Ammonium ion specific electrode and method therewith

• US 3,869,354 A
• Filed: 04/06/1973
• Issued: 03/04/1975
• Est. Priority Date: 04/06/1973
• Status: Expired due to Term

• Current Assignee: Joseph G. Montalvo Jr
• Original Assignee: Joseph G. Montalvo Jr
• Inventors: Montalvo, Joseph G. Jr.
• Primary Examiner(s): Kaplan, G. L.
• Application Number:
  US05/348,673
• Time in Patent Office: 697 Days
• Field of Search: 204/195P,195B,1T
• US Class Current: 205/778
• CPC Class Codes: G01N 27/3335 the membrane containing at least one organic component G01N27/3271 takes precedence; aspects concerning the enzyme reagent in enzyme electrodes C12Q1/001

Abstract

An electrode specific for ammonium ion is made by covering the surface of a monovalent cationic electrode with a membrane permeable to ammonia but impermeable to interfering cations such as sodium and potassium. A thin layer of buffer-electrolyte is trapped between the surface of the electrode and the ammonia permeable membrane. The reference electrode is placed, via a small plastic tubing, in the buffer-electrolyte trap. When this electrode device is dipped into a solution containing ammonia ion, of which there is an equilibrium concentration of ammonia, ammonia gas (dissolved in the sample solution) passes through the gas permeable membrane over the electrode to again produce ammonium ion. The latter is potentiometrically sensed by the active surface of the monovalent cationic electrode.

Claims

1. AN AMMONIUM ION SPECIFIC ELECTRODE, COMPRISING:

A MONOVALENT CATIONIC ELECTRODE HAVING AN ACTIVE SURFACE PORTION THEREON SENSITIVE TO AMMONIUM ION;

AN AMMONIA PERMEABLE, CATION IMPERMEABLE MEMBRANE SURROUNDING THE ACTIVE SURFACE OF SAID ELECTRODE, AND A LAYER OF ELECTROLYTE BEING BUFFERED TO MAINTAIN A ELECTRODE, SAID ELECTROLYTE BEING BUFFERED TO MAINTAIN A CONSTANT PH THEREIN AS AMMONIA DIFFUSES THEREINTO.

2. An ammonium ion specific electrode in accordance with claim 1 further including:

a buffer-electrolyte permeable spacer placed between said electrode and said membrane.

3. An ammonium ion specific electrode, in accordance with claim 2, wherein said spacer comprises a layer of cellophane.

4. An ammonium ion specific electrode, in accordance with claim 3 wherein said spacer further includes a layer of nylon netting between said layer of cellophane and said membrane.

5. An ammonium ion specific electrode in accordance with claim 1 wherein said membrane is selected from the group consisting of 50:

50 silicone-polycarbonate film, collodion film, 40% leucine/60% methionine film and CO2 silastic film.

6. An ammonium ion specific electrode in accordance with claim 5 wherein said membrane is 50:

50 silicone-polycarbonate film.

7. An ammonium ion specific electrode in accordance with claim 2 further including a layer of nylon netting outside said layer of membrane and in contact therewith.

8. An ammonium ion specific electrode in accordance with claim 1 wherein said buffer electrolyte contains tris (hydroxymethyl) aminomethane.

9. AN APPARATUS FOR SELECTIVELY DETECTING AMMONIUM ION IN THE PRESENCE OF INTERFERING CATIONS COMPRISING:

AN AMMONIUM ION SPECIFIC ELECTRODE IN ACCORDANCE WITH CLAIM 1, A REFERNCE ELECTRODE IN CONTACT WITH SAID BUFFER-ELECTROLYTE LAYER, AND A POTENTIOMETER MEANS FOR MEASURING THE POTENTIAL DIFFERENCE BETWEEN SAID AMMONIUM ION SPECIFIC ELECTRODE AND SAID REFERENCE ELECTRODE.

10. A METHOD FOR SELECTIVELY DETECTING AMMONIUM ION IN THE PRESENCE OF INTERFERING CATIONS COMPRISING:

PLACING THE APPARATUS OF CLAIM 9 INTO A SOLUTION TO BE TESTED, AND BUFFERING THE TEST SOLUTION TO A PH MORE BASIC THAN THE PH OF SAID BUFFER-ELECTROLYTE, WHEREBY THE PRESENCE OF AMMONIUM ION WILL BE SELECTIVELY DETECTED BY SAID APPARATUS TO A HIGH SENSITIVITY AND WILL APPEAR ON SAID POTENTIOMETER.