QUANTIFICATION OF GLYPHOSATE AND ITS METABOLITE, AMINOMETHYL PHOSPHONIC ACID, IN WUYI ROCK TEA USING HIGH-PERFORMANCE LIQUID CHROMATOGRAPHY-TANDEM MASS SPECTROMETRY

Glyphosate (GLY), which is a commonly used herbicide in tea plantations worldwide, effectively controls the spread of gramineous and broadleaf weeds. However, owing to its toxicity, the maximum residue limits of GLY in food have become increasingly stringent. In this study, we developed an analytical method for accurate and precise quantification of trace levels of GLY and its main metabolite, aminomethyl phosphonic acid (AMPA), in Wuyi Rock tea using high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS). The method was based on a rapid detection kit including solid-phase extraction columns and derivatisation agents. The limits of quantification of GLY and AMPA in Wuyi Rock tea samples were 0.03 and 0.05 mg/kg, respectively. Good linear calibrations curves (R2 >= 0.996) were achieved for GLY and AMPA solutions in the concentration range 2-100 ng/mL. The recovery values of the samples spiked with 16, 80, and 160 mu g/kg of the analytes ranged between 89.32% and 97.62%, and the relative standard deviations ranged between 2.02% and 3.86%. Compared with the standard method currently used to analyse tea samples in China, the HPLC-MS/MS method requires lower amounts of reagents and shorter pretreatment times, involves facile operation, is highly accurate, and presents a low detection limit. Therefore, the method is suitable for batch detection and analysis of GLY and AMPA in Wuyi Rock tea samples.