Extraction of beta-endosulfan and endosulfan sulphate in soils with supercritical CO2

Extraction of organochlorine pesticides from indigenous soils with supercritical CO2 was optimized using Soxhlet extraction as the reference method to evaluate the recoveries. The extraction cell temperature and pressure, and the restrictor temperature, were studied. The best conditions were 400 atm at 50 deg. C for the extraction cell, and a 50 μm (inner diameter), 40 cm fused silica restrictor heated to 180 deg. C. Extraction was carried out for 10 min in the static mode and for 20 min in the dynamic mode, with methanol as the modifier. Collection of the extracted analytes was performed in CH2Cl2. The recoveries with superficial CO2, relative to those obtained with solvent extraction, were 175 and 148% (10 and 39% relative standard deviation) for beta-endosulfan and endosulfan sulphate, respectively. (author). 8 refs, 3 figs, 1 tab