Simultaneous determination of ascorbic acid, dopamine, and uric acid based on double-walled carbon nanotubes/choline-modified electrode

Abstract

A novel protocol for simultaneous determination of ascorbic acid (AA), dopamine (DA) and uric acid (UA) based on double-walled carbon nanotubes (DWNTs)/choline (Ch) modified glassy carbon electrode (GCE) was presented. Ch was covalently immobilized on the GCE through oxygen atoms. The Ch monolayer provides a positively charged monolayer, which could attract negatively charged DWNTs through electrostatic interaction. In the simultaneous determination of aforementioned three analytes using CV, the electrochemical signals were well separated into three oxidation peaks with peak potential differences of 0.182 V (AA–DA), 0.146 V (DA–UA) and 0.328 V (AA–UA). In amperometric studies of AA, DA and UA, the modified electrode exhibited wide linear ranges of 0.10–777 μM, 0.06–314 μM and 0.25–344 μM and low detection limits of 0.03, 0.03, and 0.05 μM, respectively. Amperometric responses of AA, DA and UA were within 1 s. Moreover, this modified electrode was further applied to determine AA, DA and UA in real samples with satisfactory results.