Chemically modified electrode for in vivo monitoring of brain catecholamines

A chemically modified graphite paste electrode was developed to allow catecholamines to be electrochemically distinguished from ascorbic acid and the dopamine metabolite 3,4-dihydroxyphenylacetic acid (DOPAC). Interference from 5-hydroxyindoles is eliminated through appropriate choice of electrode potential. The electrode gives linear current responses with increasing concentrations of catecholamines unaffected by the presence of ascorbic acid or DOPAC and exhibits long-term response stability in brain tissue. Examples are provided demonstrating the selectivity of the electrode to changes in extracellular dopamine in the rat striatum.