Determination of fluoroquinolones in foods using ionic liquid modified Fe3O4/MWCNTs as the adsorbent for magnetic solid phase extraction coupled with HPLC

Abstract

In this work, a simple and sensitive method based on Fe₃O₄/multi-walled carbon nanotubes/ionic liquid (Fe₃O₄/MWCNTs/IL) as the adsorbent for magnetic solid phase extraction coupled with high performance liquid chromatography was developed for the determination of trace fluoroquinolones in foods. After a simple one-pot solvothermal synthesis, Fe₃O₄/MWCNTs were further modified with an amine-terminated ionic liquid to enhance their dispersibility and extraction capacity. The morphology, structure and magnetic properties of the composite adsorbent were characterized by transmission electron microscopy, X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, X-ray diffraction spectrometry and vibrating-sample magnetometry. Under the optimized extraction and detection conditions, the studied fluoroquinolones were enriched effectively and separated well and their UV signals were linear to their concentrations in the range of 4–1000 ng mL⁻¹, with correlation coefficients ranging from 0.9958 to 0.9990. The enrichment factors were 29.1–43.9 fold and the limits of detection were 0.33–0.78 ng mL⁻¹. The spiked recoveries were 85.4–105.9% for milk and 85.2–103.7% for pork samples, with relative standard deviations of 0.8–5.7%. The developed method provided a fast, sensitive and reliable determination platform for fluoroquinolones in complex real samples.