Rapid multi-residue screening of antibiotics in muscle and kidney by liquid chromatography-electrospray ionization-tandem mass spectrometry.

A new approach for simple and rapid multi-residue screening of antibiotics in muscle and kidney by liquid chromatography-tandem mass spectrometry (LC-MS/MS) is described. Nineteen analytes from five classes of antibiotics, i.e. tetracyclines, sulfonamides, quinolones, beta-lactams and macrolides were included in the method. The recently registered drug acetylisovaleryltylosin and its metabolite 3-ortho-acetyltylosin, for which no methods of analysis have been published so far, are among the analytes. The samples were extracted by a single extraction using 70% methanol, diluted with water and injected in the LC-MS/MS. The total run time for each sample was 15 min. At least 60 samples could be analysed and evaluated in 24 h. The accuracy of the method is sufficiently good for screening of antibiotics at the maximum residue limit (MRL) in both muscle and kidney from pig, cattle, sheep, deer, horse and reindeer. Validation was performed according to Commission Decision 2002/657/EC. In addition, a possible way of rapid and simple confirmation of the analytes in muscle is suggested.