GB2089997A - Replaceable junctions for reference electrodes - Google Patents
Replaceable junctions for reference electrodes Download PDFInfo
- Publication number
- GB2089997A GB2089997A GB8137794A GB8137794A GB2089997A GB 2089997 A GB2089997 A GB 2089997A GB 8137794 A GB8137794 A GB 8137794A GB 8137794 A GB8137794 A GB 8137794A GB 2089997 A GB2089997 A GB 2089997A
- Authority
- GB
- United Kingdom
- Prior art keywords
- reference electrode
- junction
- removable
- encasing body
- electrode
- 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.)
- Granted
Links
- 239000003792 electrolyte Substances 0.000 claims abstract description 24
- 239000000919 ceramic Substances 0.000 claims description 14
- 239000011521 glass Substances 0.000 claims description 11
- 239000012488 sample solution Substances 0.000 claims description 9
- 239000000243 solution Substances 0.000 description 19
- 150000002500 ions Chemical class 0.000 description 9
- 238000001914 filtration Methods 0.000 description 7
- 238000005259 measurement Methods 0.000 description 6
- 239000000523 sample Substances 0.000 description 6
- -1 silver ions Chemical class 0.000 description 5
- 230000000694 effects Effects 0.000 description 4
- 239000000463 material Substances 0.000 description 4
- 239000004743 Polypropylene Substances 0.000 description 3
- 239000004020 conductor Substances 0.000 description 3
- 239000008151 electrolyte solution Substances 0.000 description 3
- 238000003780 insertion Methods 0.000 description 3
- 230000037431 insertion Effects 0.000 description 3
- 239000012528 membrane Substances 0.000 description 3
- 239000000203 mixture Substances 0.000 description 3
- 229920001155 polypropylene Polymers 0.000 description 3
- VEXZGXHMUGYJMC-UHFFFAOYSA-M Chloride anion Chemical compound [Cl-] VEXZGXHMUGYJMC-UHFFFAOYSA-M 0.000 description 2
- WCUXLLCKKVVCTQ-UHFFFAOYSA-M Potassium chloride Chemical compound [Cl-].[K+] WCUXLLCKKVVCTQ-UHFFFAOYSA-M 0.000 description 2
- 239000010425 asbestos Substances 0.000 description 2
- 239000007853 buffer solution Substances 0.000 description 2
- GTKRFUAGOKINCA-UHFFFAOYSA-M chlorosilver;silver Chemical compound [Ag].[Ag]Cl GTKRFUAGOKINCA-UHFFFAOYSA-M 0.000 description 2
- 238000005253 cladding Methods 0.000 description 2
- 239000000835 fiber Substances 0.000 description 2
- 239000012530 fluid Substances 0.000 description 2
- 239000007788 liquid Substances 0.000 description 2
- 238000001139 pH measurement Methods 0.000 description 2
- 239000004033 plastic Substances 0.000 description 2
- 239000011148 porous material Substances 0.000 description 2
- 229910052895 riebeckite Inorganic materials 0.000 description 2
- 229920006395 saturated elastomer Polymers 0.000 description 2
- 230000035945 sensitivity Effects 0.000 description 2
- UCKMPCXJQFINFW-UHFFFAOYSA-N Sulphide Chemical compound [S-2] UCKMPCXJQFINFW-UHFFFAOYSA-N 0.000 description 1
- 229910052946 acanthite Inorganic materials 0.000 description 1
- 125000000129 anionic group Chemical group 0.000 description 1
- 238000000137 annealing Methods 0.000 description 1
- 230000002547 anomalous effect Effects 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 239000000872 buffer Substances 0.000 description 1
- 229940075397 calomel Drugs 0.000 description 1
- 230000002596 correlated effect Effects 0.000 description 1
- 230000001419 dependent effect Effects 0.000 description 1
- 238000009792 diffusion process Methods 0.000 description 1
- ZOMNIUBKTOKEHS-UHFFFAOYSA-L dimercury dichloride Chemical compound Cl[Hg][Hg]Cl ZOMNIUBKTOKEHS-UHFFFAOYSA-L 0.000 description 1
- 229920006333 epoxy cement Polymers 0.000 description 1
- 238000011067 equilibration Methods 0.000 description 1
- 150000004677 hydrates Chemical class 0.000 description 1
- 230000036571 hydration Effects 0.000 description 1
- 238000006703 hydration reaction Methods 0.000 description 1
- 230000002209 hydrophobic effect Effects 0.000 description 1
- 150000002632 lipids Chemical class 0.000 description 1
- 230000013011 mating Effects 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 238000000034 method Methods 0.000 description 1
- 239000012466 permeate Substances 0.000 description 1
- 238000003969 polarography Methods 0.000 description 1
- 229920000131 polyvinylidene Polymers 0.000 description 1
- 235000011164 potassium chloride Nutrition 0.000 description 1
- 239000001103 potassium chloride Substances 0.000 description 1
- 238000001205 potentiostatic coulometry Methods 0.000 description 1
