Selective determination of polychlorinated biphenyls in waste oils using liquid–liquid partition followed by headspace solid-phase microextraction and gas chromatography with atomic emission detection

A procedure for the determination of the total content of polychlorinated biphenyls (PCBs) in industrial oil samples using gas chromatography coupled to atomic emission detection (GC–AED) is presented. Analytes were extracted from the samples using dimethylsulfoxide (DMSO), this extract was diluted with water, and PCBs were concentrated on a PDMS–DVB solid-phase microextraction (SPME) fibre using the headspace (HS) mode. Fibres were thermally desorbed for 3 min in the splitless injection port of the GC–AED system. Influence of liquid–liquid extraction conditions on the performance of the analytical procedure is presented and the need of a sample oxidation step, previous to the extraction of the PCBs with DMSO, discussed. Working under optimal conditions, quantification limits from 0.5 to 1 μg/g (total PCBs content) were obtained for several Aroclor mixtures in transformer oil samples. The repeatability of the whole sample preparation procedure (liquid–liquid partition followed by headspace SPME and GC–AED determination) ranged from 4 to 7%.