Electrochemical detection of hydrogen peroxide at platinum-modified diamond electrodes for an application in melamine strip tests

Electrochemical detection of hydrogen peroxide (H₂O₂) at a platinum-deposited boron doped diamond was studied for an application in melamine strip test. Deposition of Pt particles at a boron-doped diamond surface was performed using cyclic voltammetry method. The method was also used for electrochemical measurements. The oxidation-reduction peak currents of H ₂O₂ at + 0.6 V and - 0.1 V (vs. Ag/AgCl), respectively were found to be linear in the concentration range of 0.05-20 mM (R² = 0.99). Linearity was also observed to be dependent on horseradish peroxidase (HRP) concentration in the constant concentration of H₂O₂. The method was then applied in immunochromatographic strip test for melamine detection to determine the activity of HRP labeled at melamine antibody. Taking an assumption that the activity of HRP was equivalent to melamine concentration, linearity of the current responses to the concentrations of standard melamine solutions in the range of 5-100 μg/ml could be achieved. Limit of detection of 0.51 μg/ml was estimated. The obtained results demonstrated that the designed biosensor for detection of H₂O₂ could be applied for the quantitative and selective detection of melamine.