Residue analysis of macrolides in poultry muscle by liquid chromatography–electrospray mass spectrometry

A liquid chromatography–mass spectrometry method is proposed for the determination of seven macrolides authorised in the EU as veterinary drugs for food-producing animals. Sample treatment involves extraction of the analytes with a water–methanol mixture containing metaphosphoric acid and clean-up by SPE with a cation-exchange cartridge. Separation was carried out in an end-capped silica-based C18 column and mobile phases consisting of water/acetonitrile mixtures containing trifluoroacetic acid. A gradient elution, from 28 to 40% acetonitrile was used. Detection was performed by mass spectrometry with electrospray ionisation in the positive mode. Several parameters affecting the mass spectra were studied. The protonated molecular ion was selected for quantitation purposes under selected ion monitoring mode. Detection limits were in the range 1–20 μg l−1. Recoveries ranged between 56 and 93% with RSD lower than 12%. The method has been successfully applied for multiresidue determination of seven macrolides below the MRLs established by the European Union.