Simultaneous Determination of Dopamine and Uric Acid In The Presence Of Ascorbic Acid by Using Indole Derivative Modified Glassy Carbon Electrode
Dopamine (DA) the most significant among the class of catecholamines, plays an important role in the function of the central nervous, cardiovascular, renal and hormonal systems [1] On the other hand, uric acid (UA) is the principal final product of purine metabolism in the human body [2] It has been shown that extreme abnormalities of UA levels are symptoms of several diseases. Simultaneous determination of UA and neurotransmitters, especially DA is a problem of critical importance for biomedical chemistry, neurochemistry, diagnostic and pathological research. At traditional solid electrodes, electroactive UA can be irreversibly oxidized in aqueous solution and DA can be reversibly oxidized at potentials close to that of UA. Therefore, simultaneous electrochemical detection of dopamine (DA) and uric acid (UA) is generally difficult at unmodified carbon electrode because of the interference with one another and with ascorbic acid (AA) so far, many chemically modified electrodes have been reported for this task [2] In this study, the simultaneous determination of DA and UA were investigated in the presence of AA at indole derivative modified glassy carbon electrode by using differential pulse voltammetric method. While these three biomolecules were not distinguished at bare glassy carbon electrode, interferences were eliminated by using indole derivative modified electrode. Because, at the modified electrode, any peak current was not detected for AA and the peak potential of UA was shifted toward more positive values, so that the peak of DA could be separated from that of UA and AA peaks. Thus, in addition to the removal of interferences, a simple analytical method was also improved for their determination in routine analysis. The optimisation of the entire analytical method, its validation and the application of the developed method to physiological samples will be presented.