Comparative study of three extraction procedures for imazamethabenz-methyl in agricultural soil☆

Abstract 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 methanol, water at pH 11 or methanol-modified supercritical CO 2 were found to be the most suitable methods. These three procedures are suitable for sample amounts of 2 g and fortification levels of 6 mg/kg, giving herbicide recoveries near 90%. Subsequent determination of the herbicide in the extracts is carried out using HPLC with an octadecylsilane 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 achieved in the three procedures were always lower than 0.05 mg/kg in routine analysis.