Abstract: An HPLC-MS/MS (high performance liquid chromatography coupled with tandem mass spectrometry) method has been developed for the determination of isoxaflutole and its two metabolite residues in maize. The isoxaflutole and its metabolite residues in samples were extracted into acetic acid-cetonitrile (1:99, V/V) by means of high-speed homogenization, subjected to liquid-liquid partition in the presence of added anhydrous magnesium sulfate and sodium acetate, cleaned up with primary secondary amine (PSA), octadecylsilane (ODS) and graphitized carbon black for purpose of eliminating such most matrix interferences as lipids, pigments, etc before HPLC-MS/MS analysis and subsequent quantification by an external standard method. The average recovery rates of isoxaflutole and its metabolites from spiked samples ranged between 74.8% and 107.2% with a relative standard deviation of 6.45%－11.15% across the spike levels of 0.010, 0.050 mg/kg and 0.100 mg/kg. The detection limit was 0.01 mg/kg and 0.005 mg/kg for isoxaflutole and its metabolites, respectively. This method was sensitive, accurate, time-saving, simple, and suitable for the detection of isoxaflutole and its metabolite residues in maize.

Key words: isoxaflutole and its metabolites, high performance liquid chromatography coupled with tandem mass spectrometry(HPLC-MS/MS), maize