INDEPENDENT COMPARISON OF SOXHLET AND SUPERCRITICAL-FLUID EXTRACTION FOR THE DETERMINATION OF PCBS IN AN INDUSTRIAL SOIL

An independent comparison between supercritical fluid extraction (SFE) and Soxhlet extraction methods was conducted as part of a certification of PCB congeners in industrial soil. The study was performed in the framework of the PCB group for the Measurements and Testing Program (former BCR) under the Commission of the European Union. It involved 21 selected and independent laboratories experienced in congener-specific PCB analysis. The comparison was performed using both interlaboratory and intralaboratory data. SFE was performed independently by three laboratories, and the obtained data showed that SFE is a very competitive alternative in terms of both accuracy and precision. The soil was certified for eight PCB congeners ranging from 7.0 to 137 mu g/g with interlaboratory RSDs of 9-13% using all but two (out of 34) individual results from the SFE group.