Kinetic study and characterization of a platinum electrode/sensitive membrane for malachite green detection

Purpose The purpose of this work is to explore electrical properties of an electrochemical sensor designed for the detection of malachite green (MG) present in an aqueous solution. Design/methodology/approach The present sensor consists in the spatial coupling of a polymeric membrane and an ion-sensitive electrode (platinum electrode). The preparation of the polymeric membrane involves the incorporation of an ionophore (D2HPA), a polymer (polyvinylchloride [PVC]) and a plasticizer (dioctyl phthalate [DOP]). Several techniques have been used to characterize this sensor: the cyclic voltammetry, the electrochemical impedance spectroscopy and the optical microscopy. The sensibility, the selectivity and the kinetic study of a modified platinum electrode have been evaluated by cyclic voltammetry. Findings The obtained results reveal the possibility of a linear relationship between the current of reduction peaks and MG concentration. A linear response was obtained in a wide-concentration range that stretches from 10(-5) to 10(-13) mol L-1, with a good correlation coefficient (0.976) and a good detection limit of 5.74 x 10(-14) mol L-1 (a signal-to-noise ratio of 3). In addition, the voltammetric response of modified electrode can be enhanced by adding a layer of Nafion membrane. Under this optimal condition, a linear relationship was obtained, with a correlation coefficient of 0.986 and a detection limit of 1.92 x 10(-18) mol L-1. Originality/value In the present research, a convenient, inexpensive and reproducible method for the detection of MG was developed. The developed sensor is capable of competing against the conventional techniques in terms of speed, stability and economy.