Electrochemically synthesized partially reduced graphene oxide modified glassy carbon electrode for individual and simultaneous voltammetric determination of ascorbic acid, dopamine and uric acid

Abstract

We report here an efficient and simple approach for the preparation of a partially reduced graphene oxide modified glassy carbon electrode (RGO-GCE). The modification of the RGO-GCE consists of three steps. These include (i) chemical synthesis of graphite oxide by a modified Hummer's method, (ii) exfoliation of graphite oxide to graphene oxide (GO) by ultra-sonication and (iii) controlled partial electrochemical reduction in 0.1 M phosphate buffered medium (pH 3.0) via potentiodynamic cycling (2 cycles) to obtain a partially reduced graphene oxide modified glassy carbon electrodes (RGO-GCE). The behaviour of the RGO-GCE towards ascorbic acid (AA), dopamine (DA) and uric acid (UA) was investigated by differential pulse voltammetry, with an enrichment time of 3 minutes. This showed that the modified electrode has good precision (1.42, 1.92 and 2.20% for AA, DA and UA, respectively) and resolution at pH 3.0 for all three molecules, which enables their individual and simultaneous determination. Under the optimized conditions, the electrochemical sensor showed a wider linear response for AA, DA and UA in the concentration ranges of 4 × 10⁻⁵ to 1 × 10⁻³ M, 1 × 10⁻⁷ to 1 × 10⁻⁴ M and 8 × 10⁻⁷ to 8 × 10⁻⁴ M with detection limits of 4.2 × 10⁻⁶, 8 × 10⁻⁹ and 6 × 10⁻⁷ M, respectively, based on 3 times the standard deviation of the blank with minimal fouling effects. Detailed spectral (IR and Raman), morphological (SEM and TEM) and electrochemical characterization studies were also reported. Finally, the performance of the RGO-GCE based sensor was successfully tested for analysing UA and quantitative recoveries of AA and DA in serum samples.