Development of conducting composite materials for electrochemical sensing in organic media

Several electrochemical transducers have been developed for use in organic media. These transducers are based on rigid conducing dispersed composites prepared from a mixture of graphite ponder in a polymer matrix. The behavio r of composites based on silicone, several epoxies, polyester and polyureth ane was studied in organic solvents like acetone, acetonitrile, ethanol, ch loroform and tetrahydrofuran. The composites were characterized using cycli c voltammetry and were calibrated with Ferrocene. Composites with silicone or epoxy showed a high stability in organic solvents. These composites have a homogeneous surface and they show high stability and reproducibility whi le performing electrochemical measurements. The surface of these devices ca n be renewed by a simple polishing procedure using alumina paper: The plast ic nature of these materials makes them modifiable, permitting the incorpor ation of fillers before they are cured. To test their rapacity for biosensi ng in organic media, the matrix of one transducer was biologically modified a with horseradish peroxidase (HRP) producing a graphite-epoxy-HRP biocomp osite. A biosensor built with this material responded linearly to lauroyl p eroxide between 10(-6) and 10(-5) M in acetonitrile and the enzyme remained stable in the biocomposite.