Electrochemical reference electrode

• US 4,002,547 A
• Filed: 07/22/1974
• Issued: 01/11/1977
• Est. Priority Date: 08/21/1970
• Status: Expired due to Term

• Current Assignee: Rosemount Incorporated (Emerson Electric Company)
• Original Assignee: Beckman Instruments, Inc. (Danaher Corporation)
• Inventors: Neti, Radhakrishna M., Bing, Colin C.
• Primary Examiner(s): Tung, T.
• Application Number:
  US05/490,544
• Time in Patent Office: 904 Days
• Field of Search: 204/195 F, 204/195 M, 204/1 T, 204/296, 260/92.1 S
• US Class Current: 204/435
• CPC Class Codes: G01N 27/301 Reference electrodes

Abstract

An electrochemical reference electrode for use in ion potential measurements of solutions. The liquid junction structure of the electrode comprises a hydrophobic polymer having a suitable salt distributed therethrough and held in place to prevent leaching by a filamentary structure of the polymer. The liquid junction structure is a diffusion membrane material and permits ionic communication between the salt bridge solution of the electrode and the sample solution essentially by means of diffusion, rather than by liquid flow. The entire electrode body may be made of the polymeric material. The electrode is particularly suited for process applications.

Claims

1. An electrochemical reference electrode comprising:

an electrode body of liquid impermeable polymeric material, said electrode body forming a closed internal chamber;

a water soluble salt selected from the group consisting of potassium chloride, sodium chloride, and potassium nitrate distributed through at least a portion of said liquid impermeable polymeric material to form a liquid junction structure in said electrode body, at least some of said water soluble salt being in particulate form and being held in place by a filamentary coating of said polymeric material;

an internal half cell disposed in said chamber;

means for making an electrical connection to said internal half cell; and

,

an internal filling solution in said internal chamber;

said electrode having no path for leakage of a test solution into said internal chamber or for leakage of said internal filling solution into a test solution when said electrode is immersed in a test solution.

2. An electrochemical reference electrode as claimed in claim 1 wherein:

the polymeric material is polytetrafluoroethylene;

said water soluble salt is about 5 to about 30% by weight; and

,

said particles are from about 10 to about 1,000 microns in size.

3. An electrochemical reference electrode as claimed in claim 2 wherein the polytetrafluoroethylene used to form said liquid junction is in the form of filaments having an average length of about 35 microns.

4. An electrochemical reference electrode as claimed in claim 1 wherein additionally:

said liquid impermeable polymeric material has glass fibers distributed throughout.