Determination of 24 Sulfonamides in Milk by Ultra Performance Liquid Chromatography Combined with Quadrupole Mass Spectrometry

A novel method has been developed for the rapid separation and determination of 24 sulfonamides(SAs) in milk by ultra performance liquid chromatography-quadrupole mass spectrometry(UPLC-MS/MS) in 10 min.Sulfonamides residues from milk were extracted with acetonitrile,followed by homogenizing,ultrasound treating and centrifuging.The extract was dried under nitrogen stream,redissolved in the mobile phase and defatted with n-hexane saturated by acetonitrile.The chromatographic analysis was performed on an ACQUITY UPLCTM BEH C18 column(1.7 μm,100 mm×2.1 mm i.d.) by a gradient elution employing of 0.2% formic acid-acetonitrile(9∶1,by volume) as a mobile phase.The analytes were detected using electrospray ionization tandem mass spectrometry with multiple reaction monitoring(MRM) in positive ion scan mode.The calibration curves showed good linearity in the range of 1-200 μg/L for all SAs with detection limits of 0.04-1.35 μg/kg.The recoveries of 24 SAs at the spiked concentration levels of 10,20 and 50 ng/g ranged from 61% to 117%with RSD of 2.92%-18.98%.The results obtained indicated that UPLC-MS/MS method was rapid and sensitive,and was suitable for confirmatory assay of SAs residues in milk according with international demand into execution.