Enantiomeric Composition of Chiral Polychlorinated Biphenyls in Marine Species and Sediment from Masan Bay

Abstract

Chiral environmental chemistry is a new area of research that can provide enhanced insight into environmental fate processes. The enantiomers of a chiral compound may exhibit different biological and toxicological properties from each other and from the racemic mixture, the form in which most chiral xenobiotics are released to the environment. Therefore, understanding the environmental behavior of the enantiomers is important for determining the hazards they pose. Of the 209 PCB congeners, 78 display axial chirality in their non-planar conformations. Nineteen of these atropisomers, as they are called, have three or four ortho chlorines, which provide sufficient steric hindrance to rotation about the central C-C biphenyl bond so that their enantiomers remain stable in the environment. In this study, enantiomeric fractions (EFs) for eight polychlorinated biphenyl atropisomers were measured in environmental matrices by using chiral gas chromatography/mass spectrometry. To observe the change of enantiomeric composition of PCBs in a food chain, sediment, polycheata and flatfish were collected from Masan Bay of Korea. Food web relationship was confirmed with stomach content analysis and stable isotope (13C and 15N) analysis. Nonbiological matrices such as sediment and seawater showed relatively racemic composition of the atropisomers compared to biological matrices, indicating that PCBs were metabolized enantioselectively in biota. Polycheata showed a similar enantiomeric composition with stomach content of flatfish. Compare to polycheata, flat fish showed an enantioselective accumulation for CBs 91, 84, 136, 132 and 149. For CBs 136 and 149, (-)-enantiomer was selectively accumulated in flatfish.