鸡蛋中代谢物液相色谱-串联质谱联用测定

Determination of dimetridazole and its hydroxylated metabolite in eggs using liquid chromatography-tandem mass spectrometry

目的建立测定鸡蛋中二甲硝咪唑及其羟基代谢物的高效液相色谱-串联质谱法。方法样品加入氘代内标，经乙酸乙酯提取，氮气吹干，再用0．1％甲酸-正己烷（1＋1）溶解残渣，水相过滤后，电喷雾离子化（ESI＋），多反应监测模式定量。结果方法线性好，二甲硝咪唑及其羟基化代谢物的线性范围分别为0．03～50μg／L，0．11～50μg／L；线性相关系数分别为0．9989，0．9996，检出限为0．009μg/kg，0．03μg/kg；在1，4，10μg/kg3个浓度水平加标，二甲硝咪唑的回收率在90．4％～98．5％之间，变异系数CV〈4．4％，代谢物的回收率在85．2％～102．5％之间，CV〈5．6％。结论方法灵敏度高、准确度好，能满足鸡蛋中准确定性、定量要求，为二甲硝咪唑的溯源调查和卫生监督提供了科学依据。

Objective A liquid chromatography-tandem mass spectrometry（ LC- MS/MS） method was developed to quantify and confirm the presence of dimetridazole（DMZ） and its hydroxylated metabolite DMZOH in eggs. Methods Deuteriated DMZ was employed as an internal standard. Samples were extracted with ethyl acetate, then evaporate just to dryness under nitrogen. The residue was redissolved in 0.1% formic acid-hexane（ 1 ＋ 1, v/v）, formic acid phase was used for analysis. Quantitative results were based on multiple reaction monitoring mode after ionization in the positive electrospray ionization mode. Results The calibration curve of DMZ and DMZOH showed good linearity in the range of 0.03 ～ 50μg/L with correlation coefficient of 0.998 9 and the range of 0.11 ～ 50 μg/L with r = 0.999 6 respectively. The detection limits were 0.009 μg/kg and 0.03 μg/kg. The average recoveries at three spiked levels（1, 4, 10 μg/kg） were between 90.4% and 98.5% within CV〈4.4% for DMZ, and between 85.2% and 102.5% within CV〈5.6% for DMZOH. Conclusion The method can identify and quantify DMZ and its metaholite DMZOH in eggs. It is simple and sensitive, suitable for statutory residue testing.