Metabolic study of enrofloxacin and metabolic profile modifications in broiler chicken tissues after drug administration

•Identification of new metabolites from enrofloxacin in chicken tissues by LC–HRMS.•Distribution of enrofloxacin and their metabolites in chicken tissues.•Classification of medicated chicken samples by PCA and PLS-DA.•Tentative identification of markers from medicated chicken tissue samples. In this work, the identification and distribution of the metabolites from enrofloxacin (ENR) in liver, kidney and muscle tissues from broiler chickens subjected to a pharmacological treatment was studied. In addition, qualitative analyses of changes in the metabolic profile in those tissues after drug administration were also investigated. As a result, a total of 31 different metabolites from ENR were identified, which ciprofloxacin (CIP) and desethylene-ENR were the major metabolites. After four days of withdrawal period, most of the metabolites were excreted, but residues of ENR and CIP still persisted in tissues at a concentration under the permitted maximum residue limit (MRL). Non-medicated, medicated and post-treatment samples of chicken tissues were clearly clustered according to their metabolite profile by principal component analysis and partial least squares discriminant analysis, which indicates that endogenous metabolites have not returned to their original levels after the withdrawal period. A total of 22 relevant mass features contributing to this separation as potential markers of chicken samples were tentatively identified.