ISOLATION AND CHARACTERIZATION OF POLYCHLORINATED BIPHENYL (PCB) ATROPISOMERS

High-performance liquid chromatography on permethylated beta-cyclodext rin derivatized silica was used to isolate enantiomers of stable atrop isomeric polychlorinated biphenyls. The separations were performed in the reversed phase mode (85% methanol) at subambient temperature (0 de grees C). Several injection/fractionation cycles were performed for ea ch atropisomer. In this way milligram quantities of pure (>98%)enantio mers could be isolated. These enantiomers were characterised by polari metry. The specific optical rotation seems to increase as the degree o f chlorination decrease, e.g., PCB#196 (octachlorinated) and PCB#84 (p entachlorinated) exhibit a rotation of ca. 30 and 240 degree . ml . g( -1). dm(-1), respectively (lambda = 436 nm). Furthermore, the (-)-enan tiomers always elute prior to the (+)-enantiomers. This implies that P CB atropisomers with similar spatial conformation have similar optical rotation properties. Copyright (C) 1996 Elsevier Science Ltd