Determination of Chloramphenicol Residues in Casing by Ultra Performance Liquid Chromatography-Electrospray Tandem Mass Spectrometry

A comprehensive analysis method based on ultra performance liquid chromatography-electrospray ionization mass spectrometry(UPLC/MS /MS) with negative mode has been developed for the determination of chloramphenicol residues in casing.The multi-reaction monitoring mode was employed for the determination.Casing samples were extracted by ethyl acetate,and then defatted with n-hexane. Sample solutions was concentrated and purified by Oasis HLB solid phase extraction cartridges.The separation was performed on a Waters ACQUITY UPLCTM BEH C18(1.7 μm,2.1 mm×50 mm)column with gradient elution using acetonitrile and water at a flow rate of 0.4mL/min.Identification of chloramphenicol was done using the retention times and the distribution of diagnosticion pairs;the precursor/product ion transitions(321.0/257.0 and 321.0/152.0) were monitored.Quantification of the chloramphenicol by the peak areas of higher signal precursor/product ion transition(321.0/257.0).The limits of detection(LOD) of the method was 0.05 μg/kg and the limits of quantification(LOQ) was 0.1 μg/kg.The recoveries were between 91% and 97%.The relative standard deviations were below 10%.