Gas chromatographic retention index system for polychlorinated biphenyls: possibilities and limitations

Abstract

The identification of individual polychlorinated biphenyls (PCBs) congeners would be easier if a proper reference series were available to calculate retention indices when using electron capture detectors, which are insensitive to the n-alkanes. In a previous work, a mixture of PCBs showing a linear dependence of retention on the number of chlorine atoms in both isothermal and programmed temperature analysis was suggested for reference purposes. Retention index values referred to this series, I PCB, can be calculated and used for identification. In this work a wide collection of columns was tested in order to check the linearity of the proposed reference series. The effect of the initial temperature and heating rate of the programmed runs on the reproducibility of the results was investigated. Retention data of the congeners belonging to the reference series are given together with retention indices of toxic PCB congeners calculated for various columns. The inversion of the elution order or the shift of retention values on columns of different polarities are shown.