Voltammetric Detection of Dopamine and Ascorbic Acid Using a Multi-Walled Carbon Nanotubes/Schiff Base Complex of Cobalt-Modified Glassy Carbon Electrode

The surface of the glassy carbon electrode (GCE) is modified with the composite of new Cobalt complex with a tetradentate Schiff base ligand derived from 3-ethoxysalicylaldehyde and 4,5-dimethyl orthophenylenediamine (CoOEtSal) and multi-walled carbon nanotube (MWCNT). The electrochemical oxidation of ascorbic acid (AA) and dopamine (DA) at the modified electrode was studied using the cyclic and differential pulse voltammetric techniques (CV and DPV). The effect of the scan rate and pH of the buffered solution on the electrode response is studied. An acceptable resolution of more than 285 mV for anodic oxidation waves of AA and DA is obtained using the modified glassy carbon electrode, and makes it very efficient for the simultaneous detection of these compounds. The Results show good peak resolution for AA and DA and the sub-micromolar detection limits for these compounds (0.07 and 0.04 μM for AA and DA respectively). The modified GCE was used successfully for the recovery of the analytes in human urine samples.