- 102000004169 proteins and genes Human genes 0.000 description 1
- 108090000623 proteins and genes Proteins 0.000 description 1
- 238000006479 redox reaction Methods 0.000 description 1
- 229910052709 silver Inorganic materials 0.000 description 1
- 239000004332 silver Substances 0.000 description 1
- FSJWWSXPIWGYKC-UHFFFAOYSA-M silver;silver;sulfanide Chemical compound [SH-].[Ag].[Ag+] FSJWWSXPIWGYKC-UHFFFAOYSA-M 0.000 description 1
- 239000007790 solid phase Substances 0.000 description 1
- 239000002904 solvent Substances 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 208000024891 symptom Diseases 0.000 description 1
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
- G01N27/301—Reference electrodes
Landscapes
- Chemical & Material Sciences (AREA)
- Life Sciences & Earth Sciences (AREA)
- Health & Medical Sciences (AREA)
- Physics & Mathematics (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Electrochemistry (AREA)
- Molecular Biology (AREA)
- Analytical Chemistry (AREA)
- Biochemistry (AREA)
- General Health & Medical Sciences (AREA)
- General Physics & Mathematics (AREA)
- Immunology (AREA)
- Pathology (AREA)
- Investigating Or Analyzing Materials By The Use Of Electric Means (AREA)
Abstract
A reference electrode (30) comprises an enclosure containing a half-cell electrode (32), a half-cell electrolyte (36) and a reference junction positioned in an outlet (38) for the electrolyte. The half-cell electrode is connectable to an external measuring means. A removable and replaceable reference junction comprises a removable body (44) encasing a porous member (46). The porous member (46) is in length only up to about one half the length of the encasing body (44) and is fixedly inserted through the outlet (38). <IMAGE>
Description
SPECIFICATION
Improved replaceable junctions for reference electrodes
The present invention relates to reference electrodes, and the reference electrode portion of combination electrodes, which are employed to provide the stable reference portentials required by a variety of electroanalytical techniques, such as ion-selective electrode measurements, controlled potential coulometry, polarography, and the like. More particularly, the present invention is concerned with a reference electrode and the reference electrode portion of a combination electrode, each having an improved removable and replaceable junction.
A reference electrode is most frequently used in conjunction with an ion-sensitive electrode, either separately or in combination, to measure the activity (which is a function of concentration) of a given ion in a sample solution. Consequently, the discussion which follows primarily relates to such use. It is to be understood, however, that such discussion is not intended to in any way limit the scope of the present invention.
The two electrodes, i.e., the reference electrode and the ion-selective electrode, both of which are immersed in the sample solution, typically are connected to a means for measuring the potential difference between the two electrodes, e.g., an electrometer. The reference electrode provides a constant electromotive force or potential against which the potential of the ion-selective electrode is compared. The latter potential consists of a constant component from the electrochemical half-cell of the ion-selective electrode and a variable component which is the potential across the sensing membrane and which is dependent upon the activity (concentration) of the ion being measured. The variable component, then, is readily correlated with ion activity (concentration) by known means.To give accurate results, the potential of the reference electrode should not change with the composition of the sample.
The reference electrode is designed to be minimally sensitive to changes in the external, sample ionic environment. It consists of at least three components: (1 ) a half-cell electrode (typically a silver-silver chloride mixture), (2) a half-cell electrolyte (typically 4 M potassium chloride solution saturated with silver ions), and (3) a reference junction. The half-cell electrode and half-cell electrolyte constitute an electrochemical half-cell having a known, stable, constant electrical potential. Direct physical, and therefore electrical, contact between the half-cell electrolyte and the sample solution is established through the reference junction which usually consists of a porous ceramic plug, metal or asbestos fibre bundle, sintered plastic, or like means of achieving a fluid mechanical leak.
