Investigating the electrochemical behaviour and detection of uric acid on ITO electrodes modified with differently doped N-graphene films

Abstract

Sensitive and selective electrochemical sensors based on indium-doped tin oxide electrodes (ITO) modified with differently nitrogen-doped graphene (NGr) films were successfully developed for the individual and simultaneous determination of uric acid (UA) in the presence of ascorbic acid (AA). The influence of the contents of various N-configurations on the detection of UA on the NGr/ITO based sensors is herein reported for the first time. The contents of various N-configurations on the NGr/ITO electrodes displayed varying promotional effects of the electro-oxidation of UA; attributed to the unique properties of the NGr films arising from the N-configurations. In particular, three N-doped materials prepared with varying amount of graphitic-N, pyrrolic-N, and pyridinic-N allowed the individual detection of UA, in the presence of AA, in the concentration range from 2 to 320μM with the detection limits of 0.043μM to 0.19μM. Finally, the NGr/ITO-based sensors exhibited successful simultaneous detection of UA and AA, depicting detection limits of 0.051–0.19μM and 0.93–5.1μM within the concentration ranges of 6–280μM and 8–800μM, for the detection of UA and AA, respectively. The study provided insight into an understanding as to how the different contents of N-configurations influenced the electrocatalytic activity of NGr/ITO electrodes for the individual and simultaneous detection of uric acid.