Extraction of quinolones from milk samples using bentonite/magnetite nanoparticles before determination by high-performance liquid chromatography with fluorimetric detection.

In this work, bentonite magnetic nanoparticles synthesized by a typical coprecipitation method were used as the adsorbent for the magnetic solid-phase extraction of six quinolones (ciprofloxacin, difloxacin, enrofloxacin, norfloxacin, sarafloxacin, and lomefloxacin) from milk samples followed by high-performance liquid chromatography with fluorimetric detection. Under the optimized conditions, the linear quantitation range for the six quinolones was 0.3-200 ng/mL, and the correlation coefficients of the calibration curves ranged from 0.9994 to 0.9999. The detection limit of the method was 0.1 ng/mL. Recoveries of quinolones from pure and low-fat spiked milk samples varied from 80.4 to 92.7% and from 81.3 to 93.5%, respectively. These results demonstrated that the proposed method for the determination of six quinolones in milk samples was rapid, reliable, and efficient.