Determination of Residual Imidacloprid in Vegetables and Fruits by Spe and GC-MS

Hyphenated GC-MS was applied to the determination of residual imidacloprid in vegetables and fruits. The sample was pretreated and the imidocloprid was extracted with acetonitrile. After filtration,an aliquot of the acetonitrile solution was taken and evaporated to dryness. Two mL of CH2Cl2 was added to the residue,and the solution was separated on the florisil solid-phase extraction column. The eluate was taken and ready for GC-MS analysis after evaporation to dryness and taking up the residue with 2.0 mL of CH2Cl2. The operation conditions of GC-MS analysis were optimized and the selected ion mode (SIM) was taken. Limit of detection obtained by the proposed method was 0.006 3 mg·kg-1,which is much lower then those required by some foriegn standards. In the analysis of samples of rape and frozen taro by this method,RSD′s found were less than 5.5%,and recoveries in the range of 80.0%-89.0% were obtained.