Enantioselective determination of various chlordane components and metabolites using high-resolution gas chromatography with a β-cyclodextrin derivative as chiral selector and electron-capture negative ion mass spectrometry detection

Abstract

Enantioenriched fractions of various chiral chlordane compounds (heptachlor, cis-chlordane, trans-chlordane) and metabolites (cis- and trans-heptachlorepoxide, oxychlordane) were used to evaluate a high-resolution gas chromatography (HRGC) column with heptakis-[2,3-dimethyl-6-t-butyldimethylsilyl]-β-cyclodextrin (TBDM) as chiral selector and enantiomer elution sequences were determined. The enantioenriched fractions were previously isolated from the racemates by enantioselective high-performance liquid chromatography (HPLC) using a permethylated β-cyclo-odextrin. Additionally, two octachlordanes, U82 and MC5, were isolated as racemates from technical chlordane using HRGC and then used for reference purposes. The TBDM column enantiomerically resolved cis- and trans-chlordane, MC5, cis- and trans-heptachlorepoxide, and oxychlordane; it did not enantiomerically resolve heptachlor, the octachlordane U82 and the nonachlordane MC6. A 12-m column resulted in a better enantiomer resolution than a longer (23-m) column of the same type due to a lower elution temperature. The TBDM column was used to analyze technical chlordane and chlordane residues in the fish oil reference material SRM 1588, a cod liver oil. Isomer and enantiomer ratios of chlordane residues in this reference material are reported and compared to those reported in earlier studies on the same material and to data on other fish species from the Baltic.