Voltammetric Ion Sensor

• US 7,799,204 B2
• Filed: 10/14/2005
• Issued: 09/21/2010
• Est. Priority Date: 10/15/2004
• Status: Expired due to Fees

• Current Assignee: Roche Diagnostics Operations Incorporated (Roche Holding AG)
• Original Assignee: Oxford Biosensors Limited
• Inventors: Zhang, Jie, Bond, Alan Maxwell, Harris, Alexander Richard
• Primary Examiner(s): Neckel; Alexa D
• Assistant Examiner(s): DIETERLE, JENNIFER M
• Application Number:
  US11/665,107
• Publication Number:
  US 20080011606A1
• Time in Patent Office: 1,803 Days
• Field of Search: 204/416, 204/405, 204/418, 204/433, 205/789, 205/787.5, 205/775, 205/792.5, 205/789.5
• US Class Current: 205/789
• 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
• CPC Class Codes: G01N 27/48 using polarography, i.e. measuring changes in current under a slowly-varying voltage

Abstract

A method and device for the quantitative determination of an ion in a fluid which comprises subjecting the fluid to voltammetry using a sensing electrode which comprises an electrically conducting support having a surface which is coated with a support matrix, the support matrix containing an electroactive species capable of being oxidised or reduced to form a charged species, and an ionophore.

Claims

1. A method for the quantitative determination of an ion in a fluid which comprises subjecting the fluid to voltammetry using a sensing electrode which comprises an electrically conducting support having a surface which is coated with a support matrix, the support matrix being a single layer containing (a) an electroactive species capable of being oxidised or reduced to form a charged species and (b) an ionophore, the support matrix having been obtained by drying a coating solution comprising the support matrix material, the electroactive species, and the ionophore;

wherein the ionophore and the electroactive species are two different chemicals.

2. A method according to claim 1, wherein the support matrix additionally contains a solvent capable of at least partially dissolving the electroactive species and the ionophore.

3. A method according to claim 2, wherein the solvent is a plasticizer.

4. A method according to claim 2, wherein the solvent is an ionic liquid.

5. A method according to claim 4, wherein the ionic liquid is selected from 1-ethyl-3-methylimidazolium bis(trifluoromethane sulfonyl)amide (emim.tfsa), N-butyl-methylpyrrolidinium bis(trifluoromethanesulfonyl)amide (P14.tfsa) and trihexyl(tetradecyl)-phosphonium tris(pentafluoroethyl)trifluorophosphate (aph4.cph12).

6. A method according to claim 1, wherein the support matrix additionally contains an ionic salt which is substantially insoluble in the fluid.

7. A method according to claim 6, wherein the ionic salt is selected from tetra(C₄-C₁₆ alkyl) ammonium salts.

8. A method according to claim 7, wherein the ionic salt is selected from tetrabutylammonium tetraphenylborate (TBATPB), tetrahexylammonium tetraphenylborate (THATPB), tetraheptyl ammonium perchlorate (THAClO₄) and tetraheptylammonium borate.

9. A method according to claim 1, wherein the electroactive species is hydrophobic.

10. A method according to claim 1, wherein the electroactive species undergoes reversible oxidation/reduction.

11. A method according to claim 1, wherein the electroactive species is selected from decamethylferrocene (DMFc), 1,1′

-dimethylferrocene (DiMFc) and 7,7,8,8-tetracyanoquinodimethane (TCNQ).

12. A method according to claim 1, wherein the sensing electrode has at least one dimension of less than 50 μ

m.

13. A method according to claim 1, wherein the support matrix comprises a dielectric ink.

14. A method according to claim 1, which comprises contacting the fluid with the measuring electrode and with one or more further electrodes, supplying a time varying potential to the sensing electrode and determining the potential at which the resulting current is at a maximum.

15. A method according to claim 1, wherein the fluid is a body fluid selected from blood, urine and saliva.

16. A method according to claim 1, wherein the concentration of the ion in the fluid is from 0.1 μ

mol dm<sup>−

3</sup> to 1.0 mol dm<sup>−

3</sup>, preferably from 0.1 mmol dm<sup>−

3</sup> to 1.0 mol dm<sup>−

3</sup>.

17. An electrode comprising an electrically conducting support having a surface which is coated with a support matrix, the support matrix being a single layer containing (a) an electroactive species capable of being oxidised or reduced to form a charged species and (b) an ionophore, the support matrix having been obtained by drying a coating solution comprising the support matrix material, the electroactive species, and the ionophore;

wherein the ionophore and the electroactive species are two different chemicals.

18. A device for the quantitative determination of an ion in a fluid which comprises an electrode as defined in claim 17 and one or more further electrodes.

19. A device according to claim 18, wherein the electrodes are present as conducting tracks on a single base.

20. A device according to claim 18, which comprises two or more electrodes, each such electrode comprising an electrically conducting support having a surface which is coated with a support matrix, the support matrix being a single layer containing (a) an electroactive species capable of being oxidised or reduced to form a charged species and (b) an ionophore, the support matrix having been obtained by drying a coating solution comprising the support matrix material, the electroactive species, and the ionophore;

wherein the ionophore and the electroactive species are for each such electrode two different chemicals.