Electrochemical detector cell

• US 5,399,256 A
• Filed: 01/07/1994
• Issued: 03/21/1995
• Est. Priority Date: 01/07/1994
• Status: Expired due to Fees

• Current Assignee: Bioanalytical Systems, Inc.
• Original Assignee: Bioanalytical Systems, Inc.
• Inventors: Bohs, Curtis E., Kissinger, Peter T., Linhares, Michael C.
• Primary Examiner(s): Niebling, John
• Assistant Examiner(s): Bell, Bruce F.
• Application Number:
  US08/178,913
• Time in Patent Office: 438 Days
• Field of Search: 204/409, 204/412, 204/416, 204/418, 204/419, 204/415, 204/420, 422/82.01, 422/82.03, 73/61.52, 73/61.44, 73/61.56, 73/61.57, 73/61.58, 73/61.59, 73/61.61
• US Class Current: 204/409
• CPC Class Codes: G01N 2030/645 electrical conductivity detectors
• CPC Class Codes: G01N 27/49 Systems involving the determination of the current at a single specific value, or small range of values, of applied voltage for producing selective measurement of one or more particular ionic species
• CPC Class Codes: G01N 30/64 Electrical detectors

Abstract

An electrochemical detector cell includes a first block having a planar first working surface, and a first working electrode embedded in the first block member. The first working electrode includes analyte contacting surface disposed co-planarly with the first working surface. A second block member has the second working surface placeable in an opposed, adjacent relation to the first working surface, and has an inlet port disposed an opposed, adjacent relation to the analyte contacting surface of the first working electrode. The second block also includes a coupling means for permitting an analyte delivery tube to be coupled to the second block member to position an end of the analyte delivery tube adjacent to the inlet port. A generally circular circumferential channel for collecting analyte is disposed radially outwardly of the first working electrode. An outlet is disposed at the channel for conducting analyte away from the channel. A reference electrode is disposed in a diametrically opposed relation to the outlet, and a ring-like gasket is placeable between the first and second block members for maintaining the first and second working surfaces in a predetermined spaced relation. The gasket includes a radially inner diameter disposed radially outwardly of the channel. The inlet port, channel, first working electrode, first working surface, second working surface, gasket and outlet port are configured to create a generally centrosymmetric thin layer radial flow path for the analyte across the working electrode, and between the first and second working surfaces, into the channel and out of the outlet port.

Claims

1. An electrochemical detector cell for detecting the presence of an analyte in a material sample, the detector cell comprising:

(1) a first block member having a first working surface;

(2) a first working electrode means disposed on the first working surface;

(3) a second block member having

(a) a second working surface placeable in an opposed adjacent relation to the working surface of the first block member; and

(b) an inlet means having an inlet port disposed in an opposed adjacent relation to the first working surface; and

(4) a circumferential channel means for collecting analytes that have passed over the first working electrode,

the inlet port, channel means, first working electrode means, the first working surface and second working surfaces are configured to create a generally centrosymmetric radial thin layer flow path for the analyte across the working electrodes, between the first and second working surfaces and to the channel means.

2. The cell of claim 1 wherein the first working electrode means is disposed in an opposed adjacent relation to the inlet port.

3. The cell of claim 2 wherein the first working electrode means includes an analyte contacting surface disposed generally co-planar with the first working surface, the analyte contacting surface is disposed between about 5 and 100 micrometers from the inlet port means.

4. The cell of claim 2 wherein the first working electrode includes an analyte contacting surface having a diameter between about two and ten times larger than the diameter of the inlet port means.

5. The cell of claim 2 further comprising a second working electrode disposed radially outwardly from the first working electrode means.

6. The cell of claim 5 wherein the second working electrode comprises a ring shaped working electrode.

7. The cell of claim 5 wherein the second working electrode comprises an array of working electrodes disposed at spaced intervals.

8. The cell of claim 1 wherein the first working electrode means includes at least two working electrodes disposed in parallel, and spaced radially outwardly from the inlet means of the second block member.

9. The cell of claim 1 wherein the inlet means includes a coupling means for permitting an analyte delivery means to be coupled to the second block member to position an end of the analyte delivery means adjacent to the inlet port.

10. The cell of claim 1 further comprising a microbore chromatography column having a downstream end, wherein the inlet means includes coupling means for coupling the downstream end of the chromatography column adjacent to the inlet port.

11. The cell of claim 10 wherein the coupling means comprises a fitting receiving cavity formed within the second block member, the fitting receiving cavity including a generally cylindrical axially inwardly disposed downstream end receiving portion for receiving the downstream end of the chromatography column, a frustoconical portion and an axially outwardly disposed generally cylindrical, threaded portion.

12. The cell of claim 11 wherein the inlet port has a diameter of less than about 1 mm, and the distance between the downstream end of the chromatography column and the working electrode is less than about 1 mm.

13. The cell of claim 1 wherein the second block member has a generally planar working surface, and an outlet port disposed adjacent the channel means.

14. The cell of claim 13 wherein the outlet port includes an axially extending outlet passageway, the outlet passageway including means for receiving an outlet tube.

15. The cell of claim 1 wherein the channel means comprises a generally circular channel disposed radially outwardly from the inlet port, and

the second block member includes an outlet port disposed at the channel means.

