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Simultaneous Determination of Dopamine and L-Ascorbic Acid by Modified Carbon Paste Electrode with Ni (II) Cyclam Complex

Author(s): Leila Farzin | Mohammad Reza Milani Hosseini

Journal: American Journal of Analytical Chemistry
ISSN 2156-8251

Volume: 02;
Issue: 02;
Start page: 289;
Date: 2011;
Original page

Keywords: Macrocyclic Compound | Carbon Paste Electrode | Dopamine | Ascorbic Acid

The electroanalysis of dopamine (DA) and ascorbic acid (AA) by square wave voltammetry has been performed at a modified carbon paste electrode with macrocyclic ligand 1, 4, 8, 11-tetraazacyclotetradecane (cyclam) and monolayer of Ni (II) cyclam. In pH 7.2 buffer solutions, the electrostatic reaction of AA with di-positive monolayer shifts the oxidation potential to less positive potential, while the electrostatic repulsion of DA with the monolayer shifts the oxidation potential of DA to more positive potential. The separation between the oxidation peaks of AA and DA at the present di-positive monolayer modified electrode (252 mV) was larger than that (187 mV) at the cyclam modified electrode. In addition, the catalytic oxidation of AA by oxidized DA has been advantageously eliminated at the modified carbon paste electrode with cyclam and Ni (II) cyclam complex. Thus, the determination of DA in the presence of an excess of AA is possible with the present modified electrodes.
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