WO1995010040A1 - Electro-chemical detector - Google Patents
Electro-chemical detector Download PDFInfo
- Publication number
- WO1995010040A1 WO1995010040A1 PCT/GB1994/002089 GB9402089W WO9510040A1 WO 1995010040 A1 WO1995010040 A1 WO 1995010040A1 GB 9402089 W GB9402089 W GB 9402089W WO 9510040 A1 WO9510040 A1 WO 9510040A1
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- electrode
- micro
- fluid
- signal
- applied signal
- Prior art date
Links
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N27/00—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
- G01N27/26—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating electrochemical variables; by using electrolysis or electrophoresis
- G01N27/416—Systems
- G01N27/447—Systems using electrophoresis
- G01N27/44704—Details; Accessories
- G01N27/44717—Arrangements for investigating the separated zones, e.g. localising zones
- G01N27/4473—Arrangements for investigating the separated zones, e.g. localising zones by electric means
Definitions
- the present invention relates to electro-chemical detectors and especially to the use of such detectors for analysing a flowing stream of a fluid.
- a method of performing measurements on a flowing fluid comprising the steps of: providing a metal micro-electrode in or adjacent to the path of said fluid; applying a time-varying signal to said micro-electrode; and measuring the response of said fluid to said varying signal.
- the present invention also provides: an apparatus for performing measurements on a flowing fluid, the apparatus comprising: a metal micro-electrode array; means for conducting said flowing fluid to flow adjacent to, or in contact with, said micro-electrode array; means for applying a varying signal to said micro-electrode array; and means for measuring the response of said fluid to the applied signal.
- a metal micro-electrode which is preferably made of a noble metal such as gold or platinum, or other metal such as copper, allows different samples to be distinguished and also different measurements to be performed on each sample, thus vastly increasing the amount of information available from analysis of a fluid stream.
- the electrode is preferably made of platinum, for example deposited on a silicon wafer by photolithography.
- the applied signal preferably varies in voltage and causes a changing current response which is measured.
- the signal is preferably varied with a period less than the time taken for each sample to cross the electrode region. In a preferred embodiment the signal is varied in a series of steps, or is a continuously varying waveform.
- Fig. 1 is a schematic view of a first embodiment of the invention
- Fig. 2 is an schematic view of electrodes suitable for use in the present invention
- Fig. 3 is an enlarged view of the electrode pattern, including the micro-electrode array, suitable for use in the present invention
- Fig. 4 shows a simple waveform applied to the micro- electrode array in a first embodiment of the invention
- Fig. 5 shows results achieved with the waveform of Fig. 4.
- Fig. 6 shows a waveform with cleaning pulses applied to the micro-electrode in a second embodiment of the invention;
- Fig. 7 shows results achieved with the waveform of Fig. 6;
- Fig. 8 shows a waveform with cleaning pulses applied to the micro-electrode in a third embodiment of the invention
- Fig. 9 shows results achieved with the waveform of Fig. 8.
- Fig. 10 shows a simple waveform applied repeatedly during HPLC
- Fig. 11 shows the results achieved with the waveform of Fig. 10
- Fig. 12 shows the detector output (an electropherogram) obtained during the CZE separation of a mixture of catecholamines.
- detector output an electropherogram
- FIG. 1 shows, schematically, an embodiment of the invention.
- a capillary zone electrophoresis (CZE) apparatus l outputs a liquid stream 2.
- This stream is generated by separating out the constituents of a specimen under investigation and thus the composition of the stream varies along its length, or with time if a stationary point is observed.
- the stream might also be generated by any other suitable apparatus such as a liquid chromatography column or it might represent a sample drawn from a pipeline or a reaction vessel.
- the sample stream 2 passes over an electrode array 3, which is described in more detail below.
- the effluent stream 4 is passed to a waste container or drain 5 though it may be returned to the pipeline or reaction vessel depending on the application.
- a control unit 7 which may be a computer or dedicated hardware, provides an analysis signal to the electrode array and analyses the response. Power is provided by a power supply 6 and the results are passed to a display or storage device 8 such as a video monitor, printer, chart recorder, plotter or disk drive.
- FIG. 2 shows the electrode arrangement in greater detail.
- the liquid stream 2 arrives via a capillary tube 9 from the CZE apparatus and flows down a channel 10 defined by the electrode substrate 11 and a groove in a cap 12.
- the electrode substrate 11 is fabricated from a silicon wafer and cap 12 is made of Corning glass. They are joined using a photoresist. If an adhesive is used it is important to ensure that it does not flow into the capillary channel.
