Chemically integrating dosimeter and gas analysis methods

• US 4,267,023 A
• Filed: 11/21/1979
• Issued: 05/12/1981
• Est. Priority Date: 10/17/1977
• Status: Expired due to Term

• Current Assignee: Continental Bank NA (Bank of America Corp.)
• Original Assignee: Orion Research, Inc. (Thermo Fisher Scientific Incorporated)
• Inventors: Frant, Martin S., Soderberg, Jon
• Primary Examiner(s): Kaplan, G. L.
• Application Number:
  US06/096,572
• Time in Patent Office: 538 Days
• Field of Search: 204/1 F, 204/1 H, 204/1 P, 204/195 P, 422/83, 422/88, 422/98, 23/232 R, 23/232 E, 73/23
• US Class Current: 205/783
• CPC Class Codes: G01N 27/4162 investigating the composition of gases, by the influence exerted on ionic conductivity in a liquid conductometry in general G01N27/06; amperometric gas sensors G01N27/404
• CPC Class Codes: Y10S 436/902 Dosimeter
• CPC Class Codes: Y10T 436/172307 Cyanide or isocyanide
• CPC Class Codes: Y10T 436/175383 Ammonia
• CPC Class Codes: Y10T 436/184 Only hydrogen sulfide
• CPC Class Codes: Y10T 436/186 Sulfur dioxide
• CPC Class Codes: Y10T 436/19 Halogen containing

Abstract

A chemically integrating dosimeter for measuring gases, composed of a dual membrane system and an internal electrolyte solution. The outer membrane is a gas permeation rate controlling membrane. The inner membrane is a microporous hydrophobic protective membrane interposed between the electrolyte solution and the outer membrane. The dosimeter makes accurate determinations of time integrated exposures to various gases in the atmosphere and can be conveniently used by workers in industrial environments over a wide range of field conditions.

Claims

1. Method for detecting hydrogen sulfide gas by chemical integration comprising the steps of:

providing a gas permeable, liquid impermeable outer membrane in conjunction with a liquid impermeable microporous hydrophobic inner membrane, the latter with a gas permeation rate substantially greater than that of the outer membrane;

placing an internal electrolyte solution containing silver ions in contact with the inner membrane;

allowing hydrogen sulfide gas to diffuse through the outer membrane, through the inner membrane, and into the internal electrolyte where the outer membrane is a gas permeation rate controlling membrane, and the inner membrane is a protective membrane;

reacting the internal electrolyte with hydrogen sulfide gas to completely absorb said gas and to alter the composition of the internal electrolyte; and

measuring the change in the concentration of silver ions in the electrolyte due to the entry of hydrogen sulfide gas into the internal electrolyte, whereby the concentration of the gas is determined.

2. The method of claim 1 wherein the internal electrolyte contains a silver ion concentration buffered with a silver complexing agent.

3. The method of claim 2 wherein the number of moles of Ag⁺ ion in the internal electrolyte is in the range between two and four times the number of moles of the highest level of H₂ S to be detected, said highest level to be four times the threshold limit value of 10 ppm.

4. The method of claim 2 wherein the internal electrolyte is 7×

10^-4 M AgNO₃.

5. The method of claim 2 wherein the silver complexing agent is Na₄ EDTA.

6. The method of claim 5 wherein the concentration of Na₄ EDTA is 1 M.

7. The method of claim 2, wherein the silver complexing agent is a solution in a concentration which maintains a free silver activity in the electrolyte between 10^-6 and 10^-17.

8. The method of claim 1 wherein the outer membrane is silicone polycarbonate copolymer.

9. The method of claim 1 wherein the inner membrane is microporous polytetrafluoroethylene.

10. The method of claim 1 wherein the outer membrane is silicone rubber.

11. The method of claim 1 wherein the inner membrane is microporous polyvinylchloride.

12. The method of claim 1 wherein the inner membrane is microporous polyvinylfluoride.

13. The method of claim 1 wherein the inner membrane is polypropylene.

14. The method of claim 1 wherein the inner membrane is microporous polyethylene.

15. A chemically integrating dosimeter for measuring hydrogen sulfide gas in the atmosphere comprising:

a structural base, open on one side, for housing a solution;

an internal electrolyte solution containing silver ions and a complexing agent, placed in the structural base so that upon absorption of H₂ S gas into the electrolyte a chemical reaction occurs within the electrolyte causing a change in silver ion concentration;

a gas permeable, liquid impermeable gas permeation rate-controlling outer membrane with a permeation rate for H₂ S gas substantially lower than the diffusion rate of H₂ S gas in air, placed to cover the opening in the structural base;

a microporous hydrophobic inner membrane substantially more permeable to gases than the outer membrane, impermeable to the internal electrolyte, and interposed between the internal electrolyte solution and the outer membrane to prevent chemical attack on the outer membrane by the electrolyte and to prevent precipitate deposition from the electrolyte on the outer membrane;

means to seal the inner membrane and the outer membrane to the structural base; and

means to measure the change in concentration of silver ions Ag⁺ in the internal electrolyte.

