Determination of polychlorinated biphenyls in ash using dimethylsulfoxide microwave assisted extraction followed by solid-phase microextraction

A procedure for the determination of several coplanar and non coplanar PCBs in ash samples is described. Analytes were extracted from the samples using dimethylsulfoxide (DMSO) under the action of a microwave field, and then they were concentrated on a PDMS-DVB solid-phase microextraction (SPME) fibre using the headspace mode, after water dilution of the DMSO extract. Determinations were carried out using GC-ECD and GC-MS detection. Influences of microwave extraction (solvent volume, temperature and time) and SPME conditions (stirring, kind of SPME fibre, salt and water addition, sampling time and temperature) on the performance of the whole analytical procedure were systematically investigated. Working under optimal conditions quantification limits from 0.2 to 1.5 ng g⁻¹ were obtained for all the compounds, except for PCB 209, which could not be consistently extracted from the sample using the proposed conditions.