- An alternative, but expensive, procedure would be to use a solid low melting point glass target to sputter a layer of glass onto the cap and substrate, followed by an anodic bonding process.
- the electrodes 13, 14, 15 and 16 comprise platinum deposited on a chromium adhesion layer and are printed onto the substrate, before the cap is added, by photolithography.
- Electrode 13 is an earthing electrode provided to isolate the analytical electrodes from the high voltages used in CZE. It may be omitted. Electrode 15 is the micro-electrode array which will be described in more detail below. Electrodes 14 and 16 are guard or auxiliary electrodes. Pads are provided to enable electrical connections to the electrodes to be made.
- the electrode may also be constructed by screen printing or by building a multilayered "sandwich" of alternating metal foil and insulators. If screen printing is used the metal ink contains only about 80% metal, the remainder being binding materials.
- the edge of it which may be polished to provide a flat surface for the detector cap, comprises an array of micro-electrodes separated by insulators. Connections may be made to another edge of the sandwich. The width and separation of the micro-electrodes in the sandwich method may be increased by cutting the edge at an angle.
- the micro-electrode array consists of 8 micro-electrodes of 5 ⁇ m width at a spacing of 5 ⁇ m.
- the first guard electrode is spaced, D,, 10 mm from the earthing electrode. This distance should be large enough to ensure isolation of the analytical electrodes but, for convenience, should not be too large.
- the guard electrodes 16 and 16 are spaced, D 2 , 100 ⁇ m from the micro-electrode array and have a width, D 3 , of 100 ⁇ m.
- the precise number width and spacing of the micro- electrodes will vary between applications.
- the width may be in the range of from 0.1 to 50 ⁇ m and the spacing in the range of from 0.1 to 100 ⁇ m.
- a time-varying potential difference signal is applied between the micro-electrode array and a second electrode. This may be done either in a two electrode mode, in which the second electrode is a reference electrode, or a three electrode mode in which the second electrode is one or both of the auxiliary electrodes which are patterned on the device.
- the reference electrode may either be patterned on the device in a similar position or instead of the auxiliary electrodes or may be external to the device, as shown at 17 in Figure 2.
- the current produced at the micro-electrode array by reaction of the analyte is measured and provides the necessary information for the analysis.
- the voltage signal is varied to enable the response of the fluid to be measured at different voltages to extract maximum information.
- the fluid stream provided by the CZE apparatus may be regarded as a succession of separate samples, each of which may contain one or more components which are to be analysed. It is thus important that the complete set of measurements be taken in a time appreciably less than the time taken for the sample to cross the analytical electrode array. Thus the rate of change of the analytical signal applied to the micro-electrode must be substantially greater than the rate of flow of the fluid stream.
- the scanning rate of the analytical signal is limited by the characteristics of the electrode array, particularly its capacitance, which depends upon its dimensions, and the sensitivity of the current measuring equipment.
- Figure 4 shows a simple staircase waveform which might be used with the apparatus.
- the voltage is decreased from +0.3V to -1.4V in lOOmV steps at a rate of 1 step per second.
- Figure 5 shows the current response from a 10 ml solution of HN0 3 (0.1 M) as samples of copper ions were added. The data points are as follows: D - blank Nitric Acid; x - after the addition of 1 ml 0.1 M copper; O - after the addition of 2 ml 0.1 M copper.
- Figure 6 shows an alternative waveform which includes cleaning pulses between adjacent steps.
- the cleaning pulses comprise an oxidation pulse, to 0.6 V, followed by a reduction pulse, to -1.5 V.
- the oxidation pulse removes any metals deposited on the electrode while the reduction pulse reduces the surface oxidised platinum.
- the aim is to return the electrodes to their original state between steps.
- Figure 7 shows the test results, using the same symbols as figure 5.
- This waveform can give rise to an apparent increase in noise when metal ions are added. This is probably due to the negative potential pulse causing the metal ions to plate onto the electrode surface and also causing adsorption of hydrogen.
- a further alternative waveform, which appears to give the best results, is shown in figure 8. In this waveform only the oxidation pulse, to 0.6V, is applied, the reduction pulse is omitted.
- the test results using this waveform are shown if figure 9, in which the data points are labelled as follows: + - blank Nitric Acid; D - after the addition of 1 ml 0.1 M copper;
- similar pulses may be applied to precondition the electrode surface to favour the analysis of a particular substance, eg the hydroxy groups which form on a platinum electrode between 0.2 and 0.5V 10 facilitate the oxidation of certain analytes such as carbohydrates and alcohols.
- Figure 10 shows a simple voltage staircase waveform, form 15 500 - 1300 mV in lOO V steps of 100ms duration, which was applied repeatedly to the electrodes during the narrow bore HPLC of three catecholamines.
