ANALYSIS OF BUPROFEZIN RESIDUES IN VEGETABLE CROPS BY GAS-CHROMATOGRAPHY WITH MASS-SELECTIVE DETECTION IN SELECTED-ION MONITORING MODE

A gas chromatographic/mass selective detection (GC/MSD) method in sele cted ion monitoring (SIM) mode was used to determine buprofezin residu es in vegetable samples. The electron impact ionization mass spectrum of buprofezin shows 3 characteristic peaks at m/z 105 (base peak), 172 , and 305 (molecular ion peak), which were selected to quantify and co nfirm buprofezin residues in samples. Samples were extracted with ethy l acetate and sodium sulfate, and the extracts were cleaned up by gel permeation chromatography in an SX-3 Envirobeads column before GC/MSD analysis on a 25 m narrow-bore capillary column. Buprofezin recoveries from fortified samples of cucumber, pepper, tomato, squash, and eggpl ant were determined. The average recovery from cucumbers fortified at different levels (0.01, 0.05, 0.20, and 0.61 mg/kg) was 78%, and the s tandard deviation was 10% (n = 12). Very similar values were obtained for the 5 vegetable samples fortified at 0.20 mg/kg (n = 15). The limi t of quantitation of the method for buprofezin in cucumbers was 0.01 m g/kg.