MULTIDIMENSIONAL GAS-CHROMATOGRAPHIC SEPARATION OF SELECTED PCB ATROPISOMERS IN TECHNICAL FORMULATIONS AND SEDIMENTS

A simple dual-column gas chromatographic system,vith a six-port switch ing valve has been used to separate the atropisomers of PCB congeners 84, 91, and 95 in technical PCB formulations and in extracts of soil a nd river sediment. A capillary column coated with a methylphenylsiloxa ne stationary phase (CP-Sil 8) was used as the first column, for reten tion window selection, and a permethylated beta-cyclodextrin (Chirasil Dex) capillary column as the main separation column, Because peak over lap could not be eliminated by optimization of column temperature, the enantiomeric ratios of PCB congeners could not be determined from the original chromatograms. The correct enantiomer ratio was determined f rom the peak areas obtained by deconvolution of the chromatograms, Whe reas the PCB atropisomers considered were present in equal concentrati ons in the technical PCB formulations, analysis of a river sediment sa mple confirmed different residual concentrations of the atropisomers o f congener 95.