Carbon Paste Electrode Modified with ZrO2 Nanoparticles and Ionic Liquid for Sensing of Dopamine in the Presence of Uric Acid

Abstract

A novel carbon paste electrode modified with ZrO₂ nanoparticles and an ionic liquid (n-hexyl-3- methylimidazolium hexafluorophosphate) was fabricated. The electrochemical study of the modified electrode, as well as its efficiency for simultaneous voltammetric oxidation of dopamine and uric acid is described. The electrode was also employed to study the electrochemical oxidation of dopamine and uric acid, using cyclic voltammetry, chronoamperometry and square wave voltammetry as diagnostic techniques. Square wave voltammetry exhibits linear dynamic range from 1.0 × 10⁻⁶ to 9.0 × 10⁻⁴ M for dopamine. Also, square wave voltammetry exhibits linear dynamic range from 9.0 × 10⁻⁶–1.0 × 10⁻³ M for uric acid. The modified electrode displayed strong function for resolving the overlapping voltammetric responses of dopamine and uric acid into two well-defined voltammetric peaks. In the mixture containing dopamine and uric acid, the two compounds can be well separated from each other with potential difference of 155 mV, which is large enough to determine dopamine and uric acid individually and simultaneously. Finally, the modified electrode was used for determination of dopamine and uric acid in real samples.