Abstract: An analytical method was developed for the simultaneous determination of glyphosate, glufosinate and aminomethyl phosphonic acid residues in black and green tea by ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) coupled with a modified QuEChERS method. The samples were extracted twice with pure water, and the extraction solutions were purified by dispersive solid phase extraction with MWCNT, C₁₈, PVPP and CNT-OH adsorbents. The mass spectrometry was performed in multiple reaction monitoring (MRM) mode and quantified by external standard method. The results show that glyphosate, glufosinate and aminomethyl phosphonic acid had a good linear relationship within a certain concentration range with correlation coefficients (R²) ranging from 0.999 3 to 1.000 0 in black and green tea. The limits of detection ( LOD ) of the method were 0.005 0, 0.030 mg·kg^-1 and 0.030 mg·kg^-1, respectively. The limits of quantitation (LOQ) were 0.050, 0.10 mg·kg^-1 and 0.10 mg·kg^-1, respectively. The average spiked recovery rates and the relative standard deviations (RSD) of pesticides were in the range of 81.6%-120.0% and 0.6%-13.6%, respectively. The method is simple, inexpensive, reproducible, sensitive and suitable for the determination of glyphosate, glufosinate and aminomethyl phosphonic acid in black and green tea.

Key words: QuEChERS, tea, glyphosate, glufosinate, aminomethyl phosphonic acid