柱前衍生-超高效液相色谱-串联质谱测定茶叶中草甘膦、草铵膦及主要代谢物氨甲基膦酸残留

采用柱前衍生-超高效液相色谱-串联质谱测定茶叶中草甘膦、草铵膦及其主要代谢物氨甲基膦酸残留。利用正交试验方法,系统研究了提取与净化等前处理条件对茶叶中草甘膦、草铵膦和代谢物氨甲基膦酸检测的影响。实验结果表明,最优的前处理方案为茶叶样品经纯水旋涡提取,阳离子交换柱净化,0.5%(v/v)甲酸水溶液洗脱和9-芴甲基氯甲酸酯衍生,C_(18)色谱柱分离,超高效液相色谱-串联质谱定量分析(电喷雾正离子)。结果表明:在1~100μg/L范围内,草甘膦、草铵膦和氨甲基膦酸呈现良好的线性关系,相关系数(R~2)均大于0.991,该方法检出限为0.016 0~0.030 0 mg/kg,定量限为0.053 0~0.100 mg/kg。在0.050 0、0.400和1.20 mg/kg 3个添加水平下,草甘膦、草铵膦和氨甲基膦酸的平均回收率为78.3%~108%,相对标准偏差为5.46%~9.63%。利用该方法检测837份茶叶中草甘膦、草铵膦和氨甲基磷酸残留,检出率分别为3.46%、0.24%和4.42%,超标率为0.24%。该方法简单、快速、灵敏、准确,能够满足大批量茶叶中草甘膦、草铵膦和氨甲基膦酸残留的检测需要。

Determination of glyphosate,glufosinate, and main metabolite aminomethylphosphonic acid residues in dry tea using ultra-high performance liquid chromatography-tandem mass spectrometry

A method has been developed for the determination of glyphosate (GLY), glufosinate (GLUF), and the main metabolite aminomethylphosphonic acid (AMPA) residues in dry tea based on ultra-high performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) coupled with pre-column derivatization. A systematic study of the effects of pretreatment methods including extraction and purification procedures was designed and carried out for the determination of GLY, GLUF, and AMPA. The results indicated that the optimal pretreatment method was as follows:the tea sample was first extracted by water in vortex, and then purified by a cation exchange solid-phase extraction column with the elution of 0.5% (v/v) formic acid aqueous solution. Finally, the eluant was derivatized by 9-fluorenylmethyl chloroformate, and the target compounds were separated on a C₁₈ chromatographic column and analysed by UPLC-MS/MS (ESI⁺). GLY, GLUF, and AMPA showed good linearity in the range of 1-100 μ g/L, with correlation coefficients above 0.991. The limits of detection and limits of quantification were found to be 0.0160-0.0300 mg/kg and 0.0530-0.100 mg/kg, respectively. The average spiked recoveries of GLY, GLUF, and AMPA varied from 78.3% to 108% at three spiked levels (0.0500, 0.400, and 1.20 mg/kg), while the relative standard deviations ranged from 5.46% to 9.63%. The proposed method was utilized to detect 837 batches of tea samples. The detection ratios of GLY, GLUF, and AMPA were 3.46%, 0.24%, and 4.42%, respectively, while 0.24% of the investigated tea samples had values above maximum residue limits. The developed method is simple, rapid, sensitive, and accurate for the determination of GLY, GLUF, and AMPA in dry tea and may be used for routine analysis.