Electrochemical detection method and apparatus therefor

• US 5,389,215 A
• Filed: 04/27/1993
• Issued: 02/14/1995
• Est. Priority Date: 11/05/1992
• Status: Expired due to Term

• Current Assignee: Nippon Telegraph and Telephone Corporation
• Original Assignee: Nippon Telegraph and Telephone Corporation
• Inventors: Horiuchi, Tsutomu, Niwa, Osamu, Tabei, Hisao, Morita, Masao
• Primary Examiner(s): Tung, T.
• Application Number:
  US08/053,635
• Time in Patent Office: 658 Days
• Field of Search: 204/153.1, 204/434, 204/412
• US Class Current: 205/775
• CPC Class Codes: G01N 27/42 Measuring deposition or liberation of materials from an electrolyte; Coulometry, i.e. measuring coulomb-equivalent of material in an electrolyte

Abstract

In an electrochemical detection method using an apparatus including a first vessel and a second vessel, a reference electrolytic solution in the second vessel, first and second closely spaced working electrodes immersed in a sample solution for measurement in the first vessel, a stripping electrode immersed in the reference electrolytic solution, and an ionic conductor arranged between the first vessel and the second vessel, the reference electrolytic solution contains an electrolyte which can be deposited and dissolved by an electrochemical reaction by applying a potential to the stripping electrode. In a first stage, a pre-electrolysis potential is applied to the first working electrode with the stripping electrode being connected to the second working electrode to deposit the electrolyte in the reference electrolytic solution on the stripping electrode. In a second stage, after the second working electrode is disconnected from the stripping electrode, the potential of the stripping electrode is swept to measure a current generated when the electrolyte deposited on the stripping electrode in the first stage is dissolved from the stripping electrode, and the concentration of an analyte exiting in the sample solution for measurement is determined from the measured stripping current.

Claims

1. An electrochemical detection method using an apparatus including

a first vessel and a second vessel,

a reference electrolytic solution filled in said second vessel,

first and second closely spaced working electrodes immersed in a sample solution for measurement filled in said first vessel,

a stripping electrode immersed in the reference electrolytic solution, and

an ionic conductor, arranged between said first vessel and said second vessel, for electrically connecting the sample solution for measurement and the reference electrolytic solution, wherein

the reference electrolytic solution contains an electrolyte which can be deposited and dissolved by an electrochemical reaction by applying a potential to said stripping electrode,

in a first stage, a pre-electrolysis potential is applied to said first working electrode with said stripping electrode being connected to said second working electrode to deposit the electrolyte in the reference electrolytic solution on said stripping electrode, and

in a second stage, after said second working electrode is disconnected from said stripping electrode, the potential of said stripping electrode is swept to measure a current generated when the electrolyte deposited on said stripping electrode in the first stage is dissolved from said stripping electrode, and the concentration of an analyte in the sample solution for measurement is determined from the measured stripping current.

2. A method according to claim 1, further including the utilization of a reference electrode and an auxiliary electrode in the sample solution filled in said first vessel.

3. A method according to claim 1, wherein said ionic conductor comprises a salt bridge.

4. A method according to claim 3, further including the utilization of reference and auxiliary electrodes in an electrolytic solution in said salt bridge.

5. A method according to claim 1, further including the utilization of reference and auxiliary electrodes, which are arranged in said first vessel or said second vessel or said salt bridge arranged between said first and second vessels.

6. An electrochemical detection apparatus including

a first vessel and a second vessel,

a reference electrolytic solution filled in said second vessel,

first and second closely spaced working electrodes immersed in a sample solution for measurement filled in said first vessel,

a stripping electrode immersed in the reference electrolytic solution, and

an ionic conductor, arranged between said first vessel and said second vessel, for electrically connecting the sample solution for measurement and the reference electrolytic solution, wherein

the reference electrolytic solution contains an electrolyte which can be deposited and dissolved by an electrochemical reaction by applying a potential to said stripping electrode, and

said apparatus comprises

means for, in a first stage, applying a pre-electrolysis potential to said first working electrode with said stripping electrode being connected to said second working electrode to deposit the electrolyte in the reference electrolytic solution on said stripping electrode,

means for, in a second stage, disconnecting said second working electrode from said stripping electrode,

means for, in the second stage, sweeping a potential of said stripping electrode after said second working electrode is disconnected from said stripping electrode, and

means for, in the second stage, measuring a current generated when the electrolyte deposited on said stripping electrode in the first stage is dissolved from said stripping electrode.

7. An apparatus according to claim 6, further comprising reference and auxiliary electrodes in the sample solution filled in said first vessel.

8. An apparatus according to claim 6, wherein said ionic conductor comprises a salt bridge.

9. An apparatus according to claim 8, further comprising reference and auxiliary electrodes in an electrolytic solution in said salt bridge.

10. An apparatus according to claim 6, comprising at least two sets of first, second, and stripping electrodes.

11. An apparatus according to claim 6, further comprising reference and auxiliary electrodes, which are arranged in said first vessel or said second vessel or said salt bridge arranged between said first and second vessels.

12. An apparatus according to claim 6, wherein

said first and second vessels comprise

an insulating substrate and

a cell frame fixed on said substrate so as to have a measurement region hole and a reference region hole, and

said ionic conductor is arranged between said measurement and reference region holes of said cell.

13. An apparatus according to claim 12, wherein each of said electrodes is formed on said substrate.