Ion-selective electrode

• US 4,214,968 A
• Filed: 04/05/1978
• Issued: 07/29/1980
• Est. Priority Date: 04/05/1978
• Status: Expired due to Term

• Current Assignee: Clinical Diagnostic Systems Inc.
• Original Assignee: Eastman Kodak Company
• Inventors: Daniel, Daniel S., Chang, Jack C., Battaglia, Charles J.
• Primary Examiner(s): Kaplan, G. L.
• Application Number:
  US05/893,656
• Time in Patent Office: 846 Days
• Field of Search: 204/195 M, 204/195 F, 204/195 L, 204/195 G
• US Class Current: 204/418
• CPC Class Codes: G01N 27/3335 the membrane containing at least one organic component G01N27/3271 takes precedence; aspects concerning the enzyme reagent in enzyme electrodes C12Q1/001

Abstract

A dry-operative ion-selective electrode comprising:

(a) a dried, internal reference electrode, and

(b) in contact with the reference electrode, a hydrophobic ion-selective membrane.

The ion-selective electrode described herein requires no preconditioning prior to use in an ion-sensing operation.

The reference electrode may comprise either a metal/metal salt reference half-cell or multiple-layer redox couple reference electrode. The hydrophobic membrane includes a binder having dispersed therein a solution of an ion carrier dissolved in a suitable carrier solvent.

A preferred embodiment provides for electrodes of the type described wherein the hydrophobic membrane layer is of a predetermined, uniform thickness in regions thereof intended for contact with a sample for analysis. When necessary or desirable, the electrode includes a support. A novel technique for making measurements of ion concentration by reading electrode potential prior to equilibration of the electrode is also described.

Claims

1. A dry-operative ion-selective electrode comprising:

(a) a dried internal reference electrode comprising the dried residue of a solution of a salt and a hydrophilic polymeric binder in a solvent for the polymer and the salt; and

(b) in contact with said reference electrode a hydrophobic ion-selective membrane of predetermined uniform thickness in regions thereof intended for contact with a sample for analysis, said membrane comprising a hydrophobic binder having distributed therein an ion carrier dissolved in a carrier solvent.

2. The electrode of claim 1 further including a support, said reference electrode being disposed between said support and said membrane.

3. The electrode of claim 2 wherein said support comprises a polymeric material.

4. The electrode of claim 3 wherein said polymeric material is a cellulose acetate, poly(ethylene terephthalate), a polycarbonate or a polystyrene.

5. The electrode of claim 1 wherein said hydrophobic binder comprises a polymer selected from the group consisting of polyvinyl chloride, a polyurethane, carboxylated polyvinyl chloride, polymethine, a copolymer of poly(vinyl chloride) and poly(vinyl acetate), a silicone elastomer, a polycarbonate, a cellulose ester, a copolymer of polyvinyl chloride and polyvinylidene chloride, polyvinyl butyral, polyvinyl formal and polyvinyl alcohol.

6. The electrode of claim 1 wherein said ion carrier is selected from the group consisting of valinomycin, a cyclic polyether, tetraphenyl borate, a tetralactone, a macrolide acetone, a cyclic polypeptide, a quarternary ammonium salt, monensin, esters of monensin, A23187 and compounds of the formula ##STR6## and

8. The electrode of claim 1 wherein said ion carrier solvent is selected from the group consisting of aromatic ethers, aliphatic ethers, phthalates, phosphates, phosphonates, adipates and sebacates.

9. The electrode of claim 1 wherein the weight ratio of said carrier solvent to said hydrophobic binder ranges from about 1:

1 to about 5;

2. PG,80

10. The electrode of claim 1 wherein the thickness of said membrane varies at most about 20% in regions intended for contact with a sample for analysis.

12. The electrode of claim 10 wherein said hydrophilic binder comprises a member selected from the group consisting of polyvinyl alcohol, gelatin, agarose, polyacrylamide, polyvinyl pyrrolidone, polyhydroxyethyl methacrylate, poly(hydroxyethyl acrylate) and polyacrylic acid.

13. The electrode of claim 10 wherein said layer of insoluble salt comprises a halide salt of said metal.

14. The electrode of claim 10 further including a support which comprises an electrically insulating polymeric film, said conducting metal layer comprises silver, said layer of insoluble salt comprises a halide salt of silver, and said hydrophobic membrane comprises poly(vinyl chloride) and ion carrier selected from the group consisting of valinomycin and tetraphenyl boron and said carrier solvent is selected from the group consisting of cyclic ethers, sebacates, phthalates, adepates, phosphonates and phosphates.

