A high selective and simple electroanalytical method for simultaneous determination of dopamine, ascorbic acid and uric acid

The polymerized film of 4-methyl ortho phenylendiamine (4-MoPD) was used as electron transfer mediator onto a carbon paste electrode (CPE). The modified electrodes showed excellent catalytic activity toward oxidation of ascorbic acid, (AA), dopamine, (DA), and uric acid, (UA). The ternary mixture, which contains AA, DA, and UA can be well separated from each other at the surface of this modified electrode. Cyclic voltammetry was used for both the electrochemical synthesis of poly-(4-MoPD) on the surface of the CPE and characterization of the polymers deposited on the CPE. The high active surface area of the conducting polymer, i.e., poly-(4-MoPD) gave rise to a remarkable improvement in the electrocatalytic properties of the sensor. Three well-defined peaks at about-25, 165, and 296 mV versus Ag/AgCl were observed by using differential pulse voltammetry technique, corresponding to the voltammograms of AA, DA, and UA, respectively. The peak separations of 190, 131 and 321 mV between DA and AA, DA and UA, and UA and AA, respectively, allow us to detect DA, AA, and UA simultaneously. The value of this separation in the peak potential depends on the pH value of the aqueous solution. This approach is so simple and easy that it can be used to selectively detect DA, AA and UA in the presence of each other and also in some real samples. Copyright © 2016 American Scientific Publishers All rights reserved.