RESUMO
An efficient technique for the determination of multiclass pesticide residues ( glyphosate, aminomethyl phosphonic acid ( AMPA) and glufosinate) in four kinds of tea ( green tea, black tea, Oolong tea and Puer tea) was developed based on ultra performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). Samples were extracted with 0. 05 mol/L NaOH solution, regulated pH value with HCl, followed by purification by Oasis HLB column, and then precolumn-derived with 9-fluorenylmethyl chloroformate ( FMOC-CL ) in borate buffer. All pesticide residues studied showed good linearity with correlation coefficient ( R2 ) greater than 0. 99 in the concentration range of 5-1000 μg/L. Limits of quantitation (LOQs) of three pesticide compounds ranged from 0. 03 to 0. 08 mg/kg (S/N=10). Tea samples spiked with 0 . 1 , 0 . 4 and 4 mg/kg showed the recovery ranging from 72 . 1% to 109 . 9%, and RSDs from 0. 5% to 9. 8% (n=6). In addition, the validated method was applied to commercial samples, and all the detections were confirmed by acquiring transitions for each pesticide in samples.