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建立了超高效液相色谱-三重四极杆质谱快速测定牛奶中53种β-内酰胺类抗生素及其代谢产物残留的检测方法。牛奶样品经等量乙腈沉淀去蛋白、超滤后，以0.1％（ v/v，下同）甲酸水溶液和0.1％甲酸乙腈溶液作为流动相进行梯度洗脱，在 ACQUITY BEH C18色谱柱上实现分离，一次进样分析仅需10 min，正离子电喷雾多反应监测（ MRM）模式检测，基体工作曲线内标法定量。线性范围从方法的定量限至200μg/kg，相关系数均优于0.9911，平均加标回收率在71％~121％之间，相对标准偏差为1.7％~19％（ n=6）。方法简单、快速，每人每天可处理50多份样品，检出限能够满足我国和欧盟对兽药残留的最高限量要求，适合于牛奶样品中53种β-内酰胺类抗生素及其代谢产物的快速筛查和定量测定。

A rapid method for the determination of 53 β-lactams and their metabolites residues in milk was developed by ultra-performance liquid chromatography-triple quadrupole mass spec-trometry( UPLC-MS/MS ). The method was based on protein precipitation by adding equal quantity of acetonitrile,followed by the ultra filtration of the extracts. The analysis of the resi-dues was achieved on an ACQUITY BEH C 18 column with gradient elution using mobile phases of 0. 1% formic acid in water and acetonitrile. The analytes were detected by positive electros-pray ionization tandem mass spectrometry in the multiple reaction monitoring( MRM)mode, and quantified by matrix-matched internal standard calibration. The cycle time of each analysis was 10 min. Under the optimum operation conditions,excellent linear dynamic range was observed from the quantification limits to 200 μg/kg with the correlation coefficients better than 0. 991 1 for all the compounds. The average recoveries for all the β-lactams and their metabo-lites ranged from 71% to 121% with the relative standard deviations of 1. 7%-19%( n=6). This method enabled the screening for more than 50 samples per day by one person and also showed good performance for quantitation,and allowed the determination of the β-lactams and their metabolites residues in milk below the maximum residue levels( MRLs)according to the Bulle-tin No. 235(2002)of Ministry of Agriculture,P. R. China and EU Regulation 2377/90/EC(2008 Revised).