Development and validation of an LC-MS/MS screening method for macrolide and quinolone residues in baby food

A simple, rapid and sensitive screening method by liquid chromatography-tandem mass spectrometry (LC-MS/MS) was developed for the identification of 7 macrolides (clarithromycin, erythromycin, oleandomycin, spiramycin, tilmicosin, troleandomycin and tylosin) and 8 quinolones (ciprofloxacin, difloxacin, enrofloxacin, flumequine, moxifloxacin, nalidixic acid, norfloxacin and ofloxacin) in meat and egg-based baby foods. Sample preparation was performed using an alkaline modified QuEChERS (Quick, Easy, Cheap, Effective, Rugged, Safe) extraction method without additional clean-up steps. A simplex-lattice mixture experimental design was used in the optimization of the QuEChERS extraction solvent. The developed method was successfully validated according to the Commission Decision 2002/657/EC and the European Community Reference Laboratories Residues Guidelines regarding the validation of screening methods 20/01/2010, adopting a fixed permited tolerance for relative ion ratio. Samples of baby food (n = 44) commercialized in Rio de Janeiro, Brazil, were analyzed using the validated method and none of them presented residues of the searched macrolides and quinolones, with a screening target value of 5 µg kg^-1.