Assessment of supercritical fluid extraction of pentachlorophenol from aqueous samples

Three methods of extraction of analytes from water were compared: liquid-liquid extraction (LLE), solid phase extraction (SPE) and supercritical fluid CO2 (SFE). The method for SFE was altered to reduce time and amount of solvent used. Only 2 mt of methanol were required for SFE. The recovery of the analyte (pentachlorophenol, PCP) from 200 ppb aqueous solution was 86 % +/- 9 % with LLE, 69 % +/- 10 % with SPE and 60 +/- 13 % with SFE. The SFE was however done without acidification to pH 2 before extraction. The recovery was not affected by the presence of fulvic acid (20 mg/L) with LLE and SPE, but was reduced somewhat with SFE (from 60 to 46 %). There was no significant decrease in recovery of PCP from river water with 37 ppm suspended solids and 6.4 ppm dissolved organic carbon.