Optimization of supercritical fluid extraction for polychlorinated biphenyls from sediments

A supercritical fluid extraction (SFE) procedure for polychlorinated biphenyls (PCBs) has been optimized as an efficient method for the extraction and recovery of these compounds in native pollutants. The optimum pressure, temperature, time factors and cosolvent composition that enable maximum extraction of all PCBs were determined. A certified standard reference material (SRM 1939) was used to optimize the extraction parameters. The uses of supercritical CO2 with 15% dichloromethane modifier at 200 kg/cm2 and 80 °C, with 60 min dynamic extraction were found to be the optimum conditions. The method was then further tested by using a real world soil sample obtained from Dokai Bay, Japan. Extraction efficiencies were compared to the traditional Soxhlet extraction method. Extracts from the two procedures were analyzed by gas chromatography-mass spectrometry. Cleanup of SFE extract of the Dokai Bay sediment was performed on two miniature columns packed with graphitized carbon black and Florisil. The extract was further subjected to a sulfur cleanup with copper granules.