茶叶中草甘膦及其代谢物氨甲基磷酸的绿色检测分析

目的:建立一种绿色、无需衍生化的离子色谱串联质谱(IC-MS/MS)测定茶叶中草甘膦及其代谢产物氨甲基磷酸残留量的方法。方法:茶叶样品经20 mmol/L NaOH水溶液超声提取后，以分散固相萃取法(150 mg乙二胺-N-丙基硅烷、15 mg C₁₈、15 mg石墨化炭黑)对样品进行净化。采用IC-MS/MS测定草甘膦及氨甲基磷酸残留，以35 mmol/L氢氧化钠水溶液为流动相，在离子色谱柱AS11-HC-4μm(2 mm×250 mm)上进行分离，串联质谱多反应监测模式进行分析，并采用稳定同位素内标法进行定量。结果:草甘膦和氨甲基磷酸在5～200 ng/mL质量浓度范围内线性良好，其相关系数分别为0.999 8和0.998 2。茶叶中草甘膦和氨甲基磷酸的检出限均为0.05 mg/kg,定量限均为0.10 mg/kg。草甘膦和氨甲基磷酸的平均加标回收率分别为61.2%～104.9%,61.5%～83.2%,RSDs均<20%。结论:该方法符合绿色分析化学要求，可用于茶叶中草甘膦和氨甲基磷酸残留量的测定。

Green analysis of glyphosate and its metabolite amino methyl phosphoric acid in tea

Objective： This study aimed to develop an ion chromatography-tandem mass spectrometry (IC-MS/MS) for the analysis of glyphosate and its metabolite amino methyl phosphoric acid (AMPA) residues in tea without derivatization. Methods： Tea samples were ultrasonically extracted with 20 mmol/L NaOH aqueous solution and cleaned up by dispersive solid-phase extraction (150 mg primary-secondary amine (PSA), 15 mg C₁₈, 15 mg graphitized carbon black (GCB)). The samples were separated on an ion chromatographic column AS11-HC-4 μm (2 mm×250 mm) by using an isometric elution procedure of 35 mmol/L aqueous solution of sodium hydroxide as mobile phase. A multiple reactions monitoring (MRM) model was used to obtain the sensitivity of the method, and the isotopically labeled internal standards were applied in the calibration process. Good linearities and recoveries were obtained in the validation process. Results: The correlation coefficients R² were 0.999 8 and 0.998 2, respectively. The detection limits of glyphosate and AMPA in tea were both 0.05 mg/kg, and the quantification limits were both 0.10 mg/kg. The average recoveries of glyphosate and AMPA were 61.2%～104.9% and 61.5%～83.2%, respectively with RSDs less than 20%. Conclusion: This method meets the requirements of green analytical chemistry and can be used for routine detection of glyphosate and aminomethylphosphoric acid residues in tea.