Fabrication and Characterization of a Solid State Reference Electrode for Electroanalysis of Natural Waters with Ultramicroelectrodes

As an alternative to standard commercial reference electrodes, a solid state reference electrode is fabricated for in situ voltammetric analysis in solutions containing little or no added supporting electrolyte. In the fabrication process, a Ag/AgCl wire is coated with an electrolyte immobilized and protected with Nafion or polyurethane. The electrode potential is measured as a function of time, ionic strength, and pH. A stable potential is obtained for Nafion and polyurethane within 30−35 min in water. Both the polyurethane and Nafion solid state reference electrodes are stable for at least 90 days, but the Nafion electrode fluctuates more than the polyurethane electrode. The electrode is demonstrated using square wave anodic stripping voltammetry at a large electrode (3 mm), an ultramicroelectrode (10 μm), and an array of ultramicroelectrodes.