly without hydrolysis or complex sample preparation. The method was applied in profiling of targeted and nontargeted steroids and steroid glucuronides during pregnancy. The concentrations of 11 of 27 targeted steroids and steroid glucuronides and the concentrations of 25 nontargeted steroid glucuronides increased about 10–400 fold during the pregnancy. The concentrations of most of these 36 compounds began to increase in the first days of the pregnancy, increased gradually during the pregnancy, achieved a maximum in late pregnancy, and decreased sharply after delivery. Exceptionally, the concentrations of allopregnanolone and 17-hydroxypregnenolone started to increase later than those of the other steroids. Moreover, the concentrations of E2 glucuronides began to decrease one week before the delivery, in contrast to most of the steroids and steroid glucuronides, whose concentrations dropped sharply during the delivery. Concentrations of 34 compounds decreased noticeably when the subject was on sick leave owing a series of painful contractions. The results suggest that steroids and especially steroid glucuronides may provide a valuable diagnostic tool to follow the course of pregnancy.

Graphical abstract

An ultrasensitive quantum dots fluorescent polarization immunoassay based on the antibody modified Au nanoparticles amplifying for the detection of adenosine triphosphate

31 October 2013, 13:29:59

Publication date: 13 November 2013
Source:Analytica Chimica Acta, Volume 802
Author(s): Yanlong He , Jianniao Tian , Kun Hu , Juanni Zhang , Sheng Chen , Yixuan Jiang , Yanchun Zhao , Shulin Zhao
In this work, an ultrasensitive fluorescent polarization immunoassay (FPIA) method based on the quantum dot/aptamer/antibody/gold nanoparticles ensemble has been developed for the detection of adenosine triphosphate (ATP). DNA hybridization is formed when ATP is present in the PBS solution containing the DNA-conjugated quantum dots (QDs) and antibody-AuNPs. The substantial sensitivity improvement of the antibody-AuNPs-enhanced method is mainly attributed to the slower rotation of fluorescent unit when QDs-labeled oligonucleotides hybridize with antibody modified the gold nanoparticle. As a result, the fluorescent polarization (FP) values of the system increase significantly. Under the optimal conditions, a linear response with ATP concentration is ranged from 8×10⁻¹² M to 2.40×10⁻⁴ M. The detection limit reached as low as 1.8pM. The developed work provides a sensitive and selective immunoassay protocol for ATP detection, which could be applied in more bioanalytical systems.

Graphical abstract

Simultaneous, real-time measurement of nitric oxide and oxygen dynamics during cardiac ischemia–reperfusion of the rat utilizing sol–gel-derived electrochemical microsensors

31 October 2013, 13:29:59

Publication date: 13 November 2013
Source:Analytica Chimica Acta, Volume 802
Author(s): Sung Wook Kang , Ok Kyun Kim , Bochan Seo , Sung Ho Lee , Fu Shi Quan , Jae Ho Shin , Gi-Ja Lee , Hun-Kuk Park
In this study, we simultaneously measured nitric oxide (NO) and oxygen (O2) dynamics in the myocardium during myocardial ischemia–reperfusion (IR) utilizing sol–gel modified electrochemical NO and O2 microsensors. In addition, we attempted to clarify the correlation between NO release in the ischemic period and O2 restoration in the myocardium after reperfusion, comparing a control heart with a remote ischemic preconditioning (RIPC)-treated heart as an attractive strategy for myocardial protection. Rat hearts were randomly divided into two groups: a control group (n =5) and an RIPC group (n =5, with RIPC treatment). Myocardia that underwent RIPC treatment (182±70nM, p <0.05) released more NO during the ischemic period than those of the control group (63±41nM). The restoration value of oxygen tension (pO2) in the RIPC group significantly increased and was restored to pre-ischemic levels (92.6±36.8%); however, the pO2 of the control group did not increase throughout the reperfusion period (5.7±7.5%, p =0.001). Myocardial infarct size measurements revealed a significant decrease in cell death in the myocardium region of the RIPC group (41.44±6.42%, p =0.001) compared with the control group (60.05±10.91%). As a result, we showed that the cardioprotective effect of RIPC could be attributed to endogenous NO production during the ischemic period, which subsequently promoted reoxygenation in post-ischemic myocardia during early reperfusion. Our results suggest that the promotion of endogenous formation during an ischemic episode might be helpful as a therapeutic strategy for protecting the myocardium from IR injury. Additionally, our NO and O2 perm-selective microsensors could be utilized to evaluate the effect of drug or treatment.

