Evaluation of accelerated solvent extraction (ASE) for analysis of pesticide residues in soil

Accelerated solvent extraction, or ASE, is a new extraction technique that is similar in principle to Soxhlet extraction, but the use of elevated temp erature and pressure with ASE allows the extraction to be completed within a short time and with a small quantity of solvent. In this study, we invest igated the effect of residue aging, solvent type, and ASE conditions on the recovery of atrazine and alachlor from different soils and compared the ef ficiency of ASE with that of Soxhlet and solvent-shake extractions. With AS E, the use of dichloromethane-acetone (1:1, v/v) or methanol as solvent res ulted in significantly greater pesticide recovery than hexane. After the re sidue was aged for >2 weeks, pesticide recovery was significantly influence d by the extraction temperature in ASE vessel, and the recovery increased t o 130-140 degrees C and then decreased. The efficiency of ASE was generally better than that far Soxhlet or shake extraction using methanol-water (4:1 , v/v). ASE extraction also consumed considerably less solvent than the oth er two conventional methods.