Synthesis and application of magnetic polystyrene polymer composites for magnetic solid-phase extraction of three fluoroquinolones from milk samples

In this study, magnetic polystyrene polymers (Fe3O4 @PLS) with both hydrophilic and hydrophobic groups were synthesized for magnetic solid-phase extraction. Experimental parameters, including solution pH, adsorption time, elution solvent, elution volume and elution time, were optimized. A magnetic solid-phase extraction method using Fe3O4 @PLS as adsorbent for three fluoroquinolones (FQs), including enrofloxacin, ofloxacin and ciprofloxacin, in milk substrates was established with high-performance liquid chromatography. Under the optimized experimental conditions, the limits of detection of the three FQs were 0.41–0.45 µg/kg and the limits of quantitation of the three FQs were 1.37–1.51 μg/kg. The recoveries of three FQs in milk samples were 96.5–118.6%. The method was successfully applied to the detection of three FQs in 20 kinds of milk. The results showed that the proposed method had the advantages of easy operation, rapid and efficient enrichment and separation of analytes, which proved its reliability and applicability. The adsorption property of Fe3O4 @PLS was significantly improved compared with ProElut polystyrene polymers (PLS), which provided a new idea for the development of magnetic polymer materials and expanded the application of magnetic polymers in the pretreatment of complex samples. •A magnetic adsorbent of Fe3O4 @PLS was prepared by solvothermal reaction.•Fe3O4 @PLS was developed as a novel adsorbent for MSPE.•An MSPE–HPLC method was established for determination of three fluoroquinolones in milk.•The recoveries and precisions of the three FQs were 96.5–118.6% and 1.2–2.6%.•Adsorption mechanism of fluoroquinolones on Fe3O4 @PLS was discussed.