COMPARISON OF SELECTIVITIES FOR PCBS IN GAS-CHROMATOGRAPHY FOR A SERIES OF CYANOBIPHENYL STATIONARY PHASES

Selectivity for polychlorinated biphenyl (PCB) congeners was examined for a series of cyanobiphenyl stationary phases, and the results were compared to a nonpolar 5% phenyl methylpolysiloxane phase and a shape- selective smectic liquid crystalline phase. For all of the columns stu died, the degree of ortho substitution of the congener was found to be a significant factor controlling chromatographic retention of PCBs. T he retention pattern on six different cyanobiphenyl phases followed th e same general pattern as on the liquid crystalline column, though the trends were more exaggerated on the liquid crystalline phase. While t he general retention pattern was similar for all of the cyanobiphenyl phases studied, subtle differences were observed, resulting in signifi cant selectivity differences. For isomeric planar PCB congeners, eluti on order could be correlated to length-to-breadth ratios. Among the cy anobiphenyl phases, the p,p- and the o,p,p-cyanobiphenyl phases had th e greatest enhancement of retention for planar congeners. A shape-sele ctive test mixture reflected the similarity of retention on the cyanob iphenyl phases to both the 5% phenyl methylpolysiloxane phase and the smectic liquid crystalline phase. (C) 1995 John Wiley & Sons, Inc.