QuEChERS-气相色谱-三重四级杆串联质谱法测定茶叶中草甘膦和氨甲基膦酸残留

Determination of Glyphosate and Aminomethyl Phosphonic Acid Residues in Tea by QuEChERS and Gas Chromatography-Triple Quadrupole Mass Spectrometry

建立气相色谱-三重四极杆质谱测定茶叶中草甘膦和氨甲基膦酸的分析方法。茶样经超纯水、二氯甲烷提取后,与三氟乙酸酐-七氟丁醇进行衍生反应,衍生后产物经乙二胺-N-丙基硅烷(PSA)、石墨化碳(GCB)、C18混合净化剂净化,TG-1701MS(30 m×0.25 mm,0.25μm)分离,气相色谱-串联质谱进行测定。试验详细考察了PSA、GCB、C18用量对草甘膦和氨甲基膦酸添加回收率的影响,结果表明,2 m L衍生液中加入50 mg PSA、25 mg GCB和25 mg C18时净化效果最好。在5μg/L^500μg/L范围内,草甘膦和氨甲基膦酸均有良好的线性关系(r2>0.999),定量限(LQD)(S/N=10)分别为0.03 mg/kg和0.015 mg/kg,样品加标浓度为0.50、1.00 mg/kg和2.50 mg/kg时,草甘膦的平均回收率为86.1%~101.2%,相对标准偏差(RSD)(n=6)为3.2%~6.7%;氨甲基膦酸的平均回收率为83.6%~103.4%,相对标准偏差(RSD)(n=6)为3.6%~7.3%。该方法样品前处理简单,分析时间短,回收率和精密度等均符合草甘膦和氨甲基膦酸检测技术的要求,适用于茶叶中草甘膦和氨甲基膦酸残留的检测。

A method for glyphosate（PMG）and aminomethyl phosphonic acid（AMPA）residues in tea by Qu ECh ERS and gas chromatography-triple quadrupole mass spectrometry（GC-MS/MS）was developed. The sample was extracted with ultrapure water and dichloromethane,and then PMG and AMPA were derivatized using heptafluorobutanol and trifluoroacetic anhydride. The derivatives of PMA and AMPA were purified by a mixed sorbent of primary secondary amine（PSA）,graphitized carnon black（GCB）and C18,separated on a TG-1701 MS column（30 m ×0.25 mm,0.25 μm） and finally detected with gas chromatography-triple quadrupole mass spectrometry（GC/MS/MS）in selected reaction monitoring（SRM）mode. The quantification analysis was performed by external standard. The effects of the amounts of PSA,GCB and C18 added on the recoveries of PMG and AMPA were investigated. The results showed that the purification effect was best when 50 mg PSA,25 mg GCB and 25 mg C18 in 2 m L of the derivatives were added. The method showed a good linearity（r20.999）in the range of 5 μg/L-500 μg/L. The limits of quantification（LQDs,S/N=10）of PMG and AMPA were 0.03 mg/kg and 0.015 mg/kg. At the spiked levels of 0.50 mg/kg,1.00 mg/kg and 2.50 mg/kg,the recoveries of PMG and AMPA were 86.1 %-101.2 % and 83.6 %-103.4 % respectively,and the relative standard deviations（RSDs）（n=6）of PMG and AMPA were 3.2 %-6.7 % and 3.6 %-7.3 %,respectively. This method is simple,rapid and characterized with acceptable sensitivity and accuracy to meet the requirements for the analysis of PMG and AMPA in tea.