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 certificati on 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-specifi c PCB analysis. The comparison was performed using both interlaborator y and intralaboratory data. SFE was performed independently by three l aboratories, and the obtained data showed that SFE is a very competiti ve alternative in terms of both accuracy and precision. The soil was c ertified for eight PCB congeners ranging from 7.0 to 137 mu g/g with i nterlaboratory RSDs of 9-13% using all but two (out of 34) individual results from the SFE group.