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 microg/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%.