气相色谱-串联质谱法测定不同原产国抗草甘膦 转基因大豆中草甘膦及其代谢物的残留量

目的利用气相色谱-串联质谱(gas chromatography-tandemmass spectrometry,GC-MS/MS)法对防城港口岸进境的不同原产国抗草甘膦转基因大豆中的草甘膦及其代谢物-氨甲基膦酸的残留量进行检测,对比分析其差异。方法采集原产自美国、巴西、阿根廷和乌拉圭的抗草甘膦转基因大豆各3批,样品磨碎后过筛,用水提取,再用盐酸沉淀蛋白,用二氯甲烷萃取脂肪,上层清液经阳离子交换柱(CAX柱)净化后,再与七氟丁醇和三氟乙酸酐进行衍生化反应,用柠檬醛-乙酸乙酯溶液定容,GC-MS/MS分析。结果草甘膦和氨甲基膦酸在2.5~100 ng/mL浓度范围内的质量浓度与峰面积间的线性相关性较好(r0.999),检出限均为0.05 mg/kg。样品的加标浓度为0.05、0.5和2.0 mg/kg时的平均回收率为77.1%~96.5%,相对标准偏差小于8.8%(n=6)。结论本方法的准确度高、精密度良好,能满足检测工作的实际需求。

Determination of residues of glyphosate and its metabolite in roundup ready soybean imported from different original countries by gas chromatography-tandem mass spectrometry

Objective To detect the residues of glyphosate (PMG) and its metabolite-aminomethyl phosphonic acid (AMPA) in roundup ready soybean imported from different original countries in Fangchenggang port by gas chromatography-tandem mass spectrometry (GC-MS/MS), and analyze the differences. Methods Three batch samples of each country were collected from the roundup ready soybeans imported from the United States, Brazil, Argentina and Uruguay. The procedures of sample were as follows: sifted after being pulverized, extracted by water, then the protein in sample was precipitated with hydrochloric acid and the fat was extracted with dichloromethane. After purification by cation exchange column (CAX), the supernatant extract obtained from the above steps was reacted derivatively with heptafluorobutanol and trifluoroacetic anhydride. The product was diluted with citral-ethyl acetate solution and then analyzed by GC-MS/MS. Results The calibration curves between mass concentration and peak area of PMG and AMPA showed good linearities (r>0.999) in the range of 2.5~100 ng/mL, and the detection limits were both 0.05 mg/kg. The average recoveries of spiked samples were between 77.1% and 96.5% when the added concentrations were 0.05, 0.5 and 2.0 mg/kg, respectively, and the relative standard deviations (RSDs) were less than 8.8% (n=6). Conclusion This method is accurate and precise, which can meet the requirements of detection.