The article hypothesizes that certain triglycerides, formed by unsaturated fatty acids, may attribute to the bitter taste; however, the role of these triglycerides remains a mystery. The good news is I should be able to taste food normally within a week or so.

I’ve eaten pine nuts in large quantities in the past but never experienced any taste problems, so perhaps it depends on the nuts’ origin.

(more…)

Zhaohui Wang and coauthors used a laser pulse to heat a gold substrate onto which a self-assembled monolayer of long-chain hydrocarbon molecules had been formed. The researchers used coherent vibrational spectroscopy to measure the heat conduction as it traveled through the chain of molecules via distinct vibrations. The heat flowed through the chains at about 1 kilometer per second in agreement with theoretical predictions.

_{References:
“Ultrafast Flash Thermal Conductance of Molecular Chains,” by Z. Wang, J.A. et al., Science, 317, pp 787-90, DOI:10.1126/science.1145220
“Molecules Take the Heat,” by A. Nitzan, Science, 317 pp.759-60, DOI: 10.1126/science.1147011}

Nano Liquid Chromatography

1. Nano Liquid Chromatography - Reloaded
2. Definition of Nano Liquid Chromatography
3. Columns in Nano LC
4. Nano LC Sensitivity

In theory, the analyte sensitivity increases on decreasing the column inner diameter; however, because of the very low sample volumes injected - 20-60 nL, nano liquid chromatography cannot be considered as an analytical method of high sensitivity.

There are several research studies that focused on the improvement of sensitivity by using techniques such as on-column focusing[1] and 2-D separation[2].

_{1. “Trace Level Determination of Organophosphorus Pesticides in Water with the New Direct-Electron Ionization LC/MS Interface”, Achille Cappiello et al., Analytical Chemistry, 2002 vol. 74 pp. 3547-54}

_{2. “Fully automated micro- and nanoscale one- or two-dimensional high-performance liquid chromatography system for liquid chromatography-mass spectrometry compatible with non-volatile salts for ion exchange chromatography” by Masuda, J. et al., Journal of Chromatography A 2005, 1063, pp. 57�??69.}

The method uses a short column packed with 2.7μm “fused-core” silica particles that are made by fusing a 0.5μm layer of porous silica onto a solid silica particle[1]. These unique particles enable very rapid chromatographic separation at a relatively low backpressure.

Ultra-high-pressure liquid chromatography (UHPLC) is another chromatographic technique that allows the system to handle the high backpressure resulting from the stationary phase with sub-2μm particles. UHPLC offers advantages in chromatographic resolution, speed, and sensitivity over conventional HPLC systems.

(more…)

EPA and DHA (docosahexaenoic acid) are the two main long-chain polyunsaturated fatty acids, also frequently referred to as “omega-3″. These lipids are primarily found in oily fish and shellfish. Some researches theorized that the consumption of the aquatic creatures and, hence, DHA/EPA is a key to the brain development of our prehistoric ancestors some 150,000 years ago^[2]. Omega-3s also have been found to reduce the risk of heart disease and stroke.

Chakraborty and Raj concentrated EPA from chemically hydrolyzed sardine oil using urea fractionation with methanol at different temperatures and urea/lipids ratios followed by argentation neutral alumina column chromatography. The urea-fatty acid complexes were analyzed by gas-liquid chromatography and gas chromatography-mass spectroscopy that revealed the highest EPA concentration of 48% was at 4 C and 4:1 urea/fatty acid ratio.

Lipid chemists heavily employ argentation chromatography - a technique that dependents on polar complexes that reversibly form between the silver ions and double bonds of the fatty acyl residues of lipids.

I get the science behind the silver ion chromatography, but what about the smell in the lab? You can only imaging that fish stench that permeates everything in its path and comes home with you on your clothes.