Graphical abstract

An ultrasensitive method for the determination of melamine using cadmium telluride quantum dots as fluorescence probes

31 October 2013, 13:29:59

Publication date: 13 November 2013
Source:Analytica Chimica Acta, Volume 802
Author(s): Xiafei Li , Jin Li , Huiyan Kuang , Lei Feng , Shoujun Yi , Xiaodong Xia , Haowen Huang , Yong Chen , Chunran Tang , Yunlong Zeng
An ultrasensitive and simple method for the determination of melamine was developed based on the fluorescence quenching of thioglycolic acid (TGA) capped CdTe quantum dots (QDs) at pH 11.0. In strong alkaline aqueous solution, the selectivity of the method has been greatly improved due to most heavy metal ions show no interference as they are in the precipitation form or in their anion form. Furthermore, CdTe quantum dots have higher quantum yields at higher pH. The method has a wider concentration range and lower detection limit. The influence factors on the determination of melamine were investigated and the optimum conditions were determined. Under optimum conditions, the fluorescence intensity change of TGA coated CdTe quantum dots was linearly proportional to melamine over a concentration range from 1.0×10⁻¹¹ to 1.0×10⁻⁵ molL⁻¹ with a correlation coefficient of 0.9943 and a detection limit of 5×10⁻¹² molL⁻¹. The mechanism of fluorescence quenching of the QDs has been proposed based on the infrared spectroscopy information and electrophoresis experiments in presence of melamine under alkaline condition. The proposed method was employed to detect trace melamine in milk powder and pet feeds with satisfactory results.

Graphical abstract

Inkjet printing lanthanide doped nanorods test paper for visual assays of nitroaromatic explosives

31 October 2013, 13:29:59

Publication date: 13 November 2013
Source:Analytica Chimica Acta, Volume 802
Author(s): Liang Hong , Qingsong Mei , Lei Yang , Cheng Zhang , Renyong Liu , Mingyong Han , Ruilong Zhang , Zhongping Zhang
The facile and sensitive strategies for detections of nitroaromatic explosives are highly desirable in many challenging environments, especially for homeland security against terrorism. Here, we inkjet printed polyethylenimine (PEI)-coated Ce, Tb co-doped NaGdF4 nanorods (NaGdF4:Ce/Tb NRs) onto common filter paper to construct test paper for visual and instant detections of a typical explosive 2,4,6-trinitrophenol (TNP). Polyethylenimine molecules not only facilitate the formation of uniform NaGdF4 nanorods but also provide specific recognized sites for TNP by the acid–base pairing interaction. The resultant TNP bound at the surface of PEI-coated NaGdF4:Ce/Tb NRs can strongly quench the phosphorescence with a remarkably high quenching constant by the charge transfer mechanism from NaGdF4:Ce/Tb NRs to TNP. By printing of the probe on a piece of filter paper, trace amounts of TNP can be visually detected by the appearance of a dark color against a bright green background under a UV lamp. This test paper can detect TNP as low as 0.45ngmm⁻² by the naked eye, which provides a potential application in the rapid, on-line detections of explosives.

Graphical abstract

Faster Drying of Deep Well Microplates

2013-11-01T09:32:00.003+00:00

Genevac’s new generation heat transfer plates for centrifugal evaporators enable almost any deep well plate to be dried up to 50% faster than previously possible.

Evaporation from microplates, especially deep well plates, can be extremely slow. The design of deep well plates makes it particularly difficult for an evaporator system to transfer enough heat for rapid drying, especially with higher boiling point solvents such as water or DMSO. In addition, often the wells in deep-well plates are supported above the level of the skirt and need support to prevent the plate from deforming in a centrifugal evaporator.

The new Genevac heat transfer plate design has a central flexible pad that deforms and moulds itself to the exact shape of your deep well plate. This intimate contact achieves the same level of heat transfer as from specially cut aluminium heat transfer plates but at a much lower cost. In addition the novel flexible heat transfer pad is proven to eliminate plate deformation.

Quick and easy deep well plate drying is now a reality with the fast stack microplate swing accessory and new flexible heat transfer plates. For further information please visit www.evaporatorinfo.com/info12_e.html or contact Genevac now on +44-1473-240000 / +1-845-255-5000 or email salesinfo@genevac.co.uk.

