Newsletter 4/2000, the latest news in chemical analysis and testing at WCAS.

Gas Analysis

The composition of gasses is important for a wide variety of applications:

Blisters or bubbles in plastics,
Head space in products,
Combustion products,
Medical and electronic devices,
Composition of gas mixtures,
Purity of gasses in manufacturing,
Fermentation processes,
Purity of gasses in hospitals

The composition of gasses in a system can indicate whether the system has developed a leak, oxidation or some other chemical reaction has occurred, or if the system has been correctly handled. Bubbles can develop in products through electrolysis, oxidation, or microbiological action. Many processes require accurate control of the atmospheres. The identity and purity of gasses in hospitals, manufacturing, medical devices, and products is very important.

By injecting a sample onto two different columns with two different detectors both the fixed gasses (N2, O2, CO, CO2, CH4) and hydrocarbons (C1-C9) can be determined. The fixed gasses are chromatographically separated on a molecular sieve column. Helium is used as the carrier gas for nitrogen, oxygen, carbon monoxide, carbon dioxide, and methane. For the analysis of hydrogen and helium, argon is used as the carrier. Detection limits using a thermal conductivity detector are typically

0.01% by volume. In addition to the fixed gasses, hydrocarbons such as methane, ethane, ethene, and others up through C9 are separated on an alumina column. Normal-, iso-, saturated and unsaturated hydrocarbons can be separated up through C5. Each component is detected using a flame ionization detector with detection limits for hydrocarbons of approximately 1 ppm. Click here for more information on gas analysis.

Cr(VI) and Permanganate

When using EPA 7199 (ion chromatography coupled with post column colorimetric detection), we have seen an interference when high levels of permanganate are present in a sample. Of course almost any type of colored species may interfere with the more traditional colorimetric analysis such as EPA 7196 offered by most other labs.

With the addition of ion chromatography in 7199, such interferences are minimized. Even so, large concentrations of permanganate do interfere. This interference appears to be due to a reaction of permanganate with the post-column reagent that gives a colored species with much less absorbance at 540 nm than either permanganate itself or the complex of chromium species with the post-column reagent. Thus permanganate causes a problem in 7199 when permanganate is

present in great excess over the chromate species.

We now have found conditions which further reduce this interference. Using a different anion column, such as that used for EPA 300.0 to separate common inorganic anions, we have been able to separate permanganate and chromate. Detection with suppressed conductivity gives a detection limit of 0.1 ppm. An actual field sample rich in permanganate which gave a result of over 300 ppm Cr(VI) by EPA 7199 gave a result of 2 ppm by this method with an average recovery of a matrix spike of 96%. Further work is ongoing to achieve lower detection limits using post column colorimetry and to document interference levels.

Click on hexavalent chromium for more information.

Fungi and Indoor Air Quality Issues

by Sharon Harney, Ph.D., Microbiology Lab Supervisor, Forensic Analytical, 310.763.2374, Guest Article

With the increasing concern over indoor air quality and ‘sickbuilding syndrome’ has also come an interest in fungi, both as a allergenic agent and as a indicator of construction defect or building maintenance issues.

The fungi, commonly known as moulds (or molds), make up the kingdom Eumycota, an extremely large group of organisms, with over 70,000 species described. When including undescribed species, it is estimated that there are between 1-1.5 million species. Fungal types most frequently encountered in air quality studies include zygomycetes, ascomycetes, basidiomycetes, and hyphomycetes.

Medically, fungi are responsible for a number of diseases and allergies. Pathogenic portions of fungi include spores, which can cause allergic responses, and mycotoxins, metabolites produced by fungi which can be poisonous in low doses. Mycotoxigenic poisoning can be very severe and result in death. Trichothecenes, a large group of mycotoxins, are produced by a number of fungi, including Stachybotrys chartarum and a number of Fusarium species. Aflatoxins are another large group of mycotoxins that are produced by Aspergillus species. Aflatoxins have been reported as mutagenic and carcinogenic.

Other common genera of fungi that produce mycotoxins include Penicillium, Pithomyces, Cladosporium and Alternaria. While several fungi cause disease in otherwise healthy individuals, most fungal diseases are more often associated with immunosuppressed individuals.

Environmentally, fungi are capable of degrading a wide range of substrates, including dead and live plant material, paper, wood, food products, clothing material, etc. Fungi are the major decomposers of wood and wood products. As such they become an added concern in indoor air quality issues when mold growth may not only be making building occupants ill, but may also be degrading the structural integrity of the building. This then compounds a medical issue by adding a potential real property cost or loss. As a group, the fungi can colonize almost every substrate. Growth requirements vary between fungi. Most fungi have a fairly high humidity requirement, but there are a number of xerophilic species that require very little water. As long as there is a carbon and nitrogen source, it is pretty certain that under the appropriate environmental conditions, a fungus can grow. Determining what, where and why mold is growing is the first step toward resolving a fungal exposure issue. As there are no regulatory levels or standards for fungal investigation and evaluation, your best allies in designing and executing an effective investigation are an experienced mycologist and consultant.

FDA and Aluminum

Aluminum (Al) is of concern in dialysis fluids and in some drugs for injection. While blood levels are normally 0-2 痢/L, dialysis patients have elevated levels of aluminum, >20 痢/L. Early links of aluminum to Alzheimer’s disease are currently thought to be unimportant.

FDA has established a 25 痢/L limit for products used in total parenteral nutrition (TPN) therapy. Manufacturers of large volume parenterals (LVPs),

small volume parenterals (SVPs), and pharmacy bulk packages (PBPs) used for TPN therapy must submit validated methods for monitoring aluminum to FDA by January 26, 2001 [Federal Register 65, No.17, January 26, 2000].

WCAS has validated test methods for aluminum. We test for aluminum in a variety of biological, pharmaceutical, and environmental samples using ICPMS. Detection limits are usually in the 1-10 痢/L range depending on the sample type.

Laboratory Tidbits

The AAPS Meeting and Exposition is being held in Indianapolis, Indiana this year from October 29 thru November 2. Eric Lindsay and Craig Hechanova are planning to be manning our booth which will be number 1435. We will be taking orders for our new CD which has our QAM, web site, fee schedules, and many other items that you have asked for. You can also put your card in for a new give away that we will have at the show. Hope to see you all there!

Web site changes are always happening at www.wcas.com! We have just enhanced the navigation to make it easier to get around. We are also continuously adding new technical articles. Please check it out!

We are sponsoring the ACS meeting on November 16. John Dolan will be speaking on LC troubleshooting horror stories. You can get more information at their web site at www.scalacs.org.

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Scott Stone