_{[1] “Eicosapentaenoic Acid Enrichment from Sardine Oil by Argentation Chromatography”, Kajal Chakraborty and R. Paul Raj J. Agric. Food Chem., ASAP Article DOI: 10.1021/jf071407r
[2] “The possible role of long-chain, omega-3 fatty acids in human brain phylogeny”, J G Chamberlain, Perspect Biol Med, 1996 vol. 39 pp. 436-45
“Evidence for the unique function of docosahexaenoic acid during the evolution of the modern hominid brain”, M A Crawford et la., Lipids, 1999 vol. 34 Suppl pp. S39-47}

The authors Eugene F. Barry (University of Massachusetts Lowell) and Robert L. Grob (Villanova University) discuss the development, performance, selection, and technology of columns for gas chromatography and include a handy list of packed column separations and guidelines for column selection in Appendices A and B. A subject index completes the book.

Book Description

Gas Chromatography (GC) is the most widely used method for separating and analyzing a wide variety of organic compounds and gases. There have been many recent advancements in both packed column and capillary column GC. With numerous options and considerations, selecting the right column can be complicated. This resource provides essential guidance for scientists and technicians, including:

• Methods of choosing both capillary and packed columns
• Selection of dimensions (column length, I.D., film thickness, etc.) and type of column
• Guidelines for proper connections of the column to the injector and detector
• United States Pharmacopeia and National Formulary chromatographic methods
• ASTM, EPA, NIOSH, and OSHA column selection specifications
• Information on the advantages of computer assistance in GC and multidimensional GC
• Comprehensive information on column oven temperature control

(more…)

135th Birthday

1. Happy Birthday Professor Tsvet!
2. Chromatogram on the ceiling
3. Colorgram
4. From Switzerland to Russia
5. The Little Botanists

I am continuing the series dedicated to the chromatography�??s founder Mikhail Tsvet. So, in 1897 he moves to Russia from Switzerland, and here is his first impression of Russia:

“…during the first six months that I have been in Russia, in vain, I have been trying to force myself to feel that I have a Russian heart beating in my chest! I traveled throughout Russia. I visited Moscow, the holly city, and my eyes and ears were widely opened… Nothing moved, nothing responded in me. In my homeland I felt like a foreigner. And this feeling deeply and desperately is weighing on my mind… Now I regret that I left Europe…”

(more…)

Here is what I found based on the last 60 days of statistics:

1. People used 1966 various search terms
2. The top 20 keywords are:

Top 20

Then I looked at the correlation between the search keyphrase and the landing page and discovered that very frequently people end up on the wrong pages.

For example, someone searched for “principles of chromatography” and Yahoo! took him/her to my home page where I may have talked about “principles of chromatography” a month ago but this post is no longer on the front page.

Here is another one. The search term was “soy milk bad reactions” and Google presented the person with “Soy Milk, Good or Bad? HPLC vs CZE - Part 2” - the post about a study that compares HPLC and CZE methods for QC of soy beverages.

Alas, because of my choice of the words for the title, this post attracts visitors that google with the keywords such as “soy milk is it bad or good”, “soy milk bad”, “bad reaction from soy milk”, “soy milk versus cow milk”, “soy milk good vs bad”, “soy milk is it bad for health” and etc. Obviously, these poor souls won’t find the answers to their questions from my comparison of HPLC to CZE, sorry!

So I decided to go through some of the unanswered questions and answer them one post at time, so next time someone searches for “types of hplc detectors” they won’t be staring at the post on “Iodized Table Salt“.

The physical properties of the semiconductor materials in each cell allow one to absorb light at longer wavelengths and the other to absorb light at shorter wavelengths. Researchers have made tandem solar cells before, but the vapor-deposition methods used to produce the multilayer structure have made the cells relatively expensive.

Jin Young Kim and colleagues now describe a cheaper method for making a tandem semiconducting polymer cell, in which all of the layers, including the electrode connecting the two units, are processed from solution. They used bulk heterojunction materials made from semiconducting polymers and fullerene derivatives.

The cell�??s efficiency exceeds 6 percent at illumination of 200 milliwatts per cm2, which is quite good for cells produced via an all-solution method.

