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EP0988535A1 - Detecteur pour la mesure de la conductivite electrolytique - Google Patents

Detecteur pour la mesure de la conductivite electrolytique

Info

Publication number
EP0988535A1
EP0988535A1 EP98923915A EP98923915A EP0988535A1 EP 0988535 A1 EP0988535 A1 EP 0988535A1 EP 98923915 A EP98923915 A EP 98923915A EP 98923915 A EP98923915 A EP 98923915A EP 0988535 A1 EP0988535 A1 EP 0988535A1
Authority
EP
European Patent Office
Prior art keywords
electrodes
detector
capillary
tube
range
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP98923915A
Other languages
German (de)
English (en)
Inventor
Erhard Schnell
Andreas J. Zemann
Dietmar Volgger
Günther Karl Bonn
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Individual
Original Assignee
Individual
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Individual filed Critical Individual
Publication of EP0988535A1 publication Critical patent/EP0988535A1/fr
Withdrawn legal-status Critical Current

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
    • G01N27/02—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance
    • G01N27/22—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance by investigating capacitance
    • G01N27/226—Construction of measuring vessels; Electrodes therefor
    • 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 invention relates to a detector for measuring the electrolytic conductivity of a liquid in a tube or a capillary, which has a first and a second electrode to be connected to an AC voltage source, which are arranged outside the tube or the capillary, and an evaluation device.
  • Such detectors are used in particular for the purpose of detecting and quantifying ions separated by electrophoresis or chromatography.
  • Such a detector is described, for example, by Vacik et al., Journal of Chromatography 320 (1985) 233-240.
  • this detector In this detector, four electrodes lying opposite one another are arranged outside the glass tube, two of which are fed by a high-frequency voltage in the MHz range and the signal is tapped at the other two electrodes, which signal is subsequently amplified and evaluated.
  • this detector Compared to previous detectors, in which there was galvanic contact between electrodes and solution, this detector has the advantage that the electrodes are not contaminated or changed by solution components.
  • this detector is relatively complicated in its construction and has the further disadvantage that not only the electrolytic resistance of the solution but also the capacitive impedance is included in the measurement result due to the high frequencies that have to be used.
  • the object of the invention is therefore to provide an improved detector of the type mentioned at the beginning. According to the invention, this is achieved in a detector of the type mentioned at the outset in that the first and the second electrodes are arranged at a distance from one another along the liquid path in the longitudinal direction of the tube or the capillary.
  • the electrodes can advantageously be designed as a metal tube surrounding the tube or the capillary or conductive charging.
  • the resolution or separation power of the detector can be adjusted by changing the distance between the first and second electrodes.
  • the electrodes surround the tube or the capillary in a ring.
  • Fig. 1 is a schematic representation of the detector according to the invention
  • Fig. 2 is an equivalent circuit diagram for the electrode arrangement
  • a tube or a capillary 1 for example made of quartz, glass or
  • the capillary 1 is connected to a conventional system for electrophoresis or chromatography.
  • a first electrode 3 and a second electrode 4 are arranged on the outside of the capillary 1 and connected via lines 5, 6 to an oscillator (not shown) as an AC voltage source.
  • the first and the second electrodes 3, 4 are arranged along the liquid path in the longitudinal direction of the capillary 1 at a distance d from one another.
  • the electrodes 3, 4 surround the capillary 1 in a ring shape in the form of a cylinder jacket and each extend over a length D which is in the range between 0.5 and 7 cm, preferably in the range between 2 and 3 cm.
  • the distance d between the electrodes 3, 4 is, depending on the desired resolution or separation performance of the detector, in the range between 1 and 7 mm, preferably in the range between 2 and 5 mm.
  • the measurement signal is tapped as a voltage drop across resistor 7 (for example 10 k ⁇ ) and fed to an amplifier 8 and a rectifier 9.
  • a capacitance could also be used instead of the resistor 7.
  • the amplified and rectified signal can then be fed via line 10, for example, to an analog-digital converter and a computer unit for display and evaluation.
  • the detector and all connections are surrounded by a shield that is at ground potential.
  • a zero point compensation known from indirect UV detection and from measurements with detectors which have electrodes that are in contact with the liquid is used.
  • the electrode arrangement together with the liquid 2 in the capillary 1 in an equivalent circuit as two capacitors 1 1 and 12 with an intermediate resistor 13 are shown.
  • the capacitors 11 and 12 are each formed by one of the electrodes 3 and 4 together with the liquid 2 adjacent to the electrode 3, 4, while the resistor 13 is essentially formed by the liquid 2 in the area between the two electrodes 3, 4.
  • Due to the relatively large length of the electrodes 3, 4 in the range between 0.5 and 7 cm, preferably between 2 and 3 cm, the frequency of the alternating voltage applied to the electrodes 3, 4 can be kept relatively low and in the range of the higher audio or lower ultrasound frequency (for example in the range between 15 and 40 kHz).
  • the AC voltage can have a sinusoidal shape as well as another shape, for example a rectangular shape.
  • the electrodes can be produced by applying so-called conductive lacquer on the outside of the tube or capillary 1.
  • a metal layer applied in another way, for example by vapor deposition, could also be used, or a metal tube, the inside diameter of which is adapted to the outside diameter of the capillary 1, could be used in each case.
  • FIG. 3 A comparison of the measurement curve 15, which was obtained with the detector according to the invention, with the measurement curve 14a, 14b, which was obtained with the conventional indirect UV detection, is shown in FIG. 3.
  • Eight inorganic cations are detected using an electrolyte containing 20 mM 2-morpholinoethanesulfonic acid (MES) and 20 mM histidine at pH 6. It can be seen that the structures of curve 14a had to be enlarged by a factor of 10 (curve 14b) in order to obtain structures of approximately the same size as for measurement curve 15, which was recorded with the detector according to the invention.
  • the base noise in the measurement curve 14b is therefore significantly greater than in the measurement curve 15.
  • a change in the electrode length D between 2 and 3 cm showed no significant change in the signal of the detector, while with shorter electrode lengths D the amplification of the amplifier 8 had to be increased, which increased the base noise somewhat.

