Abstract: A ultra performance liquid chromatography-tandem mass spectrometry(UPLC-MS/MS) method for the determination of bifenazate and its metabolite bifenazate-diazene in papaya was established. The sample was extracted with acetonitrile and acetic acid(0.25%) from the papaya after treated with a homogenizer. The organic phase was then separated from water phase by adding sodium chloride. Divided the organic phase and added 0.25% ascorbic acid into centrifuge tubes, derived 60 min. Finally, the target analyte was separated by a Waters ACQUITY UPLC BEH C18 column（50 mm×2.1 mm，1.7 μm. A tandem quadrupole mass spectrometer operated in MS/MS mode for multiple reaction monitoring(MRM) was used for the qualitative and quantitative analysis of the constituents, respectively. The results showed that the average recoveries of bifenazate and bifenazate-diazene ranged from 78.3 % to 109.8 % with RSDs of 4.0% -8.8% at the spiking levels from 1.0 to 10.0 ng/kg (n=5).The calibration curves showed good linearity in the range of 0.25-2.0 ng/mL, with the correlation coefficient over 0.999. The limits of quantification(LOQs) were 0.001 mg/kg for bifenazate, the method is available for the determination of bifenazate pesticide residues in papaya.

Key words: ultra performance liquid chromatography-tandem mass spectrometry(UPLC-MS/MS), papaya, bifenazate, bifenazate-diazene, residue