Multi-residue determination of antibiotics in fish by liquid chromatography-tandem mass spectrometry.

A multi-residue method for the determination of 34 antibacterial drugs (three aminoglycosides, nine β-lactams, nine fluoroquinolones, three macrolides, five sulfonamides, trimethoprim and four tetracyclines) in fish samples by LC-MS/MS was developed. The procedure enables the isolation of residues based on double extraction of the fish sample with m-phosphoric acid and heptafluorobutyric acid as an ion-pair agent and acetonitrile. All compounds were determined at the same time on a C18 column with gradient elution. The method was validated according to the requirements of European Decision 2002/657/EC. Specificity, recovery, repeatability, within-laboratory reproducibility, decision limit CCα and detection capability CCβ were calculated. CCα ranged from 55.3 to 1085 µg kg(-1) and CCβ ranged from 59.5 to 1141 µg kg(-1). The overall recoveries were from 96% to 111% with respect to the internal standards.