Surface-Linked C60/70-Polystyrene Divinylbenzene Beads as a New Chromatographic Material for Enrichment of Coplanar PCBs

Abstract

Chromatographic materials consisting of polystyrene divinylbenzene (PSDVB) covalently bonded to C60 and C70 fullerenes offer a new electron donor-acceptor (EDA) adsorbent with high sample capacity. These materials are of particular utility when used as high-pressure liquid chromatographic (HPLC) columns to fractionate and enrich coplanar polychlorinated biphenyls (PCBs) from other PCB isomers. Of all the mobile phases tested, hexane provided the best separations. With selected isomer mixtures to develop a fractionation scheme, we separated Aroclors 1242, 1248, 1254, and 1260 into three fractions and analyzed then by gas chromatography-electron capture detector (GC-ECD) to determine isomer profiles. PCB congeners with increasing numbers of chlorine substituted in the o,o′- positions are less strongly retained while nonachloro- and decachloro-biphenyl are minimally retained. Some partially planar mono-o,o′-Cl isomers coelute with di-o,o′-Cl PCB isomers; except for the higher Cl7-8 mono-o,o′-chlorinated isomers, the di-o,o′-Cl PCB isomers are well separated from non-o,o′-isomers; highly chlorinated coplanar PCBs form strong EDA complexes with the pi-electron donor C60/70-PSDVB surface. When hexane is used as the mobile phase, the C60/70-PSDVB stationary phase yields HPLC fractions that can be directly analyzed by GC-EC. Chlorinated dibenzo-p-dioxins and -dibenzofurans are also retained by this stationary phase and elute with hexane or hexane-methylene chloride mixtures. This adsorbent should provide the required enrichment of coplanar PCB congeners to permit their GC or GC-mass spectroscopic analysis.