Method and apparatus for trace metal testing

• US 5,292,423 A
• Filed: 04/07/1992
• Issued: 03/08/1994
• Est. Priority Date: 04/09/1991
• Status: Expired due to Term

• Current Assignee: Ecossensors Limited
• Original Assignee: New Mexico State University Technology Transfer Corporation
• Inventors: Wang, Joseph
• Primary Examiner(s): Niebling, John
• Assistant Examiner(s): Bell, Bruce F.
• Application Number:
  US07/864,942
• Time in Patent Office: 700 Days
• Field of Search: 204/413, 204/434, 204/412
• US Class Current: 204/434
• CPC Class Codes: G01N 27/42 Measuring deposition or liberation of materials from an electrolyte; Coulometry, i.e. measuring coulomb-equivalent of material in an electrolyte
• CPC Class Codes: G01N 33/48714 for determining substances foreign to the organism, e.g. drugs or heavy metals drugs by chemical analysis G01N33/94
• CPC Class Codes: G01N 35/1095 for supplying the samples to flow-through analysers for a specific analyser see relevant groups, e.g. under G01N15/00, G01N21/00, G01N27/00, G01N30/00, H01J49/00

Abstract

Disclosed are a method and apparatus for trace metal testing using mercury-coated screen printed electrodes. Both voltammetric and potentiometric stripping analysis are used. Sample solutions were tested employing both stirring and non-stirring, as well as aeration and deaeration procedures. Microliter samples suitable for slide mounting were also employed.

Claims

1. A method of analyzing trace metals comprising the steps of:

a) providing a plurality of electrodes screen-printed on a substrate;

b) electrolytically depositing a metal film upon at least one of the plurality of screen-printed electrodes; and

c) analyzing a sample for heavy metal content by using electrochemical stripping analysis with the plurality of electrodes.

2. The method of claim 1 wherein the step of providing a plurality of screen-printed electrodes further comprises the step of providing at least one reference electrode.

3. The method of claim 2 wherein the step of providing at least one reference electrode further comprises the step of providing a screen-printed Ag/AgCl electrode.

4. The method of claim 1 wherein the step of providing a plurality of screen-printed electrodes further comprises the step of providing at least one screen-printed carbon electrode.

5. The method of claim 1 wherein the step of analyzing a sample for heavy metal content comprises the step of performing anodic stripping voltammetry on the sample.

6. The method of claim 1 wherein the step of analyzing a sample for heavy metal content comprises the step of performing potentiometric stripping analysis on the sample.

7. The method of claim 1 further comprising the step of preconcentrating the heavy metal upon an electrode.

8. The method of claim 1 wherein the step of analyzing a sample for heavy metal content further comprises the step of deaerating the sample.

9. The method of claim 1 wherein the step of analyzing a sample for heavy metal content further comprises the step of stirring the sample.

10. The method of claim 1 wherein the step of analyzing a sample for heavy metal content further comprises the step of analyzing a microliter sample solution.

11. The method of claim 10 wherein the step of analyzing a microliter sample solution comprises the step of analyzing a sample of body fluid.

12. The method of claim 10 wherein the step of analyzing a microliter sample solution comprises the step of analyzing drinking water.

25. The method of claim 1 wherein the step of electrolytically depositing a metal film comprises the step of electrolytically depositing mercury.

26. The method of claim 1 wherein the step of electrolytically depositing a metal film comprises the step of electrolytically depositing a member selected from the group consisting of platinum, silver, and gold.

29. The method of claim 7 wherein the step of preconcentrating the heavy metal comprises the step of causing adsorptive accumulation of at least one heavy metal upon said metal film.

31. The method of claim 11 wherein the step of analyzing a sample of body fluid comprises the step of analyzing a member selected from the group consisting of blood and urine.

33. The method of claim 1 wherein the step of analyzing a sample for heavy metal content further comprises the step of anaylzing a sample of liquid food.

35. The method of claim 1 wherein the step of providing a plurality of electrodes further comprises providing a plastic substrate.

