Optimization of perchlorination conditions for some representative polychlorinated biphenyls

The yield of decachlorobiphenyl (DCB) from representative Aroclors (50 to 6000 ng) using antimony pentachloride as perchlorinating agent was extremely temperature dependent below 236/sup 0/C for a reaction period of 2 h. At 288/sup 0/C, a 35-min reaction period was sufficient to obtain DCB yields >80% for Aroclors 1016, 1242, 1254, and 1268. The perchlorination process was shown to be first order. The temperature dependence of the reaction times below 236/sup 0/C was largely responsible for the inconsistent perchlorination yields reported previously in the literature. The extraction of DCB with hexane from a HCl-acidified perchlorinated solution and subsequent column chromatography on silica gel were also essential after the perchlorination to quantitate the DCB by /sup 63/Ni electron capture/gas chromatography. The structures of the two nonachlorobiphenyls, which were the penultimate stable intermediates before DCB, were found. The methodology to use the technique for air and blood samples was described. 24 references, 3 figures, 2 tables.