Simultaneous determination of quinolones in fish by liquid chromatography coupled with fluorescence detection: Comparison of sub‐2 μm particles and conventional C18 columns

A simple and effective multi‐residue analysis method is presented for the extraction and determination of eleven quinolones (pipemidic acid, enoxacin, norfloxacin, ciprofloxacin, lomefloxacin, enrofloxacin, gatifloxacin, difloxacin, oxolinic acid, nalidixic acid and flumequine) in fish tissues. In this study, multi‐residue separations on four columns packed with 5 μm or sub‐2 μm particles were simultaneously developed for the purpose of comparison. Various gradients were optimized and best resolutions were achieved on each column. A short and sub‐2 μm particle‐sized HPLC column was chosen for its advantages in analysis time and column performance. Additionally, considering the matrix effect of the complex crude fish tissue, an effective extraction protocol was also established for sample pre‐treatment procedure. Good recoveries (71–98%) were obtained from samples fortified with a mix of eleven quinolones at three levels, with satisfactory relative standard deviations and limits of detection. As a result, the sub‐2 μm HPLC column and proposed analytical procedures have been evaluated and applied to the analysis of different fish tissues. Detectable residues were observed in 8 of 30 samples, at concentrations ranging from 4.74 to 23.27 μg/kg.