As used herein, the term "half-cell electrode" means the solid-phase, electron-conducting contact with the half-cell electrolyte, at which contact the half-cell oxidation-reduction reaction occurs which establishes the stable potential between the half-cell electrolyte and the contact.
Because the junction electrolyte and the measured sample usually differ in ionic strength and transference, a "liquid junction potential" typically develops across the reference junction.
Variation in this junction potential from sample to sample is a source of error in electrode measurements, and one goal of reference electrode technology is to make the junction potential as small, stable, and reproducible as possible. But the reference junction, for various reasons usually involving clogging, can become wholly or partly inoperable Clogging of junction pores by foreign materials disrupts the direct physical contact which is required to establish a stable, reproducible liquid junction potential between the internal and measured solutions.
Also, clogging typically introduces fixed ionic charge into the junction, which causes an anomalous increase in junction potential in lowionic-strength measurements. Also, in many reference electrode designs, the internal filling solution flows out of the reference electrode into the measured solution. We have found that this flow generally results in faster and more accurate response, since the flow serves to flush the previously measured solution more rapidly from the junction and also serves to increase the ionic strength at the junction surface, thereby reducing anomalies due to fixed space-charge in the junction. Clogging blocks this beneficial flow of junction electrolyte, leading to slower, less accurate measurements. Finally, clogging increases the electrical resistance of the junction, which causes a proportionate increase in the electrical noise of the measurement.Thus, typical symptoms of a clogged junction include slow, erratic, noisy, and often erroneous response
Junction clogging may arise from a variety of sources, both extrinsic and intrinsic. For example, the proteins and lipids present in many measured samples tend, because of electrostatic and hydrophobic forces, to bind to and permeate many junction materials. Also, certain components of the filling solution tend to precipitate when coming into contact with the measured solution within the junction. For example, AgCI and Ag2S tend to precipitate within the junction of Ag/AgCI reference electrodes immersed in dilute chlorideand sulphide-containing samples, respectively.
In the prior art, failure of the reference junction has usually meant replacement of the entire reference electrode, an expensive, undesirable solution where the reference junction is often the least expensive component of the reference electrode. Attempts to replace the reference junction by the laboratory practitioner have usually ended in failure, since in most high-quality electrodes, the junction is permanently fused or cemented to the electrode body. Even in electrode designs where the junction is held within an orifice by friction or pressure alone, the junction is typically too fragile to withstand the forces required for removal or insertion. Finally, even if the junction could be removed by force, some portion of the porous junction material would have to extend beyond the electrode body to allow traction.But we have found that protrusion of the porous material into the measured solution may contribute somewhat to slow and inaccurate response by introducing an element of spherical rather than planar diffusion. A flat junction surface is perferably, which is incompatible with protrusion of the porous member.
It is an object of this invention to provide an improved reference electrode.
A more specific object of this invention is to provide a reference electrode including an improved replaceable reference junction.
Another object of this invention is to provide a reference junction of design and strength capable of being removed and replaced by the equipment operator.
In accordance with the present invention, there is provided a reference electrode comprising an enclosure containing a half-celi electrode, a halfcell electrolyte, and a reference junction positioned in an outlet for the electrolyte, the halfcell electrode being connectable to an external measuring means, wherein a removable and replaceable reference junction comprising a removable encasing body encases a porous member, the said porous member being in length only up to about one half the length of the encasing body, and being fixedly inserted through the said outlet.
In a preferred embodiment of the present invention, one end of the porous member is positioned in the capillary tube so as to be flush with an end of the capillary tube and to extend through the tube up to about one half of the length of the tube, preferably up to about one third of the length of the capillary tube.
In another preferred embodiment of the present invention, a pH or other ion-selective sensing bulb also extends through the grommet in a combination electrode configuration.
In the accompanying drawings:
Figure 1 of the drawing is a schematic of a typical pH measurement system, illustrating the essential components thereof.
Figure 2 of the drawing depicts in cross-section a conventional reference junction positioned in a reference electrode.
Figure 3 of the drawing depicts in cross-section a reference junction of the present invention positioned in a reference electrode.
Figure 4 of the drawing depicts in cross-section a plurality of replaceable junctions of the present invention in a shippable container.
Figure 5 of the drawing depicts in cross-section an enlarged view of the reference junction of the present invention.
Figure 6 depicts a partial cross-section of a combination electrode with the junction of the present invention.
Figure 7 depicts in partial cross-section an alternative design exemplifying the present invention.
