Chemical testing systems

• US 4,181,500 A
• Filed: 01/22/1976
• Issued: 01/01/1980
• Est. Priority Date: 01/22/1976
• Status: Expired due to Term

• Current Assignee: Burroughs Wellcome and Co.
• Original Assignee: Burroughs Wellcome and Co.
• Inventors: Cowsar, Donald R., Harrison, Steadman D. Jr.
• Primary Examiner(s): Marcus, Michael S.
• Application Number:
  US05/651,424
• Time in Patent Office: 1,440 Days
• Field of Search: 23/253 TP, 23/230 R, 23/230 B, 252/408, 422/55, 422/56, 422/57, 422/58
• US Class Current: 436/99
• CPC Class Codes: G01N 33/525 Multi-layer analytical elements
• CPC Class Codes: Y10T 436/148888 Uric acid

Abstract

A test system and method is described for determining if a material (e.g. uric acid) oxidizable by iodine is present in an aqueous fluid in an amount equal to or greater than a predetermined amount and which includes a dry solid iodine indicator and a dry solid means for rapidly generating iodine in situ upon activation thereof to color said indicator, said system preferably being in test strip form.

As another feature of this invention there is provided a solid source of basic anions capable upon activation of neutralizing excess protons remaining after generating iodine in situ to permit rapid oxidation of the material oxidizable by said iodine without substantially interfering with the rapid generation of said iodine.

Claims

1. A test strip for determining if a material oxidizable by iodine is present in an aqueous solution in an amount greater than a predetermined amount, comprising support material having impregnated therethrough at least a portion of water activatable generator means in solid dry form for generating an effective amount of iodine in situ and color indicator means for indicating the presence of iodine, said means for generating iodine comprises an iodide salt, an iodate salt and an acid, and a source of basic anions in dry solid form for neutralizing protons formed during generation of said iodine.

2. The test strip of claim 1 including means defining a well for at least a portion of said generator, indicator and source means.

3. The test strip of claim 1 in which the indicator means is starch.

4. The test strip of claim 1 in which the system includes means to separate red blood cells from said indicator.

5. The test strip of claim 1 wherein said indicator, said iodide salt and said iodate salt are impregnated in an absorbent material.

6. The test strip of claim 5 in which said source of basic anions is impregnated in said absorbent material.

7. The test strip of claim 6 in which said acid is impregnated in a porous material which is in physical contact with said absorbent material whereby said aqueous solution passing through the acid impregnated porous material will cause the flow of acid into said absorbent material to initiate the generation of iodine in situ.

8. A test strip comprising a first inert layer having means for the receipt of fluid, a porous layer positioned under said means and supporting acid in solid dry form, an absorbent layer positioned below said porous layer and in intimate contact therewith, said absorbent layer impregnated with a source of basic anions, a color indicator, an iodate salt and an iodide salt, said acid, iodate salt and iodide salt being present in an amount to generate an effective amount of iodine.

9. The test strip of claim 8 in which said inert layer is clear.

10. The test strip of claim 8 in which the indicator means is starch.

11. The test strip of claim 8 in which said first inert layer includes a filter to separate red blood cells from said indicator.

12. The test strip of claim 8 in which the iodine is first substantially entirely generable prior to said basic source providing substantial amounts of basic anions.

13. A test strip comprising a porous first layer supporting acid in solid particulate dry form, a second layer coupled to said porous layer, said second layer supporting an acid activatable iodine source in solid particulate dry form, a source of basic anions in solid particulate dry form and an iodine indicator in solid particulate dry form, said acid and said acid activatable source of iodine being present in an amount to generate an effective amount of iodine and said source of basic anions being present in an amount sufficient to reverse the pH from acid to alkaline after generation of iodine.

14. The test strip of claim 13 in which said second layer is of absorbent material.

15. The test strip of claim 13 in which the acid activatable iodine source comprises an iodide salt and an iodate salt.

16. The test strip of claim 15 in which said acid is impregnated in said first layer and in which said second layer is impregnated with said source of basic anions, said iodine indicator, said iodide salt and said iodate salt.

17. The test strip of claim 13 in which said iodine source comprises a compound containing iodine in a strong covalent bond.

18. A test strip comprising filter means for separating red blood cells from blood, a porous layer positioned under said filter means and supporting acid in solid dry form, an absorbent layer positioned below said porous layer and in intimate contact therewith, said absorbent layer supporting a source of basic anions, a color indicator, an iodate salt and an iodide salt, all in solid dry form, said acid, iodate salt and iodide salt being present in an amount to generate an effective amount of iodine, and an insert layer coupled to said absorbent layer.

19. The test strip of claim 18 in which said inert layer is peelable.

20. The test strip of claim 18 in which said inert layer is clear.

21. The method of determining if the level of a material oxidizable by iodine in an aqueous test fluid is greater than a predetermined amount which comprises applying said test fluid to a test strip comprising an acid, an acid activatable source of iodine comprising an iodide salt and an iodate salt, a source of basic anions in an amount sufficient to reverse the pH from acid to alkaline after the generation of iodine and iodine indicator all dry solid form, and allowing the fluid to react therewith and thereafter observing the color of the indicator.

22. The method of claim 21 in which the iodine indicator is starch.

23. The method of claim 21 in which the material oxidizable by iodine is uric acid.