CA2173464A1 - Method and device for the determination of substances in solution - Google Patents
Method and device for the determination of substances in solutionInfo
- Publication number
- CA2173464A1 CA2173464A1 CA002173464A CA2173464A CA2173464A1 CA 2173464 A1 CA2173464 A1 CA 2173464A1 CA 002173464 A CA002173464 A CA 002173464A CA 2173464 A CA2173464 A CA 2173464A CA 2173464 A1 CA2173464 A1 CA 2173464A1
- Authority
- CA
- Canada
- Prior art keywords
- electrode
- accordance
- determination
- measuring probe
- dissolved
- 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.)
- Abandoned
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
- G01N27/28—Electrolytic cell components
- G01N27/30—Electrodes, e.g. test electrodes; Half-cells
- G01N27/38—Cleaning of electrodes
-
- 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
- G01N27/49—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
Abstract
A method for the determination of dissolved substances, in particular oxygen, is described, which is distinguished by an open, diaphragm-free system in a potentiostatic three-electrode arrangement with mechanical self-cleaning. A novel possibility for generating the required reference potential by means of a current-loaded metal electrode offers the option of the employment of the most diverse electrode materials and permits the removal of cross sensibilities in the determination of the dissolved substances.
The corresponding apparatus provides the integration of the potentiostat, the electronic controls and the signal processing in one and the same measuring probe. It permits the determination of different analysis media.
The method described has its application in technical processing installations, in particular in sewage and potable water processing systems, in food technology, in pharmaceutical technology and in biotechnology, as well as in chemical-technical processes.
The corresponding apparatus provides the integration of the potentiostat, the electronic controls and the signal processing in one and the same measuring probe. It permits the determination of different analysis media.
The method described has its application in technical processing installations, in particular in sewage and potable water processing systems, in food technology, in pharmaceutical technology and in biotechnology, as well as in chemical-technical processes.
Description
~173~64 Method and Apparatus for Determ;n;n~ Dissolved Substances The invention relates to a method for operating an open measuring probe with mechanical self-cleaning and a three-electrode arrangement in accordance with claim 1 and a corresponding apparatus therefor in accordance with claim 5.
The measurement of dissolved oxygen is performed in accordance with DIN 38408, for examplç, wherein either the idiometric titration of Winkler (DIN 38408-G21) is employed, or the dissolved oxygen is determined by means of measurement with a diaphragm-covered oxygen probe (DIN 38408-G22). Among the diaphragm-covered oxygen probes are, for example, Clark sensors, Makereth sensors and the sensors of Connery, Taylor and Muly.
They essentially differ by the construction of the sensor or the type of electrode material employed.
The measuring principle on which these oxygen probes are based is identical and is described in what follows: a portion of the dissolved oxygen corresponding to the total concentration is electro-chemically converted at one of the electrodes. The current flowing in the process and registered as the primary measurement signal functionally depends on the oxygen concentration. The electrode potential required for conversion is generated either by polarization by means of an external voltage source or by suitable electrode reactions in the system itself.
A device of the last mentioned type is known from EP
144,325. In accordance with this patent an arrangement with two electrodes is described, which essentially consist of different materials, wherein both electrodes are completely embedded in an insulating material with the exception of their effective free ends. A movable, driven grinding element is provided for cleaning ~173464 these electrode end faces, wherein the shape, the size and the mutual distance of the effective electrode surfaces remain unchanged during continuing grinding of the electrodes and the insulating material. The effect of a current flowing between an amalgam electrode (cathode) and an iron or zinc electrode (anode), whose value is a function of the actual oxygen concentration, is used for generating the measuring signal. Thus, polarization takes place only by means of the potentials being formed at the anode. In part these are only partially defined and are subject to various effects, so that the oxygen signal, for example, is subject to cross interference. A result of this are instabilities of the oxygen signal and non-linearities caused by cross effects, such as occur for example in the presence of tensides from laundry and cleaning materials in the measured solution. Also disadvantageous is the use of only a few possible electrode materials, which limits the use of the probe to defined analysis media.