- the three catecholamines (hydroquinone, dopamine and catechol, all 5mM) were separated on a Tachsphere 50DS reverse 20 phase column (15 cm x 3.9 mm, HPLC Technology Ltd) at ambient temperature using a flow rate of 0.66 ml min *1 .
- the eluant was a 70:30 mixture of pH3 phosphate/citrate buffer and methanol.
- Fig. 11 shows the results obtained, clearly showing the separation of the three catecholamines. 25
- the voltage of the applied signal is varied to carry out the different measurements on the sample stream.
- any other parameter of the signal eg current, frequency or polarity, may be varied.
- Fig. 12 shows, as an example, the output from the detector (an electropherogram) during a CZE separation of a
Abstract
Description
Claims
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
EP94927717A EP0722568A1 (en) | 1993-10-01 | 1994-09-26 | Electro-chemical detector |
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
GB939320286A GB9320286D0 (en) | 1993-10-01 | 1993-10-01 | Electro-chemical detector |
GB9320286.9 | 1993-10-01 |
Publications (1)
Publication Number | Publication Date |
---|---|
WO1995010040A1 true WO1995010040A1 (en) | 1995-04-13 |
Family
ID=10742857
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
PCT/GB1994/002089 WO1995010040A1 (en) | 1993-10-01 | 1994-09-26 | Electro-chemical detector |
Country Status (3)
Country | Link |
---|---|
EP (1) | EP0722568A1 (en) |
GB (1) | GB9320286D0 (en) |
WO (1) | WO1995010040A1 (en) |
Cited By (16)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
DE19610005A1 (en) * | 1996-03-14 | 1997-09-18 | Thomson Brandt Gmbh | On=screen=display television set |
WO1998009161A1 (en) * | 1996-08-26 | 1998-03-05 | The Regents Of The University Of California | Electrochemical detector integrated on microfabricated capillary electrophoresis chips |
WO1998049549A1 (en) * | 1997-04-30 | 1998-11-05 | Orion Research, Inc. | Capillary electrophoretic separation system |
US5906723A (en) * | 1996-08-26 | 1999-05-25 | The Regents Of The University Of California | Electrochemical detector integrated on microfabricated capillary electrophoresis chips |
US5965001A (en) * | 1996-07-03 | 1999-10-12 | Caliper Technologies Corporation | Variable control of electroosmotic and/or electrophoretic forces within a fluid-containing structure via electrical forces |
WO2000042424A1 (en) * | 1999-01-11 | 2000-07-20 | The Regents Of The University Of California | Microfabricated capillary electrophoresis chip and method for simultaneously detecting multiple redox labels |
US6790341B1 (en) * | 1996-11-01 | 2004-09-14 | University Of Washington | Microband electrode arrays |
EP2306183A1 (en) * | 2009-09-16 | 2011-04-06 | Integrated Microsystems Austria GmbH | Sample analysis device |
US8308929B2 (en) * | 2006-12-06 | 2012-11-13 | The Trustees Of Columbia University In The City Of New York | Microfluidic systems and methods for screening plating and etching bath compositions |
US8475642B2 (en) | 2005-04-08 | 2013-07-02 | The Trustees Of Columbia University In The City Of New York | Systems and methods for monitoring plating and etching baths |
US8496799B2 (en) | 2005-02-08 | 2013-07-30 | The Trustees Of Columbia University In The City Of New York | Systems and methods for in situ annealing of electro- and electroless platings during deposition |
US8529738B2 (en) | 2005-02-08 | 2013-09-10 | The Trustees Of Columbia University In The City Of New York | In situ plating and etching of materials covered with a surface film |
US8985050B2 (en) | 2009-11-05 | 2015-03-24 | The Trustees Of Columbia University In The City Of New York | Substrate laser oxide removal process followed by electro or immersion plating |
WO2016008962A1 (en) * | 2014-07-18 | 2016-01-21 | Fraunhofer-Gesellschaft zur Förderung der angewandten Forschung e. V. | Sensor for detecting a liquid in a fluid channel |
US20160054261A1 (en) * | 1999-04-21 | 2016-02-25 | Osmetech Technology | Use of microfluidic systems in the electrochemical detection of target analytes |
CN112191284A (en) * | 2020-06-18 | 2021-01-08 | 天津大学 | Laboratory analysis platform on microfluidic ultrasonic electrochemical chip |
Citations (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
CH659327A5 (en) * | 1982-11-23 | 1987-01-15 | Inst Elektrokhimii Akademii Na | Method and apparatus for determining the organic carbon content of water or of an aqueous solution |