16. The dosimeter of claim 15 wherein the outer membrane is silicone rubber.

17. The dosimeter of claim 15 wherein the outer membrane is silicone polycarbonate copolymer.

18. The dosimeter of claim 15 wherein the inner membrane is microporous polytetrafluoroethylene.

19. The dosimeter of claim 15 wherein the inner membrane is microporous polyvinylchloride.

20. The dosimeter of claim 15 wherein the inner membrane is microporous polyethylene.

21. The dosimeter of claim 15 wherein the inner membrane is microporous polyvinylfluoride.

22. The dosimeter of claim 15 wherein the inner membrane is microporous polypropylene.

23. The dosimeter of claim 15 wherein the internal electrolyte is silver nitrate.

24. The dosimeter of claim 15 wherein the silver complexing agent is a solution in a concentration which maintains a free silver activity in the electrolyte between 10^-6 and 10^-17.

25. The dosimeter of claim 15 wherein the silver complexing agent is Na₄ EDTA.

26. The dosimeter of claim 15 wherein the concentration of Na₄ EDTA is 1 M and the concentration of AgNO₃ is 7×

10^-4 M.

27. A chemically integrating dosimeter for measuring sulfur dioxide gas in the atmosphere comprising:

a structural base, open on one side, for housing a solution;

an internal electrolyte solution containing bromide ion and mercuric bromide placed in the structural base so that upon absorption of SO₂ gas into the electrolyte a chemical reaction occurs within the electrolyte causing a change in bromide ion concentration;

a gas permeable, liquid impermeable gas permeation rate-controlling outer membrane with a permeation rate for SO₂ gas substantially lower than the diffusion rate of SO₂ gas in air, placed to cover the opening in the structural base;

a microporous hydrophobic inner membrane substantially more permeable to gases than the outer membrane, impermeable to the internal electrolyte, and interposed between the internal electrolyte solution and the outer membrane to prevent chemical attack on the outer membrane by the electrolyte and to prevent precipitate deposition from the electrolyte on the outer membrane;

means to seal the inner membrane and the outer membrane to the structural base; and

means to measure the change in concentration of bromide ions Br^- in the internal electrolyte.

28. The dosimeter of claim 27 wherein the outer membrane is silicone rubber.

29. The dosimeter of claim 27 wherein the outer membrane is silicone polycarbonate copolymer.

30. The dosimeter of claim 27 wherein the inner membrane is microporous polytetrafluoroethylene.

31. The dosimeter of claim 27 wherein the inner membrane is microporous polyvinylchloride.

32. The dosimeter of claim 27 wherein the inner membrane is microporous polyethylene.

33. The dosimeter of claim 27 wherein the inner membrane is microporous polyvinylfluoride.

34. The dosimeter of claim 27 wherein the inner membrane is polypropylene.

35. The dosimeter of claim 27 wherein the internal electrolyte contains an acetic acid buffer.

36. The dosimeter of claim 27 wherein the internal electrolyte contains dimethylformamide.

37. The dosimeter of claim 27 wherein the internal electrolyte solution is 1×

10^-3 M mercuric bromide (HgBr₂) in 5×

10^-3 M acetic acid buffer (HOAc/NaOAc) at pH 4.8 with 1% dimethylformamide.

38. Method for detecting sulfur dioxide gas by chemical integration comprising the steps of:

providing a gas permeable, liquid impermeable outer membrane in conjunction with a liquid impermeable microporous hydrophobic inner membrane, the latter with a gas permeation rate substantially greater than that of the outer membrane;

placing an internal electrolyte solution containing bromide ion and mercuric bromide in contact with the inner membrane;

allowing sulfur dioxide gas to diffuse through the outer membrane, through the inner membrane, and into the internal electrolyte where the outer membrane is a gas permeation rate controlling membrane, and the inner membrane is a protective membrane;

reacting the internal electrolyte with sulfur dioxide gas to completely absorb said gas and to alter the composition of the internal electrolyte; and

measuring the change in the concentration of bromide ions in the electrolyte due to the entry of sulfur dioxide gas into the internal electrolyte, whereby the concentration of the gas is determined.

39. The method of claim 38 wherein the outer membrane is silicone rubber.

40. The method of claim 38 wherein the outer membrane is silicone polycarbonate copolymer.

41. The method of claim 38 wherein the inner membrane is microporous polytetrafluoroethylene.

42. The method of claim 38 wherein the inner membrane is microporous polyvinylchloride.

43. The method of claim 38 wherein the inner membrane is microporous polyvinylfluoride.

44. The method of claim 38 wherein the inner membrane is polypropylene.

45. The method of claim 38 wherein the internal electrolyte contains an acetic acid buffer.

46. The method of claim 38 wherein the internal electrolyte contains dimethylformamide.

47. The method of claim 38 wherein the internal electrolyte solution is 1×

10^-3 M mercuric bromide (HgBr₂) in 5×

10^-3 M acetic acid buffer (HOAc/NaOAc) at pH 4.8 with 1% dimethylformamide.