It is the object of the instant invention to propose a method for determining electro-active substances in solution, in particular oxygen, and a suitable apparatus, based on an open, i.e. diaphragm-free measuring probe with mechanical self-cleaning, which by means of a three-electrode arrangement is essentially free of cross effects, can always be optimally adapted to the measuring problem, and by means of which linearity can be `
improved, along with simultaneously increased stability of the neutral point.
This object is attained in accordance with the invention with a method according to the wording of claim 1, and with an apparatus according to the wording of claim 5. The invention will be described in detail below by means of the drawings. Shown are ln:
~ 7346~
Fig. 1, the principle of the three-electrode arrangement in a schematic representation with a reference electrode under current load, Fig. 2, an exemplary embodiment of an oxygen probe with a three-electrode arrangement, Fig. 3, an exemplary embodiment of an oxygen probe with a three-electrode arrangement in a top view, Fig. 4, an oxygen signal with a three-electrode arrangement in comparison with previous ones, Fig. 5, an oxygen signal with a three-electrode arrangement in a sulfide-containing solution, Fig. 6, an oxygen signal with a three-electrode arrangement in a tenside-containing solution.
Fig. 1 shows the principle of the three-electrode arrangement in a schematic representation. A work electrode 4, a backplate electrode 5 and a reference electrode 6 are in the container 1 which contains a solution of dissolved substances 2.
The dissolved substances are preferably those which are susceptible to ampero-metric determination, which are therefore electro-chemically active at the predetermined polarization voltage, such as oxygen, chlorine and other disinfectants and heavy metals. The work electrode 4 is made, for example, of noble metal, noble metal alloys, steel, graphite materials, glassy carbons or conducting polymers. The backplate electrode is mostly made of noble metal, steel, pure metals, graphite materials or glassy carbons. The reference electrode 6 is made of iron, zinc, silver, copper or alloys. The reference electrode 6 is in the near vicinity of the work electrode 4 in order to obtain the smallest possible ohmic voltage drop.
A modified potentiostat 7 is provided for operating the measuring arrangement, which connects the backplate electrode 5 or the reference electrode 6 via lines 8 or 9. The work electrode 4 is connected to the ground of the potentiostat 7 via the line 10.
The potentiostat 7 essentially contains a controllable regulator 11, whose output provides a selectable voltage at the output 12, which is defined in reference to the potential of the reference electrode. The modified potentiostat 7 furthermore contains a constant current source 13, which is switched in such a way that in a branch circuit the reference electrode is continuously under a load of constant current density. The main circuit of the measuring arrangement is led from the potentiostat 7 via the line 8, the backplate electrode S, the solution with the dissolved substances 2, the work electrode 4 and the line 10. The instrument 14 is used for measuring the current in the line 8.
The solution with the dissolved substances 2 is an electrolyte whose conductivity is a function of the type of the dissolved substances and can vary over a wide range.
By means of the employment of such a three-electrode arrangement it is possible to predetermine or set arbitrary polarizing voltages in a defined manner and to minimize cross effects in this way, improve linearity and stabilize the neutral points.
Considerably greater flexibility and combination possibilities of the electrode materials surprisingly result, in addition to the advantages regarding the elimination of cross effects, improvement of linearity and stability described ùp to now. These advantages not only resulted with the use of the previously described amalgam electrode, but also with a multitude of electrodes which are mostly safe for food, such as those made of noble metals, steel, graphite materials, glassy carbon or conducting polymers, such as polypyrroles. Another of the past disadvantages has been removed because of the possibility of the specific selection of the electrode materials. Other materials than those used up to now (iron/zinc) are also possible for the ~173464 backplate electrode, wherein chemically resistant ones, such as special steel, noble metals or glassy carbon are preferably employed.
