HPLC-DAD determination of imidacloprid in onion

Imidacloprid is an insecticide most commonly used on vegetables, potato sugar beet, fruit, cereal, maize and rice. Imidacloprid residue has been determined in spiked onion and in onion samples. Sample preparation consisted of dichlormethane extraction of imidacloprid from onion, followed by purification of the obtained extract on a LC-Florisil disposable cartridge. The HPLC-DAD method bas been developed on reversed-phase for separation of imidacloprid with a mixture of 0.01 M phosphate buffer (pH = 3.15): acetonitrile. Recovery of imidacloprid, repeatability, linearity limit of detection and limit of quantifi-cation have been determined.