Reference: “Efficient Tandem Polymer Solar Cells Fabricated by All-Solution Processing,” by J.Y. Kim et al.
DOI: 10.1126/science.1141711

This spring I had become an avid admirer of the young asparagus shoots. And practically everyday for breakfast I had steamed or, sometimes, boiled organic asparagus served with cold pressed flaxseed oil and a little bit of soy sauce.

The taste was incredible, and I could never get enough of it. I even “promoted” asparagus to my second most favorite vegetable (after the fresh green peas, of course) but then came the smell…

It took me a few days to confirm the pattern:

asparagus for breakfast –> 15 - 20 min later –> a pungent odor of rotten cabbage in urine.

I immediately assumed that there is something wrong with my metabolism because when I questioned my friends they had no clue what I was talking about it. None one them smelled anything unusual in their urinary discharge after consuming asparagus.

I never got around to research my “problem” until yesterday when I was reading “Carbon Tet” blog and I saw Greg’s post about asparagus. Well, it turns out that I am ok. In fact, I am the lucky one who has the enzyme to break down asparagusic acid found in young asparagus plants.

The asparagus odor “problem” was first described by a Scottish mathematician and physician John Arbuthnot (1667-1735). In his book published in 1731 he wrote:

“asparagus… affects the urine with a foetid smell (especially if cut when they are white) and therefore have been suspected by some physicians as not friendly to the kidneys; when they are older, and begin to ramify, they lose this quality; but then they are not so agreeable”.

And since then more than a dozen of a research work was published on the subject.

Two of the studies conducted in 1956 and 1987 revealed that about 40-43% of the United Kingdom population produced the odor. Other similar studies were undertaken in Israel and China but concluded that all individuals excrete odorous urine following asparagus ingestion; however, these investigations have been subjective, the urine was smelled by individuals.

But in 1987 Waring and colleagues [1] examined the volatiles above urine samples. GC/MS (Gas Chromatography / Mass Spectrometry) identified six compounds above the “smelly” urine samples that were absent in the samples without the odor: methanethiol, dimethyl sulfide, dimethyl disulfide, bis(methylthio)methane, dimethyl sulfoxide, and dimethyl sulfone.

Out of these six, the most pungent compounds methanethiol (CH3-S-H) and dimethyl sulfide (CH3-S-CH3) probably give most of the odor, but the presents of bis(methylthio)methane (CH3-S-CH2-S-CH3) and methylsulfonylmethane (CH3)2SO2 could add sweet aroma.

Of the many sulfur-containing compounds found in asparagus only asparagusic acid (1,2-dithiolane-4-carboxylic acid) and its derivatives may be reduced in the body to its free thiol form, which could be methylated and then be a substrate for thionase-β-lyase activity liberating methanethiol.

Dimerization of methanethiol would yield dimethyl disulfide, while methylation and subsequent sulfur oxidation would give dimethyl sulfide, sulfoxide, and sulfone.

References:
1. “The chemical nature of the urinary odour produced by man after asparagus ingestion.”, Waring RH, Mitchell SC, Fenwick GR., Xenobiotica. 1987 Nov;17(11):1363-71.

Technorati Tags: asparagus

Scientists from Georgian Institute of Technology created a prototype nanogenerator that can generate electricity inside a human body.

Tiny little devices traveling in our bloodstream while performing complete blood analysis and monitoring our well-being is the future of implantable biosensors. However, these nanorobots will need to be self-powered and there are two ways for achieving it - either to use a battery or to harvest energy from the environment.

Generating electricity “on-board” is a very attractive option for in vivo medical application because biological systems provide a great medium for converting chemical, thermal, or mechanical energy to electricity ensuring a lifetime operation.

Zhong Lin Wang and colleagues have developed a DC (direct-current) nanogenerator that converts mechanical energy into electricity. The basic principle is to use piezoelectric and semiconducting coupled nanowires (NWs), such as zinc oxide (ZnO). The nanogenerator used in the experiments was 2 mm2 and had a million of nanowires.

