IDENTIFICATION OF THE (+)-ENANTIOMERS AND (-)-ENANTIOMERS OF CHIRAL CHLORDANE COMPOUNDS USING CHIRAL HIGH-PERFORMANCE LIQUID-CHROMATOGRAPHY CHIROPTICAL DETECTION AND CHIRAL HIGH-RESOLUTION GAS-CHROMATOGRAPHY MASS-SPECTROMETRY

Synthetic racemic (+/-)-cis-chlordane, (+/-)-trans-chlordane, (+/-)-chlordene, (+/-)-heptachlor, (+/-)-heptachlorepoxide, and (+/-)-oxychlordane were analyzed by chiral high-performance liquid chromatography (HPLC) using refractive index (RI) and chiroptical detection. Chiroptical detection allowed the assignment of the (+)- and (-)-enantiomers of all compounds although some were almost unresolved and showed no apparent enantiomer resolution by other detection means (RI). In this way, a single chiral HPLC column system with permethylated beta-cyclodextrin (PMCD) allowed the isolation of up to 100 mu g of individual enantiomers at a time, or of nonracemic fractions enriched with one or the other enantiomer. These isolates were then used to identify the (+)- and (-)-enantiomers using, chiral high-resolution gas chromatography (HRGC). Since the absolute configurations of the (+)- and (-)-enantiomers of these chiral chlordane compounds are known, it was possible to assign the exact structures to the enantiomers resolved and, retrospectively, to those detected at residue levels in aquatic vertebrate species and in human adipose tissue. The method was also applied to the isolation and identification of the cu-hexachlorocyclohexane enantiomers, and it should be valuable in other situations where chiral environmental contaminants are involved.