COMPARATIVE-STUDY OF 3 EXTRACTION PROCEDURES FOR IMAZAMETHABENZ-METHYL IN AGRICULTURAL SOIL

Three procedures for the extraction of imazamethabenz-methyl in soils, using (a) various organic solvents, (b) water at different pH values and (c) supercritical carbon dioxide, were compared. Extraction with m ethanol, water at pH 11 or methanol-modified supercritical CO2 were fo und to be the most suitable methods. These three procedures are suitab le for sample amounts of 2 g and fortification levels of 6 mg/kg, givi ng herbicide recoveries near 90%. Subsequent determination of the herb icide in the extracts is carried out using HPLC with an octadecylsilan e column, a mobile phase of acetonitrile-water (40:60), a flow-rate of 1 ml/min and ultraviolet detection at 210 nm. The detection limits ac hieved in the three procedures were always lower than 0.05 mg/kg in ro utine analysis.