Electrochemical Detection of Dopamine in the Presence of Ascorbic Acid Using Overoxidized Polypyrrole/Graphene Modified Electrodes

Abstract

Overoxidized polypyrrole/graphene modified glassy carbon electrode (PPyox/graphene/GCE) has been prepared and applied for the fabrication of dopamine sensors without the interference of ascorbic acid. Compared to bare GCE, a substantial negative shift of the anodic peak potential and dramatic increase of current signal were observed and the separations between the anodic and cathodic peaks of dopamine was obviously decreased, demonstrating that PPyox/graphene/GCE exhibited favorable electron transfer kinetics and electrocatalytic activity towards the oxidation of dopamine. Furthermore, PPyox/graphene/GCE exhibited good ability to suppress the background current from large excess ascorbic acid. The electrochemical detection of dopamine in the presence of ascorbic acid (1 mM) showed two linear ranges with a transition point at 25.0 μM. The sensor displayed a linear range of 25.0 μM–1.0 mM DA with a correlation coefficient of 0.996, a sensitivity of 0.015 μA/μM, and a linear range of 0.5 μM–10.0 μM DA with a correlation coefficient of 0.997, a sensitivity of 0.094 μA/μM. The detection limit was 0.1 μM with a signal/noise ratio of 3.