A Novel Electrochemical Biosensor Based on a Modified Gold Electrode for Hydrogen Peroxide Determination in Different Beverage Samples

In the present work, an electrochemical biosensor is constructed based on a Nafion nano composite polymer, toluidine blue (TB) and catalase enzyme-modified gold electrode (AuE). The TB molecules were strongly adsorbed on the Nafion/AuE. The electrochemical properties of this biosensor were examined. Cyclic voltammetry was used at various scan rates to investigate the redox properties of the Nafion and TB-modified AuE (Nafion/TB/AuE). The electron transfer coefficient, alpha, and the electron transfer rate constant, k (s), were found to be 0.48 and 12.1 +/- 0.3 s(-1) in pH 7.0, respectively. The Nafion, TB, and catalase-modified AuE (Nafion/TB/catalase/AuE) exhibited excellent electrocatalytic response to the reduction of hydrogen peroxide (H2O2). Using cyclic voltammetry, kinetic parameters such as electron transfer coefficient, alpha, and heterogeneous rate constant, k', were determined for the reduction of H2O2 at this biosensor surface. Differential pulse voltammetry exhibited two linear dynamic ranges and a detection limit of 0.25 mu M for H2O2.