absence (---) of 3.7 mM methionine. Supporting electrolyte, 0.5M phosphate buffer at pH 7.0; scan rate, 0.25 V s .

The potential utility of immobilized Rh2POM as an oxidation catalyst was demonstrated by using it in a sol-gel based composite [33]. The study had two goals, namely to characterize this CCE and to compare the immobilized Rh2POM to mvRuOx as an electrocatalyst for the oxidation of biochemical compounds. The CCE was prepared from a sol of methyltrimethoxysilane that was doped with Rh2POM and graphite powder. The resulting polishable solid comprised the working electrode in cyclic voltammetry and in an amperometric detector coupled to a reverse-phase HPLC system.