Electrochemical Determination of Dopamine in the Presence of Ascorbic Acid Using a Poly(3-Acetylthiophene) Modified Glassy Carbon Electrode

Mehmet Aslanoglu*, Sultan Abbasoglu, Serpil Karabulut, Aysegul Kutluay
Department of Chemistry, University of Harran, Sanliurfa 63510, Turkey
Phone: +904143440020 ext. 1264, Fax: +904143440051
E-mail: maslanoglu@harran.edu.tr

Abstract
A glassy carbon electrode (GCE) was modified with electropolymerization of 3-acetylthiophene in acetonitrile using cyclic voltammetry. The modified electrode showed an excellent electrocatalytic effect on the oxidation of dopamine (DA). The poly(3-acetylthiophene) modified electrode also accelerated the rate of electron transfer reaction of DA. Compared with a bare GCE, the modified electrode exhibits a distinct shift of the oxidation potential of DA in the cathodic direction and a marked enhancement of the current response. The separation between anodic and cathodic peak potentials (∆Ep) for DA is 195 mV and 34 mV at bare and modified glassy carbon electrodes, respectively. The poly(3- acetylthiophene) modified GCE was used for the determination of dopamine (DA) in 0.1 M phosphate buffer solution (PBS) at pH 4.0. The peak current increases linearly with the concentration of DA in the range of 1.0 · 10^–6 ~ 1.0 · 10^–4 M. The detection limit was 3.8 · 10^–8 M by square wave voltammetry. The modified electrode has successfully been applied for the detection of DA in the presence ascorbic acid (AA). The proposed method also showed excellent stability and reproducibility.

Keywords: Chemically modified electrode, 3-acetylthiophene, dopamine, ascorbic acid, electropolymerization.