A Glassy-Carbon Electrode for Voltammetry H. E. ZITTEL and F. J. MILLER Analytical Chemistry Division, Oak Ridge National laboratory, Oak Ridge, Tenn.
b A new form of carbon known as "glassy" carbon has been used as an indicator electrode in voltammetry. Glassy carbon is a gas-impermeable, electrically conductive material highly resistant to chemical attack. It is suitable for use over the potential range from about +1.2 to -0.8 volts vs. S.C.E. in acid medium. Voltammetric studies have been made of solutions of Ce(lll1, Ce(IV), Cr(VI), Fe(ll), Hg(l), Fe(CN)6-4, Ag(l), Cu(ll), and UOz(ll). For most of these ions a peak type wave that approaches ideality was obtained. The E, and i, values for these ions are for the most part reproducible under the conditions stated and appear to be analytically usable. The electrode was fabricated by molding glassy carbon into an epoxy rod with a central tube to permit an Hg contact. The assembly is rugged and the electrode requires no pretreatment or treatment between uses. In ease of fabrication and maintenance the glassy carbon electrode (G.C.E.) compares very favorably with the pyrolytic graphite electrode (P.G.E.) and other solid electrodes.
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USE of carbon for electrodes in voltammetry is not new, recently introduced forms of this material are of particular interest. Primary among these are pyrolytic, impregnated, and glassy carbon. Adams ( 1 ) discusses the behavior of graphite, as well as other solid electrodes, in voltammetry. Pyrolytic graphite is being studied as an electrode for voltammetry of both aqueous and nonaqueous systems (7, 9). "Glassy carbon" is a proprietary preparation of the Tokai Electrode Manufacturing Co. (11). It is gas-impermeable, highly resistant to chemical attack, electrically conductive, and obtainable in a relatively pure state. Although its properties are discussed by Yamada and Sat0 (12),many analytical chemists apparently have been unaware of its existence. Use of glassy carbon as an electrode in analytical chemistry has not been reported. It has many properties in common with pyrolytic graphite; however, it is isotropic rather than anisotropic. An electrode of pyrolytic graphite must be properly oriented, and the edges of the planes of the graphite must be sealed. These limitations should not exist for an electrode made of glassy carbon. LTHOUGH THE
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ANALYTICAL CHEMISTRY
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