Electrochemical detection of dopamine in the presence of excess ascorbic acid using glassy carbon electrodes modified with conducting polymers

Thesis Type: Postgraduate

Institution Of The Thesis: Orta Doğu Teknik Üniversitesi, Faculty of Arts and Sciences, Department of Chemistry, Turkey

Approval Date: 2018




In this study, the main goal was to prepare new modified electrodes to be used in the dopamine (DA) determination in the presence of ascorbic acid (AA). For this purpose, the surface of glassy carbon electrodes (GCE) were modified with poly(3,4-ethylenedioxythiophene) (PEDOT), polyoxometalate (POM) doped PEDOT, poly (9-amino fluorene) (P9AF) and poly(9-fluorene carboxylic acid) (PFCA) by using electrochemical polymerization method. The modified electrodes were used as a working electrode in the presence of excess AA in DA determination using differential pulse voltammetry (DPV). The results showed that PEDOT-POM electrodes enhanced the current response of DA compared to that of PEDOT modified electrode. The effect of pH on the performance of POMs was evaluated. Electrochemical oxidation of DA in the presence of AA on glassy carbon electrode modified with P9AF was also investigated. It was found that modified electrode with P9AF can separate the oxidation potential of AA and DA at pH=4 and pH=5 phthalate buffer media. On the other hand, PFCA modified GC electrode exhibited well-separated oxidation potentials for AA and DA in different buffer solutions. The limit of detection of DA in the presence of 15 mM AA at pH=4 was calculated as 5.2 µM in the concentration range from 0.03 mM to 1.5 mM. It was observed that the proposed electrode still has high stability when stored at dry ambient conditions for three days. Satisfactory results with good recovery values were obtained for the determination of DA in dopamine injection solution.