In the past decade, electrochemists have begun modifying electrode surfaces with polymer composites. Each of those composites had advantages over the standard polymer modified electrode. Usually, the major advantage is increased sensitivity. However, years of chromatographic research have proven that tailoring the surface of glass beads can increase the selectivity of a system. The same principle should be applicable to polymer film composites. This research is based upon making glass bead/ion exchange polymer composites with unique interfaces that alter the selectivity of redox species on the basis of physical and chemical characteristics. This is accomplished by modifying the surface of glass beads with organosilanes of varying chain lengths and functional groups. The significance of this research lies in its ability to alter the selectivity of polymer modified electrodes. A surface-modified glass bead/Nafion composite was designed that excludes Ru(bpy)(3)(2+) from the film. The surface-modified glass bead/Nafion composites were able to alter electrochemical flux for hydroquinone, methylviologen, and Ru(bpy)(3)(2+). Composites have no significant effects on the electrochemical flux of Fe3+.