Determination of Glyphosate and Glufosinate-Ammonium Residues in Tea by UPLC-MS/MS

A rapid method was developed for the determination of glyphosate (GLY) and glufosinate-am monium (GLUF)in tea using ultra-high performanc e liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). The sample was extracted with NaOH solution and after pH adjustment with HCl, the extract was cleaned up with N-(n-propyl)ethyenediamine (PSA), and then was derivatized with 9-fluorenylmethyl chlorformate (FMOC-Cl) in borate buffer solution. The derivatives of GLY and GLUF were detected with positive electrospray ionization-mass spectrometry (ESI-MS/MS) in the multiple reaction monitoring (MRM) mode. The quantification was performed by external standard method. The method showed a good linearity (r > 0.995) in the range of 0.005-0.50 μg/mL. The limit of detection (LOD) and the limit of quantization (LOQ) were 0.05 and 0.08 mg/kg for both GLY and GLUF, respectively. At spiked levels of 0.08, 0.10, 1.0, 2.0 and 4.0 mg/kg, the recoveries of GLY and GLUF were 75.6%-95.5% and 76.0%-96.6%, with relative standard deviations(RSDs) (n = 10) of 3.24%-8.38% and 3.05%-7.85%, respectively. This method proved to be simple and rapid, and its sensitivity and accuracy could meet the requirements for the simultaneous analysis of GLY and GLUF in tea. © 2019, China Food Publishing Company. All right reserved.