Establishment and Application of Molecularly Imprinted Electrochemical Sensors for the Detection of Chloramphenicol Residues in Foods of Animal Origin

A novel electrochemical sensor was fabricated for the rapid and sensitive detection of chloramphenicol (CAP). The experiments combined molecular imprinting technology with electrochemical workstation, using multi-walled carbon nanotubes (MWCNTs) and gold-platinum nanoparticles to double sensitize the electrode, which was used to enhance the electron transfer rate on the surface of the glassy carbon electrode (GCE) and enhance the current response value of the electrochemical sensor, thus reducing the detection limit. Characterization was carried out using scanning electron microscopy and electrochemical methods. Study the adsorption performance of molecularly imprinted modified electrodes through adsorption kinetics experiments and isothermal adsorption experiments, and analyze their selectivity. Detect chloramphenicol in actual samples of chicken, fish, and milk using modified electrodes and analyze their detection effectiveness. Results showed that, the modification effect of the electrode could be clearly seen from the cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS), and the enhancement of the electron conduction rate on the electrode surface by MWCNTs and gold-platinum nanoparticles (Au-PtNPs) was obvious. The adsorption properties of the molecularly imprinted modified electrodes were studied by adsorption kinetic tests and isothermal adsorption tests to determine the adsorption properties and analyze their selectivity. The experiments showed good selectivity for its structural analogues, and the analyticity of the sensor was evaluated, and the sensor showed good linearity between CAP concentrations of 0.66 and 56.66 µg/L with R²>0.99 and a detection limit of 0.45 nmol/L (0.146 µg/L). The recoveries of CAP were 83.72%~103.43% with the relative standard deviations (RSDs) of 2.61%~6.03% in the assays of actual samples of chicken, fish and milk, respectively, which met the requirements of GB/T 27404-2008 for quantitative analysis and detection (the measured components were <0.1 mg/kg and the recoveries ranged from 60% to 120%). Compared with other literature methods, the test method has extremely low detection limits.