Abstract
The oxidation of 5-hydroxytryptophan (5-HTPP) at a glassy carbon electrode was not suited for electroanalysis because of surface passivation. Both mixed-valence ruthenium oxide with cyano crosslinks (RuOx) and a pentaerythritol-based metallodendrimer with RuIIterpyridine units (RuIIDen) provided electrocatalytic oxidation without passivation. The former was used as an electrochemically deposited film on glassy carbon, and the latter was a component of a composite electrode with a sol-gel binder. Flow-injection analysis with amperometric detection at constant applied potential yielded detection limits of 0.16 μM and 50 nM 5-HTPP with RuOx and RuIIDen catalysts, respectively.