This nanogenerator has the potential of directly convert hydraulic energy in the human body, such as flow of body fluid, blood flow, heart beat, and contraction of blood vessels, into electric energy. But for now, a prototype of the nanogenerator is driven by ultrasonic waves through a metal frame suspended in air and creates a 25-35 nA current while submerged in 0.9% NaCl - a normal saline solution.

Reference: “Integrated Nanogenerators in Biofluid”, Nano Letters doi: 10.1021/nl0712567 S1530-6984(07)01256-8

Chemical reactions generally accelerate when temperature increase. However, in today’s issue of Science Magazine [1] a research group from France revealed a class of gas-phase reaction between oxygen atoms and alkenes that just do the opposite - the rate coefficients increase as the temperature is lowered.

Reactions of this sort may be taking place in interstellar clouds, which are difficult to study directly. Hassan Sabbah and colleagues have performed rate measurements between oxygen atoms and ethene, propene, 1-butene, cis-, trans-, and iso- butene over a range of temperatures from 20 to 300 Kelvin. Then they modeled the unusually rapid low-temperature rates, providing a theoretical framework for predicting reaction rates in systems that may be useful for understanding the chemistry of interstellar clouds.

1. “Understanding Reactivity at Very Low Temperatures: The Reactions of Oxygen Atoms with Alkenes”, doi:10.1126/science.1142373

In 2005, a group of researches from Italy analyzed water samples from the Po River in northern Italy for the presence of cocaine and its main urinary metabolite - benzoylecgonine (BE)[1]. They took samples each day for four different days and extracted cocaine and BE by solid-phase extraction followed by analysis on LC - MS/MS with electrospray ionization.

Though the concentrations of benzoylecgonine and cocaine in the river were small - 25 and 1.2 ng/L, it is equivalent to 4 kg of cocaine per day that flows down the river or 40,000 (!) doses per day based on a typical cocaine dose.

This year, Italian researches form the Institute for Atmospheric Pollution (IAP) theorized that if cocaine is in water, it could also be present in the air[2]. For example, cocaine seizures by the authorities and snorting can both release cocaine particles.

The group conducted a broad study of the composition of airborne particulates in Rome as well as the province of Taranto in southern Italy and the more remote location of Algiers.

Researches Angelo Cecinato and Catia Balducci from the IAP sampled inhalable air particles of diameter below 10 µm. The samples then undergone Soxhlet extraction followed by clean up on basic alumina column chromatography and analysis by Gas Chromatography Mass Spectrometry (GC/MS). (more…)

Nano Liquid Chromatography

1. Nano Liquid Chromatography - Reloaded
2. Definition of Nano Liquid Chromatography
3. Columns in Nano LC
4. Nano LC Sensitivity

As I mentioned in the last post from this series, capillary columns of 10–100 μm inner diameter are commonly used in nano-liquid chromatography setups. They are typically made either from fused silica or PEEK materials currently found in your everyday Gas Chromatography or HPLC, respectively.

There are three basic types of capillary columns used in nano-liquid chromatography: packed, monolithic, and open tubular.

Packed Capillary Column
Packed columns are made by “stuffing” the capillary with silica-modified particles of 3–5 μm. Though recently, particles of even smaller sizes 1.5–1.8 μm were successfully employed in ultra performance LC (UPLC).

Such a small particle size provides nano-liquid chromatography systems with higher efficiency, resolution, selectivity, and shorter analysis time; however, it does increase the backpressure.

Due to the high cost and limited types of stationary phases available, many research labs pack the columns “in-house”. But it is a difficult and skill-demanding process. The trick is to make the particles of the same diameter and to avoid undesirable void volumes.

So far, the application of packed capillary columns is the most explored option in nano-liquid chromatography.

Monolithic Capillary Column
Monoliths are a block of continuous materials made of highly porous rods with two types of pore structures (macropores and mesopores of different sizes), which allow the use of higher flow rates and thus reduces the analysis time.

