Determination of simazine and cymoxanil in soils by microwave-assisted solvent extraction and HPLC with reductive amperometrical detection

A microwave-assisted extraction (MAE) method was optimized for the herbicide simazine and the fungicide cymoxanil in soil samples. The experimental variables that affect MAE, such as temperature, extraction time and solvent volume, were studied. It was concluded that these pesticides could be efficiently extracted from soil samples in a microwave oven with 10 mL of acetonitrile at 90 degreesC for 5 min The analysis of extracts has been carried out by high performance liquid chromatography with amperometric reductive detection (HPLC-ED). The detector, equipped with a hanging mercury drop electrode (HMDE), operated in direct current mode at -1.2 V vs Ag/AgCl, when a mobile phase consisting of phosphate buffer-acetonitrile (95:5, v/v) was used. The procedure developed involving MAE and HPLC-ED provided detectability in soil samples of 30 mug kg(-1), acceptable recoveries (range 82.3-100.3%) and RSDs of lower than 5% for cymoxanil and simazine.