Enantioselective analysis and enantiomeric bias of atropisomeric PCBs
- Univ. of Tubingen (Germany). Inst. of Organic Chemistry
78 out of the possible 209 PCB congeners are axially chiral in their nonplanar conformations and 19 form stable enantiomers (atropisomers) due to restricted rotation around the central carbon-carbon bond at ambient temperatures. At least nine of the conformationally stable chiral PCBs are present in commercial formulations and are expected to accumulate in the environment. The separation of the enantiomers of most of the chiral PCBs has been achieved by gas chromatography on various different cyclodextrin phases. Recently, the authors described the use of multidimensional gas chromatography (MDGC) with an achiral-chiral column combination for the enantioselective analysis of chiral PCBs of technical mixtures. This method was applied to the determination of enantiomeric ratios (ER) of the chiral PCBs 132, 95 and 149 in human milk samples, both ECD and MS (SIM) detection has been used. All samples analyzed showed an enrichment of the second eluting enantiomer with ER values ranging from 0.45--0.85 in the case of PCB 132, an enrichment of the first eluting enantiomer with ER values ranging from 1.05--1.7 in the case of PCB 95 and racemic or nearly racemic mixtures in the case of PCB 149. This method has also been used for the analysis of the chiral PCBs mentioned above in river sediment samples after steam-distillation solvent extraction (SDE).
- OSTI ID:
- 398230
- Report Number(s):
- CONF-9511137--; ISBN 1-880611-03-1
- Country of Publication:
- United States
- Language:
- English
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