Ion test means having a hydrophilic carrier matrix

• US 4,649,123 A
• Filed: 07/02/1985
• Issued: 03/10/1987
• Est. Priority Date: 05/12/1983
• Status: Expired due to Term

• Current Assignee: Miles Laboratories, Inc. (Bayer AG)
• Original Assignee: Miles Laboratories, Inc. (Bayer AG)
• Inventors: Charlton, Steven C., Hemmes, Paul, Lau, Arthur L. Y.
• Primary Examiner(s): Turk, Arnold
• Application Number:
  US06/751,257
• Time in Patent Office: 616 Days
• Field of Search: 422/56, 422/57, 422/58, 436/73, 436/74, 436/79, 436/172, 436/175, 436/169, 436/170, 427/2
• US Class Current: 436/79
• CPC Class Codes: G01N 31/22 using chemical indicators G01N31/02 takes precedence
• CPC Class Codes: G01N 31/221 for investigating pH value
• CPC Class Codes: G01N 33/52 Use of compounds or compositions for colorimetric, spectrophotometric or fluorometric investigation, e.g. use of reagent paper and including single- and multilayer analytical elements immunological elements G01N33/54386; involving labelled immunochemicals G01N33/58; for haemoglobin or occult blood G01N33/72
• CPC Class Codes: G01N 33/84 involving inorganic compounds or pH
• CPC Class Codes: Y10T 436/25125 Digestion or removing interfering materials

Abstract

A test means for determining the presence of an ion in an aqueous test sample, a method for preparing it and a method for using it. The test means comprises a hydrophilic carrier matrix incorporated with finely divided globules of a hydrophobic vehicle. The hydrophobic vehicle contains an ionophore capable of forming a complex with the ion and a reporter substance capable of interacting with the complex of ionophore and ion to produce a detectable response. The test means of this invention is useful for clinical determinations of serum potassium. The test means forms the reagent layer in a multilayer format which is particularly suited to whole blood electrolyte determinations and does not require washing or wiping before use.

Claims

1. A test means for determining the presence of an ion in an aqueous test sample, the test means comprising a hydrophilic carrier matrix incorporated with finely divided globules of a hydrophobic vehicle, said vehicle containing

an ionophore capable of forming a complex with a specific ion to be determined, and

a reporter substance capable of interacting with the complex of the ionophore and the ion to produce a detectable response.

2. The test means of claim 1 which additionally includes a buffer incorporated in the hydrophilic carrier matrix.

3. The test means of claim 1 which additionally includes an interferant removal substance which substance is capable of removing interfering ions.

4. The test means of claim 1 in which the test sample is whole blood and in which the hydrophilic carrier is additionally incorporated with sufficient sodium chloride to impart hematocrit independence to the ion determination.

5. The test means of claim 1 in which the hydrophilic carrier matrix is additionally incorporated with light scattering centers.

6. The test means of claim 5 in which the light scattering centers are composed of titantium dioxide particles.

7. The test means of claim 1 in which the hydrophilic carrier matrix is a hydrophilic polymer.

8. The test means of claim 7 in which the hydrophilic polymer is gelatin.

9. The test means of claim 7 in which the hydrophilic carrier matrix additionally comprises a porous material capable of supporting the integrity of the finely divided globules.

10. The test means of claim 9 in which the porous material is paper.

11. The test means of claim 1 in which the specific ion to be determined is a cation and the reporter is a neutral compound having a dissociable proton, which proton is capable of dissociating upon interaction of the reporter with the complex of the ionophore and the cation to produce a detectable response.

12. The test means of claim 11 in which the reporter substance is one capable of producing the appearance of, or change in, fluorescence in the presence of the complex of the ionophore and cation.

13. The test means of claim 12 in which the reporter substance is fluorescein or a derivative thereof.

14. The test means of claim 11 in which the reporter is one capable of producing the appearance of, or change in, color in the presence of the complex of the ionophore and the cation.

15. The test means of claim 14 in which the reporter substance is a compound having the structure ##STR14## in which X is a halogen or pseudohalogen;

in which each R, same or different, is a 2-, 3-, 5-, or 6-position substituent, or multiple substituents thereof selected from a lower alkyl, intermediate alkyl, aryl or a fused ring at the 2,3-or 5,6-position; and

n is 0 to 4.

