Elution pattern of planar chlorinated biphenyls and 2,3,7,8-polychlorinated dibenzo-p-dioxins/dibenzofurans on chromatographic adsorbents and factors affecting the mechanism of retention - Possibilities of selective separation of both families

A possible retention mechanism for planar chlorinated biphenyls and 2,3,7,8-polychlorinated dibenzo-p-dioxins/dibenzofurans on alumina and Florisil columns is proposed. The influence of factors such as the surface activity of the adsorbents as well as the volume, selectivity and polarity of the solvents has been studied. A very similar elution pattern was found for alumina and Florisil. These results suggested that retention of the compounds on the surface of the adsorbent depends on the planarity of the molecule, on the localisation of the rr-electron cloud and, less clearly, on the extended pi-electron cloud of the congener. The best separation between both families with the highest recoveries of individual polychlorinated biphenyl and polychlorinated dibenzo-p-dioxins/dibenzofuran congeners was obtained by using 6 g of Florisil activated at 450 degrees C for 24 h.