Magnetic solid-phase extraction of norfloxacin by core-shell magnetic nanoparticles

Abstract

Two magnetic metal-organic frameworks were synthesized with a core-shell structure. Maghemite (γ-Fe2O3) as the magnetic core was used to prepare γ-Fe2O3@SiO2, γ-Fe2O3@SiO2-NH2 and γ-Fe2O3@SiO2-NH2-COOH nanoparticles (MNPs) via tetraethyl orthosilicate (TEOS), (3-aminopropyl)trimethoxysilane (APTMS) and glutaric anhydride (GA). γ-Fe2O3@SiO2-NH2-COOH nanoparticles were further modified by Core-Shell package of Tb-BDC-NH2 and Tb-BDC, in which the ligands were 2-aminoterephthalic acid (H2BDC-NH2) and terephthalic acid (H2BDC). IR spectra were used for structure determination of γ-Fe2O3, γ-Fe2O3@SiO2, γ-Fe2O3@SiO2-NH2-COOH and γ-Fe2O3@SiO2-NH2-COOH/Tb-BDC nanoparticles. Magnetic solid-phase extraction (MSPE) of norfloxacin (Nor) experiments exhibited that, for γ-Fe2O3@SiO2-NH2-COOH/Tb-BDC-NH2 nanoparticles, the best adsorption was obtained at pH = 6. For γ-Fe2O3@SiO2-NH2-COOH/Tb-BDC nanoparticles, the best adsorption was obtained at pH = 4. γ-Fe2O3@SiO2-NH2-COOH/Tb-BDC nanoparticles exhibit characteristic TbIII emission spectra at 490 (5D4→7F6), 545 (5D4→7F5), 585 (5D4→7F4) and 621 nm (5D4→7F3) after MSPE of norfloxacin. X-ray photoelectron spectroscopy (XPS) spectra are used for determination of γ-Fe2O3@SiO2-NH2-COOH, γ-Fe2O3@SiO2-NH2-COOH/Tb-BDC and γ-Fe2O3@SiO2-NH2-COOH/Tb-BDC + Nor nanoparticles. XPS results showed that coordination occurs between γ-Fe2O3@SiO2-NH2-COOH/Tb-BDC nanoparticles and Nor.