Segmented Flow, Flow Injection and Discrete Analyzers

Autoanalyzers

2011-08-03T19:24:00.000-07:00

I'm curious as to the future of the wet chemistry auto analyzer. It is a decent technique that revolutionized the laboratory industry back in 1957. Currently, I see a dwindling of the technique with replacement by discrete analyzers and ion chromatography, however, fully automated methods that cannot be don by discrete or IC will demand a flow analyzer. These methods are cyanide, phenols, surfactants, total nitrogen, and total phosphorus.

Comments?

Am I missing the obvious?

2011-06-07T19:20:00.001-07:00

I thought I was being perfectly clear in all the articles on the difference between available, WAD, and CATC cyanide. The difference is, there is no difference. These are not "method defined" analytes. These are a class of cyanide compounds pertaining to some well defined metal-cyanide complexes. These complexes are cyanide bound to the following metals, zinc, cadmium, mercury, nickel, copper, and silver. Also included in the definition is any cyanide that exists as the anion or the acid in solution.

Just because the WAD and CATC methods incompletely recover some of the above mentioned complexes does not make the results of these methods "method defined", instead, it makes the results of these methods inaccurate. There is but one correct number to get when you desire to measure the cyanide concentration that contains weak and dissociable cyanide. The only accurate way to get this result is ligand exchange gas diffusion Amperometry known as OIA1677. This result is the correct number if WAD or CATC disagrees with OIA-1677.

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Accuracy in Chemical and Environmental Analysis

2011-05-30T11:45:00.001-07:00

I used to be in the mineral assay business. You know, said mineral is of some purity and it is your job to determine the concentration of the major and minor elements in the material. If it is a whole rock analysis you expect the total of the sum of the constituents, usually as oxides, to equal somewhere near 100%. a good assay may be 99.5 - 100.25%. you can see that 1% error is tolerable, but 10% error is a disaster.

The sampling was important too. What good is an extremely accurate assay if you merely walked up to a pile of rock and grabbed some? Elaborate sampling schemes were created so that representative samples, sometimes weighing tons, were brought back to the lab. These samples were crushed, split, crushed, split, and mixed until a small envelope remained. The powder in this small envelope represented the entire mountain of rock that was sampled. Accuracy of your sampling and analysis is verified by similar sampling and analysis at other laboratories, sometimes half way across the world. It was not uncommon for results to agree within a few tenths of a per cent.

Enter environmental testing. Regulations are the driver; not a cost of raw material. The accuracy of your environmental result is judged by the laboratory QA/QC program. And no one seems to pay attention to the sampling at all. In the environmental testing world, there is great scrutiny on the laboratory. The method must be followed to the letter, all QC checks must be done, and in control before results can be reported. The sample and testing must be traceable all the way from collection to disposal. This includes where that little bottle has been, who had it, what temperature it was at, who withdrew aliquots, who processed it, who tested it, who reviewed the testing, etc. Without this information, well, people have gone to jail. But how accurate is this data? I mean, who sampled it and how? Are laboratory analysts under undue pressure to accurately analyze samples that do not even represent that which was supposed to be sampled? Does a precise/accurate analysis of a scoop of dirt from a contaminated field statistically represent the contamination in the field, or does it only represent the contamination in that scoop? Is there sample homogenization occurring during sampling or even prior to subsampling, or does the lab procedure merely require grabbing a scoop from the top of a jar?

What about water, and Wastewater effluents? Does a grab sample from a pipe represent a 24 hour process? Does a 24 hour composite truly reflect the releases of an entire month? Were the analytes stable as they were being collected and stored, or do their concentrations change with time? Are the required sample preservation techniques valid, or were they arbitrarily created using limited data and a few sample matrices?

These are just some questions that I have been toiling with over the past few months. It seems to much emphasis is placed on analysis without much concern whether the analysis truly represents what is being analyzed. Sure, it's always easy to continue on without questioning, but if you do not question it is not science.

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A Flow Injection Analyzer

2010-12-29T20:22:00.001-08:00

The OI Analytical FS3100 FIA

www.oico.com

Cyanide Analysis, Quick and Accurate

2008-11-07T12:06:00.000-08:00

Analyze Cyanide Quickly, and Accurately.

Stop wasting time distilling samples and fill your wallet with cash!

Finally an amazingly simple way to measure cyanide in your laboratory and double or triple profits immediately.

Are you tired of wasting time and spending money on time-consuming, inaccurate, distillation bottlenecks?

How about sample throughput? Are you sick of your inability to expand by increasing workloads?

Are your clients getting ahead of you, or charging less effectively stealing your business because you can’t keep up?

The secret that will save you money is the OI CNSolution. Its unique capability of analyzing for all forms of cyanide without time consuming and costly distillations eliminates distillation and minimizes interferences producing more reliable results and allowing faster turn around times.

Even if Distillation is required, Gas diffusion – amperometry is superior.

The colorimetric methods used in most laboratories require determining total cyanide after distillation by EPA 335.4 or SM4500. The OI CNSolution has been proven more accurate than colorimetric methods.

