Highly sensitive and selective determination methyldopa in the presence of ascorbic acid using OPPy/TY/Au modified electrode

An enzymeless biosensor, based on electrodeposition of overoxidized polypyrrole (OPPY) onto gold electrode and modified with titan yellow (TY), was investigated in this study. OPPY/TY/Au showed electrocatalytic activity for the oxidation of methyldopa (MDA) in acetate buffer solution. The electrochemical performance of the modified electrodes was investigated by differential pulse voltammetric (DPV) method. The resulting biosensor exhibited excellent performance for MDA determination with a wide linear range (50 nM to 20 μM), a highly reproducible response (RSD of 2.3%), low percentage of the interferences and long-term stability. The calculated detection limit was 17 nM. In order to verify the reliability of the biosensor, it was applied to the determination of MDA in human serum and pharmaceutical samples.