Multiresidue analysis of pesticides in vegetables and fruits by supercritical fluid extraction and liquid chromatography-tandem mass spectrometry.

A multiresidue method for analyzing pesticides in vegetables and fruits by supercritical fluid extraction (SFE) and LC-MS/MS was developed. The sample preparation and SFE parameters were optimized for extracting LC-amenable polar and medium-polarity pesticides. High recoveries were achieved for most of the tested pesticides by extracting a 1 : 1 : 1 sample-Celite-anhydrous magnesium sulfate mixture with supercritical carbon dioxide at 16.4 MPa at 40℃ for 30 min with methanol added as a modifier. The recoveries of 117 pesticides fortified with 0.01 mg/kg of each pesticide were 70-120%, and the relative standard deviations were less than 25% for 112 pesticides in tomato and 103 pesticides in cucumber. No significant differences were observed in the residue concentrations determined in real samples by the SFE method and the liquid extraction method (the modified Japanese official method). Higher recoveries of polar pesticides, such as acephate and methamidophos, were achieved by the developed SFE method than by the liquid extraction method.