Supercritical fluid extraction of pesticide residues from strawberries

A supercritical fluid extraction (SFE) method for the determination in strawberries of a number of commonly used organochlorine insecticides, organophosphorus pesticides, and dichloroanilide fungicides is described. Gas chromatography was used to examine the extracts, with both electron-capture detection and either flame photometric or nitrogen phosphorus detection. Confirmation was performed by gas chromatography-mass spectrometry. The analytes were extracted with supercritical carbon dioxide at 4000 psi and 50 degrees C with a run time of 20 min, which corresponded to an extraction volume of 20-30 mL of carbon dioxide. In developing the method, the operating parameters of temperature, pressure, extraction time, collection solvent, and sample preparation were optimized. Recoveries ranged from 74 to 126% (with the exception of iprodione), and a method precision of +/-3-18% was obtained for spiking levels of 0.08-3.7 mg/kg. The method was validated for the following organochlorine insecticides and organophosphorus pesticides: aid-in, dichloran, dieldrin, p,p'-DDE(TDE), p,p'-DDD, p,p'-DDT, alpha-endosulfan, beta-endosulfan, endosulfan sulfate, diazinon, dichlorvos, ethion, malathion, methyl parathion, methyl pirimiphos, mevinphos E+Z, and parathion; and the following dichloroanilide fungicides: iprodione, procymidone, and vinclozolin. The SFE procedure was quicker, more environmentally friendly, and more cost effective than the traditional solvent extraction methods.