Monolithic polymer columns were first used in the late 1980s, but monolithic silica columns did not become commercially available until 2000. Presently four types of monolithic capillary columns can be found: particle fixed, silica based, polymer based, and molecular imprinted monolith.

Up-to-date there is not much research information on application of monolithic capillary in nano-LC.

Open Tubular (OT) Capillary Column
In open tubular liquid chromatography column, the capillary wall is coated with highly permeable porous material that serves as the stationary phase.

The OT capillary has lower sample loading capacity of the column, because only a small surface area is available for analyte interaction that can result in column overloading causing peak asymmetry and poor efficiency.

Two-thirds of U.S. oil consumption is used to meet transportation energy needs, so unless there is a way to safely and efficiently store hydrogen on board a vehicle, it will be impossible to make a step forward to a hydrogen based economy.

Hydrogen Storage Methods

Presently there are three major directions in research and development of hydrogen storage systems:

• Gaseous Hydrogen - storing hydrogen as a gas in tanks under high pressure. Recently 10,000-psi tanks made of lightweight carbon-fiber�??reinforced composites have been demonstrated and certified; however, the energy content of hydrogen at even at 10,000 psi is only 1/8th of gasoline at the same volume.

• Liquid Hydrogen - storage of liquid hydrogen in cryogenic containers offers a significant advantage: more hydrogen can be stored in a given volume as a liquid than can be stored in gaseous form. A major drawback of liquid storage is a lot of energy required for liquefaction, plus the loss of hydrogen due to evaporation.

• Solid-state - storing hydrogen in metal hydrides, in complex hydride materials, and in nanostructured materials. Researchers believe that metal hydrides may represent ideal storage systems. An example of metal hydride would be sodium borohydride (NaBH4) that by produces hydrogen while reacting with water:

(more…)

]]> http://www.justchromatography.com/general/carbon-nanoscrolls-h2/feed http://www.justchromatography.com/organic-chemistry/translational-vibrational http://www.justchromatography.com/organic-chemistry/translational-vibrational#comments Thu, 21 Jun 2007 18:00:35 +0000 Chemist http://www.justchromatography.com/organic-chemistry/translational-vibrational Has anyone seen today’s issue of Science? There is a research paper by Shannon Yan and colleagues “Do Vibrational Excitations of CHD₃ Preferentially Promote Reactivity Toward the Chlorine Atom?” I had a difficult time following the authors - physical-molecular chemistry is not my strongest field, but nevertheless …

The study shows the energy of the moving molecules can unexpectedly promote a chemical reaction as effectively as the energy from within the chemical bonds. Until now, there has been a general assumption characterized as the Polanyi rules that the energy dynamics of reactions of small molecules with two and three atoms were simple - the vibrational energy of the bonds determines reactivity. However, a series of precisely controlled molecular collision experiments now challenges this model.

The P. Chem. scientist discovered that when CHD₃ collides with Cl atoms to form CD₃ and HCl, translational energy (produced by the movement of molecules in relation to each other) promoted the reaction as effectively as selective excitation of the C-H stretch vibration.

(DOI: 10.1126/science.1142313)

]]> http://www.justchromatography.com/organic-chemistry/translational-vibrational/feed http://www.justchromatography.com/yahoo-answers/response-factor http://www.justchromatography.com/yahoo-answers/response-factor#comments Thu, 21 Jun 2007 12:10:56 +0000 Chemist http://www.justchromatography.com/yahoo-answers/response-factor “What is the response factor in chromatography?” is a question on Yahoo Answers.

So far there has been two answers:

1) A wordy and a bit confusing text book reply tailored more towards Gas Chromatography.

Response Factor

The size of a spectral peak is proportional to the amount of the substance that reaches the detector in the GC instrument. No detector responds equally to different compounds. Results using one detector will probably differ from results obtained using another detector. Therefore, comparing analytical results to tabulated experimental data using a different detector does not provide a reliable identification of the specimen.

