ELECTROCATALYTIC AMPEROMETRIC DETECTION AT POLYMERIC COBALT PHTHALOCYANINE ELECTRODES

Glassy carbon electrodes modified with a coating of a cobalt phthalocyanine containing polymer offer attractive features for applications as electrocatalytic amperometric sensors following liquid chromatography. These electrodes, which are formed by the anodic electropolymerization of CO-4,4',4",4"'-tetraaminophthalcyanine, exhibit electrocatalytic properties similar to those of earlier carbon paste electrodes containing Co phthalocyanine monomer added directly to the paste mixture. However, the polymer electrodes also offer increased stability and a compatibility with organic solvents not obtainable with the carbon paste version. The performance of the polymer electrodes is illustrated here for the detection of thiols following reversed-phase liquid chromatography. Determination of picomole quantities of various thiols is possible at low positive potentials in mobile phases composed of 50% methanol or acetonitrile. Furthermore, the response of the electrodes is extremely stable, with more than 80% of the initial activity retained after 40 hours of continous use.