EP0475713A1 (en) * | 1990-09-10 | 1992-03-18 | The Board Of Trustees Of The Leland Stanford Junior University | End-column electrical and electrochemical detector for capillary zone electrophoresis |
US5169510A (en) * | 1992-03-02 | 1992-12-08 | Oread Laboratories | Ion-permeable polymer joint for use in capillary electrophoresis |
-
1993
- 1993-10-01 GB GB939320286A patent/GB9320286D0/en active Pending
-
1994
- 1994-09-26 EP EP94927717A patent/EP0722568A1/en not_active Withdrawn
- 1994-09-26 WO PCT/GB1994/002089 patent/WO1995010040A1/en not_active Application Discontinuation
Patent Citations (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
CH659327A5 (en) * | 1982-11-23 | 1987-01-15 | Inst Elektrokhimii Akademii Na | Method and apparatus for determining the organic carbon content of water or of an aqueous solution |
EP0475713A1 (en) * | 1990-09-10 | 1992-03-18 | The Board Of Trustees Of The Leland Stanford Junior University | End-column electrical and electrochemical detector for capillary zone electrophoresis |
US5169510A (en) * | 1992-03-02 | 1992-12-08 | Oread Laboratories | Ion-permeable polymer joint for use in capillary electrophoresis |
Non-Patent Citations (1)
Title |
---|
Y.F. YIK: "MICELLAR ELECTROKINETIC CAPILLARY CHROMATOGRAPHY OF VITAMINE B6 WITH ELECTROCHEMICAL DETECTION", JOURNAL OF CHROMATOGRAPHY, vol. 585, no. 1, 25 October 1991 (1991-10-25), AMSTERDAM, NL, pages 139 - 144, XP000242212 * |
Cited By (22)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
DE19610005A1 (en) * | 1996-03-14 | 1997-09-18 | Thomson Brandt Gmbh | On=screen=display television set |
US6413401B1 (en) | 1996-07-03 | 2002-07-02 | Caliper Technologies Corp. | Variable control of electroosmotic and/or electrophoretic forces within a fluid-containing structure via electrical forces |
US5965001A (en) * | 1996-07-03 | 1999-10-12 | Caliper Technologies Corporation | Variable control of electroosmotic and/or electrophoretic forces within a fluid-containing structure via electrical forces |
WO1998009161A1 (en) * | 1996-08-26 | 1998-03-05 | The Regents Of The University Of California | Electrochemical detector integrated on microfabricated capillary electrophoresis chips |
US5906723A (en) * | 1996-08-26 | 1999-05-25 | The Regents Of The University Of California | Electrochemical detector integrated on microfabricated capillary electrophoresis chips |
US6045676A (en) * | 1996-08-26 | 2000-04-04 | The Board Of Regents Of The University Of California | Electrochemical detector integrated on microfabricated capilliary electrophoresis chips |
US6790341B1 (en) * | 1996-11-01 | 2004-09-14 | University Of Washington | Microband electrode arrays |
WO1998049549A1 (en) * | 1997-04-30 | 1998-11-05 | Orion Research, Inc. | Capillary electrophoretic separation system |
US6159353A (en) * | 1997-04-30 | 2000-12-12 | Orion Research, Inc. | Capillary electrophoretic separation system |
US6361671B1 (en) | 1999-01-11 | 2002-03-26 | The Regents Of The University Of California | Microfabricated capillary electrophoresis chip and method for simultaneously detecting multiple redox labels |
WO2000042424A1 (en) * | 1999-01-11 | 2000-07-20 | The Regents Of The University Of California | Microfabricated capillary electrophoresis chip and method for simultaneously detecting multiple redox labels |
US9557295B2 (en) * | 1999-04-21 | 2017-01-31 | Osmetech Technology, Inc. | Use of microfluidic systems in the electrochemical detection of target analytes |
US20160054261A1 (en) * | 1999-04-21 | 2016-02-25 | Osmetech Technology | Use of microfluidic systems in the electrochemical detection of target analytes |
US8529738B2 (en) | 2005-02-08 | 2013-09-10 | The Trustees Of Columbia University In The City Of New York | In situ plating and etching of materials covered with a surface film |
US8496799B2 (en) | 2005-02-08 | 2013-07-30 | The Trustees Of Columbia University In The City Of New York | Systems and methods for in situ annealing of electro- and electroless platings during deposition |
US8475642B2 (en) | 2005-04-08 | 2013-07-02 | The Trustees Of Columbia University In The City Of New York | Systems and methods for monitoring plating and etching baths |
US8308929B2 (en) * | 2006-12-06 | 2012-11-13 | The Trustees Of Columbia University In The City Of New York | Microfluidic systems and methods for screening plating and etching bath compositions |