Figure 1 shows the elements of a pH measurement system. pH electrode 1 and reference electrode 3 are partially immersed in sample solution 5 inside of container 8 and both electrodes are electrically connected by conductors 13 and 1 5 to electrometer 1 7. The potential across the glass sensing-membrane 7 changes in proportion to differences in pH between external sample solution 5 and a pH buffer solution 9 contained within the sensor membrane. An electro-chemical half-cell 10 is used to establish a stable electrical connection between the buffer solution and the wire conductor going to the electrometer. This half-cell has a fixed potential usually determined by the chloride ion concentration of the buffer.The difference in potential between the external solution 5 and the positive electrometer terminal now changes with pH; and it is this change in potential that is to be monitored. The role of the reference electrode is to establish a fixed half-cell potential between the external measured solution and the negative electrometer terminal. In measurements of unknown solutions, the half-cell cannot be directly immersed in the sample, since its potential will vary with the unknown anionic, e.g., chloride ion activity, of the solution.
Therefore, an indirect reference connection is made by immersing the reference half-ceil 11 into a known electrolyte 1 9 (usually AgCI-saturated 4M KCI), and then establishing physical and electrical contact between this electrolyte and the measured solution through a reference junction 21 positioned in outlet 23. The reference junction usually consists of a porous ceramic plug, asbestos fibre, or other means of achieving a fluid mechanical leak. The reference junction functions primarily as a flow restrictor and filtration member, and also serves to define the shape of the interface between the solutions. Ideally, the junction is sufficiently porous to allow a iow resistance contact, preferably, well below 10K ohm, between the external and internal solutions, but is not so porous that the solutions become mutually contaminated.
As previously mentioned, Figure 2 is a detailed cross-sectional view of a conventional reference electrode and Figure 3 is a detailed cross-sectional view of the reference electrode of Figure 2, but including a reference junction as in the present invention.
In Figures 2 and 3, reference electrode 30 includes electrochemical half-cell 32, electrical conductor 34, electrolyte solution 36 and outlet 38 through which the reference junction will communicate with the sample solution, not shown. In Figure 2, ceramic plug 40 is inserted into outlet 38, while in Figure 3, a grommet 42 is fixedly inserted into the outlet, through which there is found hollow glass capillary tube 44 having porous ceramic plug 46 encased therein and extending about one third of the way up the tube. The tube and encased plug comprise the replaceable reference junction per se of this invention.
Figure 4 depicts in cross-section a shipping container 39 formed of mating screw cap lid 41 and body 43, in which there is placed a pluraiity of replaceable junctions 45 of the present invention.
In the shipping container, the replaceable junctions are completely immersed in solution 50, which is preferably the inner electrolyte into which the reference junction will be inserted so that an equilibration time is not required when the junction is inserted into the reference electrode.
Figure 5 depicts a preferred embodiment of the improved replaceable junction of the present invention in which glass capillary tube 52 of about two millimetres in outside diameter, about one millimetre in internal diameter and about twelve millimetres long is employed as the encasing sheath. A porous ceramic plug 54, about one millimetre in diameter and about 3 millimetres long is inserted into one end of the 12 millimetre long tube. A high flame, say about 1 2500C, is run over the outside of the tube encasing the ceramic to seal or clad the glass to the ceramic. Thereafter, end 56 of the tube is ground flat to the ceramic and end 58 is firepolished or bevelled to facilitate insertion into the grommet. Where desired, annealing of the cladding can be carried out.
Figure 6 is a cross-section of the lower end of a combination electrode 60 where both glass electrode 62 and reference junction 70 extend through grommet 66. Junction electrolyte 68 is contained within the combination electrode body.
Reference half-cell 64 extends into this electrolyte. Reference junction 70 extends through the grommet.
Furthermore, since a general feature of the present invention is the encasing of the porous junction member within an encasing body which facilitates its removal and insertion into the body of the reference electrode, this may be achieved by means other than those illustrated above. For example, rather than affixing the grommet to the electrode body, grommet means could be incorporated as an integral part of the removable encasing body.
In a further example, no grommet would be used, but either the removable encasing body itself or the reference electrode orifice would be made of a slightly compressible material, e.g., polypropylene, allowing a tight, leak-free fit between the junction-encasing body and electrode body. In Figure 7, removable polypropylene encasing body 80 for porous ceramic member 82 fits tightly into glass orifice 84 formed in electrode body 86.
