KOH assisted activation of microwave exfoliated graphite oxide for selective voltammetric determination of dopamine and uric acid in the presence of ascorbic acid

In this study, an activated porous graphite oxide (PG) with a superior surface area of ~ 3010 m² g^{− 1} was applied as electrode component for discrimination of dopamine (DA) and uric acid (UA) via cyclic voltammetry (CV), in the presence of high content of ascorbic acid (AA). Contributable to microwave exfoliation and KOH assisted activation, the as-prepared PG remarkably improves the signal at glassy carbon electrode (GCE) for analyte. The electrochemical performance of PG/GCE was studied with CV and electrochemical impedance spectroscopy (EIS) measurements. The CV data implied that the PG film effectively enlarges the electro-active area of the working electrode while the EIS data revealed that the PG modification enhances the electron transfer kinetics between analyte and electrode. The peak separations between DA, UA and AA were remarkably enlarged and their redox peak currents were enhanced. This makes the proposed sensor feasible for simultaneous determination of DA and UA in the presence of AA. Under optimum conditions, the oxidation peak currents for DA and UA increased linearly over concentration ranges of 0.5–60 μM and of 0.5–100 μM, with detection limits of 0.04 μM and 0.02 μM (at a signal-to-noise ratio of 3, S/N = 3), respectively. Applications of the PG/GCE for urine and serum analyses were investigated. The results with good recoveries indicate the feasibility of the developed electrode in clinic sensing application.