分散固相萃取/液相色谱-串联质谱法测定茶叶中草甘膦及其代谢物氨甲基膦酸的残留量

Determination of Glyphosate and Aminomethylphosphonic Acid Residues in Tea by Dispersive Solid-phase Extraction Combined with High Performance Liquid Chromatography-Tandem Mass Spectrometry

建立了一种分散固相萃取结合高效液相色谱-串联质谱法测定茶叶样品中草甘膦（PMG）及其代谢物氨甲基膦酸（AMPA）残留量的分析方法.样品经0.2％甲酸水超声提取,层状氢氧化镁铝水滑石（Mg-Al-LDHs）吸附富集,碳酸钠溶液洗脱后,以9-芴基氯甲酸酯（FMOC-Cl）为衍生剂衍生2h,Kinetex C18柱（50mm×2.1 mm,2.6 μm,Phenomenex）分离,以乙腈-5 mmol/L乙酸铵水溶液（含0.2％甲酸）为流动相梯度洗脱,电喷雾正离子模式电离（ESI＋）,多反应监测（MRM）模式检测,同位素内标法定量.草甘膦及其代谢物氨甲基膦酸在10～1 000 ng/mL范围内具有良好线性,相关系数均大于0.999,检出限和定量下限分别为0.015 mg/kg和0.05 mg/kg;在不同基质中,0.05,0.1,1.0 mg/kg 3个加标水平的平均回收率为86.6％ ～95.7％,相对标准偏差为5.1％～12.2％.该方法具有简便、快速、灵敏度高、准确性强等特点,可用于茶叶中草甘膦及其代谢物氨甲基膦酸残留的快速检测.

A method for the determination of glyphosate （PMG） and aminomethylphosphonic acid （AMPA） residues in tea was developed using dispersive solid-phase extraction （dSPE） combined with high performance liquid chromatography -tandem mass spectrometry（ HPLC -MS/MS）. The samples were ultrasonically extracted with 0.2% formic acid, and then enriched and cleaned up with Layered Double Hydroxides （ Mg - A1 - LDHs） absorbent. The analytes were derived with fluorenylmethyl- chloroformate（FMOC- C1） in sodium carbonate solution for 2 h. The separation of the target com- pounds were performed on a Phenomenex Kinetex C18 column （50 mm x 2. 1 mm, 2.6 Ixm） using acetonitrile-5 mmol/L ammonium acetate（containing 0. 2% formic acid） as mobile phase by gradi- ent elution. The identification and quantification of the drugs were carried out by positive electrospray ionization（ESI ） in multiple reaction monitoring（MRM） mode, the quantification analysis was per- formed by the isotopically labelled internal standard method. The calibration curves showed good line- arities in the range of 10 - 1 000 ng/mL with correlation coefficients（ r2） more than 0. 999. The lim- its of detection（LOD） and the limits of quantitation（LOQ） were 0. 015 mg/kg and O. 05 mg/kg, respectively. The average recoveries of PMG and AMPA in 0. I and 1.0 mg/kg were between 86.6% and 95.7% , different matrices at spiked levels of 0.05, with relative standard deviations（RSDs） of 5. 1% - 12.2% . The developed method is simple, rapid and sensitive, and is suitable for the rapid determination of trace PMG and AMPA residues in tea.