High-Resolution Gas Chromatographic/High-Resolution Mass Spectrometric Analysis of Human Serum on a Whole-Weight and Lipid Basis for 2,3,7,8-Tetrachlorodibenzo-p-dioxin

We describe an analytical method to measure 2,3,7,8-tetra-chlorodlbenzo-p-dioxin (TCDD) and other TCDD Isomers In human serum; the method uses a highly specific cleanup procedure and hlgh-resolutlon gas chromatography/hlgh-res-olutlon mass spectrometry. The 2,3,7,8-TCDD Is quantified by the Isotope dilution technique with [¹³C₁₂]-2,3,7,8-TCDD as the Internal standard. Other TCDD Isomers are estimated by using published relative response factors. The 1.25 part-per-quadrllllon (ppq) limit of detection for 200-g samples is more than adequate for determining 2,3,7,8-TCDD concentrations In human serum specimens. The method Is modified for analyzing 50-g and 10-g serum samples. Analytical accuracy is demonstrated by the results obtained in analyzing spiked samples. The method is shown to be unaffected by a number of potentially Interfering compounds. A series of quality control material Is used to verify system performance. For 200-g samples containing 25.8 ppq of native 2,3,7,8-TCDD, a coefficient of variation (CV) of 13.0% Is observed (n = 20). For 10-g samples from a pool fortified with 2,3,7,8-TCDD (1.9 parts per trillion, n = 22), a CV of 15.5% is observed.