Just Published: Vibrational Spectroscopy

2013-10-31T09:21:00.003+00:00

A new issue of this journal has just been published. To see abstracts of the papers it contains (with links through to the full papers) click here:

Vibrational Spectroscopy

http://rss.sciencedirect.com/publication/science/5293

Selected papers from the latest issue:

Far-infrared investigation of kaolinite and halloysite intercalates using terahertz time-domain spectroscopy

30 October 2013, 21:17:54

Publication date: November 2013
Source:Vibrational Spectroscopy, Volume 69
Author(s): D. Zich , T. Zacher , J. Darmo , V. Szöcs , D. Lorenc , M. Janek
Two clay minerals from the kaolin group, namely well-ordered kaolinite and poorly ordered halloysite, were investigated by terahertz time-domain spectroscopy (THz-TDS). Both clay samples were used for preparation of their respective intercalates using dimethyl sulfoxide (DMSO) and potassium acetate (KAc) with water. The intercalates were also characterized by X-ray powder diffraction and Fourier transform infrared spectroscopy. The dielectric behaviour of clay samples was investigated in the far-infrared region of 0.2–2.7THz corresponding to about 6.7–89.9cm⁻¹. The frequency dependence of the power absorption coefficient revealed clear absorption bands for DMSO intercalates but not for KAc with water. For kaolinite – DMSO intercalate a distinct doublet at 1.70THz (56.6cm⁻¹) and 1.88THz (62.6cm⁻¹), and for halloysite – DMSO intercalate a single broad band centred around 1.72THz (57.3cm⁻¹) were found. These bands are reported for the first time in this type of intercalation substances and indicate the application potential of THz time-domain spectroscopy for use in the investigation and detection of chemical behaviour of molecular species introduced into the interlayer space of layered substances such as clays and clay minerals. Additionally, the qualitative characteristics of observed bands of DMSO intercalates in the THz region reasonably resembled the structural order/disorder of used kaolinite and halloysite samples.

Vibrational spectroscopy of phthalocyanine and naphthalocyanine in sandwich-type (na)phthalocyaninato and porphyrinato rare earth complexes. Part 15: The IR characteristics of phthalocyanine in homoleptic tetrakis(phthalocyaninato) rare earth(III)-cadmium(II) quadruple-deckers

30 October 2013, 21:17:54

Publication date: November 2013
Source:Vibrational Spectroscopy, Volume 69
Author(s): Hong Shang , Hailong Wang , Wenjun Li , Jianzhuang Jiang
The infra-red (IR) spectroscopic data for a series of twelve sandwich-type homoleptic tetrakis[2,3,9,10,16,17,23,24-octa(octyloxy)phthalocyaninato] rare earth(III)-cadmium(II) quadruple-decker complexes [Pc(OC8H17)8]M[Pc(OC8H17)8]Cd[Pc(OC8H17)8]M[Pc(OC8H17)8] (M=Y, Pr–Yb except Pm) have been collected with resolution of 2cm⁻¹ and their interpretation in terms tried by analogy with the IR characteristics of bis(phthalocyaninato) cerium double-decker [Pc(OC8H17)8]Ce[Pc(OC8H17)8] in which the macrocyclic ligands exist as the phthalocyanine dianion. Similar to the bis/tris(phthalocyaninato) rare earth sandwich counterparts, all the absorptions contributed primarily by or at least containing contribution from the vibrations of pyrrole or isoindole stretching, breathing or deformation or aza stretching in the IR spectra of these quadruple-decker compounds show dependent nature on the rare earth ionic size. The shift toward higher energy direction in the frequencies of these vibrations along with the decrease of the rare earth radii reveals the effective and increasing π–π interactions in these quadruple-decker sandwich compounds in the same order. Nevertheless, the decreased sensitivity of the frequencies of the above mentioned vibration modes in particular the weak absorption band due to the isoindole stretching at 1414–1416cm⁻¹ for the quadruple-decker on rare earth metal size in comparison with corresponding band for bis(phthalocyaninato) rare earth counterparts indicates the relatively weaker π–π interaction in these quadruple-deckers than in the double-deckers.

