OPTIMIZATION OF SUPERCRITICAL-FLUID EXTRACTION FOR POLYCHLORINATED-BIPHENYLS FROM SEDIMENTS

A supercritical fluid extraction (SFE) procedure for polychlorinated b iphenyls (PCBs) has been optimized as an efficient method for the extr action and recovery of these compounds in native pollutants. The optim um pressure, temperature, time factors and cosolvent composition that enable maximum extraction of all PCBs were determined. A certified sta ndard reference material (SRM 1939) was used to optimize the extractio n parameters. The uses of supercritical CO2 with 15% dichloromethane m odifier at 200 kg/cm(2) and 80 degrees C, with 60 min dynamic extracti on were found to be the optimum conditions. The method was then furthe r tested by using a real world soil sample obtained from Dokai Bay, Ja pan. Extraction efficiencies were compared to the traditional Soxhlet extraction method. Extracts from the two procedures were analyzed by g as chromatography-mass spectrometry. Cleanup of SFE extract of the Dok ai Bay sediment was performed on two miniature columns packed with gra phitized carbon black and Florisil. The extract was further subjected to a sulfur cleanup with copper granules.