Anodic Voltammetry and Its Analytical Application to the Detection and Simultaneous Determination of Hypoxanthine, Xanthine, and Uric Acid

Abstract

The voltammetric oxidation of hypoxanthine, xanthine, and uric acid was investigated by means of linearsweep voltammetry, cyclic voltammetry, and controlled-potential coulometry. Hypoxanthine, xanthine, and uric acid each gave a single oxidation peak at a different potential, with a stationary glassy carbon electrode, over the wide pH range of 0–13. Hypoxanthine was initially oxidized in a two-electron step to xanthine, which was then further oxidized in a two-electron step to uric acid, as well as the enzymatic oxidation. All three substances were strongly adsorbed on the surface of the glassy carbon electrode, so that the concentration vs .anodic peak current curves were not linear. The adsorption on the electrode was very dependent on the pH, and especially at pH values around neutrality the anodic peaks were ill-defined. However, in such acid solutions as H3PO4 and H2SO4, the voltammetric oxidation was a diffusion-controlled process and the differences between the peak potentials were most pronounced (ca. 400 mV). Consequently, it was possible to determine simultaneously three hydroxypurine bases by using 1 M H2SO4 or 1 M H3PO4 as a supporting electrolyte, without prior treatment or separation procedures.

Carbon materials for the electrooxidation of nucleobases, nucleosides and nucleotides toward cytosine methylation detection: a review

“…Finally, it is worth mentioning that there still exists some controversy regarding the role of adsorption in the electrochemical determination of the components of DNA with glassy carbon electrodes. While some groups have reported an adsorption effect for this electrode 89,[102][103][104] , opposite results have been published by other groups. For example, Gilmartin and Hart observed no effect of adsorption on glassy carbon electrodes.…”

Differential Pulse Voltammetric Determination of Uric Acid on Carbon‐Coated Iron Nanoparticle Modified Glassy Carbon Electrodes

“…Since the oxidation of UA is known to occur by a twoelectron transfer, and the number of protons involved was predicted to be two [14,21], we studied the effect of pH of supporting electrolyte (here is PBS) on the peak current and peak potential of UA at the CIN/GC in the range of pH 4.0 -7.5. Figure 2 displays the plot of anodic peak current of UA vs. pH of PBS.…”

Insights into the Oxidation Chemistry of 2‐Hydroxypurine by Electrochemical Methods

“…trihydroxypurines have been reported to undergo oxidation at less positive potential than dihydroxy-or monohydroxypurines [21].…”