Raman spectroscopy analysis of pigments on Diego Velázquez paintings

30 October 2013, 21:17:54

Publication date: November 2013
Source:Vibrational Spectroscopy, Volume 69
Author(s): P.C. Gutiérrez-Neira , F. Agulló-Rueda , A. Climent-Font , C. Garrido
Raman micro-spectroscopy has been used for the identification of the pigments used by the Spanish painter Diego Velázquez (1599–1650), considered one of the greatest painters in art history. The set of cross-sectional samples studied belongs to paintings of the Museo del Prado collection and correspond to the three known periods of the artist's activity. We have obtained information on the chemical composition and crystal structure of the pigments used for various colours. The results are consistent with previous elemental composition determined by other analytical methods.

Prediction of glycoprotein secondary structure using ATR-FTIR

30 October 2013, 21:17:54

Publication date: November 2013
Source:Vibrational Spectroscopy, Volume 69
Author(s): S.P. Lewis , A.T. Lewis , P.D. Lewis
Glycoproteins are important biomolecules with a diverse array of structural and signaling functions in biology. Determination of glycoprotein secondary structure is becoming increasingly important in aiding the understanding of how these molecules function in biological environments and disease. Furthermore, glycoproteins such as mucins are being evaluated in various nano-engineering processes that require knowledge of how the underlying secondary structure might alter in different target environments. We have developed an analytical procedure for predicting the secondary structures of glycoprotein using ATR-FTIR on dry film. Using Bovine submaxillary mucin (BSM) as a glycoprotein model, we determined the additive infrared spectral pattern of acetyl amino sugars and amino acids that could contribute to the absorbance in the Amide I band of BSM through empirical data. We show through subtraction of these spectra how the absorbance pattern of the protein backbone can be determined in order to predict glycoprotein secondary structure. The analysis predicted a predominant pattern of random coil, beta sheet and beta turn secondary structure for BSM after carbohydrate and amino acid spectral subtraction in agreement with other methods. Our relatively simple approach can be applied to predict secondary structure in other glycoproteins.

Structure and vibrational spectroscopy of the fenbufen–β-cyclodextrin inclusion complex

30 October 2013, 21:17:54

Publication date: November 2013
Source:Vibrational Spectroscopy, Volume 69
Author(s): Ferenc Billes , Antonio Hernanz , Hans Mikosch , Ioan Bratu
The structure and host–guest interactions in the inclusion complex (179 atoms) of β-cyclodextrin with fenbufen are studied. Fenbufen, the biphenyl derivative γ-oxo-(1,1′-biphenyl)-4-butanoic acid, is a widespread analgesic and non-steroidal anti-inflammatory drug. Its inclusion complex with β-cyclodextrin improves the oral bioavailability and entails fewer side-effects. Optimized molecular structures, atomic net charges and vibrational spectra have been computed for the host and guest molecules, as well as for the inclusion complex. The functional density theory with the B3LYP/3-21+G method/basis set has been applied. The calculated vibrational frequencies have not been scaled, and the simulated spectra have been compared with those obtained experimentally. The host–guest interactions have been investigated in detail.

Synthesis and mesomorphic investigation of calamitic liquid crystalline system ethyl-[4-(4′-decyloxy)benzoyloxy]-benzoate (4-EDBB): A temperature dependent micro-Raman study and DFT calculations

30 October 2013, 21:17:54

Publication date: November 2013
Source:Vibrational Spectroscopy, Volume 69
Author(s): Rajib Nandi , K. Vikram , Sachin Kumar Singh , Bachcha Singh , Ranjan K. Singh
A new liquid crystalline material containing diester linking group ethyl-[4-(4′-decyloxy)benzoyloxy]-benzoate (4-EDBB) was synthesized. The phase transition temperatures were noted by differential scanning calorimetry (DSC), the texture pattern were observed by polarizing optical microscopy (POM) and temperature dependent Raman study was employed to observe the transitions as well as to understand the molecular rearrangement during phase transition. The transitions were observed with all the three techniques but the Raman signature of crystal→smectic A transition is many fold and more precise and accurate. The correlation between intermolecular interaction and phase behaviour has been discussed using temperature dependence Raman data of CH in-plane bending and CO stretching vibrations. With the help of DFT method the possible dimers of 4-EDBB were optimized and the rotational isomers were also investigated. There exists weak hydrogen bonds at room temperature, which breaks as the temperature is increased causing the CH in-plane bending to shift lower and CO stretching vibrations to shift higher. The discussion of the temperature dependent Raman data reveals that at crystal→smectic A transition as a result of intra-molecular rotation the molecules transform from trans- to cis- conformer.

