Electrochemical Determination of Oxalate at Pyrolytic Graphite Electrodes

Abstract

The electrocatalytic oxidation of oxalate at several carbon based electrodes including basal plane (BPPG) and edge plane (EPPG) pyrolytic graphite and glassy carbon (GC) electrode, was studied. The electrodes were examined for the sensing of oxalate ions in aqueous solutions and all three electrodes showed a response to oxalate additions. The peak of oxalate oxidation at BPPG electrode appeared at lower potential, þ 1.13 V vs. SCE, than at EPPG (þ 1.20 V vs. SCE) and GC electrode (þ 1.44 V vs. SCE). Oxalate oxidation at BPPG electrode was studied in more details for response characteristics (potential and current), effects of pH, temporal characteristics of response potential and current. The results indicated that oxalate oxidation proceeds as two-electron process at the BPPG electrode with a transfer coefficient b and a diffusion coefficient D evaluated to be 0.45 and 1.03 (AE 0.04) Â 10 À5 cm 2 s À1 respectively. The BPPG electrode was found to be suitable for oxalate determination in aqueous media showing linear response to oxalate concentration with a sensitivity of 0.039 AM À1 and a limit of detection of 0.7 mM.

Solid-state synthesis, characterization, UV-induced coloration and photocatalytic activity – The Sr6Bi2O11, Sr3Bi2O6 and Sr2Bi2O5 bismuthates

“…However, addition of ammonium oxalate significantly affects the processes of the oxidative half-reaction. The redox potential of ammonium oxalate is +1.15 eV [50]. This means that the oxidative decomposition of ammonium oxalate will be the predominant process rather than the Bi III  Bi V process for which the redox potential is +1.59 eV, and as such the photocatalytic activity of Sr 3 Bi 2 O 6 is diminished.…”

Colourimetric and fluorescent detection of oxalate in water by a new macrocycle-based dinuclear nickel complex: a remarkable red shift of the fluorescence band

“…6b The oxalate content is clinically determined in urine using several techniques including high performance liquid chromatography, gas chromatography, ion chromatography and enzyme assays which are quite expensive instruments and often require time-consuming sample preparation. 7 …”

TEMPO as a Promising Electrocatalyst for the Electrochemical Oxidation of Hydrogen Peroxide in Bioelectronic Applications

“…[27][28][29][30] It is important to note that there are no known redox mediators for oxalate oxidase, so all oxalate oxidase biosensors have had to operate via the detection of the hydrogen peroxide enzymatic product. Designs include electrochemical detection of oxalate using edge plane and basal plane pyrolytic graphite electrodes 28 where there was a high overpotential and electrochemical detection of H 2 O 2 using multiwalled carbon nanotube-gold nanoparticle composites, 28 carboxylated multi-walled carbon nanotubes in a polyaniline composite film, 30 and chromium hexacyanoferrate 27 as catalysts. Here, cyclic voltammetry was used to examine the use of TEMPO with oxalate and OxOx in phosphate buffer at pH 5.2 ( Figure 5).…”