13. Apparatus for heavy metal trace testing comprising:

means for providing a plurality of electrodes screen-printed on a substrate;

means for electrolytically depositing a metal film upon at least one of said plurality of screen-printed electrodes; and

means for analyzing a sample for heavy metal content by electrochemical stripping analysis with said plurality of electrodes.

14. The apparatus of claim 13 wherein said means for providing a plurality of screen-printed electrodes further comprises means for providing at least one reference electrode.

15. The apparatus of claim 14 wherein said means for providing at least one reference electrode further comprises means for providing a screen-printed Ag/AgCl electrode.

16. The apparatus of claim 13 wherein said means for providing a plurality of screen-printed electrodes further comprises means for providing at least one screen-printed carbon electrode.

17. The apparatus of claim 13 wherein said means for analyzing a sample for heavy metal content comprises means for performing anodic stripping voltammetry on the sample.

18. The apparatus of claim 13 wherein said means for analyzing a sample for heavy metal content comprises means for performing potentiometric stripping analysis on the sample.

19. The apparatus of claim 13 further comprising means for preconcentrating said heavy metal upon an electrode.

20. The apparatus of claim 13 wherein said means for analyzing a sample for heavy metal content further comprises means for deaerating said sample.

21. The apparatus of claim 13 wherein said means for analyzing a sample for heavy metal content further comprises means for stirring said sample.

22. The apparatus of claim 13 wherein said means for analyzing a sample for heavy metal content further comprises means for analyzing a microliter sample solution.

23. The apparatus of claim 22 wherein said microliter sample solution comprises a sample of body fluid.

24. The apparatus of claim 22 wherein said microliter sample solution comprises drinking water.

27. The apparatus of claim 13 wherein said metal film comprises mercury.

28. The apparatus of claim 13 wherein said metal film comprises a member selected from the group consisting of platinum, silver, and gold.

30. The apparatus of claim 19 wherein said means for preconcentrating said heavy metal comprises means for causing adsorptive accumulation of at least one heavy metal upon said metal film.

32. The apparatus of claim 23 wherein said sample of body fluid comprises a member selected from the group consisting of blood and urine.

34. The apparatus of claim 13 wherein said means for analyzing a sample for heavy metal content further comprises means for analyzing a sample of liquid food.

36. The apparatus of claim 13 wherein said substrate comprises plastic.

37. A method of analyzing trace metals comprising the steps of:

a) providing a plurality of electrodes upon a plastic substrate;

b) electrolytically depositing a metal film upon at least one of the plurality of electrodes; and

c) analyzing a sample for heavy metal content by using electrochemical stripping analysis with the plurality of electrodes.

38. The method of claim 37 wherein the step of analyzing a sample for heavy metal content comprises the step of performing anodic stripping voltammetery on the sample.

39. The method of claim 37 wherein the step of analyzing a sample for heavy metal content comprises the step of performing potentiometric stripping analysis on the sample.

40. The method of claim 37 wherein the step of analyzing a sample comprises the step of analyzing a sample of body fluid.

41. The method of claim 40 wherein the step of analyzing a sample of body fluid comprises the step of analyzing a member selected from the group consisting of blood and urine.

42. Apparatus for heavy metal trace testing comprising:

a) means for providing a plurality of electrodes upon a plastic substrate;

b) means for electrolytically depositing a metal film upon at least one of said plurality of electrodes; and

c) means for analyzing a sample for heavy metal content by electrochemical stripping analysis with the plurality of electrodes.

43. The apparatus of claim 42 wherein said means for analyzing a sample for heavy metal content comprises means for performing anodic stripping voltammetery on said sample.

44. The apparatus of claim 42 wherein said means for analyzing a sample for heavy metal content comprises means for performing potentiometric stripping analysis on said sample.

45. The apparatus of claim 42 wherein said means for analyzing said sample comprises means for analyzing a sample of body fluid.

46. The apparatus of claim 45 wherein said means for analyzing a sample of body fluid comprises means for analyzing a member selected from the group consisting of blood and urine.