Chloramine amperometric sensor

• US 7,087,150 B2
• Filed: 05/03/2002
• Issued: 08/08/2006
• Est. Priority Date: 05/03/2002
• Status: Expired due to Fees

• Current Assignee: Rosemount Analytical, Inc. (Emerson Electric Company)
• Original Assignee: Rosemount Analytical, Inc. (Emerson Electric Company)
• Inventors: Feng, Chang-Dong
• Primary Examiner(s): Olsen, Kaj K.
• Application Number:
  US10/138,359
• Publication Number:
  US 20030205465A1
• Time in Patent Office: 1,558 Days
• Field of Search: 204/415, 204/430, 204/431, 205/778.5, 205/780, 205/780.5
• US Class Current: 205/780
• CPC Class Codes: G01N 27/4045 for gases other than oxygen
• CPC Class Codes: G01N 33/0049 Halogenated organic compounds
• CPC Class Codes: G01N 33/184 Herbicides, pesticides, fungicides, insecticides or the like

Abstract

A chloramine amperometric sensor includes a sensor body with an electrolyte disposed inside the sensor body. A membrane is coupled to the sensor body and adapted to pass chloramine therethrough. A reference electrode is disposed in the electrolyte and coupled to a first conductor. A second conductor is coupled to a working electrode that is disposed proximate the membrane. The working electrode is constructed from a noble metal in non-compact form. The non-compact form can be a Gas Diffusion Electrode, which can include metal mesh, carbon paper, carbon cloth, metal/carbon powder loaded on a porous membrane or any combination thereof.

Claims

1. In a chemical sensor, a method of measuring chloramine, the method comprising:

placing a solution containing chloramine in fluidic communication with a membrane permeable to chloramine;

providing a working electrode having a noble metal in non-compact form, wherein the working electrode at least partially submerged in electrolyte;

diffusing the chloramine through the membrane into the working electrode;

measuring a current between the working electrode and a reference electrode disposed in the electrolyte; and

determining the chloramine from the measured current.

2. The method of claim 1, wherein the sensor comprises a sensor body positionable within the solution containing chloramine.

3. The method of claim 2, wherein the non-compact form is a gas diffusion electrode.

4. The method of claim 3, wherein the gas diffusion electrode is loaded with the noble metal in a powdered form.

5. The method of claim 4, wherein the noble metal is platinum.

6. The method of claim 5, wherein gas diffusion electrode includes carbon cloth and wherein the platinum is loaded onto the gas diffusion electrode at approximately 80% on the carbon cloth.

7. The method of claim 3, wherein the gas diffusion electrode includes a carbon cloth.

8. The method of claim 2, wherein the non-compact form of the working electrode is a mesh.

9. The method of claim 8, wherein the working electrode is constructed from gold mesh.

10. The method of claim 2, wherein the pH of the electrolyte is within the range of about 9.0 to about 11.0.

11. The method of claim 2, wherein the sensor has an output that is linear in concentrations of chloramine ranging from about 0 ppm to about 8.0 ppm.

12. The method of claim 2, wherein the reference electrode is constructed from silver.

13. The method of claim 2, wherein the electrolyte includes potassium chloride.

14. The method of claim 13, wherein the potassium chloride is present at a concentration of about 0.1 M.

15. The method of claim 2, and further comprising:

coupling an analysis device to the reference electrode and the working electrode, the analysis device adapted to provide a sufficient working potential and to measure a current flowing between the reference electrode and working electrode and provide an indication of chloramine concentration in the specimen based on the current.

16. The method of claim 15, and further comprising transmitting data indicative of the concentration with the analysis device.