关键词: 氟虫腈及其代谢物, 同位素内标法, QuEChERS技术, 气相色谱-串联质谱法, 茶叶

Abstract: Based on the quick, easy, cheap, effective, rugged and safe (QuEChERS) technique, a method for the simultaneous determination of the residues of fipronil and its metabolites in tea was developed by gas chromatography-tandem mass spectrometry (GC-MS/MS). The samples were added with the internal standard of fipronil-13C2,15N2, and then extracted with acetonitrile after water soaking. The extract was dehydrated with sodium chloride (NaCl) and anhydrous magnesium sulfate (MgSO4) and purified by dispersive solid phase extraction with N-propyl ethylenediamine (PSA) and graphite carbon (GCB) sorbents. The analytes were detected by tandem mass spectrometry using multiple reaction monitoring (MRM), and quantified by the internal standard method. A good linearity in the concentration range of 0.4–100 μg/L with correlation coefficients (R2) > 0.995 was observed. The limits of quantification (LOQs) for both fipronil and its metabolites were 1 μg/kg. The recoveries of fipronil and its metabolites at four spiked levels (1, 5, 20 and 200 μg/kg) were in the range of 76.72%–96.53% with relative standard deviations (RSDs, n = 6) between 4.76% and 13.07%. The method was found to be simple, sensitive, accurate and suitable for the rapid quantitative analysis of fipronil and its metabolites in tea. Its sensitivity could meet the requirement for the residual limitation of the EU and Japan.

Key words: fipronil and its metabolites, isotope internal standard, QuEChERS, gas chromatography-tandem mass spectrometry, tea