Analysis of 24 Sulfonamide Residues in Bovine Milk by Ultra Performance Liquid Chromatography-Electrospray Ionization Tandem Mass Spectrometry

A confirmative method was developed to detect 24 sulfonamide residues in bovine milk simultaneously,which included sulfaguanidine,sulfanilamide,sulfisomidine,sulfacetamide,sulfadiazine,sulfathiazole,sulfapyridine,etc,by ultra performance liquid chromatography coupled with electrospray ionization tandem mass spectrometry ( UPLC-ESI-MS/MS). In this method,the samples were extracted and purified. The UPLC separation was performed on an ACQUITY UPLCTM BEH C18 column ( 100 mm × 2. 1 mm i. d. ,1. 7 μm) utilizing a gradient elution program of acetonitrile and water ( containing 0. 25% acetic acid) as the mobile phase. Identification and quantification were achieved by UPLC-ESI-MS/MS in positive mode and multiple reactions monitoring. Good linearities were observed in the range of 5 -100 μg/kg with correlation coefficients above 0. 99. The method was validated at 5,25 and 50 μg/kg. The validation results were as follows:the average recoveries of 24 antibiotics ranged from 64. 2% to 110. 9% with the relative standard deviations of 3. 2% -13. 1%. The detection limits of the method were 0. 21 -1. 62 μg/kg. The method could meet the requirements of both domestic and international legislation.