Rapid and selective extraction of multiple sulfonamides from aqueous samples based on Fe3O4–chitosan molecularly imprinted polymers

Abstract

Highly selective magnetic molecularly imprinted polymers (MMIPs) for the adsorption of sulfonamides (SAs) were prepared by surface imprinted technology using active Fe₃O₄–chitosan (Fe₃O₄–CS) as the core and a mixture of sulfamethazine (SMZ) and sulfamethoxazole (SMX) as mixed template molecules. The optimum crosslinker types and contents were evaluated based on the analysis of adsorption parameters (Q, K_d and k) and regeneration of the MMIPs. The structure, morphology, magnetism, thermostability, adsorption and recognition properties of the MMIPs were characterized using Fourier transform infrared (FT-IR) spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM), vibrating sample magnetometry (VSM), thermogravimetric analysis (TGA) and re-binding experiments, respectively. The results showed that the superparamagnetic particles with a homogeneous polymer film exhibited the maximum adsorption capacity (Q_(SMX) = 4.32 mg g⁻¹; Q_(SMZ) = 4.13 mg g⁻¹), good selective recognition of SAs (k_(SMX) = 3.52; k_(SMZ) = 3.83) and a fast adsorption rate (t = 9 min). Furthermore, molecularly imprinted polymers-magnetic dispersive solid-phase extraction (MIPs-MDSPE) coupled with a HPLC method was developed for the enrichment and determination of seven SAs in five different water samples, with recoveries and relative deviations (RSD) ranging from 85.02 to 102.98% and from 2.77 to 6.47%, respectively. SMX was detected in influent and effluent sewage samples, at concentrations of 112 and 64 ng L⁻¹, respectively.