A “response factor” must be calculated for each substance with a particular detector. A response factor is obtained experimentally by analyzing a known quantity of the substance into the GC instrument and measuring the area of the relevant peak. The experimental conditions (temperature, pressure, carrier gas flow rate) must be identical to those used to analyze the specimen. The response factor equals the area of the spectral peak divided by the weight or volume of the substance injected. If the technician applies the proper technique, of running a standard sample before and after running the specimen, determining a response factor is not necessary.

2) This cute answer is from “Alright22″ who obviously had “hands-on” experience with chromatography - thin-layer chromatography of M&M candies.

It depends on the experiment. If you rub a green m & m into a solvent and place the filter into the solvent, the dye used to make the green will soak into the filter into bars of yellow and blue, and thus you will prove they are using yellow and blue dye to make green tints on m & ms. The response factor may be how quickly the result appears, or how much evidence is revealed, or how long the experiment will take.

So far these are all the answers received. Let’s see if anybody else would shine more light on the response factor in chromatography.

]]> http://www.justchromatography.com/yahoo-answers/response-factor/feed http://www.justchromatography.com/hplc/hplc-for-pharmaceutical-scientists http://www.justchromatography.com/hplc/hplc-for-pharmaceutical-scientists#comments Wed, 20 Jun 2007 15:37:14 +0000 Chemist http://www.justchromatography.com/hplc/hplc-for-pharmaceutical-scientists “HPLC for Pharmaceutical Scientists” is a new hardcover book edited by Yuri V. Kazakevich and Rosario LoBrutto with a price tag of $159 at Amazon.

This is an excellent book for both novice and experienced pharmaceutical chemists that provides a unified approach to HPLC with a balanced treatment of the theory and practice of HPLC in the pharmaceutical industry.

The book spells out the role of HPLC throughout drug development process from drug discovery to quality control and manufacturing and gives detailed specifics of HPLC application in each stage of drug development.

The text also covers the latest advancements and trends in hyphenated and specialized HPLC techniques (LC-MS, LC-NMR, Preparative HPLC, High temperature HPLC, high pressure liquid chromatography).

Here is a detailed review by Ira Krul from Northeastern University. (more…)

]]> http://www.justchromatography.com/hplc/hplc-for-pharmaceutical-scientists/feed http://www.justchromatography.com/general/trusting-chinese-meds http://www.justchromatography.com/general/trusting-chinese-meds#comments Mon, 18 Jun 2007 13:00:37 +0000 Chemist http://www.justchromatography.com/general/trusting-chinese-meds …well, the prescription ones at least. With Chinese manufacturers considering to increase exports of drug ingredients and perhaps even begin shipping finished drug products to the United States, an article “Trusting medicine from China: Close FDA scrutiny of Chinese pharmaceutical ingredients extends only to those for prescription drugs” in Chemical & Engineering News (C&EN) questions allegations that foreign-made ingredients often are manufactured in factories that have never been inspected by the U. S. Food and Drug Administration (FDA). (more…)
]]> http://www.justchromatography.com/general/trusting-chinese-meds/feed http://www.justchromatography.com/nano-hplc/nano-lc-definition http://www.justchromatography.com/nano-hplc/nano-lc-definition#comments Mon, 18 Jun 2007 04:09:43 +0000 Chemist http://www.justchromatography.com/nano-hplc/nano-lc-definition

Nano Liquid Chromatography

1. Nano Liquid Chromatography - Reloaded
2. Definition of Nano Liquid Chromatography
3. Columns in Nano LC
4. Nano LC Sensitivity

It is interesting to note that 20 years later there is still no clear definition of nano-LC. Due to a relatively large size of the columns used in nano-HPLC (10-140 μm), the method does not fall within the realm of the conventional definition of nanotechnology - “the control of matter on a scale smaller than 1 micrometre”.

