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

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.