Absolute configuration of atropisomeric polychlorinated biphenyl 183 enantiomerically enriched in human samples. 
Polychlorinated biphenyls (PCBs) are still of serious concern as a potential health hazard due to their persistency and bioacumulation.  Of 209 possible PCB congeners, with varying number and position of chlorine atom(s), 19 are chiral.  These are mostly highly chlorinated and tend to remain longer against the biological decompositions, suffering biological deracemization in the environment.  In this work, we have unequivocally determined the absolute configurations of important chiral PCBs 183 and 171, as well as 132, through the combined theoretical and experimental investigations of the chiroptical properties (circular dichroism and optical rotation), which will be valuable in elucidating the mechanism of biological enantiomer enrichment of PCBs in the environment.