Development of a multi-class method for the identification and quantification of residues of antibiotics, coccidiostats and corticosteroids in milk by liquid chromatography–tandem mass spectrometry

Even if coccidiostats are not generally employed in dairy cows, maximum levels for these substances in milk samples have been set up in Commission Regulation 124/2009. Due to public health concerns regarding the presence of veterinary drug residues in milk, the aim of the present work is to report a multi-class high performance liquid chromatography–tandem mass spectrometry method for the simultaneous extraction, identification and quantification of seven coccidiostats, seven antimicrobial agents, three corticosteroids and an antifungal agent. Validation was conducted following the guidelines established in the European Commission Decision 2002/657/CE at the maximum concentration permitted in milk by the European Union for each drug. The method was successfully applied in 100 raw milk samples collected from ten local dairy farms and 15 milk samples bought in supermarkets. This method could be applied in routine analysis of milk samples by the dairy industry, replacing the current, non-differentiating, screening method.