Abstract:
Objective To develop a method for determining trifloxystrobin and its metabolite trifloxystrobin acid simultaneously in coffee by liquid chromatography-mass spectrometry (LC-MS).
Method The sample was ultrasonically extracted with acetonitrile (including φ=1% acetic acid), and salted out with sodium chloride and anhydrous magnesium sulfate. After high-speed centrifugation, the supernatant was purified by C18 dispersive solid-phase extraction and detected by LC-MS. The quantitative determination was conducted by ESI (+) ionization mode and multi-reaction monitoring (MRM).
Result The recovery rates of trifloxystrobin in coffee fruits ranged from 87.8% to 106.7%, and the relative standard deviation (RSD) ranged from 1.3% to 5.8% when the additive amount of trifloxystrobin ranged from 0.01 to 2.00 mg·kg–1. The recovery rates of trifloxystrobin in coffee beans ranged from 83.2% to 88.1%, and the RSD ranged from 2.0% to 6.2%. The recovery rates of trifloxystrobn acid in coffee fruits ranged from 71.5% to 106.0%, and the RSD ranged from 1.0% to 6.1%. The recovery rates of trifloxystrobn acid in coffee beans ranged from 84.4% to 105.2%, and the RSD ranged from 1.0% to 5.2%. The minimum detectable amounts of both trifloxystrobin and trifloxystrobin acid in coffee were 2.5 × 10–12 g, and the minimum limits of quantitation were 0.01 mg·kg–1.
Conclusion This method is simple, rapid and stable, and can meet the requirement for detecting the residues of trifloxystrobin and its metabolites in coffee samples.