Susan L. Head

Use of reference pools to compare the qualitative and quantitative determination of polychlorinated biphenyls by packed and capillary gas chromatography with electron capture detection. Part 1. Serum

Serum for reference pools of in vivo polychlorinated biphenyls (PCBs) was obtained from four goats that had received one dose (100 mg kg-1) of a selected technical Aroclor (AR) (1016, 1242, 1254 or 1260) and were allowed to recover for 30 d. These pools were used to assess the differences in an analytical method that determines and quantifies PCBs using packed-column gas chromatography (PCGC) (quantified on the basis of mean mass percent. data for grouped PCB peaks) and capillary-column gas chromatography (CCGC) (quantified on the basis of percent. composition data for specific congeners). With CCGC, results were statistically significantly different (p less than or equal to 0.0002) from results with PCGC for ARs 1016, 1242 and 1254 but not for AR 1260 (p = 0.23). When comparing these gas chromatographic methods using bovine serum spiked in vitro with the same ARs at 17-25 p.p.b., it was found that the methods were not statistically significantly different for any of the ARs (p = 0.30-0.92). Levels of serum PCB determined by the two methods for 12 persons, divided into two groups according to exposure, were compared using the paired t-test. Group 1 consisted of three persons with dietary and/or environmental exposure; one with dietary and/or environmental exposure in addition to occupational exposure dating back 20 years. Group 2 consisted of eight persons with recent occupational exposure.(ABSTRACT TRUNCATED AT 250 WORDS)

Comparison or Two Deproteinization Methods for the Determination of DDT and DDT Metabolites in Serum

Abstract The quantitative determination of dichlorodiphenyltrichloroethane (DDT) and DDT metabolites in the parts-per-billion range was compared by using methanol deproteinization and formic acid deproteinization methods. The methanol deproteinization method gave higher recoveries of fortified (in vitro) serum than the formic acid method. The methanol deproteinization method also gave excellent precision in the analyses of DDT and DDT metabolites in human serum that contained either in vivo bound or in vitro fortified DDTs.

Determination of Phenols and Cresols in Urine by Gas Chromatography

Abstract A rapid, simple, and sensitive method was developed for the determination of three cresol isomers and phenol in urine. The sample was spiked with m-chlorophenol, as internal standard, and hydrolyzed with sulfuric acid at ambient temperature. The hydrolyzed solution was saturated with ammonium sulfate and extracted with ethyl acetate. The extract was injected without derivatization into a gas chromatograph fitted with a flame ionization detector and a glass column packed with 0.1% SP 1000 on Carbopack C. All four analytes, which eluted within 13 minutes, were quantified from standard curves. The method was evaluated by analysis of spiked urine pools from laboratory workers and samples of urine from workers in a coal gasification plant.

Problems associated with interferences in the analysis of serum for polychlorinated biphenyls

During a recent survey to determine serum concentrations of polychlorinated biphenyls (PCBs) among people living around New Bedford, MA, U.S.A., an unidentified contaminant precluded the quantification of some early eluting Webb and McCall peaks. Loss of data is estimated to have reduced reported serum levels by 12%. Efforts to identify the contaminant by gas chromatography with an electron-capture detector, a Hall electrolytic condutivity detector, and mass spectrometer were not successful. Researchers ascertained, however, that the contaminant is not a PCB, it does not contain halogens, but it may contain phthalates. Vacutainer tubes and closures for serum storage bottles are suspected sources of contamination.

Selection of a Base Serum for the Preparation of Quality Control Pools Containing Environmental Analytes

Abstract At two laboratories, an analytical method to determine polychlorinated biphenyis (PCBs) in serum was evaluated for its ability to recover in vitro-spiked PCBs from bovine and human serum. Statistically significant differences (p < 0.05) were found in the results obtained for the two matrices at both laboratories. Previously an interlaboratory bias between the laboratories of + 3.3% had been established by using bovine serum; however, with human serum the average interlaboratory bias was -9.5% resulting in a change in absolute bias of approximately 13%. The analytes determined in the base materials before they were in vitro-spiked with PCBs were dichlorodiphenyldichloroethylene (p,p′-DDE), PCBs, and serum lipids (i.e., total cholesterol, triglycerides, free cholesterol and phospholipids). The concentration of analytes and lipids was higher in base human serum than in base bovine serum.