The development and validation of a method to determine flonicamid and its metabolites as TFNA (4-trifluoromethylnicotinic acid), TFNG (N-(4-trifluoromethylnicotinoyl) glycine) and TFNA-AM (4-trifluoromethylnicotinamide) in bell pepper samples by ultra-high-performance liquid chromatography coupled to Orbitrap mass spectrometry (UHPLC-Orbitrap-MS) was performed. A fast and simple extraction procedure with acidified acetonitrile and salts (magnesium sulfate and sodium chloride) was used. The methodology was validated, checking for specificity, recovery, precision, limits of detection (LODs) and limits of quantification (LOQs). The recoveries ranged from 84% to 98%, and precisions were lower than 17%. Finally, LODs ranged from 1 µg kg-1 (flonicamid) to 6 µg kg-1 (TFNA-AM), while LOQs ranged from 10 µg kg-1 (flonicamid) to 30 µg kg-1 (TFNA-AM). Bell pepper samples were analysed and concentrations up to 98 µg kg-1 (flonicamid) were detected, although the sum of flonicamid and metabolites did not exceed the maximum residue limit (MRL) set by the European Union.
Keywords: Flonicamid; HRMS; Orbitrap; QuEChERS; TFNA; TFNA-AM; TFNG; UHPLC; metabolites.