EP2306183A1 (en) * | 2009-09-16 | 2011-04-06 | Integrated Microsystems Austria GmbH | Sample analysis device |
US8985050B2 (en) | 2009-11-05 | 2015-03-24 | The Trustees Of Columbia University In The City Of New York | Substrate laser oxide removal process followed by electro or immersion plating |
WO2016008962A1 (en) * | 2014-07-18 | 2016-01-21 | Fraunhofer-Gesellschaft zur Förderung der angewandten Forschung e. V. | Sensor for detecting a liquid in a fluid channel |
US10156537B2 (en) | 2014-07-18 | 2018-12-18 | Fraunhofer-Gesellschaft zur Förderung der angewandten Forschung e.V. | Sensor for detecting a liquid in a fluid channel |
CN112191284A (en) * | 2020-06-18 | 2021-01-08 | 天津大学 | Laboratory analysis platform on microfluidic ultrasonic electrochemical chip |
Also Published As
Publication number | Publication date |
---|---|
GB9320286D0 (en) | 1993-11-17 |
EP0722568A1 (en) | 1996-07-24 |
Similar Documents
Publication | Publication Date | Title |
---|---|---|
Lu et al. | Pulsed amperometric detection of carbohydrates separated by capillary electrophoresis | |
WO1995010040A1 (en) | Electro-chemical detector | |
US6790341B1 (en) | Microband electrode arrays | |
Kounaves | Voltammetric techniques | |
CA1167526A (en) | Electrochemical detection system | |
Ye et al. | Amperometric detection in capillary electrophoresis with normal size electrodes | |
US5131999A (en) | Voltammetric detector for flow analysis | |
EP0418404B1 (en) | Method of determining optimum operating conditions in an electrochemical detector and electrochemical detector using the method | |
Armstrong-James et al. | Quantitative ionophoresis of catecholamines using multibarrel carbon fibre microelectrodes | |
EP1010005B1 (en) | Electronic tongue | |
Wang et al. | A flow detector based on square-wave polarography at the dropping mercury electrode | |
WO1983004095A1 (en) | Gas sensor and method of using same | |
Feldman et al. | Electrochemical determination of low blood lead concentrations with a disposable carbon microarray electrode | |
Tercier‐Waeber et al. | A Novel Voltammetric Probe with Individually Addressable Gel‐Integrated Microsensor Arrays for Real‐Time High Spatial Resolution Concentration Profile Measurements | |
Uhlig et al. | Chip-array electrodes for simultaneous stripping analysis of trace metals | |
RU2564516C2 (en) | Capacitance measurement method and its application | |
CN100353161C (en) | Electrochemical time-measuring electric potential detector | |
Gardner et al. | Development of a microelectrode array sensing platform for combination electrochemical and spectrochemical aqueous ion testing | |
Yun et al. | Analysis of heavy-metal ions using mercury microelectrodes and a solid-state reference electrode on a Si wafer | |
US5342492A (en) | System for electrokinetic separation and detection where detection is performed at other than separation electric field | |
Gunasingham et al. | Computer-assisted rapid-scan cyclic staircase voltammetry in normal-phase high-performance liquid chromatography | |
JP3356507B2 (en) | Taste sensor | |
EP0969281A2 (en) | The use of screen-printed electrodes in the electrochemical analysis of electroactive species | |
US4142944A (en) | Apparatus and methods for effluent stream analysis | |
KR100829928B1 (en) | Device for Measuring Hematocrit of Blood and Method using the same |
Legal Events
Date | Code | Title | Description |
---|---|---|---|
AK | Designated states |
Kind code of ref document: A1 Designated state(s): US |
|
AL | Designated countries for regional patents |
Kind code of ref document: A1 Designated state(s): AT BE CH DE DK ES FR GB GR IE IT LU MC NL PT SE |
|
DFPE | Request for preliminary examination filed prior to expiration of 19th month from priority date (pct application filed before 20040101) | ||
121 | Ep: the epo has been informed by wipo that ep was designated in this application | ||
WWE | Wipo information: entry into national phase |
Ref document number: 1994927717 Country of ref document: EP |
|
ENP | Entry into the national phase |
Ref country code: US Ref document number: 1996 619609 Date of ref document: 19960528 Kind code of ref document: A Format of ref document f/p: F |
|
WWP | Wipo information: published in national office |
Ref document number: 1994927717 Country of ref document: EP |
|
WWW | Wipo information: withdrawn in national office |
Ref document number: 1994927717 Country of ref document: EP |