Improved extraction procedures for polychlorinated biphenyls in solid samples with aqueous sodium hydroxide under autoclave conditions

The efficacy of the extraction of polychlorinated biphenyls (PCBs) from var nish-infiltrated insulating papers as a model of solid materials with an aq ueous sodium hydroxide (NaOH) by autoclaving at 121 degrees C for 30 min wa s compared with those for the conventional procedures, i.e., saponification with 1 N ethanolic NaOH in a boiling water bath for 60 min and extraction with benzene in a Soxhlet apparatus. The newly invented autoclaving method was found to be superior to the conve ntional ones, yielding approximately 5- to 6-fold cumulative PCB congeners without being accompanied by extended decomposition. Therefore, the autocla ve-based sample treatment is recommended for more accurate determination of PCBs in the case of PCB-impregnated solid materials such as hardened oils and resin-coated or -infiltrated papers instead of being treated convention ally. (C) 2000 Elsevier Science Ltd. All rights reserved.