"Negative electrocatalysis"-based specific analysis of dopamine at basal plane HOPG in the presence of structurally related catecholamines

Oxidations of dopamine and structurally related catecholamines were shown to proceed with essentially different overpotentials at basal plane HOPG electrodes as compared to glassy carbon electrodes, consistent with the concept of "negative electrocatalysis". Electrode reactions of norepinephrine, epinephrine, and catechol slowed down on HOPG to a higher extent than oxidation of dopamine. Larger overpotentials for norepinephrine, epinephrine, and catechol oxidations allowed analytical discrimination and specific 0.05 to 4 mu M detection of dopamine in an artificial cerebrospinal fluid in the presence of 0.5M ascorbic acid and excessive amounts of norepinephrine, epinephrine and catechol. The results offer a new simple and powerful strategy for designing electrodes for specific analysis of dopamine in biological systems.