Filter for gas sensor

• US 7,491,547 B1
• Filed: 11/02/2004
• Issued: 02/17/2009
• Est. Priority Date: 11/07/2003
• Status: Active Grant

• Current Assignee: ChemDAQ, Inc.
• Original Assignee: ChemDAQ, Inc.
• Inventors: Warburton, Piers Richard
• Primary Examiner(s): Drodge; Joseph W
• Application Number:
  US10/979,038
• Time in Patent Office: 1,568 Days
• Field of Search: 422/58, 422 83- 86, 422/101, 436/127, 436/142, 436/177, 204/431, 204/432, 73/232, 73/317, 555/22, 555/24, 555/25, 952/73, 952/85
• US Class Current: 436/127
• CPC Class Codes: G01N 33/0014 by eliminating a gas by a chemical reaction G01N33/0013; a chemical reaction taking place or a gas being eliminated in one or more analysing channels G01N33/0024
• CPC Class Codes: Y10T 436/20 Oxygen containing
• CPC Class Codes: Y10T 436/216 Unsaturated [e.g., ethylene, diene, etc.]
• CPC Class Codes: Y10T 436/25375 Liberation or purification of sample or separation of material from a sample [e.g., filtering, centrifuging, etc.]

Abstract

A filter that allows specific detection of ethylene oxide by a non-specific electrochemical gas sensor through the removal of potential interferent gases, such as alcohols, and carbon monoxide. The filter contains an oxidizing agent that will oxidize the interferent gas but not ethylene oxide or alternatively a polymeric material that allows selective hydrogen bonds to the interferent gas but not ethylene oxide. This filter is intended for use with ambient air gas monitors, such as those employed to enhance work-place safety.

Claims

1. A method for the detection of ethylene oxide comprising:

passing a gaseous sample through a filter,

wherein the filter comprises an oxidizing agent, and

wherein the filter is capable of oxidizing and reducing passage of an easily oxidizable volatile compound, and is substantially non-reactive with ethylene oxide; and

allowing passage of ethylene oxide through the filter medium;

passing the filtered gaseous medium to an ethylene oxide sensor; and

monitoring the presence of ethylene oxide in the filtered gaseous medium.

2. The method of claim 1, wherein the oxidizing agent is selected from the group consisting of manganese dioxide, lead dioxide, silver (II) oxide and an oxide of vanadium.

3. The method of claim 1, wherein the sensor and the filter are disposed in a single housing.

4. The method of claim 1, wherein the sensor is disposed in a housing separate from the filter.

5. The method of claim 1, wherein the sensor is an electrochemical sensor.

6. The method of claim 1, wherein the easily oxidizable volatile compound comprises ethanol, isopropanol or carbon monoxide.

7. A method for the detection of ethylene oxide comprising:

passing a gaseous medium through a filter, wherein the filter comprises silver (II) oxide,

wherein said filter is capable of oxidizing and reducing passage of an easily oxidizable volatile compound, and is substantially non-reactive with ethylene oxide,

passing the filtered gaseous medium to an ethylene oxide sensor, and

monitoring the presence of ethylene oxide in the filtered gaseous medium.

8. The method of claim 7, wherein the sensor and the filter are disposed in a single housing.

9. The method of claim 7, wherein the sensor is disposed in a housing separate from the filter.

10. The method of claim 7, wherein the sensor is an electrochemical sensor.

11. The method of claim 7, wherein the filter is capable of removing one or more easily oxidizable volatile-compounds selected from the group consisting of ethanol, isopropanol, and carbon monoxide from the gaseous medium, thus preventing the easily oxidizable compound from reaching the ethylene oxide sensor.

12. The method of claim 7, wherein the passing occurs by diffusion.

13. A method for the detection of ethylene oxide comprising:

passing a gaseous medium through a filter,

wherein the filter comprises a polymeric organic compound,

wherein the polymeric organic compound comprises a functional group selected from a group capable of passive hydrogen bonding, a basic group, and a strongly acidic group, and

wherein the filter is capable of reducing passage of an alcohol and allowing passage of ethylene oxide;

passing the filtered gaseous medium to an ethylene oxide sensor, and

monitoring the presence of ethylene oxide in the filtered gaseous medium.

14. The method of claim 13, wherein the polymeric organic compound comprises a pyridine, a quaternary ammonium salt, an amine, an amine salt, a sulfonic acid or a mixture thereof.

15. The method of claim 13, wherein the sensor and the filter are disposed in a single housing.

16. The method of claim 13, wherein the sensor is disposed in a housing separate from the filter.

17. The method of claim 13, wherein the sensor is an electrochemical sensor.

18. The method of claim 13, wherein the alcohol is ethanol or isopropanol.