Simultaneous Detection of Ascorbic Acid, Dopamine, and Uric Acid At Choline Monolayer Supported Multiwalled Carbon Nanotubes Film

Abstract: A novel, rapid and convenient method for the simultaneous detection of ascorbic acid (AA), dopamine (DA), and uric acid (UA) was developed at a multiwalled carbon nanotube (MWCNT)/choline(Ch) monolayer-modified glassy carbon electrode (GCE). The Ch was covalently immobilized on the surface of GCE through oxygen atom. The Ch monolayer provides a positively charged surface with –N⁺(CH₃)₃ polar groups, so that it can attract negatively charged MWCNTs to the surface. Hence, the MWCNT/Ch film exhibited remarkable electrocatalytic activities towards the oxidation of AA, DA and UA due to the advantages of high electrode activity, large surface area, prominent antifouling property, and high electron transfer kinetics. Individual and simultaneous determination of AA, DA and UA were studied by all sorts of electrochemical means. All aforementioned analytes showed well-defined catalytic oxidation peaks at MWCNT/Ch/GCE. The peak separations between AA and DA, DA and UA are sufficiently large for their potential recognition and simultaneous detection in mixture. Under the optimum conditions, the designed MWCNT/Ch/GCE exhibited low detection limit, high sensitivity and wide linear range for simultaneous detection of AA, DA, and UA.