Development and validation of an ultra performance liquid chromatography-quadrupole time of flight-mass spectrometry (in MS mode) method for the quantitative determination of 20 antimicrobial residues in edible muscle tissue of European sea bass.

A UPLC-QTOF-MS method for the simultaneous determination of 20 veterinary drug residues and metabolites (tetracyclines, quinolones, sulfonamides and diaminopyrimidines) in edible muscle plus skin tissue of European sea bass (Dicentrarchus Labrax) was developed. For the identification of analytes a positive electrospray ionization quadropole time-of flight mass spectrometer operating in MS mode (UPLC-QTOF-MS) was used. MS mode provides high chromatographic resolution and accurate mass measurements in both MS and MS/MS modes simultaneously in a single run. Separation was achieved on a UPLC BEH C18 (50 mm × 2.1 mm, 1.7 μm) column in a gradient elution program of 10 min. Examined antibiotics were isolated easily after a simple solid-liquid extraction procedure with acidic acetonitrile (0.1% v/v formic acid) and NaEDTA 0.1 M. Recovery rates from muscle plus skin tissue ranged from 93.8% to 107.5% for all targeted compounds. The detection limits and the limits of quantification ranged from 2.22 to 15.00 μg/kg, and from 6.67 to 45.46 μg/kg, respectively. The developed method was validated in terms of selectivity, matrix effect, linearity, accuracy, precision, stability and sensitivity, CCα and CCβ according to European Union Decision 2002/657/EC. The proposed method was applied for the analysis of contaminated fish samples after in feed administration of danofloxacin mesylate.