Due to the fact that this is an open probe, i.e. not covered with a diaphragm, conventional reference electrode systems are no longer suitable. A completely new path is taken here. In the process, action is taken on the mixed potential which is formed on a metal electrode (for example made of iron). For example, in order to utilize an iron electrode as the reference electrode for the potentiostatic oxygen determination, its potential must be independent of the oxygen content in the solution and of accompanying substances. This is achieved by using an anodic current flowing over the reference electrode which suppresses the cathodic partial current during the mixed potential formation. It is possible to reduce the oxygen dependency of such an electrode, through which current flows, to an unexpected low value of maximally i 10 mV by a chronologically constant current load of a defined value. Furthermore, the potential surprisingly displays only low sensitivity to accompanying substances, in particular sulfide and iron. The good potential constancy assures a potentiostatic operation of an open three-electrode arrangement with mechanical self-cleaning. Besides iron, other pure metals such as zinc, silver and copper as well as alloys can be used as electrode materials.
Fig. 2 shows an exemplary embodiment of such a measuring probe with a three-electrode arrangement which, as an immersion probe, is provided with a handle 18. All three electrodes are placed on one level inside a probe cup 16. The required electronic elements (potentiostat and measured value processing) are components of the probe and housed in the housing of the drive motor 15. This has the advantage that only two wires 17a and 17b - - ~17346~
are required for signal transmission and that transmission distances of several hundreds of meters are possible.
Fig. 3 shows the exemplary embodiment of such a measuring probe with a three-electrode arrangement in a top view. The work electrode 4, the reference electrode 6 and the backplate electrode 5 are made concentric, however, other geometric arrangements are also possible. The surface of the reference electrode 6 is very small compared with the surface of the work electrode 4 which, in turn, is less than that of the backplate electrode 5. All three electrodes are continuously cleaned by the grinding device 19.
Fig. 4 shows oxygen signals with the three-electrode arrangement in comparison with previously achieved oxygen signals, such as have been achieved with an oxygen probe (S12) manufactured in accordance with Patent EP 144,325. The oxygen signals (S12-3E) determined by means of the invention are linear over the entire possible measuring range from O to approximately 50 mg/l. In comparison with this, the signal of the previously described oxygen probe (S12) is bent off the straight line starting approximately at 15 mg/l. Because of good linearity a simple calibration is also achieved in the upper measuring range.
Fig. 5 shows oxygen signals with a three-electrode arrangement measured in a sulfide-containing solution. In the process, the oxygen concentration was increased from 0.5 to 8 mg/l in a constant sulfide concentration of 50 mg/l. The electrode poisoning of the previously described oxygen electrode resulted in that the measured signal (S12) had no relationship with the actual oxygen content of the solutisn. In contrast and surprisingly, the probe signal (S12-E3) of the three-electrode arrangement is practically not affected at all.
Fig. 6 shows oxygen signals with a three-electrode arrangement measured in a tenside-containing solution. The anionic tenside, sodium dodecylbenzene sulfonate, is added to a 2173~64 constant oxygen content of approximately 8 mg/l. With the previously described oxygen probe the effect of the tenside led to a reduction of the signal (S12). In the process, a deviation of approximately 30~ results at 50 mg tenside/l. Unaffected by the tenside content, the probe of the invention with a three-electrode arrangement shows an unexpected constant measured signal (S12-3E).
The method and apparatus of the type described are used for the determination of dissolved substances in technical processing installations, in particular in sewage and potable water processing systems, in food technology, in pharmaceutical technology and in biotechnology, as well as in chemical-technical processes.
It is important for the invention that the attainment in accordance with the invention of the object is distinguished by:
- an open, diaphragm-less system with a potentiostatic three-electrode arrangement with mechanical self-cleaning, - a novel possibility for generating the required reference potential by means of a metal electrode under current load, - the possibility of the employment of the most diverse electrode materials, - the integration of the potentiostat into the measuring probe, - the possibility to determine various analysis media, - and the removal of cross-sensitivities.
The measurement of dissolved oxygen is performed in accordance with DIN 38408, for examplç, wherein either the idiometric titration of Winkler (DIN 38408-G21) is employed, or the dissolved oxygen is determined by means of measurement with a diaphragm-covered oxygen probe (DIN 38408-G22). Among the diaphragm-covered oxygen probes are, for example, Clark sensors, Makereth sensors and the sensors of Connery, Taylor and Muly.