Landscapes

  • Health & Medical Sciences (AREA)
  • Chemical & Material Sciences (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Analytical Chemistry (AREA)
  • Physics & Mathematics (AREA)
  • Electrochemistry (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Biochemistry (AREA)
  • General Health & Medical Sciences (AREA)
  • General Physics & Mathematics (AREA)
  • Immunology (AREA)
  • Pathology (AREA)
  • Molecular Biology (AREA)
  • Investigating Or Analyzing Materials By The Use Of Electric Means (AREA)

Abstract

L'invention concerne un détecteur pour la mesure de la conductivité électrolytique d'un liquide dans un tube capillaire comportant une première et une deuxième électrode se raccordant à une source de tension alternative, lesquelles sont disposées à l'extérieur du tube capillaire, ainsi qu'un système d'évaluation. Les première et deuxième électrodes (3, 4) sont disposées espacées l'une de l'autre le long de la trajectoire du liquide dans le sens longitudinal du tube capillaire (1).
EP98923915A 1997-06-12 1998-06-10 Detecteur pour la mesure de la conductivite electrolytique Withdrawn EP0988535A1 (fr)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
AT0101697A AT405884B (de) 1997-06-12 1997-06-12 Detektor zur messung der elektrolytischen leitfähigkeit
AT101697 1997-06-12
PCT/AT1998/000142 WO1998057160A1 (fr) 1997-06-12 1998-06-10 Detecteur pour la mesure de la conductivite electrolytique

Publications (1)

Publication Number Publication Date
EP0988535A1 true EP0988535A1 (fr) 2000-03-29

Family

ID=3504970

Family Applications (1)

Application Number Title Priority Date Filing Date
EP98923915A Withdrawn EP0988535A1 (fr) 1997-06-12 1998-06-10 Detecteur pour la mesure de la conductivite electrolytique

Country Status (4)

Country Link
US (2) US20020011846A1 (fr)
EP (1) EP0988535A1 (fr)
AT (1) AT405884B (fr)
WO (1) WO1998057160A1 (fr)

Families Citing this family (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6572752B1 (en) 1999-09-29 2003-06-03 Hitachi, Ltd. Capillary electrophoretic instrument and capillary array assembly
US6491805B1 (en) * 2000-05-23 2002-12-10 Agilent Technologies, Inc. Sample-analysis system with antisynchronously driven contactless conductivity detector
US7602369B2 (en) * 2004-05-04 2009-10-13 Sharp Laboratories Of America, Inc. Liquid crystal display with colored backlight
JP4194532B2 (ja) * 2004-06-16 2008-12-10 キヤノン株式会社 情報処理装置及びジョブ転送制御方法
WO2008067615A1 (fr) * 2006-12-07 2008-06-12 The University Of Queensland Procédé et appareil de contrôle non intrusif de matériaux transportés par des canalisations
KR101011827B1 (ko) * 2008-06-10 2011-02-07 한국표준과학연구원 비접촉식 전기전도도 측정장치
CA2751165C (fr) 2009-02-05 2017-08-22 National Research Council Of Canada Capteur pour mesurer la concentration d'un solvant ou d'un solute dans un systeme mixte en solution
CN102854275B (zh) * 2012-07-29 2014-11-12 安徽皖仪科技股份有限公司 基于dsp的离子色谱数字电导检测装置

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2402030A1 (de) * 1974-01-17 1975-07-24 Wolfgang Dipl Phys Dr Issel Kapazitive elektrode fuer feuchtemessung an pflanzen
CA1017001A (en) * 1974-10-18 1977-09-06 Sed Systems Ltd. Fluid conductivity detecting means

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
See references of WO9857160A1 *

Also Published As

Publication number Publication date
US20020008522A1 (en) 2002-01-24
ATA101697A (de) 1999-04-15
AT405884B (de) 1999-12-27
WO1998057160A1 (fr) 1998-12-17
US20020011846A1 (en) 2002-01-31

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