Determination of organochlorine pesticides from agricultural soils using pressurized liquid extraction

A method to determine thirteen organochlorine pesticides from soils samples has been developed using pressurized liquid extraction (PLE) and gas chromatography electron-capture detection. The variables optimized have been: type of solvent, number of cycles, temperature, time, flush volume and pressure. The optimal conditions have been hexane-acetone (1:1), 1 cycle, 50 degrees C, 60% of flush volume and 1500 psi. The results obtained indicate that most of these compounds can be recovered quantitatively with RSDs lower than 10% and detection limits ranged between 0.3-200 ng center dot kg(-1) for the pesticides studied. Under the optimized conditions, the proposed method has been applied to the analysis of agricultural soils. Aldrin and p, p'-DDT have been found in most of these samples at low mu g center dot kg(-1) levels.