16. The test means of claim 14 in which the reporter substance is a compound having the structure ##STR15## in which R'"'"' is H or lower alkyl, R* is H or intermediate alkyl and X is a halogen or pseudohalogen.

17. The test means of claim 16 in which R'"'"' is methyl and R* is n-decyl.

18. A method for preparing a test means for determining the presence of an ion in an aqueous test sample, the method comprising the steps of:

(a) forming a first mixture of water and a hydrophilic polymer;

(b) forming a second mixture of a hydrophobic vehicle, an ionophore capable of forming a complex with a specific ion to be determined and a reporter substance capable of interacting with the complex of the ionophore and the ion to produce a detectable response,

(c) combining the first and second mixtures to produce a stable emulsion of finely divided globules of the second mixture in the first mixture,

(d) coating the emulsion onto a porous material capable of supporting the integrity of the finely divided globules; and

(e) evaporating the water from the emulsion to produce a hydrophilic carrier matrix incorporated with finely divided globules of the second mixture.

19. The method of claim 18 in which the porous material is paper.

20. A method for preparing a test device for determining the presence of an ion in an aqueous test sample, the method comprising the steps of:

(a) forming a first mixture of water and a hydrophilic polymer;

(b) forming a second mixture of a hydrophobic vehicle, an ionophore capable of forming a complex with a specific ion to be determined and a reporter substance capable of interacting with the complex of the ionophore and the ion to produce a detectable response;

(c) combining the first and second mixtures to produce a stable emulsion of finely divided globules of the second mixture in the first mixture,

(d) coating the emulsion onto a support member having an upper, substantially flat face; and

(e) evaporating the water from the emulsion to produce a hydrophilic carrier matrix incorporated with finely divided globules of the second mixture, the emulsion being thereby affixed to the flat face of the support member.

21. A multilayer test device for determining the presence of an ion in an aqueous test sample, comprising:

(a) a reagent layer including a hydrophilic carrier matrix incorporated with finely divided globules of a hydrophobic vehicle, the globules containing

(i) an ionophore capable of forming a complex with a specific ion to be determined, and

(ii) a reporter substance capable of interacting with the complex of the ionophore and the ion to produce a detectable response; and

(b) a reflecting layer disposed on top of the reagent layer and in laminar relationship thereto, the reflecting layer including one or more materials which act as a background in order to facilitate the determination of a detectable response in the reagent layer.

22. The multilayer test device of claim 21, wherein the background material of the reflecting layer is titanium dioxide.

23. The multilayer test device of claim 21 additionally comprising a transparent support member disposed on the reagent layer on the side opposed to the reflecting layer.

24. The multilayer test device of claim 21, in which the reflecting layer additionally includes a hydrophilic polymer.

25. The multilayer test device of claim 24, in which the reflecting layer additionally includes a buffer.

26. The multilayer test device of claim 24 in which the sample is whole blood and which additionally includes sufficient sodium chloride, incorporated in either the reagent layer, the reflecting layer or both, to impart hematocrit independence to the ion determination.

27. The multilayer test device of claim 21 additionally comprising an opacifying layer in laminar relationship to the reflecting layer and disposed on top of the reflecting layer, the opacifying layer containing particles for imparting an opaque appearance to the opacifying layer.

28. A multilayer test device of claim 27, in which the opacifying particles are particles of carbon black.

29. The multilayer test device of claim 28 in which the sample is whole blood and which additionally includes sufficient sodium chloride incorporated in any or each of the layers to impart hematocrit independence to the ion determination.

30. The multilayer test device of claim 28, in which the opacifying layer additionally comprises a hydrophilic polymer.

31. The multilayer test device of claim 30 in which the hydrophilic polymer is gelatin.

32. A multilayer test device of claim 30, in which the opacifying layer additionally comprises a buffer.

33. A process for the determination of unbound calcium in an aqueous fluid sample, comprising the steps of:

(a) contacting the multilayer test device of claim 21 with an aqueous fluid sample; and

(b) determining the response in the reagent layer.