They essentially differ by the construction of the sensor or the type of electrode material employed.
The measuring principle on which these oxygen probes are based is identical and is described in what follows: a portion of the dissolved oxygen corresponding to the total concentration is electro-chemically converted at one of the electrodes. The current flowing in the process and registered as the primary measurement signal functionally depends on the oxygen concentration. The electrode potential required for conversion is generated either by polarization by means of an external voltage source or by suitable electrode reactions in the system itself.
A device of the last mentioned type is known from EP
144,325. In accordance with this patent an arrangement with two electrodes is described, which essentially consist of different materials, wherein both electrodes are completely embedded in an insulating material with the exception of their effective free ends. A movable, driven grinding element is provided for cleaning ~173464 these electrode end faces, wherein the shape, the size and the mutual distance of the effective electrode surfaces remain unchanged during continuing grinding of the electrodes and the insulating material. The effect of a current flowing between an amalgam electrode (cathode) and an iron or zinc electrode (anode), whose value is a function of the actual oxygen concentration, is used for generating the measuring signal. Thus, polarization takes place only by means of the potentials being formed at the anode. In part these are only partially defined and are subject to various effects, so that the oxygen signal, for example, is subject to cross interference. A result of this are instabilities of the oxygen signal and non-linearities caused by cross effects, such as occur for example in the presence of tensides from laundry and cleaning materials in the measured solution. Also disadvantageous is the use of only a few possible electrode materials, which limits the use of the probe to defined analysis media.
It is the object of the instant invention to propose a method for determining electro-active substances in solution, in particular oxygen, and a suitable apparatus, based on an open, i.e. diaphragm-free measuring probe with mechanical self-cleaning, which by means of a three-electrode arrangement is essentially free of cross effects, can always be optimally adapted to the measuring problem, and by means of which linearity can be `
improved, along with simultaneously increased stability of the neutral point.
This object is attained in accordance with the invention with a method according to the wording of claim 1, and with an apparatus according to the wording of claim 5. The invention will be described in detail below by means of the drawings. Shown are ln:
~ 7346~
Fig. 1, the principle of the three-electrode arrangement in a schematic representation with a reference electrode under current load, Fig. 2, an exemplary embodiment of an oxygen probe with a three-electrode arrangement, Fig. 3, an exemplary embodiment of an oxygen probe with a three-electrode arrangement in a top view, Fig. 4, an oxygen signal with a three-electrode arrangement in comparison with previous ones, Fig. 5, an oxygen signal with a three-electrode arrangement in a sulfide-containing solution, Fig. 6, an oxygen signal with a three-electrode arrangement in a tenside-containing solution.
Fig. 1 shows the principle of the three-electrode arrangement in a schematic representation. A work electrode 4, a backplate electrode 5 and a reference electrode 6 are in the container 1 which contains a solution of dissolved substances 2.
The dissolved substances are preferably those which are susceptible to ampero-metric determination, which are therefore electro-chemically active at the predetermined polarization voltage, such as oxygen, chlorine and other disinfectants and heavy metals. The work electrode 4 is made, for example, of noble metal, noble metal alloys, steel, graphite materials, glassy carbons or conducting polymers. The backplate electrode is mostly made of noble metal, steel, pure metals, graphite materials or glassy carbons. The reference electrode 6 is made of iron, zinc, silver, copper or alloys. The reference electrode 6 is in the near vicinity of the work electrode 4 in order to obtain the smallest possible ohmic voltage drop.
A modified potentiostat 7 is provided for operating the measuring arrangement, which connects the backplate electrode 5 or the reference electrode 6 via lines 8 or 9. The work electrode 4 is connected to the ground of the potentiostat 7 via the line 10.
