COMPETITIVE-BINDING OF CATECHOLAMINES, INDOLEAMINES, ACETYLCHOLINE, AND RELATED METABOLITES TO VARIOUS GLASSY-CARBON MATERIALS

We have previously demonstrated the utility of a pre-column containing glassy carbon particles in the determination of acetylcholine and choline by liquid chromatography with electrochemical detection (Ikarashi et al., 1992). Such a precolumn adsorbs neurochemically related catechol and indole derivatives and, thus, prevents interference in the chromatogram for acetylcholine and choline. In the current studies, we report the results of examining three important and related characteristics of this adsorption process. First, the source materials and conditions used in the preparation of the glassy carbon particles substantially affect adsorption of the 'interfering' catecholamines, indoleamines, and related metabolites. Second, the primary adsorption sites appear to have a substantial amount of graphite-like, rather than diamond-like, character. Third, the Langmuirian adsorption of the catechol and indole compounds is at least partly competitive, indicating the probable involvement of common adsorption sites.