HEXACHLOROCYCLOHEXANES IN HUMAN BLOOD-SERUM

A simplified method allowing the determination of trace concentrations (ng/ml) of hexachlorocyclohexanes in human sera suitable for the anal ysis of large numbers of samples has been developed. Comparison of aci d (cone. H2SO4,) and basic (5 M KOH) digestion has shown that good rec overies are obtained with the former when an internal standard, 1,2,4, 5-tetrabromobenzene (TBB), is used to correct for volatilization losse s. Good separation between alpha-, beta- and gamma-HCH isomers, TBB, h exachlorobenzene and some interfering compounds is obtained with DB-5 columns. The use of electron-capture detection (ECD) or negative ion c hemical ionization mass spectrometry (NICI-MS) in the selected ion mon itoring mode (m/z 71) provides sufficient sensitivity for quantitative determination. ECD is the most sensitive method for beta-HCH and NICI -MS for the other isomers. GC-NICI-MS is needed for the unambiguous de termination of delta-HCH due to the coelution with one interfering com pound. The method has been successfully applied to the analysis of a s eries of 625 samples collected in a population situated near the efflu ents of an organochlorinated solvent factory. The results have shown t hat beta-HCH is selectively accumulated in human sera and prompt to th e preferential investigation of the toxic effects of this isomer in hu mans and mammals. (C) 1997 Elsevier Science B.V.