Selective extraction of polychlorinated biphenyls from dairy products using steam distillation solvent extraction at normal pressure

A simultaneous steam distillation-solvent extraction (SDE) procedure was us ed 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-mu g/l levels in spiked water samples, the SDE apparatus did not prove to be an efficient way of extracting endogenous PCBs from dai ry products. In an attempt to optimise the simultaneous extraction-clean-up procedure proposed, the different variables affecting the SDE were systema tically investigated in depth. These studies have shown that both the extre mely low concentration levels of the PCBs in this kind of matrix and the in trinsic complexity of the samples investigated were very important factors affecting the efficiency of SDE for endogenous PCB extraction. Recoveries b elow 10% were found when different types of dairy products and spiked sampl es were investigated. (C) 1998 Elsevier Science B.V. All rights reserved.