Occurrence of antimicrobial residues in tilapia (Oreochromis niloticus) fillets produced in Brazil and available at the retail market.

This study was carried out to assess the occurrence of antimicrobial residues in samples of tilapia (Oreochromis niloticus) fillets collected at the State of São Paulo retail market and produced from fish farmed in Brazil. For this purpose, a liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS) method was validated and used to quantify residues of 25 antibacterial drugs (2 β-lactams, 8 quinolones, 2 macrolides, 5 sulfonamides, 4 tetracyclines, 3 amphenicols and 1 sulfonamide potentiator). For the sample preparation step the QuEChERS approach was performed. Chromatographic separation was conducted using a Zorbax SB C18 column. Method validation was performed based on European and Brazilian guidelines. The validation parameters (linearity, intra- and inter-day precision, accuracy, decision limit, detection capability and robustness) attended the adopted validation guidelines. Limits of detection and quantitation were also determined. Antimicrobial drug residues were quantitated in the incurred samples by using matrix-matched analytical curves. Oxytetracycline, florfenicol and, for the first time, enrofloxacin residues are reported in tilapia fillet samples from Brazil, though, in accordance with the European and Brazilian regulatory framework. Thus, our results draw attention to the use of veterinary products in fish farming in Brazil. Monitoring of veterinary drug residues is essential to ensure the safety of fish products available to the consumer, as well as to keep fish as a food commodity.