Preparation of magnetic molecularly imprinted polymer for selective identification of patulin in juice

A highly efficient and selective method was successfully developed by using magnetic molecularly imprinted polymers (MMIPs) combined with high performance liquid chromatography (HPLC) to quickly determine patulin (PAT) in juice. MMIPs was prepared by surface imprinting method using Fe₃O₄ nanoparticles as supporter, 2-oxindole as virtual template, (3-Aminopropyl) triethoxysilane (APTES) as functional monomer and tetraethyl orthosilicate (TEOS) as crosslinking agent. The structure of the product was characterized by vibrating sample magnetometer (VSM), Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), and thermogravimetric analysis (TGA). The results showed that MMIP with a particle size of about 450 nm was successfully prepared, the imprinted molecular layer accounted for about 11.6% of the total mass, and the saturation magnetization was about 6.82 emu/g. The maximum adsorption capacities (Qmax) of kinetic and thermodynamic adsorption experiments were 1.97 mg/g and 4.241 mg/g, respectively. The adsorption process was highly selective and fitted well with the pseudo-second-order model. Langmuir model demonstrated that the binding sites were evenly distributed on the surface of the MMIPs. Scatchard analysis showed that MMIPs had two types of binding sites with Qmax of 4.53 mg/g and 5.73 mg/g, respectively. In the actual sample application, the limit of detection (LOD) and the limit of quantification (LOQ) were 3 μg/kg and 10 μg/kg. And the recovery rate of the sample was 86.44-95.50%. MMIPs possessed excellent applicability with stability of 1.11-3.16% and accuracy of 0.63-1.94%. These results indicated that MMIPs had good performance in separating PAT and was suitable for determining PAT in actual samples.