Abstract: Abstract：A ultra performance liquid chromatography-tandem mass spectrometry(UPLC-MS/MS) method for simultaneous determination of chloramphenicol, thiamphenicol and florfenicol residues in fees, raw milk and dairy products was developed. Extraction method, mobile phase and mass spectrometry conditions for feed, raw milk, liquid milk, fermented milk, milk drinks, milk powder, milk tablet and frozen drinks were studied. Protein was precipitated by cooling down and compounds were extracted with acetonitrile, extraction solution was delaminated by saturated sodium chloride. After the supernatant was dried under nitrogen and then redissolved, fat of solution was removed by adding n-hexane. The compounds were analyzed by a negative electrospray ion multiple reaction monitoring mode with a mobile phase composed of acetonitrile and water. The limits of quantification was 0.1 μg/kg for chloramphenicol, thiamphenicol and florfenicol. The matrix effects, the recovery rate, and RSD were 57.9%~139.2%, 64.3%~ 120.2% and 2.1%~10.0% at fortification levels of 0.1-2.5 μg/kg for chloramphenicol, thiamphenicol and florfenicol, respectively. This method is simple, convenient, fast and suitable for the quantification and confirmation of chloramphenicol, thiamphenicol, and florfenicol in feed, milk and dairy products.

Key words: Ultra Performance Liquid Chromatography-Tandem Mass Spectrometry (UPLC-MS/MS), Chloramphenicol, Forage, Dairy Products