Extraction of PCDD/PCDF from soil with supercritical CO2: Optimization by a three-lever factorial design approach

Two factors (pressure and temperature) varied over three levels were optimi zed for the extraction of PCDD/F from native contaminated soil with toluene -modified supercritical carbon dioxide. Temperature had a strong positive e ffect on the recovery. The most efficient extraction was achieved at 120 de greesC. This is in contrast to the influence of the temperature on the extr action of HCH, where a higher recovery is obtained at 60 degreesC than at 1 50 degreesC. The optimized conditions found for this soil were applied to t he analysis of a BCR (European Commission) reference material prepared from contaminated industrial soil. The results are in good agreement with those of an interlaboratory study.