Electrode preconditioning

• US 20090159464A1
• Filed: 06/29/2005
• Published: 06/25/2009
• Est. Priority Date: 06/29/2004
• Status: Active Grant

• Current Assignee: Roche Diabetes Care Inc. (Roche Holding AG)
• Original Assignee: Roche Diagnostics Operations Incorporated (Roche Holding AG)
• Inventors: Bond, Alan Maxwell, Hyland, Mark
• Granted Patent: US 8,282,797 B2
• Time in Patent Office: Days
• US Class Current: 205/790
• CPC Class Codes: G01N 27/308 at least partially made of carbon
• CPC Class Codes: G01N 27/4045 for gases other than oxygen

Abstract

An electrochemical sensing method comprising: (a) providing an electrochemical cell having a working electrode and a pseudo reference electrode; (b) providing a sample comprising a metal, the sample being in contact with the working electrode and the metal being capable of being oxidised or reduced at the working electrode when the metal is bound to the working electrode; (c) preconditioning the working electrode by (i) applying a time varying preconditioning potential between the working and pseudo reference electrodes; and/or (ii) baking the working electrode; and/or (iii) air-ageing the working electrode; and (d) applying a measuring potential between the working and pseudo reference electrodes and, during application of said measuring potential, measuring the current generated by oxidation/reduction of the metal at the working electrode.

Claims

1. An electrochemical sensing method comprising

(a) providing an electrochemical cell having a working electrode and a pseudo reference electrode;

(b) providing a sample comprising a metal, the sample being in contact with the working electrode and the metal being capable of being oxidised or reduced at the working electrode when the metal is adsorbed on the working electrode;

(c) preconditioning the working electrode by (i) applying a time varying preconditioning potential between the working and pseudo reference electrodes; and

/or (ii) baking the working electrode; and

/or (iii) air-ageing the working electrode; and

subsequently

(d) applying a measuring potential between the working and pseudo reference electrodes and, during application of said measuring potential, measuring the current generated by oxidation/reduction of the metal at the working electrode,

wherein steps (a), (b), (c)(i), (c)(ii) and (c)(iii) may be carried out in any order and step (d) is carried out after steps (a), (b) and (c).

2. A method according to claim 1, wherein step (c)(i) comprises varying the applied potential between a first applied potential of no more than −

0.5V and a second applied potential of at least 1.1V.

3. A method according to claim 2, wherein step (c)(i) comprises scanning the applied potential by decreasing the applied potential from substantially zero to said first applied potential and then increasing the applied potential to said second applied potential.

4. A method according to claim 3, wherein step (c)(i) comprises scanning the applied potential twice.

5. A method according to claim 1, wherein the rate of potential change in step (c)(i) is from 10 mVs⁻

1 to 2 Vs<sup>−

1</sup>.

6. A method according to claim 1, wherein the sample comprises cobalt (II) and the method comprises electrochemically detecting the presence of cobalt (II) in the sample.

7. A method according to claim 1, wherein step (c)(ii) comprises baking the working electrode at a temperature of from 70 to 130°

C.

8. A method according to claim 1, wherein step (c)(iii) comprises exposing the working electrode to air for from 10 to 20 days at a temperature of 18 to 25°

C.

9. A device comprising

an electrochemical cell having a working electrode and a pseudo reference electrode;

a potentiostat for applying a potential between the working and pseudo reference electrodes;

a controller for controlling the potentiostat so that firstly a time varying preconditioning potential is applied and subsequently a measuring potential is applied; and

means for measuring the current across the cell.

10. A device according to claim 9, which additionally comprises a composition comprising a metal which is capable of being oxidised or reduced at the working electrode when the metal is adsorbed on the working electrode.

11. A device according to claim 9, wherein the controller is adapted so that the potentiostat applies a time varying preconditioning potential which varies between a first applied potential of no more than −

0.5V and a second applied potential of at least 1.1 V.

12. A device according to any one of claim 9, wherein the controller is adapted so that the potentiostat applies a time varying preconditioning potential by carrying out a preconditioning scan of the applied potential comprising decreasing the applied potential from substantially zero to said first applied potential and then increasing the applied potential to said second applied potential.

13. A device according to claim 12 wherein the controller is adapted so that the potentiostat carries out two said preconditioning scans of the applied potential.

14. A device comprising

an electrochemical cell having a working electrode and a pseudo reference electrode;

a potentiostat for applying a potential between the working and pseudo reference electrodes;

a controller for controlling the potentiostat; and

means for measuring the current across the cell;

wherein the working electrode is a preconditioned electrode obtained by subjecting the electrode to baking or air-ageing.

15. A device according to claim 14, wherein the controller is as defined claim 9.

16. (canceled)