ENANTIOSELECTIVE DETERMINATION OF CHLORDANE COMPONENTS USING CHIRAL HIGH-RESOLUTION GAS-CHROMATOGRAPHY MASS-SPECTROMETRY WITH APPLICATION TO ENVIRONMENTAL-SAMPLES

Technical chlordane was examined using both achiral and chiral high-resolution gas chromatography (HRGC) with detection by electron capture, negative ionization mass spectrometry (ECNI-MS). The enantiomer separation of several chiral octachlordanes including cis- and trans-chlordane was achieved and enantiomeric ratios of approximately 1:1 were determined using a modified beta-cyclodextrin as the chiral selector. The method was then applied to tissue extracts of several aquatic vertebrate species collected from the Baltic Sea (herring, salmon, and seal) and from Antarctica (penguin). The isomer profiles of the octa- and nonachlordanes observed in the biological samples using achiral HRGC-MS differed from those observed in a technical chlordane mixture, with some minor components of the technical mixture showing much higher abundance in the aquatic samples. Chiral HRGC now showed enantiomeric ratios of several chiral octachlordanes differing from 1:1 in each of these aquatic species. The changed enantiomeric compositions likely result from enantioselective biological processes and not from abiotic processes such as chemical, distribution, or transport processes in the environment. The results reinforce previous data showing the presence of these contaminants in biota from the most remote area on earth, Antarctica.