Collect. Czech. Chem. Commun. 2004, 69, 419-425

Non-Cottrell Behavior of the Dopamine Redox Reaction Observed on the Carbon Fibre Microelectrode by the Double-Step Voltcoulometry

Katarína Gmucováa,*, Jozef Orlickýb and Juraj Pavlásekc

a Institute of Physics, Slovak Academy of Sciences, Dúbravská cesta 9, 845 11 Bratislava, Slovak Republic
b Institute of Molecular Physiology and Genetics, Slovak Academy of Sciences, Limbová 3, 833 34 Bratislava, Slovak Republic
c Institute of Normal and Pathological Physiology, Slovak Academy of Sciences, Vlárska 5, 833 34 Bratislava, Slovak Republic


The redox reaction of the neurotransmitter dopamine at the carbon fibre microelectrode was studied by several electrochemical methods. It was found that under conditions usual in a living body, the diffusion current fullfils, within experimental errors, the behavior theoretically predicted by the Cottrell equation. Nevertheless, attention should be paid to the fact that unsupported or weakly supported conditions give rise to a non-Cottrell response of diffusion current. Moreover, similar changes were observed if the dopamine concentration was either lower such as several units of μmol l-1, or about 100 μmol l-1 or higher. The non-Cottrell behavior of diffusion current involves the nonlinearity of the dopamine calibration curve obtained by pulse techniques. The present work is aimed at pointing out that such behavior of the measured data could lead to misinterpretation of the obtained dopamine concentration. Similar features could be also achieved for the other catecholamines.

Keywords: Dopamines; Redox chemistry; Coulometry; Kinetics; Carbon fibre microelectrode; Cottrell equation; Supporting electrolyte; Electrochemistry.

References: 14 live references.