Chloramphenicol determination in milk by liquid chromatography – tandem mass spectrometry

A high-performance liquid chromatography – tandem mass spectrometry (HPLC– MS–MS) method was developed for the determination of chloramphenicol (CAP) in milk products. Mass spectral acquisition was done using electrospray ionization in the negative ion mode applying multiple reaction monitoring of two diagnostic transition reactions for CAP (m/z 321→152 and m/z 321→257). Milk samples were extracted with ethyl acetate and evaporated to dryness, followed by a clean-up step using the liquid–liquid extraction with carbon tetrachloride / hexane (1:1 v/v) mixture. The calibration curve showed a good linearity in the concentration range from 0.02 to 1.0 μg/kg with the correlation coefficient above 0.995. The method gave a decision limit and a detection capability of 0.050 and 0.066 μg/kg, respectively. The mean recoveries of CAP from the milk samples spiked at 0.1–0.45 μg/kg were in the range of 86–92%. The applicability of this technique was demonstrated by analysis of milk products.