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 studied, the degree of ortho substitution of the congener was found to be a significant factor controlling chromatographic retention of PCBs. The retention pattern on six different cyanobiphenyl phases followed the same general pattern as on the liquid crystalline column, though the trends were more exaggerated on the liquid crystalline phase. While the general retention pattern was similar for all of the cyanobiphenyl phases studied, subtle differences were observed, resulting in significant selectivity differences. For isomeric planar PCB congeners, elution order could be correlated to length‐to‐breadth ratios. Among the cyanobiphenyl phases, the p,p‐ and the o,p,p‐cyanobiphenyl phases had the greatest enhancement of retention for planar congeners. A shapeselective test mixture reflected the similarity of retention on the cyanobiphenyl phases to both the 5% phenyl methylpolysiloxane phase and the smectic liquid crystalline phase. © 1995 John Wiley & Sons, Inc.