Abstract: A novel electrochemical sensor was constructed for highly sensitive and selective determination of melamine by depositing a molecularly imprinted copolymer film, prepared by electrocopolymerization of gallic acid and o-phenylenediamine from aqueous electrolyte solution, onto glassy carbon electrode surface. The morphologic feature of the modified electrode was characterized via cyclic voltammetry, electrochemical impedance spectrometry, and scanning electron microscopy. The interactions between the molecularly imprinted copolymer and melamine cause the decrease in the peak currents of hexacyanoferrate, which could be used for electrochemical sensing of melamine. In this study, square wave voltammetry was selected as transducing mechanism. Several important parameters controlling the performance of the molecularly imprinted polymer (MIP) electrode were investigated and optimized. In the optimal conditions, the sensor response was sensitive to melamine from 5.0 to 100.0 nmol L-1 with good selectivity. The limit of detection based on a signal to noise ratio of 3 was low up to 1.4 nmol L-1. The method was applied successfully to determine melamine in milk products with satisfactory precision (2.11~3.38 % of relative standard deviation (RSD)) and acceptable recoveries (96.6~106.4 %), demonstrating a promising feature for applying the MIP sensor to trace detection of melamine in milk and other related products
Author keywords: Molecularly imprinted polymer, Gallic acid, o-Phenylenediamine, Electropolymerization, Melamine, Square wave voltammetry