HRGC SEPARATIONS OF 160 CHLOROBIPHENYLS IN TECHNICAL MIXTURES ON 4 POLAR NARROW-BORE COLUMNS

The separation of 160 chlorobiphenyl (CB) congeners from technical polychlorinated biphenyl (PCB) mixtures was investigated on four narrow-bore, fused silica gas chromatography (GC) columns with high temperature resistant polar stationary phases; 15% diphenyldimethylsiloxane (0.20 mum SIL-13, 50 m x 0.25 mm), 50% diphenyl dimethylsiloxane (0.25; gmm DB-17, 60 m x 0.25 mm), a series combination of 5% diphenyldimethylsiloxane (0.25 mum SIL-8, 25 m x 0.25 mm) with 1,10-dicarba-closo-dodecarborane dimethylsiloxane (0.1 mum HT-5, 25 m x 0.2 mm) and a 70% cyanopropyl silphenylene dimethylsiloxane copolymer (0.25 mum BPX-70, 50 m x 0.22mm). Technical PCB mixtures (Aroclors) and authentic standards (totally 149 CBs) were injected on the narrow-bore columns and analyzed by GC-ECD and GC-MS. Structural principles for retention of CBs and the retention mechanism of diphenyl and cyanopropyl in the stationary phase are discussed. SIL-13 proved to be an interesting alternative to the widely used SE-54 type columns. DB-17 showed a significantly changed elution order and seems the best choice of column together with SIL-8/HT-5 for parallel analysis of CB congeners. A total of 144 CBs in technical mixtures can be analyzed free of interference from other CBs imploying these two columns. Too many CB congeners co-eluted on BPX70 for this column to be useful in routine analysis of CBs.