Residues of Imidacloprid in Cabbage and Soil

Samples of cabbage and soil were extracted with a methanol and water mixture, and extracts were purified on a Al2O3-Florisil column, followed by imidacloprid determination using HPLC with a UV detector. Sample recovery varied from 88.41to 101.57%. The limit of detection was 1 ng, and the minimum detectable concentration in cabbage and soil was 0.01mg/kg. Half-life of imidacloprid in cabbage and soil was 2-4 days and 5-8 days, respectively. Carrage was treated either 3 or 4 times withtwo concentrations of imidacloprid, and 3 days after the last application residues in cabbage were below the limit of detection( 0.01 mg/kg ).