Determination of amitraz and its metabolites in vegetables and fruits by high performance liquid chromatography-tandem mass spectrometry

: A method was established for the determination of amitraz (AMZ), and its metabolites semiamitraz (DMPF), 2,4-dimethylformamidine (DMF) and 2,4-dimethylaniline (DMA) in vegetables and fruits by using high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS). The samples were diluted with 0.1 mol/L sodium hydroxide and extracted with n-hexane-isopropanol (2:1, v/v). The separation was performed on a Phenomenex Kinetex C18 column (100 mm×4.6 mm, 2.6 μm) with gradient elution using 0.1% (v/v) formic acid aqueous solution-methanol as the mobile phase. The analysis of amitraz and its metabolites were detected under electrospray positive ionization mode. The limits of quantification (LOQs) were between 0.01 and 0.4 μg/kg. The good linearities (r>0.99) were achieved for the target compounds in the range of 1.0-200.0 μg/L. The recoveries at three spiked levels (0.5, 5.0 and 20 μg/kg) in blank matrix were in the range of 62.5%-105.0% with the relative standard deviations between 7.5% and 17.6%. The method is convenient, rapid, accurate, efficient, sensitive and practical. It is suitable for the determination and confirmation of amitraz and its metabolites in vegetables and fruits, and can meet the demands of domestic and foreign regulations.