EFFECT OF ELECTROCATALYTIC AND NUCLEOPHILIC REACTIONS ON FAST VOLTAMMETRIC MEASUREMENTS OF DOPAMINE AT CARBON-FIBER MICROELECTRODES

Electrocatalytic and nucleophilic reactions constitute a potentially major hazard to the accurate voltammetric measurement of dopamine in vivo. The extent of such interactions was assessed in vitro using high-speed cyclic voltammetry at carbon fiber microelectrodes. Both ascorbic acid and glutathione decreased the height of the dopamine-o-quinone reduction peak but did not affect dopamine oxidation peak height. The effect was dependent on the electrode dimensions and voltage scan rate. Although the reactions seem to occur in vivo, they do not interfere with accurate measurement of dopamine at high-voltage scan rates.