Electrochemical behavior of dopamine at a [1,1′-binaphthalene]-4,4′-diol-modified carbon nanotube paste electrode and the simultaneous determination of dopamine, folic acid and uric acid

Abstract

The electro-oxidation of dopamine (DA), uric acid (UA), folic acid (FA), and their mixture has been studied using a modified carbon nanotube paste electrode of [1,1′-binaphthalene]-4,4′-diol (BND) using cyclic voltammetry, chronoamperometry and differential pulse voltammetry. The electrocatalytic process was greatly dependent on the pH of the supporting electrolyte. This modified electrode was quite effective, not only in the detection of DA, UA and FA but also in the simultaneous determination of these species in a mixture. The catalytic peak current obtained was linearly dependent on the DA, UA and FA concentrations in the range of 5.0–600.0 μM, 6.5–752.0 μM and 9.5–1128.0 μM, respectively, and the detection limits for DA, UA and FA were 0.49, 4.28 and 7.69 μM, respectively. The diffusion coefficient (D/cm² s⁻¹ = 6.8 × 10⁻⁶) and the kinetic parameters such as the catalytic rate constant (k/M⁻¹ s⁻¹ = 18.22 × 10³) and the electron transfer coefficient (α = 0.36) for DA were determined using electrochemical approaches.