Determination of sulfonamides and quinolones in milk by QuEChERS and ultra performance liquid chromatography-tandem mass spectrometry

A method was established for determining sulfonamides and quinolones residues in milk by QuEChERS and ultra performance liquid chromatography-tandem mass spectrometry (UPLC/MS/MS) with isotopes dilution. The analytes were extracted with acetonitrile and cleaned up with dispersive solid phase extraction. The target analytes were separated by Waters C 18 column with gradient elutionusing acetonitrile and 0.1% formate in water as mobile phases. The analytes were detected by tandem quadrupole mass spectrometry after positive electrospray ionization by multiple reaction monitoring (MRM). Internal standard method was used to determine the results. In the linear range (1～200 μg/L) of each antibiotics, the correlation coefficient was greater than 0.9965 for each analytes. The limit of detection (LOD) were 0.3～2.5 μg/kg, and the limit of quantitation (LOQ) were 1.0～7.5 μg/kg. The mean recoveries at the three spiked levels of 10～50 μg/kg were 71.6%～120.7%. The relative standard deviation (RSD) were 0.1%～7.2%. The proposed method was successfully applied to the analysis of real samples. The simplicity, sensitivity and good precision of the method made it be well suitable for determination of sulifonamides and quinolones residues in milk.