Abstract:

An ultra performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) method for the
determination of residues of bifenazate and its metabolite bifenazate-diazene in papaya was established. The sample was
extracted with acetonitrile and acetic acid (0.25%) after being homogenized. The organic phase was then separated from
water phase by adding sodium chloride and derivatized for 60 min after the addition of 0.25%. Finally, the target analytes
were 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
analyses of the constituents. The results showed that the average recoveries of bifenazate and bifenazate-diazene ranged
from 78.3% to 109.8% with relative standard deviation (RSDs) of 4.0%–8.8% at spiked 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 correlation coefficient over 0.999 8.
The limit of quantification (LOQ) was 1×10-6 mg/kg for both bifenazate and its metabolite. The method is applicable 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