亲水作用色谱-串联质谱法测定稻米中的草甘膦和氨甲基磷酸残留量

采用亲水作用色谱-串联质谱建立了同时测定稻米中草甘膦及其主要代谢物氨甲基磷酸残留量的检测方法。样品经水提取,C18固相萃取柱和超滤膜净化,以1 mmol/L乙酸铵溶液(用氨水调pH=11.0)-乙腈为流动相,亲水作用色谱柱分离,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,基质匹配标准溶液外标法定量。草甘膦和氨甲基磷酸分别在0.001～0.250 mg/L和0.0025～0.250 mg/L质量浓度范围内线性关系良好,检出限(信噪比为3)分别为0.010 mg/kg和0.020 mg/kg。通过对空白大米样品进行0.100、0.500和2.500 mg/kg 3个加标水平的回收试验,草甘膦和氨甲基磷酸的平均回收率和相对标准偏差分别为96.3%～107.3%和1.3%～9.1%(n=3)。该方法无需衍生,净化步骤简便快速,定量准确,可满足稻米中草甘膦和氨甲基磷酸残留检测要求。

Determination of glyphosate and aminomethylphosphonic acid in rice using hydrophilic interaction chromatography-tandem mass spectrometry

A method was developed for the simultaneous determination of glyphosate (Gly) and aminomethylphosphonic acid (AMPA) residues in rice using hydrophilic interaction chromatography-tandem mass spectrometry (HILIC-MS/MS). The samples were extracted with water, and purified using a C18 solid phase extraction cartridge followed by an ultrafiltration membrane to remove interfering materials. Gly and AMPA were separated on an HILIC column with the mobile phases of 1 mmol/L ammonium acetate (pH 11.0 adjusted with ammonium hydroxide) and acetonitrile, and finally detected with negative electrospray ionization (ESI-) in multiple reaction monitoring (MRM) mode. The matrix-matched external standard calibration curves were used for quantitative analysis. The sample pretreatment of Gly and its metabolite was successfully carried out without any derivatization. Under the optimal analytical conditions, the linearities of Gly and AMPA were in the concentration ranges of 0. 001 to 0. 250 mg/L and 0. 002 5 to 0. 250 mg/L respectively, with the correlation coefficients of 0. 999 5 for the both analytes. The limits of detection (S/N = 3) of the method were 0.010 mg/kg for Gly, and 0.020 mg/kg for AMPA. For all the samples, the mean spiked recoveries of Gly and AMPA were in the range from 96.3% to 107.3% at 3 spiked levels (0.100, 0.500 and 2.500 mg/kg), and the relative standard deviations (RSDs, n = 3) were in the range of 1.3%-9.1%. The method is easy, fast, sensitive and accurate, and can meet the requirements of the determination of Gly and AMPA pesticide residues in rice.