Electrochemical determination of malachite green using a multi-wall carbon nanotube modified glassy carbon electrode

Abstract

A multi-wall carbon nanotube (MWNT) film-modified electrode is described for the determination of malachite green (MG). The electrochemical profile of MG was examined using cyclic voltammetry (CV) and differential pulse voltammetry (DPV), suggesting that the MWNT film facilitates the electron transfer of MG in terms of a potential shift and then significantly enhances the oxidation peak current of MG. The experimental parameters, such as supporting electrolyte, thickness of MWNT film, scan rate and accumulation time, were optimized. Consequently, a sensitive and convenient electrochemical method is proposed for the determination of MG. The oxidation peak current is proportional to the concentration of MG over the range from 5.0 × 10−8 to 8.0 × 10−6 mol L−1 obeying the following equation: ip = 0.09 + 1.19 × 107 C (r = 0.995, ip in µA, C in mol L−1). The detection limit is 6.0 × 10−9 mol L−1 (signal to noise = 3) after 5 min of accumulation. Moreover, this method possesses good reproducibility (RSD is 5.6%, n = 8) as well as long-term stability. Finally, the new method was employed to determine MG in fish samples.