PREPARATION AND CHARACTERIZATION OF A MULTICYLINDER MICROELECTRODE COUPLED WITH A CONVENTIONAL GLASSY-CARBON ELECTRODE AND ITS APPLICATION TO THE DETECTION OF DOPAMINE

A multi-cylinder microelectrode coupled with a conventional glassy carbon disc electrode (MCM/GC) was prepared and characterized using cyclic voltammetry and chronoamperometry. It was demonstrated that in the same way as one observed a steady-state current at closely spaced microelectrodes when redox recycling takes place, the same effect can be obtained with the MCM/GC device. The experimental results obtained with K3Fe(CN)6 solutions were compared with a previously developed theory. Further, it was demonstrated that with a carbon fibre MCM/GC device, the voltammetric behaviour of dopamine is greatly improved by virtue of redox recycling, hence giving high sensitivity. The steady-state collection current was linearly related to dopamine concentration in the range 1 X 10(-4) to 5 x 10(-7) Mol l-1, and the detection limit was 2 x 10(-7) mol l-1. The influence of coexisting ascorbic acid was also investigated. This device was applied successfully in the determination of dopamine hydrochloride in pharmaceutical preparations.