Fabrication and characterization of magnetic mesoporous nanoparticles for efficient determination and magnetic separation of sulfonamides in food samples

Abstract

A magnetic, mesoporous core/shell structured Fe₃O₄@SiO₂@mSiO₂ nanocomposite was synthesized and employed as a magnetic solid phase extraction (MSPE) sorbent for the determination of trace sulfonamides (SAs) in food samples. The synthesized nanocomposite was characterized by transmission electron microscopy, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, thermogravimetric analysis, X-ray diffraction, N₂ sorption analysis and vibrating sample magnetometry. The results showed that Fe₃O₄@SiO₂@mSiO₂ possessed a mesoporous structure with a large surface area. Batch experiments were carried out to investigate the adsorption ability for SAs. Fe₃O₄@SiO₂@mSiO₂ showed fast kinetics and high adsorption capacity, and the pseudo-second-order model and Langmuir adsorption isotherm are well fitted with the experimental data, indicating that chemical adsorption might be the rate-limiting step. Moreover, the high adsorption capacity can be maintained for at least 8 runs, indicating excellent stability and reusability. The proposed method exhibited good linearity in the range of 0.2–500 μg L⁻¹, the R² values of all the analytes were greater than 0.99 and the LODs were all lower than 0.2 μg L⁻¹. Furthermore, real food samples were successfully analyzed with Fe₃O₄@SiO₂@mSiO₂ and high recoveries varying from 89.7% and 110.6% were obtained with low relative standard deviations ranging from 1.78% to 6.91%. The Fe₃O₄@SiO₂@mSiO₂ magnetic nanocomposite is a promising sorbent for the efficient extraction of SAs from complex food samples.