Analytical Sciences


Abstract − Analytical Sciences, 14(6), 1059 (1998).

Voltammetric Determination of Dopamine in a Mixture ofDopamine and Ascorbic Acid at a Deactivated Polythiophene Film ModifiedElectrode
Zhiqiang GAO* * ,David YAP*and Yimin ZHANG**
*Department of Chemistry, National University of Singapore, Kent RidgeCrescent, Singapore 119260, Republic of Singapore
**Luoyang Technological Institute, Luoyang, Henan, People's Republicof China
The voltammetric responses of dopamine (DA) and ascorbicacid (AA) at a deactivated polythiophene (PT) film modified electrode wereinvestigated. It was found that DA displays nearly identical voltammetricresponse at both a bare and the modified electrode, while the voltammetricsignal of AA is greatly suppressed at the modified electrode due to therepulsion between it and the deactivated film. Various experimentalparameters affecting the voltammetric responses of DA and AA were studied.The modified electrode was demonstrated to be very useful in selectivelydetermining DA in a mixture of DA and AA. At a 0.5 mm deactivated PT filmmodified electrode the calibration curve of DA was linear over the range of0.8 mM - 1.0 mM in the presence of 1.0 mM AA. The detection limit was 0.4mM. (Keywords: Dopamine, polythiophene, voltammetry, ascorbic acid,chemically modified electrode)