Development and Optimization of a Voltammetric Methodology Based on Bismuth Film Electrodes with Potential Application for Aflatoxin B1 Analysis

Aflatoxins are secondary metabolites of Aspergillus fungus, which contaminate various foods at trace levels. Mercury drop electrodes have been used for the quantification of aflatoxins; however, they have a negative effect on the environment. An alternative to mercury electrodes are bismuth film electrodes, with the same advantages of mercury but friendly with the environment. This work proposes the development of a voltammetric methodology for the quantification of Aflatoxin B1 (AFB1) through bismuth film electrodes. AFB1 reduction is controlled by diffusion towards the electrode's surface. Optimal conditions for the synthesis of the bismuth film were obtained by a Box-Behnken experimental design, considering the AFB1 cathodic signal as a response. Optimal conditions were: deposition potential of -280 mV, Bi3+ concentration of 600 mg/L, deposition time of 30 s. Differential pulse voltammetry (DPV) was used for AFB1 quantification, so its parameters were also optimized; optimal parameters were: current step of 10 mV, pulse width of 28 ms, pulse period of 60 ms and an amplitude of 200 mV.