Validated multiclass targeted determination of antibiotics in fish with high performance liquid chromatography-benchtop quadrupole orbitrap hybrid mass spectrometry

High performance liquid chromatography, coupled with a benchtop Q-Exactive Orbitrap high-resolution mass spectrometer, was successfully applied for the determination of 24 target antibiotics (selected beta-lactams, tetracyclines, fluoroquinolones, sulfonamids, phenicols, macrolides, cephalosporins, lincosamides, diaminopyrimidine) in fish matrices. The Q-Exactive parameters were carefully studied to accomplish the best compromise between a suitable scan speed and selectivity, considering the restrictions associated with generic sample preparation methodology. Retention time, an exact mass with tolerance of 2 ppm and data-dependent MS2 spectra were the main identifiers. The method was validated through specificity, linearity, recovery, intra- and inter-day repeatability, decision limit (CCα) and detection capability (CCβ), according to 2002/657/EC. The values of CCα and CCβ ranged from 29.2 to 36.8 and 32.5 to 48.9, respectively, while overall recovery ranged from 91.1 to 105.6%. Fifty fish samples were analysed, showing the sporadic incidence of enrofloxacin, chlortetracycline, oxytetracycline, amoxicillin and trimethoprim, albeit below the maximum residual levels.