Electrochemical sensor based on a poly(para-aminobenzoic acid) film modified glassy carbon electrode for the determination of melamine in milk

A novel and simple sensor is developed in this paper for melamine detection, which is based on an electropolymerized molecularly imprinted polymer (MIP) of para-aminobenzoic acid (pABA). The poly(para-aminobenzoic acid) (P-pABA) film was deposited in a pABA solution by potentiodynamic cycling of potential with and without the template (melamine) on a glassy carbon electrode. The surface feature of the modified electrode was characterized by electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV). The molecular imprinted sensor was tested by differential pulse voltammetry (DPV) to verify the changes in redox peak currents of hexacyanoferrate. Several important parameters controlling the performance of the P-pABA were investigated and optimized. In the optimal conditions, the relative redox peak currents of hexacyanoferrate were linear. The concentration of melamine ranged from 4.0 μM to 0.45 mM, with a linear correlation coefficient of 0.9992. The detection limit was 0.36 μM (S/N = 3). The MIP sensor was successfully applied to the determination of melamine in milk products and showed high selectivity, sensitivity, and reproducibility. The results of this research demonstrate that it is feasible to use the molecular imprinting methodology when preparing sensing devices for analytes that are electrochemically inactive.

► The fabrication procedure of the proposed electrochemical sensor is very simple, fast and with low cost. ► The modified electrode shows a low detection limit, wide linear concentration range, excellent selectivity, good repeatability and reproducibility, and fast response for the detection of melamine. ► The proposed method was successfully applied to the determination of melamine in milk products with good precision and accuracy, and can be used as a routine method for the analysis of melamine in food samples. ► The strategy proposed in this work is potentially applicable to the electrochemical determination of other important molecules without electrochemical activities.