The potentiostat 7 essentially contains a controllable regulator 11, whose output provides a selectable voltage at the output 12, which is defined in reference to the potential of the reference electrode. The modified potentiostat 7 furthermore contains a constant current source 13, which is switched in such a way that in a branch circuit the reference electrode is continuously under a load of constant current density. The main circuit of the measuring arrangement is led from the potentiostat 7 via the line 8, the backplate electrode S, the solution with the dissolved substances 2, the work electrode 4 and the line 10. The instrument 14 is used for measuring the current in the line 8.
The solution with the dissolved substances 2 is an electrolyte whose conductivity is a function of the type of the dissolved substances and can vary over a wide range.
By means of the employment of such a three-electrode arrangement it is possible to predetermine or set arbitrary polarizing voltages in a defined manner and to minimize cross effects in this way, improve linearity and stabilize the neutral points.
Considerably greater flexibility and combination possibilities of the electrode materials surprisingly result, in addition to the advantages regarding the elimination of cross effects, improvement of linearity and stability described ùp to now. These advantages not only resulted with the use of the previously described amalgam electrode, but also with a multitude of electrodes which are mostly safe for food, such as those made of noble metals, steel, graphite materials, glassy carbon or conducting polymers, such as polypyrroles. Another of the past disadvantages has been removed because of the possibility of the specific selection of the electrode materials. Other materials than those used up to now (iron/zinc) are also possible for the ~173464 backplate electrode, wherein chemically resistant ones, such as special steel, noble metals or glassy carbon are preferably employed.
Due to the fact that this is an open probe, i.e. not covered with a diaphragm, conventional reference electrode systems are no longer suitable. A completely new path is taken here. In the process, action is taken on the mixed potential which is formed on a metal electrode (for example made of iron). For example, in order to utilize an iron electrode as the reference electrode for the potentiostatic oxygen determination, its potential must be independent of the oxygen content in the solution and of accompanying substances. This is achieved by using an anodic current flowing over the reference electrode which suppresses the cathodic partial current during the mixed potential formation. It is possible to reduce the oxygen dependency of such an electrode, through which current flows, to an unexpected low value of maximally i 10 mV by a chronologically constant current load of a defined value. Furthermore, the potential surprisingly displays only low sensitivity to accompanying substances, in particular sulfide and iron. The good potential constancy assures a potentiostatic operation of an open three-electrode arrangement with mechanical self-cleaning. Besides iron, other pure metals such as zinc, silver and copper as well as alloys can be used as electrode materials.
Fig. 2 shows an exemplary embodiment of such a measuring probe with a three-electrode arrangement which, as an immersion probe, is provided with a handle 18. All three electrodes are placed on one level inside a probe cup 16. The required electronic elements (potentiostat and measured value processing) are components of the probe and housed in the housing of the drive motor 15. This has the advantage that only two wires 17a and 17b - - ~17346~
are required for signal transmission and that transmission distances of several hundreds of meters are possible.
Fig. 3 shows the exemplary embodiment of such a measuring probe with a three-electrode arrangement in a top view. The work electrode 4, the reference electrode 6 and the backplate electrode 5 are made concentric, however, other geometric arrangements are also possible. The surface of the reference electrode 6 is very small compared with the surface of the work electrode 4 which, in turn, is less than that of the backplate electrode 5. All three electrodes are continuously cleaned by the grinding device 19.
Fig. 4 shows oxygen signals with the three-electrode arrangement in comparison with previously achieved oxygen signals, such as have been achieved with an oxygen probe (S12) manufactured in accordance with Patent EP 144,325. The oxygen signals (S12-3E) determined by means of the invention are linear over the entire possible measuring range from O to approximately 50 mg/l. In comparison with this, the signal of the previously described oxygen probe (S12) is bent off the straight line starting approximately at 15 mg/l. Because of good linearity a simple calibration is also achieved in the upper measuring range.
Fig. 5 shows oxygen signals with a three-electrode arrangement measured in a sulfide-containing solution. In the process, the oxygen concentration was increased from 0.5 to 8 mg/l in a constant sulfide concentration of 50 mg/l. The electrode poisoning of the previously described oxygen electrode resulted in that the measured signal (S12) had no relationship with the actual oxygen content of the solutisn. In contrast and surprisingly, the probe signal (S12-E3) of the three-electrode arrangement is practically not affected at all.