However, most researches subscribe to the view expressed in the article “Instrumental Requirements for Nanoscale Liquid Chromatography” (DOI: 10.1021/ac9508964). The authors suggested the definition based on the flow rate range rather than the inner diameter of the tubing or its material. They proposed that the liquid chromatography method that uses packed microcolumns with 10-150 μm ID and flow rates of 10-1000 nL/min to be classified as nano-LC.

Names and Definitions for HPLC Techniques

Desciption	ID	Flow Rate
Nano HPLC	10-150 μm	10-1000 nL/min
Capillary HPLC	150-500 μm	1-10 μL/min
Micro HPLC	0.5-1.5 mm	10-100 μL/min
Mirobore HPLC	1.5-3.2 mm	100-500 μL/min
Conventional HPLC	3.2-4.6 mm	0.5-2.0 mL/min
Preparative HPLC	>10 mm	> 20 mL/min

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]]> http://www.justchromatography.com/nano-hplc/nano-lc-definition/feed http://www.justchromatography.com/nano-hplc/nano-lc-intro http://www.justchromatography.com/nano-hplc/nano-lc-intro#comments Sun, 17 Jun 2007 19:08:21 +0000 Chemist http://www.justchromatography.com/nano-hplc/nano-lc-intro

Nano Liquid Chromatography

1. Nano Liquid Chromatography - Reloaded
2. Definition of Nano Liquid Chromatography
3. Columns in Nano LC
4. Nano LC Sensitivity

Thanks to one of the readers of this blog - Farooq, I now have the full text of an excellent, 21-page review by the researches from Rome and Spain entitled “Recent applications in nanoliquid chromatography” (DOI 10.1002/jssc.200700061).

Two months ago, I did a small article about nano liquid chromatography to answer a question posted on Yahoo Answers but after reading “Recent applications in nanoliquid chromatography” I wanted to revisit the topic in more depth, so I think I am going to make this post into a series - “Nano Liquid Chromatography”

Introduction

“Nano” has recently become a very trendy word in science and technology and most of us think of nanotechnology as something very modern and new, so it is hard to imagine that nano HPLC method emerged almost 20 years ago.

In 1988 Karl Karlsson and Milos Novotny published a paper “Separation efficiency of slurry-packed liquid chromatography microcolumns with very small inner diameters” (DOI 10.1021/ac00168a006) where they reported extremely high efficiencies with micro LC columns that had the inner diameter (ID) of 44 micrometers.

Since that time great efforts have been made to miniaturize LC instrumentation by carrying out theoretical, technological, and methodological studies. Presently nano-liquid chromatography is widely used as a complementary separation technique to conventional LC, providing a great number of important applications especially in proteomics.

Next in series
]]> http://www.justchromatography.com/nano-hplc/nano-lc-intro/feed http://www.justchromatography.com/history/switzerland-russia http://www.justchromatography.com/history/switzerland-russia#comments Fri, 15 Jun 2007 04:01:49 +0000 Chemist http://www.justchromatography.com/history/switzerland-russia

135th Birthday

1. Happy Birthday Professor Tsvet!
2. Chromatogram on the ceiling
3. Colorgram
4. From Switzerland to Russia
5. The Little Botanists

This is the next post from the series dedicated to 135th birthday anniversary of Prof. Tsvet, the chromatography’s founder.

Today, the application of the principle of a chromatographic substance separation is the foundation of many breakthroughs in science and technology. The analysis of the amino acid and nucleotide sequence in proteins and nucleic acids, the isolation and purification of antibiotics and the variety of other substances are all based on the chromatographic separation.

The same principle is employed in the separation of radioactive isotopes and, hence, is used in the making of nuclear weapons and nuclear power plants…

People observed “substance separation” on leaky ceilings many times before Tsvet. So, why was he able to turn these observations into a powerful modern method of substance separation? (more…)

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]]> http://www.justchromatography.com/history/switzerland-russia/feed http://www.justchromatography.com/biochemistry/toxic-waste-eating-bacteria http://www.justchromatography.com/biochemistry/toxic-waste-eating-bacteria#comments Thu, 14 Jun 2007 18:00:10 +0000 Chemist http://www.justchromatography.com/biochemistry/toxic-waste-eating-bacteria New research on sulfate-reducing bacteria may offer good news for bioremediation efforts to clean up acid mine drainages and other environments with high levels of harmful metals.

