Electrode for potentiometric measurements

• US 3,926,764 A
• Filed: 05/19/1972
• Issued: 12/16/1975
• Est. Priority Date: 05/19/1971
• Status: Expired due to Term

• Current Assignee: Carl Goran Lamm, Jaromir Ruzicka
• Original Assignee: Carl Goran Lamm, Jaromir Ruzicka
• Inventors: Ruzicka, Jaromir, Lamm, Carl Goran
• Primary Examiner(s): Tung, T.
• Application Number:
  US05/255,236
• Time in Patent Office: 1,306 Days
• Field of Search: 204/1T,195F,195M
• US Class Current: 204/418
• CPC Class Codes: G01N 27/308 at least partially made of carbon

Abstract

An electrode for potentiometric measurements. An electrochemically active redox system sensitive to ions in solution, which may be water-soluble or sparingly soluble, is carried directly by an electrical conductor such as graphite, which is rendered hydrophobic by means of a solid hydrophobizing material such as polytetrafluoroethylene. For use as reference electrode, said electrochemically active redox system contacts a solid, water-soluble salt establishing a fixed ion activity to be sensed by the electrochemical redox system. A salt bridge of another solid salt may be included. Such reference electrode may be used as inner reference in an ion-sensitive membrane electrode.

Claims

1. AN ELECTRODE FOR POTENTIOMETRIC MEASUREMENTS COMPRISING, A. AN ELECTRICALLY CONDUCTIVE BODY WHICH COMPRISES A MIXTURE OF GRAPHITE AND A THERMOPLASTIC POLYMER HYDROPHOBIZING SAID GRAPHITE, B. A SOLID ELECTROCHEMICALLY ACTIVE ION-SENSITIVE REDOX SYSTEM IN CONTACT WITH SAID HYDROPHOBIZED GRAPHITE, C. A SOLID WATER-SOLUBLE COMPOUND WHICH IS DISSOCIABLE WITH LIBERATION OF AN IONIC SPECIE TO WHICH THE REDOX SYSTEM IS SENSITIVE, SAID SOLID COMPOUND BEING HUMID AND BEING PRESENT IN CONTACT WITH SAID SYSTEM, AND D. MEANS PERMITTING ELECTROLYTICAL COMMUNICATION AND LIMITED MOISTURE COMMUNICATION BETWEEN THE SOLID HUMID WATER-SOLUBLE COMPOUND IN THE ELECTRODE AND AN EXTERIOR SAMPLE SOLUTION.

2. An electrode according to claim 1, wherein the thermoplastic polymer is polytetrafluoroethylene.

3. An electrode according to claim 1, wherein the solid water-soluble compound (C) is present as a humid powder mass.

4. An electrode according to claim 1, wherein the solid water-soluble compound is present in a porous tablet of solid hydrophobizing material.

5. An electrode according to claim 4, wherein the solid hydrophobizing material is polytetrafluoroethylene.

6. An electrode according to claim 4, wherein the porous tablet has a surface exposable to an exterior sample solution, said surface constituting the means permitting electrolytical communication and limited moisture communication between the water-soluble compound and the exterior sample solution.

7. An electrode according to claim 1, additionally comprising a solid humid water-soluble salt positioned between the solid humid compound and said communication means and functioning as a salt bridge.

8. An electrode according to claim 1, wherein the redox system comprises mercury/mercurous chloride, and the solid water-soluble compound is potassium chloride.

9. An electrode according to claim 1, wherein the redox system comprises silver/silver chloride, and the solid water-soluble compound is potassium chloride.

10. An electrode for potentiometric measurements comprising, A. An electrically conductive body which comprises a mixture of graphite and a thermoplastic polymer hydrophobizing said graphite, B. A solid electrochemically active ion-sensitive redox system in contact with said hydrophobized graphite, C. A solid water-soluble compound which is dissociable with liberation of an ionic specie to which the redox system is sensitive, said solid compound being humid and being present in contact with said redox system, and D. An ion-selective membrane contacting the solid water-soluble compound.