16. The electrode of claim 14 wherein said conducting layer comprises a conductor selected from the group consisting of carbon, platinum, and nickel.

17. The electrode of claim 14 wherein said conductor is carbon.

18. The electrode of claim 14 wherein said conducting layer comprises a particulate conductor and a binder.

19. The electrode of claim 17 wherein said particulate conductor is particulate carbon.

20. The electrode of claim 14 wherein said hydrophilic polymer is selected from the group consisting of gelatin, polyvinyl alcohol, polyacrylic acid and poly(vinyl pyrrolidone).

21. The electrode of claim 14 wherein said redox couple comprises a material, a portion of which is in a first oxidation state and a portion of which is in a second oxidation state.

22. The electrode of claim 20 wherein the molar ratio of said portions is about 1.

23. The electrode of claim 21 wherein said redox couple comprises iron or cobalt complexes.

24. The electrode of claim 22 wherein said iron or cobalt complexes comprise, respectively, ferri/ferrocyanide ions and cobaltic/cobaltous terpyridyl ions.

25. The electrode of claim 14 wherein said hydrophobic binder comprises a polymer selected from the group consisting of polyvinyl chloride, polymethine, copolymers of poly(vinyl chloride) and poly(vinyl acetate), silicone elastomers, polycarbonates and cellulose esters.

26. The electrode of claim 14 wherein said ion carrier is selected from the group consisting of valinomycin, cyclid polyether, tetraphenyl borate, tetralactones, macrolide acetones, cyclic polypeptides, monensin, esters of monensin, A23187 and compounds of the formula ##STR9## and compounds of the following structural formulas ##STR10## wherein:

(a) R=CH₂ CON(CH₂ CH₂ CH₃)₂ ##STR11##

27. The electrode of claim 14 wherein said ion carrier solvent is selected from the group consisting of aromatic and aliphatic ethers, phosphonates and phosphates, and mixtures thereof, phthalates and sebacates.

28. The electrode of claim 14 wherein the weight ratio of said carrier solvent to said binder ranges from about 1:

1 to about 5;

2.

30. The electrode of claim 28 wherein the thickness of said dry electrolyte layer is about 0.2 mil.

7. Compounds of the following structural formulas ##STR7## wherein:

(a) R=CH₂ CON(CH₂ CH₂ CH₃)₂ ##STR8##

11. A dry-operative ion-selective electrode comprising:

(a) a dried internal reference electrode comprising a metal/metal salt reference electrode, said reference electrode comprising a conducting layer of a metal in contact with a layer of an insoluble salt of said metal, and a dried electrolyte layer comprising the dried residue of a water soluble salt having as an anion the anion of said metal salt layer and a hydrophilic polymeric binder in a solvent for the polymer and salt; and

(b) in contact with the reference electrode a hydrophobic ion-selective membrane or predetermined uniform thickness in regions intended for contact with a sample for analysis said membrane comprising an ion carrier and a carrier solvent distributed in a binder.

15. A dry-operative ion-selective electrode comprising:

(a) a dried redox internal reference electrode comprising the dried residue of a redox couple, a hydrophilic binder and a solvent over an electrically conducting layer; and

(b) in contact with the reference electrode a hydrophobic, ion-selective membrane of predetermined uniform thickness in a region thereof intended for contact with a sample for analysis, said membrane comprising a hydrophobic binder having distributed therein an ion carrier and a carrier solvent.

29. A planar, dry-operative ion-selective electrode comprising:

(a) a dried metal/metal salt internal reference electrode comprising

(1) a conducting layer of a metal,

(2) a layer of an insoluble salt of the metal of the conducting layer, and

(3) a dried electrolyte solution layer comprising the dried residue of a solution of a salt and a hydrophilic polymeric binder in a solvent for the polymer and the salt, said layer having a thickness of from about 0.1 to about 0.5 mil and comprising a hydrophilic binder having dissolved therein from about 1.40 to about 2.5 g/m² of a water soluble salt having as anion the anion of said metal salt layer, said conducting layer in contact with said layer of insoluble salt, and

(b) in contact with said electrolyte layer a hydrophobic ion-selective membrane having a predetermined uniform thickness of less than about 5 mil and comprising at least about 0.1 g/m² of an ion carrier dissolved in an ion carrier solvent dispersed in a binder the weight ratio of said carrier solvent to said binder ranging from about 1;

1 to about 5;

2.

31. The electrode of claim 29 wherein said membrane comprises from about 0.3 to about 0.5 g/m² of said ion carrier and has a thickness of about 1 mil.