Novel Electrochemical Sensor Based on Molecularly Imprinted Polymers with MWCNTs-SiO2 for Selective and Sensitive Detecting 2,4-D

In this study, we introduced molecular imprinting combined with electrochemical method to determine trace 2,4-dichlorophenoxyacetic acid (2,4-D) herbicide in standard solution and actual samples. For this purpose, we synthesis of vinyl silica coated MWCNTs in alkaline environment with surfactant, molecularly imprinted polymers were prepared on the surface of MWCNTs by free radical polymerization, following the composite materials were dissolved in chitosan solution and dropped on the glassy carbon electrode. The functionalized materials were characterized by fourier transform infrared spectroscopy, scanning electron microscopy, transmission electron microscopy, thermogravimetry and nitrogen adsorption desorption. Electrochemical performance of molecularly imprinted membrane was characterized by cyclic voltammetry, electrochemical impedance spectroscopy and differential pulse voltammetry. Selectivity, stability and reproducibility of the sensors were also studied and discussed. A good linear relationship for supervising 2,4-D from 1.0 × 10 −4 to 1.0 × 10 −8  mol L −1 with the correlation coefficient of 0.994 and a low LOD of 4.270 nmol L −1 (S/N = 3). The electrochemical sensor has been successfully applied to detect 2,4-D with a recovery rate ranges from 96.2 to 102.4% and a relative standard deviation of less than 4.74%. This work provides potential ideas for detection of trace 2,4-D in real samples.