Determination of trifloxystrobin and its metabolite in coffee by liquid chromatography-mass spectrometry

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.