Preparation of Magnetic Molecularly Imprinted Polymers Based on Polydopamine and Its Application of Determination for Zearalenone in Food

Using Fe₃O₄ nanoparticles (Fe₃O₄ NPs) as the magnetic core, quercetin as the mimic template molecule and dopamine (DA) acted as the functional monomer and cross-linker, the magnetic molecularly imprinted polymers (Fe₃O₄@PDA MIPs) were prepared by surface molecular imprinting technology based on a one-pot method, which was characterized by a transmission electron microscopy and a Fourier transform infrared spectrometer. And its adsorption performance for zearalenone was evaluated by the isothermal adsorption curve. It was shown that this magnetic MIPs were displayed maximum adsorption capacity to be 1.49 mg·g^-1 for zearalenone, and the process matched the Langmuir model. Fe₃O₄@PDA MIPs was used as an adsorbent of dispersive solid phase extraction, and the extraction parameters including the amount of Fe₃O₄@PDA MIPs, solution acidity, ultrasonic extraction time, desorption solvent type and desorption method, were optimized, which was applied to the determination of zearalenone in food samples combined with high performance liquid chromatography (HPLC)-fluorescence detector. The optimal experimental conditions were as follows:The sample uniformly shattered (40.0 g) was extracted ultrasonically for 30 min with 100 mL of the mixed solution of acetonitrile and water at the volume ratio of 9:1. After filteration, an aliquot (20 mL) of the extract was placed into a headspace vial and blown to near dryness by nitrogen. 30 mg of Fe₃O₄@PDA MIPs and 10 mL of water were added in sequence for ultrosonic extraction for 5 min. Then 2 mL of acetonitrile were used to desorb zearalenone from the MIPs twice (each 1 mL). An aliquot (0.5 mL) of desorption solution was taken and placed into a 1.5 mL-injection bottle. 0.5 mL of water was added into the above solution for HPLC determination. As shown by the results, linear relationship between values of peak area and mass concentration of zearalenone was found in the range of 1-20 μg·L^-1, with detection limit (3S/N) of 0.68 μg·L^-1. Test for recovery was made by standard addition method, giving results in the range of 80.1%-101%. Moreover, the magnetic MIPs had good stability and could be reused at least 7 times.