Synthesis of the Magnetically Nanoporous Organic Polymer Fe₃O₄@SiO₂‐NH₂‐COP and Its Application in the Determination of Sulfonamide Residues in Surface Water Surrounding a Cattle Farm

Abstract

Efficient extractions of trace antibiotic residues in the environment are a key factor for accurate quantification of the residues. A new nanoporous material, namely, magnetically covalent organic polymer (MCOP, Fe3O4@SiO2-NH2-COP) was synthesized in this work and was used for magnetic solid-phase extraction (MSPE). The combination of MSPE with high-performance liquid chromatography separation together with ultraviolet detection (HPLC-UV) was established as an effective method for the determination of four sulfonamide (SA) residues in surface water surrounding a cattle farm. The synthesized magnetic material was characterized by SEM, TEM, FT-IR, magnetic properties measurement system (MPMS), and nitrogen gas porosimetry. The material possessed many attractive features, such as a unique microporous structure, a larger specific surface area (137.93 m2·g−1) than bare Fe3O4 (24.84 m2·g−1), high saturation magnetization (50.5 emu·g−1), open adsorption sites, and high stability. The influencing parameters, including pH, the used amount of MCOPs, the type of eluent, adsorption solution, and desorption time, were optimized. Under the optimized conditions, the method conferred good linearity ranges (R2 ≥ 0.9990), low detection limits (S/N = 3, LOD, 0.10–0.25 μg·L−1), and satisfactory recoveries (79.7% to 92.2%). The enrichment factor (EF) for the four SAs was 34.13–38.86. The relative standard deviations of intraday (n = 5) and of interday (n = 3) were less than 4.8% and 8.9%, respectively. The equilibria between extraction and desorption for SAs could be reached within 150 s. The proposed method was sensitive and convenient for detecting SA residues in complex environmental matrices, and the successful application of the new MCOPs as an adsorbent was demonstrated.

The determination of 11 sulfonamide antibiotics in water and foods by developing a N-rich magnetic covalent organic framework combined with ultra-high performance liquid chromatography-tandem mass spectrometry

“…32 The peak of stretching and bending vibration of the water molecules on the surface of Fe 3 O 4 occurs at 3436 cm −1 and 1632 cm −1 . 33 Compared with the bare Fe 3 O 4 nanoparticles, the spectrum of the Fe 3 O 4 @SiO 2 showed the new characteristic peaks, including the Fe-O and Si-O stretching vibrational modes at 464, 945, and 1103 cm −1 . 34 This veried that the silica shells were successfully encapsulated onto the surface of Fe 3 O 4 .…”

“…Sulfonamides are amphoteric compounds with aromatic amine and sulfonamide amide, which can accept and donate protons, respectively. 33 The change of the pH value of the sample solution is one of the important and key points to affect the adsorption results. Because it might affect the existing forms and charged state of target analytes in the aqueous solution, as well as the surface property of adsorbents, and further influence the extraction efficiency of analytes.…”

Facile synthesis of core-shell magnetic Fe3O4@SiO2-NH2 nanoparticles and their application for rapid boron removal from aqueous solution

“…Fe 3 O 4 @SiO 2 -NH 2 was synthesized by the sol-gel method [25]. Firstly, 0.5 g freshly prepared Fe 3 O 4 MNPs were dispersed in a mixed solution of 200 mL ethanol and 100 mL water, ultra-sonicated for 3 min.…”