Preparation of sulfamethoxazole molecularly imprinted polymers based on magnetic metal-organic frameworks/graphene oxide composites for the selective extraction of sulfonamides in food samples

Novel sulfamethoxazole molecularly imprinted polymers based on magnetic metal-organic frameworks/graphene oxide composites (MOF/MGO@MIP) were synthesized using the surface molecular imprinting technique. The scanning electron microscopy, transmission electron microscopy, Fourier transform infrared spectroscopy and other characterization methods were used to analyze MOF/MGO@MIP. The adsorption performance of MOF/MGO@MIP was studied via adsorption kinetics, adsorption isotherms and selectivity experiments, and then its adsorption mechanism was investigated using various adsorption models. The adsorption results matched well with a quasi-second-order kinetic model and a Langmuir isotherm model, with the maximum adsorption capacity, equilibrium adsorption time and imprinting factor of 42.65 mg g(-1), 120 min and 1.61, respectively. Meanwhile, the MOF/MGO@MIP with excellent recyclability displayed higher adsorption capacity and selectivity than MOF/MGO@NIP. Under the optimal extraction conditions, a method base on MOF/MGO@MIP combined with high-performance liquid chromatography (MOF/MGO@MIP/HPLC-UV) was established to separate and detect trace sulfonamides in honey and milk samples, achieving lower limits of detection (LOD, 0.39-0.47 mu g kg(-1)) with an excellent linear correlation (R-z > 0.9990). The spiked recovery and relative standard deviation (RSD) were 81.38-96.71% and 1.4-6.3%, respectively. Therefore, MOF/MGO@MIP could be regarded as an efficient adsorbent for SAs pretreatment in food samples.