The low cost of operating the Gas Diffusion - Amperometric FIA instruments allows dischargers to frequently monitor their processes making it possible to quickly detect problems before they can cause serious ecological damage. Routine daily, or even hourly, testing can be realistically implemented so that exact cyanide discharge levels can be accurately known.

The OI CNSolution saves you time.

Aquatic Free Cyanide

Cyanide is about 1000 times more toxic to aquatic life than it is to humans. For this reason, it is important that free cyanide be measured in fragile aqueous environments. Free Cyanide is defined as the amount of HCN that is liberated from a solution at pH 6.0, and should only measure cyanide present in solution as HCN or as CN-.
The OI CNSolution accurately measures aquatic free cyanide by ASTM D7237-06.

The only automated method for free cyanide!

Simple Cyanide Compounds

Simple Cyanides are the readily soluble salts of cyanide such as sodium, potassium, and calcium and along with free cyanide are the only cyanide complexes likely to be present in Drinking Water.
The OI CNSolution accurately measures free cyanide in drinking water by OIA1677-DW or ASTM D6888-04. These flow injection methods are the only interference free approved methods for the determination of cyanide in drinking water that do not require time consuming and expensive preliminary distillations.

Time – consuming distillation is not required!

The OI CNSolution may also be used to accurately measure simple cyanide in milk, assorted beverages, and food extracts.

No distillation required!

Weak and Moderately Strong Metal-Cyanide Complexes

Weak to moderately strong metal-cyanide complexes are compounds that could readily release hydrogen cyanide gas from an acid. Weak Acid Dissociable (WAD), Cyanide Amenable to Chlorination (CATC), and Ligand Exchange methods have been devised in an effort to quantify these complexes.

Do you consistently get false positives or false negatives?

It’s not your fault it’s the methods fault!

CATC and WAD methods, and all distillation colorimetric methods for cyanide are proven inaccurate!

Simply changing your method will solve everything!

The OI CNSolution accurately measures Available Cyanide in wastewater by OIA1677 or ASTM D6888-04, and in ore processing and related metallurgical materials. Gas-diffusion Amperometric flow injection methods are the only interference free approved methods for the determination of available cyanide in wastewater that do not require time consuming and expensive preliminary distillations.

CATC and WAD Cyanide without distillation!
Get results within minutes instead of hours or days!
Increase Capacity up to hundreds of samples per shift!
Dramatically Increase Profits!

Strong Metal - Cyanide Complexes

Commonly known as "total" cyanide and defined by the USEPA as cyanide ion and complexes converted to hydrogen cyanide gas by reflux distillation in the presence of strong acid and the magnesium ion. Methods for the analysis of "total cyanide" include ferrous and ferric complexes along with all other previously mentioned forms. Thiocyanate or cyanate ions are not included.
Colorimetric post distillation OI CNSolution precisely measures cyanide in distilled samples according to EPA 335.4. This flow analysis method is currently the only approved method for the determination of total cyanide in wastewater samples.

EPA 335.4 and SM 4500 methods are inaccurate!

Years of testing and experiments have demonstrated that distillation and colorimetric methods of cyanide analysis do not accurately yield quantitative, or even qualitative, results in samples with complex matrices.

It has been shown that sulfide interferes significantly. Abundant literature references of efforts to minimize sulfide interference have been found to be ineffective.

The only accurate way to determine post - distillation total cyanide in sulfide bearing samples is to use the OI CNSolution in accordance with ASTM D7284-08.

Distillation is time-consuming and introduces error.

Even with post distillation Gas-Diffusion Amperometric Flow Injection Analysis it is not possible to determine total cyanide in complex samples that contain combinations of, or all of, the following ions; thiosulfate, sulfite, nitrate, nitrite, thiocyanate, and peroxide. The US 40CFR mentions that it is not possible to determine cyanide after distillation from samples containing thiosulfate or sulfite.

Eliminating distillation improves results!

The only method that determines total cyanide in these complex matrices is the Non-distillation OI CNSolution.

The UV irradiation gas-diffusion amperometry method uses low temperature, low strength UV technology to selectively disassociate cyanide ions from metal complexes while not allowing the simultaneous destruction or creation of cyanide that is common with high heat distillations.
The OI CNSolution accurately determines true total cyanide rapidly and without distillation.

Total Cyanide Results in minutes, not hours or even days!

Dramatically increase profits – no unnecessary labor costs.

Quit waiting around and decrease TAT

Continuous Flow Analysis

2006-10-14T18:37:00.000-07:00

Segmented Flow Analysis
Flow Injection Analysis
Discrete Analyzers

Geochem is an expert at Segmented Flow Analysis (SFA), Flow Injection Analysis (FIA), Discrete Analyzers, manual chemistry methods, ICAP-AES, IC, GC, GC-MS, Quality Control/ Quality Assurance of Chemical Measurements, and commercial laboratory management. Post questions regarding these topics for expert advice.