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Quick Determination of the Residues for Fipronil and Its Metabolites in Tea by QuEChERS Clean up-Gas Chromatography-Tandem Mass Spectrometry Calibrated with Isotope Internal Standard

1, 1, 1, 1,LI Zu-Guang   

  • Received:2019-02-03 Revised:2020-02-24 Online:2020-06-25 Published:2020-06-22
  • Contact: LI Zu-Guang E-mail:lzg@zjut.edu.cn

Abstract: Based on quick, easy, cheap, effective, rugged and safe(QuEChERS)technique, a method for the simultaneous determination of fipronil and its metabolites in tea was developed by gas chromatography-tandem mass spectrometry. The samples were added with internal standard of fipronil-13C2, 15N2, then extracted with acetonitrile from tea 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). The analytes were detected by tandem mass spectrometry with multiple reaction monitoring(MRM) mode, and the internal standard method was used for quantification. A good linearity in the range of 0.4~100 μg/L with correlation coefficients (R2)>0.995 was observed. The limits of the quantification(LOQs) for fipronil and its metabolites were 1 μg?kg-1. The recoveries of the 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 the relative standard deviations(RSD, n=6) between 4.76%~13.07%. The method was simple, sensitive and accurate, and was suitable for the rapid quantitative analysis of fipronil and its metabolites in tea. The sensitivity of the method can meet the requirement for residual limitation of EU and Japan.

Key words: fipronil and its metabolites, isotope internal standard, QuEChERS, GC-MS/MS, tea

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