Newsletter 3/2000, the latest news in chemical analysis and testing at WCAS.

Perchlorate

Salts of perchlorate are used in the explosives and pyrotechnics industry. Perchlorates are strong oxidants, one of the primary oxidants used in solid rocket fuel. The automotive, agricultural, biomedical, and explosives industries all have an interest in sensitive assays for this anion.

Perchlorate binds tightly to many ion

exchange columns. The chromatogram below shows the chromatography on a Dionex AS16 column with 35 mM sodium hydroxide. The sample is the EPA PT test sample having a conductivity of 470 猶/cm. Most common anions are not retained in this system, and elute in the large peak at 3-8 min. The detection limit is 2 痢/L in drinking water. Samples with high
conductivity need dilution prior to analysis.

Perchlorate - An Update

Perchlorate has become an important environmental contaminant. A by-
product of the explosive industry, it has been detected in groundwater in numerous locales. Currently EPA is especially interested in monitoring perchlorate in drinking water supplies

and has submitted Performance Evaluation samples to several laboratories. WCAS passed and is now EPA approved for perchlorate. For more information please contact Jack Northington at WCAS (562.948.2225,
ext. 103 or jack.northington@wcaslab.com), or Daniel Hautman at the EPA
(513.569.7274).

OVI per USP <467>
- An Update -

As of August 1, 2000 per the Pharmacopeial Forum, Volume 26, Number 4, benzene is no longer included in Table 1 of Method <467>, Organic Volatile Impurities (OVI). Benzene may still be required in specific monographs.

There are many different solvents which are used in pharmaceutical manufacturing. USP now mandates that at least four of these solvents be monitored in finished products: chloroform, 1,4-dioxane, methylene chloride, and trichloroethylene. Currently, five methods are in place under <467>.

These are Methods I, IV, V, VI, and a method for methylene chloride in coated tablets. These methods all use gas chromatography (GC) to measure the levels of the compounds of interest, but allow GCMS to confirm identity in complex chromatograms. Methods II and III were removed between USP 22 and 23. Methods for ethylene oxide are given in each individual monograph, not in <467>.

Methods I, V and VI are direct injection

methods, where the sample is dissolved in water (or other suitable solvent) and directly injected into the GC. They differ primarily in the GC column and conditions used for analysis. Method IV, and the method for methylene chloride in coated tablets, are headspace methods. The sample is dissolved in a solvent and heated (usually to 80蚓), then an aliquot of headspace is injected.

Methods II and III from USP 22 were purge-and-trap methods. This involves dissolving a portion of sample in water, then purging with helium to transfer the volatiles to the vapor phase. They are then trapped using a sorbent trap. When purging is complete, the trap is
rapidly heated and the volatiles swept into the GC column. Method II used
GC, while method III used GCMS.

All of the numbered methods are designed to determine the amount of the solvents listed above. However, many other solvents can also be measured. At WCAS, we have used these methods to analyze for the presence of acetonitrile, isopropanol, ethyl acetate, toluene, methanol,
dimethylformamide, and many others. Please call Eric Lindsay at ext. 300
if you have any questions.

Chemistry on the Web

Recently we discovered that you can search multiple infrared (IR) spectroscopy libraries using a variety of file formats. At ftirsearch.com, you can upload an IR scan and find the closest
matches in the libraries. Or you can search the library for a spectrum of a chemical. The libraries include the Sigma and Aldrich libraries as well as several polymer and forensic libraries. Check out the free demo.

ACD Labs has released a new version of there freeware chemical structure drawing tool ChemSketch. Download it at www.acdlabs.com. Add-ons include a tool to convert 2D structures to 3D.

One of our favorite sites is STN Easy for searching scientific literature. It’s extremely easy to use, and you can view or order copies of full journal articles on-line. www.stneasy.cas.org

Fourier Transform Infrared Spectroscopy (FTIR)

Fourier Transform Infrared Spectroscopy (FTIR) is a powerful tool for identifying types of chemical bonds in a molecule by producing an infrared absorption spectrum that is like a molecular “fingerprint”. FTIR is most useful for identifying chemicals that are either organic or inorganic. It can be used to quantitate some components of an unknown mixture and can be applied to the analysis of solids, liquids, and gasses. The term Fourier Transform Infrared Spectroscopy refers to a fairly recent development in the manner in which the data is collected and

converted from an interference pattern to a spectrum. Today’s FTIR instruments are computerized which makes them faster and more sensitive than the older dispersive instruments.

FTIR can be used to identify chemicals from spills, paints, polymers, coatings, drugs, and contaminants. FTIR is perhaps the most powerful tool for identifying types of chemical bonds (functional groups). The wavelength of light absorbed is characteristic of the chemical bond as can be seen in the annotated spectrum at the right.

For more information, click on FTIR.

DEHP, Candle Wicks, and Lead

DEHP (diethylhexyl phthalate) and lead (Pb) continue to receive attention as environmental and health hazards. DEHP is a plasticizer used commonly in PVC plastics to make it soft and flexible. PVC is in very common use in everything from power cords and computer cables to furniture and medical devices. DEHP is only one of several types of phthalates used by the plastics industry. PVC plastics are widely used in medical devices such as catheters and IV sets. According to Wired News (July 18, 2000), a recent

government panel expressed "serious concern” that critically ill male infants who are exposed to DEHP during medical treatments may suffer harm to reproductive organs.

Pb may also be a component in some PVC plastics. Several recent Prop. 65 filings cite exposure to Pb from brass keys, locks, and other hardware as well as PVC coated cables and wires. Pb keeps showing up in strange places. Most people are aware that some glass and ceramics may contain Pb, but did you know that some candle wicks contain significant Pb levels?

Laboratory Tidbits

Sample volume requirements are very important for most tests. If you are
sending samples and are not sure how much sample to send please give us a
call. Although there are method modifications we can perform, these could compromise the test and raise the detection limits. Sending the right
amount of sample in the first place will save you a lot of time and money.
Ask for Eric at ext. 300 or Craig at ext. 302 and they will tell you how much sample to send for your tests or full monographs.

AAPS Annual Meeting and Exposition will be in Indianapolis, Indiana this year from October 29 to November 2. We will be exhibiting at
booth 1435 and hope to see a lot of you there. If all goes according to plans we should have our free CD-ROM available at the exposition. It will contain our Quality Assurance Manual, pertinent SOPs, a complete copy of our web site, our fee schedules, and many other items that we feel will benefit our clients. If you would like one sent to you call Eric at ext. 300 or Mary at ext. 301.

Quick Quotes

The impersonal hand of government can never replace the helping hand of a
neighbor.
Hubert H. Humphrey

I can't make people like me, but if I wasn't me, I would like me.
Third-grader

You can make more friends in two months by becoming interested in
other people than you can in two years by trying to get other people
interested in you.
Dale Carnegie

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