超高效液相色谱-串联质谱联用法对奶粉中3种硝基咪唑残留物的测定

Simultaneous Determination of Three Nitroimidazoles in Milk Powder by Ultra Performance Liquid Chromatography-Tandem Mass Spectrometry

建立了超高效液相色谱-串联质谱联用法测定奶粉中甲硝唑（MNZ）、二甲硝唑（DMZ）和洛硝哒唑（RNZ）3种硝基咪唑类残留物的方法。样品以乙酸乙酯和乙腈提取，正己烷脱脂，浓缩过滤后进行超高效液相色谱-串联质谱分析，多反应监测正离子模式扫描。实验优化了质谱条件，并考察了方法的灵敏度、准确度、精密度和回收率。甲硝唑、二甲硝唑和洛硝哒唑的线性范围为2．5～100．0μg／L，定量下限均为2．5μg／kg，在2．5、5．0、10．0μg/kg3个水平的加标回收率为89％～112％，相对标准偏差为4．0％-7．1％。该方法简捷、灵敏度高，可用于奶粉中硝基咪唑残留的检测。

A comprehensive analytical method based on ultra performance liquid chromatography - tandem mass spectrometric （ UPLC - MS/MS ） method for the determination of trace metronidazole （MNZ）, dimetridazole（DMZ） and ronidazole（RNZ） residues in milk powder was developed. The sample was extracted by ethyl acetate - acetonitrile and defatted with n-hexane. After concentrated and filtered, the extract was analyzed by UPLC - MS/MS under positive electrospray ionization mode. Under the optimal conditions, the linear ranges were 2. 5 - 100. 0 μg/L for all target analytes and the limits of quantitation（ LOQ, S/N 〉 10） were 2. 5 μg/kg for MNZ, DMZ and RNZ. The recoveries of MNZ, DMZ and RNZ in milk powder at three spiked concentration levels of 2. 5, 5.0 and 10. 0 μg/kg ranged from 89% to 112% with relative rapid and sensitive for the determination of nitroimidazoles residues in milk powder.