LC-MS/MS测定牛奶中氟虫腈及代谢物残留量

建立了液相色谱-串联质谱(LC-MS/MS)法测定牛奶中氟虫腈及其代谢物残留量的方法。根据基质及目标物特点选择乙腈进行提取,通过比较Cleanert PEP Plus固相萃取柱,Florisil固相萃取柱、Waters Oasis PRiME HLB净化柱,氨基石墨复合柱净化效果及实验效率,选择Cleanert PEP Plus(60 mg/3 mL)固相萃取柱净化。经C18色谱柱分离,以0.1%甲酸乙腈溶液和0.1%甲酸水溶液(含浓度10 mmol/L乙酸铵)为流动相进行梯度洗脱,选择负离子多反应监测模式检测,外标法定量。结果表明1~50μg/kg范围内线性关系良好,相关系数R²>0.99。方法的检出限为0.6μg/kg,定量限为1μg/kg。在空白牛奶基质中3个不同添加水平实验中回收率为82.5%~97.4%,相对标准偏差为4.0%~10.5%。该方法简便、快速、准确、灵敏,适用于牛奶中氟虫腈及残留物的测定。

Determination of Fipronil and Its Metabolites Residues in Milk by Liquid Chromatography-Tandem Mass Spectrometry

A liquid chromatography-tandem mass spectrometry(LC-MS/MS)was established for the determination of fipronil and its metabolites in milk.The samples were extracted with acetonitrile,extract liquor was cleaned up by Cleanert PEP Plus(60 mg/3 mL),comparing with Florisil-solid phase extraction column,Waters Oasis PRiME HLB-solid phase extraction column and GCB-NH2-solid phase extraction column.The separation was performed on an Agilent Eclipse plus-C18 column with the flow phases of 10 mmol/L ammonium acetate aqueous solution containing 0.1%formic acid and acetonitrile containing 0.1%formic acid.The identification and quantitation of fipronil and its metabolites were performed by MS/MS in negative electrospray ionization(ESI-)and multiple reaction monitoring(MRM)mode.The quantitative analysis was carried out by external standard method.A good linear relationship,with the correlation coefficient(R²)greater than 0.99,was found in the mass concentration range of 1~50μg/kg.The limit of detection and limit of quantitation were 0.6μg/kg and 1μg/kg respectively.The recoveries of fipronil and its metabolites in blank milk matrixes spiked with three levels from 82.5%to 97.4%,and the relative standard deviations were between 4.0%and 10.5%.The method is simple,rapid,sensitive,accurate and suitable for the determining of fipronil and its metabolites.