Fig. 6 shows oxygen signals with a three-electrode arrangement measured in a tenside-containing solution. The anionic tenside, sodium dodecylbenzene sulfonate, is added to a 2173~64 constant oxygen content of approximately 8 mg/l. With the previously described oxygen probe the effect of the tenside led to a reduction of the signal (S12). In the process, a deviation of approximately 30~ results at 50 mg tenside/l. Unaffected by the tenside content, the probe of the invention with a three-electrode arrangement shows an unexpected constant measured signal (S12-3E).
The method and apparatus of the type described are used for the determination of dissolved substances in technical processing installations, in particular in sewage and potable water processing systems, in food technology, in pharmaceutical technology and in biotechnology, as well as in chemical-technical processes.
It is important for the invention that the attainment in accordance with the invention of the object is distinguished by:
- an open, diaphragm-less system with a potentiostatic three-electrode arrangement with mechanical self-cleaning, - a novel possibility for generating the required reference potential by means of a metal electrode under current load, - the possibility of the employment of the most diverse electrode materials, - the integration of the potentiostat into the measuring probe, - the possibility to determine various analysis media, - and the removal of cross-sensitivities.
Claims (11)
1. A method for determining dissolved substances by means of an open, diaphragm-less measuring probe provided with mechanical self-cleaning and having a work electrode (4), a backplate electrode (5) and a reference electrode (6), characterized in that the measuring probe is dipped into the solution of the dissolved substances, that an anodic current flows over the reference electrode (6) so that the cathodic partial current is essentially suppressed during the formation of the mixed potential and a defined reference potential is created in this way, that by means of this it is possible to definitely set an arbitrary and freely selectable polarization voltage, because of which the determination of the various analysis media is made possible, that active electrode surfaces are always provided by the means of the mechanical self-cleaning, that interfering cross effects are eliminated or minimized by the type of circuitry, and that by means of this the dissolved substances are determined.
2. A method in accordance with claim 1, characterized in that the dissolved substances are those which are electro-chemically converted at the work electrode (4).
3. A method in accordance with claim 1, characterized in that the dissolved substances are oxygen or chlorine.
4. Application of the method in accordance with one of claims 1 to 3 for the determination of dissolved substances in technical processing installations, in particular in sewage and potable water processing systems, in food technology, in pharmaceutical technology and in biotechnology, as well as in chemical-technical processes.
5. An apparatus for executing the method in accordance with one of claims 1 to 4, consisting of an open, diaphragm-less measuring probe provided with mechanical self-cleaning and of a work electrode (4), a backplate electrode (5) and a reference electrode (6), characterized in that the reference electrode is made of iron, zinc, silver, copper or alloys, that all three electrodes (4, 5, 6) are located in one and the same housing, and that the surfaces of the electrodes (4, 5, 6) are located on one level.
6. An apparatus in accordance with claim 5, characterized in that the measuring probe is intended for determining dissolved, electro-chemical substances which can be converted at the work electrode (4).
7. An apparatus in accordance with claim 6, characterized in that the measuring probe is intended for the determination of dissolved oxygen.
8. An apparatus in accordance with claim 6, characterized in that the measuring probe is intended for the determination of dissolved chlorine.
9. An apparatus in accordance with claims 5 to 8, characterized in that the work electrode (4) is made of noble metals, their alloys, of steel, graphite materials, glassy carbons or conducting polymers.
10. An apparatus in accordance with claims 5 to 8, characterized in that the backplate electrode (5) is made of noble metals, their alloys, of steel, graphite materials or glassy carbons.