Identification of the early postmortem metabolic state of porcine M. semimembranosus using Raman spectroscopy

30 October 2013, 21:17:54

Publication date: Available online 26 October 2013
Source:Vibrational Spectroscopy
Author(s): Rico Scheier , Jürgen Köhler , Heinar Schmidt
The metabolic conditions in the early postmortem muscle determine meat quality. Raman spectroscopy is shown to follow the early postmortem metabolism (0.5–10 h) of porcine M. semimembranosus (N = 10). To this end the Raman spectra, pH and lactate kinetics were measured in the laboratory. Raman difference spectra were utilized to identify the spectral changes and to assign them to metabolic and structural alterations in the pre-rigor (50 to 120min) and rigor (2 to 8.5 h) phases. In the Raman spectra, the decreasing pH was indicated by three signals assigned to phosphorylated metabolites and inorganic phosphate. Furthermore, the degradation of glycogen to lactate and a reduction of signal intensity of α-helical proteins were revealed. In the pre-rigor phase, degradation of phosphocreatine to creatine and reduction of oxy- to deoxymyoglobin was found. In the rigor phase, additionally, degradation of ATP to inosine monophosphate (IMP) was observed. Good agreement was achieved between measured and simulated Raman difference spectra. In the pre-rigor and rigor time frame, normal and deviating meat quality could be distinguished based on signals of phosphocreatine, ATP, IMP and α-helical proteins. This work provides a deeper understanding and the first semi-quantitative description of the early postmortem Raman spectra of meat which show potential for the non-invasive and early detection of the metabolic state of meat, and hence for the identification of deviating meat qualities.

Vibrational spectra and static vibrational contribution to first hyperpolarizability of naphthopyrans – A combined experimental and DFT study

30 October 2013, 21:17:54

Publication date: Available online 21 October 2013
Source:Vibrational Spectroscopy
Author(s): Kadali Chaitanya , Xue Hai Ju , B. Mark Heron , Christopher D. Gabbutt
Two pairs of isomeric photochromic naphthopyrans were investigated by FT-IR and FT-Raman spectroscopy and by Density Functional Theory (DFT) methods. The vibrational frequencies and contribution to first hyperpolarizabilities of the four naphthopyrans were determined at the B3LYP/6-31G (d, p) level. Comparison of the experimental and theoretical vibrational frequencies of the naphthopyrans was made. The assignments of the vibrational spectra have been carried out with the help of normal co-ordinate analysis (NCA). These results show that the ratio between pure vibrational contribution to the electronic contribution of first hyperpolarizability ( β v / β e ) increases when the 4-methoxyphenyl groups in the symmetrical isomers is replaced by 4-morpholinophenyl and phenyl group resulting in an asymmetrically substituted isomer pair. At the static limit, the low vibrational frequency modes have dominating contributions to the vibrational dipole polarizability and first hyperpolarizability.

Vibrational spectra of a ferrocenyl phosphine derivative chemisorbed on 3-aminopropylsilyl modified silica gel

30 October 2013, 21:17:54

Publication date: Available online 16 October 2013
Source:Vibrational Spectroscopy
Author(s): Vladimir Ivanovski , Miha Bukleski , Martyna Madalska , Evamarie Hey-Hawkins
Samples of silica gel dried at different temperatures, silica gel modified with 3-aminopropylsilyl (APS) and silica gel modified with APS and further with a ferrocenyl phosphine derivative were investigated by DRIFT, transmission FTIR and MicroRaman spectroscopy. The reaction between 3-aminopropyltrimethoxysilane (APTMS) and silica gel was mainly identified by the diminishing or vanishing intensity of the stretching band of the free OH groups in the silica gel. Further chemical reaction of the APS groups with a ferrocenyl phosphine derivative (suitable as ligand in homogeneous catalysis) was identified in the IR spectra by the appearance of the C=N stretching band of the formed Schiff base, and diminishing intensity of the δ(NH2) modes. According to the IR spectra the reaction of the ferrocenyl phosphine derivative with the APS-modified silica gel is almost quantitative. From the recorded IR and Raman spectra, conclusions concerning the substitution of APTMS methoxy groups during the chemisorption on silica gel were derived. Through deconvolution of the complex Raman band in the siloxy stretching region of the APS-modified silica gel, the newly formed siloxy bond was identified.

