Abstract:

An ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS-MS) method for
simultaneous determination of chloramphenicol, thiamphenicol and florfenicol residues in feed, raw milk and dairy products
was developed. The extraction procedures and the UPLC-MS-MS conditions for feed, raw milk, liquid milk, fermented milk,
milk drinks, milk powder, milk tablet and frozen drinks were studied. After protein in samples was precipitated by cooling
down, the compounds were extracted into acetonitrile, which was separated into layers in the presence of added saturated
sodium chloride. The supernatant was dried under nitrogen, and then re-dissolved before the removal of fat by addition of
n-hexane. The compounds were analyzed in a negative electrospray ion multiple reaction monitoring mode with a mobile
phase composed of acetonitrile and water by means of gradient elution. The limit of quantification (LOQ) was 0.1 μg/kg
for chloramphenicol, thiamphenicol and florfenicol. The matrix effects, recovery rates, and relative standard deviation
(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, feed, dairy products