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A facile adsorbent, a nanocomposite of Fe3O4 and reduced graphene oxide, was fabricated for the selective separation and enrichment of synthetic aromatic azo colorants by magnetic solid-phase dispersion extraction. The nanocomposite was synthesized in a one-step reduction reaction and characterized by atomic force microscopy, scanning electron microscopy, Fourier transform infrared spectroscopy, Raman spectroscopy, X-ray diffraction and Brunauer-Emmett-Teller analysis. The colorants in beverages were quickly adsorbed onto the surface of the nanocomposite with strong π-π interactions between colorants and reduced graphene oxide, and separated with the assistance of an external magnetic field. Moreover, the four colorants in beverages were detected at different wavelengths by high performance liquid chromatography with diode array detection. A linear dependence of peak area was obtained over 0.05-10 μg/mL with the limits of detection of 10.02, 11.90, 10.41, 15.91 ng/mL for tartrazine, allure red, amaranth, and new coccine, respectively (signal to noise = 3). The recoveries for the spiked colorants were in the range of 88.95-95.89% with the relative standard deviation less than 2.66%. The results indicated that the nanocomposite of Fe3O4 and reduced graphene oxide could be used as an excellent selective adsorbent for aromatic compounds and has potential applications in sample pretreatment. [ABSTRACT FROM AUTHOR]

In this paper, the novel surface molecularly imprinted polymers based on dendritic-grafting magnetic nanoparticles were developed to enrich and separate glibenclamide in health foods. The density functional theory method was used to give theoretical directions to the synthesis of molecularly imprinted polymers. The polymers were prepared by using magnetic nanoparticles as supporting materials, methacrylic acid as the functional monomer, and ethylene glycol dimethacrylate as the cross-linker. The characteristics of magnetic nanoparticles and polymers were measured by transmission electron microscope and SEM, respectively. The enriching ability of molecularly imprinted polymers was measured by Freundlich Isotherm. The molecularly imprinted polymers were used as dispersive SPE materials to enrich, separate, and detect glibenclamide in health foods by HPLC. The average recoveries of glibenclamide in spiked health foods were 81.46-93.53% with the RSD < 4.07%. [ABSTRACT FROM AUTHOR]

A novel molecularly imprinted polymers ( MIPs) coated micro-stir bar ( MSB) for Glibenclamide ( GM) was developed. The MIPs, with GM as template molecular and methacrylic acid as functional monomer, were synthesized at the surface of the silylated MSB that was filled with magnetic core as substrate. Computational simulation was used for the optimal selection of functional monomers and porogen. The thickness of MIPs coating for MSB was about 10 μm, the adsorption and desorption time were about 40 and 20 min, respectively. The MIPs coated MSB possessed mechanical stability, high adsorption capacity, and good selectivity for GM. To achieve the optimum extraction performance, several parameters including extraction and desorption time, stirring rate, extraction and desorption solvent were investigated. A method for the determination of GM in herbal dietary supplements by MIPs coated MSB coupled with HPLC- UV was established. The results exhibited good linear ranges of 10-6250 μg L−1 with the low limit of detection of GM (3.05 μg L−1) and the good recoveries (81.9-101.4%). [ABSTRACT FROM AUTHOR]