Electric Field Standing Wave Effects in FT-IR Transflection Spectra of biological tissue sections: simulated models of experimental variability

30 October 2013, 21:17:54

Publication date: Available online 3 October 2013
Source:Vibrational Spectroscopy
Author(s): Tomasz P. Wrobel , Barbara Wajnchold , Hugh J. Byrne , Malgorzata Baranska
The so-called electric field standing wave effect (EFSW) has recently been demonstrated to significantly distort FT-IR spectra acquired in a transflection mode, both experimentally and in simulated models, bringing into question the appropriateness of the technique for sample characterization, particularly in the field of spectroscopy of biological materials. The predicted effects are most notable in the regime where the sample thickness is comparable to the source wavelength. In this work, the model is extended to sample thicknesses more representative of biological tissue sections and to include typical experimental factors which are demonstrated to reduce the predicted effects. These include integration over the range of incidence angles, varying degrees of coherence of the source and inhomogeneities in sample thickness. The latter was found to have the strongest effect on the spectral distortions and, with inhomogeneities as low as 10% of the sample thickness, the predicted distortions due to the standing wave effect are almost completely averaged out. As the majority of samples for biospectroscopy are prepared by cutting a cross section of tissue resulting in a high degree of thickness variation, this finding suggests that the standing wave effect should be a minor distortion in FT-IR spectroscopy of tissues. The study has important implications not only in optimization of protocols for future studies, but notably for the validity of the extensive studies which have been performed to date on tissue samples in the transflection geometry

Gamma ray induced changes on vibrational spectroscopic properties of strontium alumino-borosilicate glasses

30 October 2013, 21:17:54

Publication date: Available online 25 September 2013
Source:Vibrational Spectroscopy
Author(s): A. Rupesh Kumar , T.G.V.M. Rao , K. Neeraja , M. Rami Reddy , N. Veeraiah
The present investigation reports the effect of influence of aluminum ions on radiation damage of strontium borosilicate glasses studied by means of spectroscopic (viz., optical absorption (OA), infrared and Raman spectra). The composition of the glasses chosen for the study is 40SrO–xAl2O3–(15-x) B2O3–40SiO2(x=5, 7.5, 10), all in mol%. The glasses were synthesized by conventional melt quenching method. Later, the samples were exposed to gamma (γ) radiation dose of strengths 10 kGy and 30 kGy with a dose rate of 1.5Gy/s using ⁶⁰Co as radiation source. The infrared spectra (IR), Raman spectra and optical absorption (OA) spectra of the samples were recorded at ambient temperature before and after irradiation. The OA spectra of the pre-irradiated samples do not exhibit any absorption bands in the UV–vis. regions and IR and Raman spectra exhibited conventional vibrational bands due to different borate, silicate AlO4 and AlO6 structural units. The OA spectra of post irradiated samples exhibited a broad absorption band in the wavelength region 600–750nm; it is attributed to electron trapped color centres. The intensity of this peak is observed to increase with increase of the γ-ray dose. Considerable changes in the intensities of various bands in the IR and Raman spectra were also observed. The changes were explained based on structural modifications taking place in the glass network due to γ-ray irradiation and finally it is concluded that the glasses mixed with 10.0 mol% of Al2O3 are relatively more radiation resistant.

Robot-Compatible Automatic Dry Down Station

2013-10-31T09:19:00.003+00:00

Porvair Sciences will officially launch the UltraVap Mistral robot-compatible automatic dry down station at Biotechnica 2013 (Hannover, Germany).

Drawing upon Porvair’s market leading position in nitrogen blow down evaporation – the UltraVap Mistral offers a simple, turnkey solution for integrating an automatic dry down step into your automated liquid handling protocol. The UltraVap Mistral is fully optimised to work with robotic liquid handling systems from suppliers including Beckman, Hamilton and Tecan and features a new “shuttle” design capable of serving and retrieving microplates to and from the robot deck without further need for off-deck handling.

With a built in colour TFT display and easy to use graphical interface, the UltraVap Mistral is Porvair’s most advance evaporator yet. Integrated method storage for 32 protocols and 5-step evaporation ramp programming combine to make the UltraVap Mistral faster and easier to use than any other blow down evaporator on the market. A wide choice of needle heads, integrated fume extraction and the possibility to connect multiple units via Ethernet all set the Mistral apart in this class of evaporator.

For further information please visit www.porvair-sciences.com/en/services-menu/equipment/ultravap-rc-microplate-evaporator/ or contact Porvair Sciences on +44-1978-666240 / int.sales@porvair-sciences.com.