DETERMINATION OF RETENTION INDEXES OF POLYCHLOROBIPHENYLS BY USING OTHER COMPOUNDS DETECTABLE BY ELECTRON-CAPTURE DETECTION OR SELECTED POLYCHLOROBIPHENYLS AS THE REFERENCE SERIES

The highest sensitivity to polychlorobiphenyls (PCBs) is offered by el ectron-capture detection (ECD), but the easy identification of individ ual congeners remains unresolved. Published retention data are of limi ted usefulness, as the lack of a uniform style and the dependence on t he analysis conditions do not permit their general use. Retention inde x values of PCBs cannot be easily referred to n-alkanes, due to the ve ry low response of these compounds to ECD, whereas other well detected reference series can be used: n-alkyl iodides were found useful for t he determination of retention indices of the first congeners of the PC B series. Retention indices obtained by using selected DCMA (Dry Colou r Manufacturers' Association) PCB reference mixtures can be directly u sed or converted to standard Kovats indices. A mixture of PCBs that sh ows a linear dependence of retention on the number of chlorine atoms o n both isothermal and programmed-temperature analysis is suggested for reference purposes. Other methods and standard mixtures used for iden tification and quantitation purposes are reviewed and discussed.