Development of a 15-class multiresidue method for analyzing 78 hydrophilic and hydrophobic veterinary drugs in milk, egg and meat by liquid chromatography-tandem mass spectrometry

The development of a multiclass, multiresidue method for analyzing veterinary drugs in food is the recent trend of research for regulatorymonitoring laboratories. This work reports a multiclass method for the determination of both hydrophilic and hydrophobic veterinary drug residues, including anthelmintics, avermectins, benzimidazoles, beta-agonists, beta-lactams, coccidiostats, corticosteroids/steroids, lincosamides, macrolides, non-steroidal anti-inflammatory drugs, phenicols, quinolones, tranquillisers, antiviral drugs and some other veterinary drugs, in milk, egg and meat. By using liquid-liquid extraction low temperature partition with centrifugation for acetonitrile (MeCN)/aqueous phase separation, hydrophilic and hydrophobic drugs were recovered separately. The MeCN phase was cleaned up with dispersive solid phase extraction. To achieve retention and separation of veterinary drugs with a wide range of polarity, ultra-performance hydrophilic interaction liquid chromatography (HILIC) and reversed phase liquid chromatography (RPLC) coupled to a tandem mass spectrometer (MS/MS) were employed. The method was successfully validated. The recoveries of the method in general ranged from 70 to 120% with precision RSD <= 20%. The limits of quantification of the method ranged from 0.1 to 10 mu g kg(-1) for the targeted veterinary drugs.