多壁碳纳米管分散固相萃取-液质联用技术测定茶叶中草甘膦、草铵膦、氨甲基膦酸残留量

Determination of glyphosate, glufosinate and aminomethylphonic acid residues in tea by liquid chromatography-tandem mass spectrometry using multi-walled carbon nanotubes as dispersive solid-phase extraction sorbent

目的：建立茶叶中草甘膦、草铵膦和氨甲基膦酸残留量的超高效液相色谱串联质谱分析方法。方法样品经水提取后采用分散固相萃取技术,以多壁碳纳米管(MWCNTS)和N-丙基乙二胺键合固相吸附剂(PSA)吸附提取液中的杂质,上清液用9-芴基氯甲酸酯(FMOC-Cl)衍生。衍生物用 BEH C18进行分离,以乙腈-4 mmol乙酸铵水溶液为流动相,电喷雾正离子模式电离(ESI+),多反应监测模式检测(MRM),外标法定量。结果方法的线性范围是0.1～1μg/mL,相关系数大于0.999,定量限为10μg/kg,以绿茶为基质,三种物质添加水平分别为0.25、0.50、1.00 mg/kg,回收率范围分别为草甘膦95%~116%,草铵膦98%~118%,氨甲基膦酸74%~84%,精密度均小于6.79%(n=6)。结论该方法具有简便快速、灵敏度高、准确性强等特点,适合于测定茶叶中草甘膦、草铵膦和氨甲基膦酸的含量。

Objective An ultra performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) analysis method was established for simultaneous determination of glyphosate, glufosinate and aminomethyl-phonic acid (AMPA) in tea. Methods The sample was extracted with water, and cleaned up by multi-walled carbon nanotubes(MWCNTS)and primary-secondary amine(PSA)as dispersive solid-phase extraction sorbent, then derived using fluorenyl methyl chloroformate(FMOC-Cl). The derivatives were separated by ACQUITY UPLC BEH C18 column, using acetonitrile and 4 mmol/L ammonium acetate as the mobile phase. The identifi-cation and quantification of glyphosate, glufosinate and AMPA were carried out by MS/MS in positive electro-spray ionization(ESI+) and multiple reaction monitoring(MRM) mode, and the quantification analysis was per-formed by external standard method. Results The calibration curve showed a good linearity in the range of 0.1～1 μg/mL with the correlation coefficient r2> 0.999. The quantification (LOQ) limits were 10 μg/kg. The average recoveries of glyphosate, glufosinate and AMPA spiked at 0.25, 0.50 mg/kg and 1.00 mg/kg levels in green tea were 95%~116%, 98%~118% and 74%~84%, and the relative standard deviations (RSD, n=6) were lower than 6.79%. Conclusion This method is simple, effective and sensitive, and it is suitable for the deter-mination and confirmation of glyphosate, glufosinate and AMPA in tea.