Selective extraction of polychlorinated biphenyls from dairy products using steam distillation–solvent extraction at normal pressure Original Research Article

A simultaneous steam distillation–solvent extraction (SDE) procedure was used for the analysis of polychlorinated biphenyls (PCBs) in dairy products. In spite of the good results previously obtained for the recovery of these pollutants at sub-μg/l levels in spiked water samples, the SDE apparatus did not prove to be an efficient way of extracting endogenous PCBs from dairy products. In an attempt to optimise the simultaneous extraction-clean-up procedure proposed, the different variables affecting the SDE were systematically investigated in depth. These studies have shown that both the extremely low concentration levels of the PCBs in this kind of matrix and the intrinsic complexity of the samples investigated were very important factors affecting the efficiency of SDE for endogenous PCB extraction. Recoveries below 10% were found when different types of dairy products and spiked samples were investigated.