超高效液相色谱-串联质谱法测定玉米中硝磺草酮及其代谢物残留量

摘要

A novel method was developed for the simultaneous determination of mesotrione and its metabolite (4-methylsulfonyl-2-nitrobenzoic acid,MNBA) in maize by ultra performance liquid chromatography coupled with tandem mass spectrometry(UPLC-MS/MS).The samples were extracted with acetonitrile-water (50∶50,V/V) solutions and an aliquot of the extract was acidified to pH 2 with formic acid and then cleaned-up by Oasis HLB cartridge.The residues were eluted from cartridge with methanol-diethyl ether (70∶30,V/V).The elutions were evaporated to appropriately dry under a stream of nitrogen,dissolved in 2 mL acetonitrile1 mmol/L ammonium acetate (75∶25,V/V).The residues were analyzed by mass spectrometry with negative ion mode using multiple-reaction monitoring (MRM) and quantification was achieved by matrix calibration.The method had a good linear correlation (correlation coefficient was above 0.99) in the range of 1-200 μg/L.The average recoveries of mesotrione and MNBA were 83.8％-101.1％ at spiked level between 5 μg/kg and 50 μg/kg with the relative standard deviation (RSD) between 5.3％ and 12.8％.The limits of quantification for mesotrione and MNBA were 1.0 and 2.0 μg/kg,respectively.%建立了超高效液相色谱-串联质谱法测定玉米中硝磺草酮及其代谢物(MNBA)的残留分析方法.样品用乙腈-水溶液提取,取适量提取液用甲酸酸化至pH 2,过HLB固相萃取柱进行净化,用甲醇-乙醚(70∶30,V/V)洗脱,洗脱液用氮气吹至近干,用1 mmol/L醋酸铵-乙腈(25∶75,V/V)定容后进行质谱分析,利用基质校正曲线对其准确定量.硝磺草酮和MNBA在1～200μg/L浓度范围内呈线性关系,相关系数均大于0.99,在添加浓度5 ～50 μg/kg范围内,硝磺草酮及其代谢物MNBA的平均回收率为83.8％ ～ 101.1％,相对标准偏差在5.3％ ～ 12.8％之间,硝磺草酮和代谢物MNBA定量限分别为1.0和2.0 μg/kg.