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 cho line by liquid chromatography with electrochemical detection (Ikarashi et al., 1992). Such a precolumn adsorbs neurochemically related catec hol and indole derivatives and, thus, prevents interference in the chr omatogram for acetylcholine and choline. In the current studies, we re port the results of examining three important and related characterist ics of this adsorption process. First, the source materials and condit ions used in the preparation of the glassy carbon particles substantia lly affect adsorption of the 'interfering' catecholamines, indoleamine s, and related metabolites. Second, the primary adsorption sites appea r to have a substantial amount of graphite-like, rather than diamond-l ike, character. Third, the Langmuirian adsorption of the catechol and indole compounds is at least partly competitive, indicating the probab le involvement of common adsorption sites.