11. An apparatus in accordance with claims 5 to 10, characterized in that means for mechanical self-cleaning are provided.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CH2496/94-1 | 1994-08-12 | ||
| CH249694 | 1994-08-12 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2173464A1 true CA2173464A1 (en) | 1996-02-22 |
Family
ID=4235120
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002173464A Abandoned CA2173464A1 (en) | 1994-08-12 | 1995-08-11 | Method and device for the determination of substances in solution |
Country Status (6)
| Country | Link |
|---|---|
| EP (1) | EP0729576A1 (en) |
| JP (1) | JPH09504376A (en) |
| KR (1) | KR960705204A (en) |
| CN (1) | CN1134191A (en) |
| CA (1) | CA2173464A1 (en) |
| WO (1) | WO1996005509A1 (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP2708882A1 (en) * | 2012-09-13 | 2014-03-19 | Alstom Technology Ltd | Cleaning and grinding of sensor head |
Families Citing this family (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB9815248D0 (en) * | 1998-07-15 | 1998-09-09 | Johnson Matthey Plc | Apparatus |
| DE19925921A1 (en) * | 1999-06-07 | 2000-12-28 | Siemens Ag | Method and gas sensor for determining the oxygen partial pressure |
| DE10047708C2 (en) | 2000-09-25 | 2003-09-18 | Kempe Gmbh | Sensor for measuring O¶2¶ concentrations in liquids |
| DE10315338A1 (en) * | 2003-04-03 | 2004-10-14 | Mettler-Toledo Gmbh | Safety device for a built-in electrode device |
| DE102004017653B4 (en) * | 2004-04-05 | 2008-05-21 | Aqua Rotter Gmbh | Voltammetric method |
| KR20100087280A (en) * | 2007-09-03 | 2010-08-04 | 라 프로세스 아날라이저스 아게 | Method and device for determining the chemical oxygen requirement of water or waste water |
| JP2008203274A (en) * | 2008-05-27 | 2008-09-04 | Tacmina Corp | Residual chlorine meter, and liquid sterilization device using it |
| CN101498681B (en) * | 2009-03-13 | 2012-05-09 | 吴守清 | Electrode for measuring trace dissolved oxygen |
Family Cites Families (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4077861A (en) * | 1976-01-28 | 1978-03-07 | Teledyne Industries, Inc. | Polarographic sensor |
| US4440603A (en) * | 1982-06-17 | 1984-04-03 | The Dow Chemical Company | Apparatus and method for measuring dissolved halogens |
| CH659526A5 (en) * | 1983-06-02 | 1987-01-30 | Zuellig Ag | DEVICE FOR ELECTROCHEMICALLY DETERMINING THE OXYGEN CONTENT IN LIQUIDS. |
-
1995
- 1995-08-11 JP JP8506887A patent/JPH09504376A/en active Pending
- 1995-08-11 KR KR1019960701847A patent/KR960705204A/en not_active Application Discontinuation
- 1995-08-11 CN CN95190763A patent/CN1134191A/en active Pending
- 1995-08-11 WO PCT/CH1995/000178 patent/WO1996005509A1/en active Application Filing
- 1995-08-11 EP EP95926823A patent/EP0729576A1/en not_active Withdrawn
- 1995-08-11 CA CA002173464A patent/CA2173464A1/en not_active Abandoned
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP2708882A1 (en) * | 2012-09-13 | 2014-03-19 | Alstom Technology Ltd | Cleaning and grinding of sensor head |
| CN103675069A (en) * | 2012-09-13 | 2014-03-26 | 阿尔斯通技术有限公司 | Cleaning and grinding of sulfite sensor head |
| US9579765B2 (en) | 2012-09-13 | 2017-02-28 | General Electric Technology Gmbh | Cleaning and grinding of sulfite sensor head |
| CN103675069B (en) * | 2012-09-13 | 2017-04-12 | 通用电器技术有限公司 | Cleaning and grinding of sulfite sensor head |
Also Published As
| Publication number | Publication date |
|---|---|
| CN1134191A (en) | 1996-10-23 |
| EP0729576A1 (en) | 1996-09-04 |
| JPH09504376A (en) | 1997-04-28 |
| KR960705204A (en) | 1996-10-09 |
| WO1996005509A1 (en) | 1996-02-22 |
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