HPLC DETERMINATION OF THE NEW INSECTICIDE IMIDACLOPRID (CHLORONICOTINYL INSECTICIDES), AND ITS BEHAVIOR IN RICE AND CUCUMBER

A rapid, sensitive, and reliable HPLC method has been developed for the determination of imidacloprid residue in nine kinds of crops and soil. The developed method consisted of extracting with acetonitrile/water (80:20 v/v), prewashing of the concentrated extracts with cyclohexane and alkaline solution, silica gel column chromatography, and finally reversed-phase HPLC. The recoveries of imidacloprid were 75-109%. The limits of determination of the method were 0.005, 0.01, and 0.02 mg/kg for crops, rice straw, and soil, respectively. The method was applied to determine residues and rate of disappearance of imidacloprid from rice (nursery box treatment, 1 g of ai/1800 cm(2)) and cucumber plants (stem injection, 20 mu g of ai/plant). The insecticide incorporated into the plants decreased rapidly with a half-life of less than 3 days. In the rice, however, it controlled the brown planthopper even at 60 days after application, with the marginal concentration of 0:01 mg/kg for practical control.