A high performance aqueous normal phase (ANP) chromatography -tandem mass spectrometric method was established for the simultaneous determination of glyphosate (GLY) and aminomethylphosphonic acid (AMPA) in plant-derived foodstuff. The sample was extracted with ultrapure grade water, and purified with anion-exchange column ( MAX) . The seperation of GLY and AMPA were carried out by ANP chromatography using 5 mmol/L ammonium acetate (A) and 5% water -95% acetonitrile ammonium acetate solution ( B) as mobile phases. The detection of target compounds was performed by MS under electrospray ionization source, negative scanning mode and multiple reaction monitoring. The external standard method was used for the quantitative analysis. The result indicated that the linear ranges of GLY and AMPA were in the concentration ranges of 10 - 500 μg/L and 20-1 000 μg/L, respectively, with correlation coefficients more than 0. 99. The limits of detection(LODs, S/N = 3) of two compounds were both 0. 01 mg/kg, and the limits of quantita-tion (LOQs, S/N = 10) were 0. 02 mg/kg for GLY and 0. 04 mg/kg for AMPA, respetively. The recoveries of GLY and AMPA in six matries ranged from 78% to 113%, with relative standard deviations (RSDs) of 3. 2 —11. 0% . The method could meet the requirements for daily food determination with its high sensitivity, recovery and selectivity.%采用反反相色谱-串联质谱法建立了直接测定植物源性食品中草甘膦(GLY)及其主要代谢物氨甲基膦酸 (AMPA)的方法.样品用水提取,阴离子交换柱(MAX)净化,以5mmol/L的乙酸铵溶液和5％水-95％乙腈的乙酸铵溶液为流动相,反反相色谱分离,采用电喷雾离子源、负离子扫描模式和多反应监测模式质谱检测,外标法定量.草甘膦和氨甲基膦酸的线性范围分别为10～500μg/L和20～1 000 μg/L,相关系数(r2)均大于0.99.方法的检出限(S/N =3)均为0.01 mg/kg,定量下限(S/N=10)分别为0.02 mg/kg和0.04 mg/kg.在6种基质中,GLY和AMPA在3个加标水平下的回收率为78％～ 113％,相对标准偏差(RSD,n=6)为3.2％～11.0％.方法的灵敏度和回收率高,选择性好,能满足日常食品检测工作的要求.
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