Sulfate-reducing bacteria is known to extract metal dissolved in anoxic waters and by isolating it into nanoscale particles. But, the tiny size of these particles (2-6 nm) makes them highly mobile and under the right conditions they can quickly redissolve.

Previous research work showed that some organics can promote aggregation of the nanoparticles which induces settling and thus decreased their solubility. John Moreau and colleagues hypothesized that natural organic matter contributes to the formation of densely aggregated nanoparticulate zinc sulfide (ZnS) spheroids.

The research team studied biofilms of sulfate-reducing bacteria collected from a flooded lead and zinc mine in Wisconsin. They report that metal-sulfide nanoparticles produced by these bacteria form aggregates that contain trapped metal-binding polypeptides and proteins, keeping the particles stuck within the biofilm and limiting their dispersion in the environment.

The research is published in June 15 issue of Science - “Extracellular Proteins Limit the Dispersal of Biogenic Nanoparticles”.

]]> http://www.justchromatography.com/biochemistry/toxic-waste-eating-bacteria/feed http://www.justchromatography.com/general/plastic-that-grows http://www.justchromatography.com/general/plastic-that-grows#comments Thu, 14 Jun 2007 17:59:29 +0000 Chemist http://www.justchromatography.com/general/plastic-that-grows A chromium catalyst is the key to efficiently converting glucose to a chemical feedstock with potential to replace many uses of crude oil including pharmaceuticals, cosmetics and plastics, scientists from Pacific Northwest National Laboratory report. As the world tries to emancipate itself from its oil addiction, researchers are seeking a clean, efficient and cost effective process that uses renewable biomass.

Hydroxymethylfurfural, or “HMF,” is a promising compound which is conventionally prepared from fructose using acid catalysts which, unfortunately, causes various side reactions, significantly increasing the cost of product purification.

Haibo Zhao and coauthors converted fructose and glucose to HMF in acid-free conditions by experimenting with 19 different metal halide catalysts such as CrCl₂ (chromium (II) chloride), CuCl₂ (copper (II) chloride), VCl₂ (vanadium (II) chloride) in a sugar-solubilizing ionic liquid solvent - 1-alkyl-3-methylimidazolium chloride.

Twelve of the metal halides tested showed 40% conversion of glucose, but only one catalyst, CrCl₂ (chromium (II) chloride), gave HMF in high yield and produced very little byproduct of levulinic acid.

Reference: “Metal Chlorides in Ionic Liquid Solvents Convert Sugars to 5-Hydroxymethylfurfural,” by H. Zhao, J.E. Holladay, H. Brown and Z. Conrad Zhang at Pacific Northwest National Laboratory in Richland, WA

#########

Here is the press-release from Northwest National Laboratory in Richland:

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]]> http://www.justchromatography.com/general/plastic-that-grows/feed http://www.justchromatography.com/biochemistry/organic-oxygen http://www.justchromatography.com/biochemistry/organic-oxygen#comments Tue, 12 Jun 2007 12:29:49 +0000 Chemist http://www.justchromatography.com/biochemistry/organic-oxygen A simple, cheap treatment using just oxygen could allow organic produce growers to store their crops for longer and go a long way towards reducing the price of organic fruit and vegetables.

I admit that I am into organic produce but mostly because it tastes better and fresher than the conventionally grown fruits and vegetables and not because I am a health freak. The big downside is the price. Currently I pay around twice as much for organic. This price difference comes from the large losses that organically grown crops sustain during storage. Conventional produce can be treated with inexpensive chemicals to aid preservation, but these cannot be used for organic produce. (more…)

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