Magnetic Imprinted Solid-Phase Extraction Combined with Imprinted Electrochemical Sensor for Rapid Detection of Erythromycin in Meat Products

This paper aims to construct a simple and rapid method for analyzing trace amounts of erythromycin (ERY) in meat products by magnetic molecular imprinted solid-phase extraction combined with imprinted electrochemical sensors. Using ERY as the template molecule, dopamine (DA) as the functional monomer, and functionalized magnetic graphene-carbon nanotube composite as the modified carrier, erythromycin magnetic molecularly imprinted polymer (MMIP) with good selectivity and sensitivity to ERY was prepared by using a novel surface imprinting technology. Then, the magnetic imprinted solid-phase extraction combined with imprinted electrochemical sensor (MMISPE-MMIP-sensor) for rapid detection system was constructed by using MMIP as solid phase extraction agent and electrochemical sensor element, respectively. The methods including cyclic voltammetry (CV) and differential pulse voltammetry (DPV) were used to discuss its electrical properties of the sensor with K₃Fe (CN)₆ solution, and its structure and morphology were characterized by fourier infrared spectroscopy (FTIR) and scanning electron microscope (SEM) and transmission electron microscope (TEM). The results showed that the surface of the carbon nanotube-graphene composite was covered with an imprinted polymer shell layer, and the shell layer have many nanoparticles on the surface. The effects of pH value of buffer solution and response time on the imprinted electrode were investigated. The results showed that the best buffer pH was 7.5, and the enrichment time was 10 min. Under this optimal conditions, the experimental conditions were optimized, the response current △I_R and the negative logarithm (-logC_ERY) of ERY concentration showed a good linear relationship in the range of 1.0×10⁻¹⁰~1.0×10⁻⁵ mol/L, the correlation coefficient was 0.991, and the lowest detection limit was 1.0×10⁻¹⁰ mol/L. The selectivity experiments of ERY on the imprinted electrode were studied by using three structural analogues AZI、STM and ROX as interferers. The results showed that the imprinted electrode only had a specific recognition effect on ERY and showed a maximum response value (0.72 mA); The results of reproducibility and stability experiments suggested that the electrode had good reproducibility and stability. The detection results suggested that the concentration of ERY enrichment in the samples were increased 9~12 times by the magnetic imprinted solid-phase extraction combined with imprinted electrochemical sensor preconcentration process.