Analysis of Fluoroquinolones in Animal Feed Based on Microwave-Assisted Extraction by LC–MS–MS Determination

An environmentally friendly method for the determination of fluoroquinolone (FQ) antibiotics including enrofloxacin, ciprofloxacin, levofloxacin, fleroxacin and sparfloxacin in four feeds is proposed. Disodium ethylenediaminetetraacetate (EDTA)–Mcllvaine buffer (0.1 mol L−1, pH 4.0) was used as an extracting solvent and the extraction process was accelerated by microwave irradiation. No organic solvents were used in the extraction procedure. The extract obtained was then cleaned up and concentrated by an Oasis hydrophilic–lipophilic balance (HLB) solid-phase extraction cartridge. The relative intra- and inter-day standard deviations obtained were in the range of 3.7–9.1 and 2.1–11.4%, respectively. In the three fortified levels of blank feed sample (30, 100 and 500 ng g−1), recoveries of FQs ranging from 61.1 to 97.9% were obtained. The analytes desorbed from HLB were analyzed by liquid chromatography–tandem mass spectrometry. The limit of detection was in the range of 5.0–9.1 ng g−1. The method presented here can be considered a promising alternative to traditional techniques using shaking or stirring for extraction, being more effective, and producing less pollution.