16. The cell of claim 15 wherein the channel is formed in the second block member and is disposed radially outwardly of the working surface, and the outlet port is disposed in the channel.

17. The cell of claim 16 wherein the first block member includes a reference electrode disposed at the channel, and positioned in a diametrically opposed relation to the outlet port.

18. The cell of claim 17 further comprising a generally ring-shaped gasket means having a radially inner diameter slightly greater than the diameter of the channel, the gasket means is placed between the first and second block members to define a radially outer boundary of the flow path.

19. The cell of claim 1 further comprising a ring-shaped gasket member placed between the first and second block members for maintaining the first and second working surfaces in a set spaced relation, the gasket means including a radially inner diameter defining a radially outer boundary of the flow path.

20. The cell of claim 1 wherein the channel means comprises a generally circular channel disposed radially outwardly from the inlet port, and the second block member includes an outlet port disposed at the channel means, further comprising

A ring-shaped gasket means having a radially inner diameter slightly greater than the channel, the gasket means is placed between the first and second block members to maintain the first and second block members in a set spaced relation, and to define a radially outer boundary of the flow path, the inlet port, first and second working surfaces, channel means, gasket means and outlet port is configured to maintain the integrity of a band of analyte as it flows from the inlet port, through the flow path and out of the outlet means.

21. The cell of claim 1 wherein the first block member includes a reference electrode without a liquid junction.

22. The cell of claim 1 wherein the first block member includes an axially extending central passageway for receiving the first working electrode means, and electrode positioning means for axially adjustably positioning the first working electrode means.

23. An electrochemical detector cell comprising

(1) a first block member having a generally planar first working surface;

(2) a first working electrode imbedded in the first block member, the first working electrode including an analyte contacting surface disposed generally co-planarly with the first working surface;

(3) a second block member having

(a) a second working surface placeable in an opposed adjacent relation to the first working surface,

(b) an inlet means having an inlet port disposed in an opposed adjacent relation to the analyte surface of the first working electrode, and

(c) a coupling means for permitting an analyte delivery means to be coupled to the second block member to position an end of the analyte delivery means adjacent to the inlet port;

(4) a generally circular channel means for collecting analyte disposed radially outwardly of the first working electrode;

(5) an outlet means disposed at the channel means for conducting analyte away from the channel means;

(6) a reference electrode disposed in a diametrically opposed relation to the outlet means; and

(7) a ring-shaped gasket means is placed between the first and second block members for maintaining the first and second working surfaces in a set spaced relation, the gasket means including a radially inner diameter disposed radially outwardly of the channel means, wherein the inlet port, channel means, first working electrode, first working surface, second working surface and gasket members and outlet port are configured to create a generally centrosymmetric thin layer radial flow path for the analyte across the working electrode and between the first and second working surfaces, into the channel means, and out the outlet port.

24. The cell of claim 23 wherein the analyte delivery means comprises a microbore chromatography column which separates a sample containing a mixture of analytes into a series of generally discreet analyte bands, the microbore chromatography column including a fitting means which mates with the coupling means for positioning a downstream end of the microbore chromatography column adjacent to the inlet port, wherein the microbore chromatography column, inlet port, first and second working surfaces, gasket means, channel means and outlet port are configured to maintain the integrity of a band of analyte as it flows from the inlet port through the flow path, through the outlet port, and away from the electrochemical detector cell.

25. A working block member electrode for use in an electrochemical detector cell for detecting the presence of an analyte in a material sample, in conjunction with an auxiliary block member having a generally central inlet port, an auxiliary block working surface, and an outlet port disposed radially outwardly from the inlet port, the working block electrode comprising,

a first block member having a generally planar first working surface,

a first working electrode imbedded in the first block member, the first working electrode including an analyte contacting surface disposed generally co-planarly with the first working surface, and in an opposed adjacent relation to the inlet port of the auxiliary block member, and

a reference electrode disposed in a diametrically opposed relation to the outlet means.

26. The electrode of claim 25 further comprising a ring-shaped gasket means placed between the working and the auxiliary block members for maintaining the first working surface and the auxiliary block working surface in a set spaced relation, the gasket means including a radially inner diameter disposed radially outwardly of the outlet path, the first working surface, first working electrode and gasket means, when joined to the auxiliary block member, defining a generally centrosymmetric radial flow path for analyte from the inlet port, across the first working electrode, and between the first working surface and the auxiliary block working surface.

27. An electrochemical detection system for detecting the presence of an analyte in a material sample, the detection system comprising:

(1) a pump means for pumping a material sample through the detection system,

(2) an injector means for injecting the material sample into the detection system,

(3) a temperature control means for controlling the temperature of the material sample,

(4) an electrochemical detector cell comprising

(a) a first block member having a first working surface;

(b) a first working electrode means disposed on the first working surface;

(c) a second block member having a second working surface placed in an opposed adjacent relation to the working surface of the first block member and an inlet means having an inlet port disposed in an opposed adjacent relation to the first working surface; and

(d) a circumferential channel means for collecting analytes,

wherein the inlet port, channel means, first working electrode means, first working surface and second working surfaces are configured to create a generally centrosymmetric thin layer radial flow path for the analyte across the working electrodes and between the first and second working surfaces; and

(5) a controller means for applying a potential to the working electrode, and measuring and recording the current across the electrodes of the electrochemical detector cell.