Ion-selective electrode and method for preparation thereof
First Claim
1. A method for preparing a dry glass electrode having an ion-selective alkali metal-containing glass membrane over a surface oxidized metal conductor for use in potentiometric analyses of aqueous media comprising the steps of:
- electrolytically etching a conductor constituted of a metal selected from the group consisting of platinum and gold in an alkaline solution containing cyanide ions and ions of the principal alkali metal of said glass;
oxidizing an etched surface of the conductor;
covering an etched and surface oxidized portion of the conductor with an ion-selective alkali metal containing glass;
heating the conductor and glass to a temperature sufficient to form a membrane of said glass over said portion and heat seal the glass to said oxide layer to provide an electrically conductive junction therebetween; and
annealing the glass by cooling it at a rate which substantially avoids phase separation in the glass.
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Abstract
A dry glass electrode for use in potentiometric analyses of aqueous media. The electrode comprises a metal conductor constituted of platinum, gold, or tantalum, a layer comprising an oxide of the metal having a thickness of between about 50 Angstrom units and about 2 microns on an outer surface of the metal conductor, and an ion-selective glass membrane over and in electrical contact with the oxide layer. The ion-selective glass has a coefficient of thermal expansion differing by less than about 25% from the coefficient of thermal expansion of the metal.
A method for producing the electrode of the invention is also disclosed.
12 Citations
16 Claims
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1. A method for preparing a dry glass electrode having an ion-selective alkali metal-containing glass membrane over a surface oxidized metal conductor for use in potentiometric analyses of aqueous media comprising the steps of:
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electrolytically etching a conductor constituted of a metal selected from the group consisting of platinum and gold in an alkaline solution containing cyanide ions and ions of the principal alkali metal of said glass; oxidizing an etched surface of the conductor; covering an etched and surface oxidized portion of the conductor with an ion-selective alkali metal containing glass; heating the conductor and glass to a temperature sufficient to form a membrane of said glass over said portion and heat seal the glass to said oxide layer to provide an electrically conductive junction therebetween; and annealing the glass by cooling it at a rate which substantially avoids phase separation in the glass. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16)
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Specification