ENHANCED SELECTIVITY IN THE ANALYSIS OF CHLOROBIPHENYLS ON A CARBORANE PHENYLMETHYLSILOXANE COPOLYMER GAS-CHROMATOGRAPHY PHASE (HT-8)

The congener specific analysis of polychlorinated biphenyls (PCBs) on a new chemically bonded stationary GC phase, HT-8 (1,7-dicarba-closo-dodecarborane phenylmethyl siloxane) is investigated. The incorporation of carborane in the polysiloxane backbone enhances selectivity and temperature stability of the phase. On a 60 m X 0.25 mm I.D. fused-silica column coated with 0.25 mu m HT-8, a total of 106 congeners in Aroclor mixtures elute as separated peaks. By the use of mass spectrometric detection 138 congeners can be analysed without interference from coeluting PCBs. In literature, no other GC phase has been reported with such a high PCB selectivity. An interesting feature of HT-8 is its near-baseline separation of the critical pair CB138/CB163. Separations for these congeners on other GC phases are reviewed. The performance of a thin film (0.15 mu m) version of the HT-8 column with fast temperature programming is tested. It is concluded that congener-specific rapid screening of seven indicator PCBs (CB28, CB52, CB101, CB118, CB138, CB153 and CB180) with a total GC run-time of 13 min is feasible with an accuracy sufficient for most purposes.