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 temperature 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 investigated the effect of residue aging, solvent type, and ASE conditions on the recovery of atrazine and alachlor from different soils and compared the efficiency of ASE with that of Soxhlet and solvent-shake extractions. With ASE, the use of dichloromethane-acetone (1:1, v/v) or methanol as solvent resulted in significantly greater pesticide recovery than hexane. After the residue was aged for >2 weeks, pesticide recovery was significantly influenced by the extraction temperature in ASE vessel, and the recovery increased to 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 other two conventional methods.