We have invented a replaceable reference junction which differs from the present invention in that the filtration member of that other invention is of the same length as the glass capillary tube, that is the filtration member is coextensive from end to end with the capillary tube. The design of the present invention responds much more rapidly than that of the other invention because we have found that the maximal time for a solution to diffuse out of the filtration member, and hence the electrode response time, increases as a function of the square of the length of the filtration member, with or without outward flow. A second improvement over the other design is lowered electrical noise sensitivity of the reference electrode of this invention.A long porous member, such as a ceramic porous plug, often has excessive electrical resistance and the electrical noise sensitivity of a reference electrode is directly proportional to its electrical resistance, which in most cases is contributed almost entirely by the reference junction. Finally, upon initial hydration, air tends to become trapped within the excessive length of ceramic used in the other invention, often resulting in a poor or open electrical connection between the sample solution and the half-cell electrolyte of the reference electrode. The shorter ceramic junction of the present invention hydrates more readily and reliably.
In the present invention, the long capillary tube provides sufficient strength and handling ability while the length of the shorter filtration member can be varied for optimum performance. With
Corning Glass Works high flow ceramic No.
003798, a three millimetre length thereof encased within a 12 millimetre long glass capillary tube has been found to give good performance in most applications. More generally, the length of the ceramic plug typically will be in the range of from about 1 to about 5 millimetres, with the cladding typically having a length of from about 10 to about 20 millimetres.
Variations of the present invention will be apparent to the skilled artisan. For example, any porous member used as a junction in reference electrodes in the art should be usable in the present invention, as long as a compatible casing is known. For example, some porous members might not be usable where the glass tube is to be fired, but a plastic casing flowing at lower temperature or sealable by means of a softening solvent or epoxy cement could be employed, for example, a porous polypropylene or polyvinylidene plug encased at the end of a non-porous tube of the same composition. It is possible for the porous member to extend out of the encasing sheath, although such a configuration is also not preferred.Also, when used, the reference junction preferably should extend beyond the grommet in both direction, and it is preferred that the filtration member end of the reference junction extend sufficiently past the bottom of the grommet so that it can be grasped by tweezers or the like for removal, while the other end of the reference junction extends into the internal electrolyte solution. Furthermore, although the present invention has been illustrated by means of single junction reference electrode embodiments, the present invention is also applicable to double junction reference electrodes where the reference junction of the present invention would preferably be used as the outer reference junction between the outer electrolyte and sample solution, although it could also be used as the internal (inner) junction, between the half-cell electrolyte and outer electrolyte, particularly in pull-apart electrode designs.
The present invention is usable with the variously employed electrochemical half-cells, such as silver-silver chloride, calomel and so forth, and could be usable even with gelled internal electrolytes.
Claims (10)
1. A reference electrode comprising an enclosure containing a half-cell electrode, a halfcell electrolyte, and a reference junction positioned in an outlet for the electrolyte, the halfcell electrode being connectable to an external measuring means, wherein a removable and replaceable reference junction comprising a removable encasing body encases a porous member, the said porous member being in length only up to about one half the length of the encasing body and being fixedly inserted through the said outlet.
2. A reference electrode as claimed in Claim 1 wherein the outlet or the removable encasing body comprises a compressible grommet.
3. A reference electrode as claimed in Claim 2 wherein the outlet comprises a compressible grommet and the removable encasing body is a cylindrical tube.
4. A reference electrode as claimed in any preceding claim wherein the porous member has a length only up to one third the length of the removable encasing body.
5. A reference electrode as claimed in any of
Claims 1, 2, 3 or 4 wherein the entire porous member is encased within the removable encasing body.
6. A reference electrode as claimed in any of
Claims 1, 2, 3 or 4 wherein the entire porous member is encased within the removable encasing body and one end thereof is flush with one end of the removable encasing body.
7. A reference electrode as claimed in any of
Claims 2, 3 or 4 wherein the entire porous member is encased within the removable encasing body and one end thereof is flush with the removable encasing body, and the reference junction is positioned in the grommet so that the open end of the removable encasing body extends into the internal electrolyte.
8. A reference electrode as claimed in any of
Claims 2, 3 or 4 wherein the entire porous member is encased within the removable encasing body and one end thereof is flush with the removable encasing body, and the reference junction is positioned in the grommet so that the open end of the removable encasing body extends into the internal electrolyte, and the end of the removable encasing body closed by the porous member extends beyond the exterior side of the grommet to be in contact with the sample solution.
9. A reference electrode according to any one of Claims 2 to 8 wherein the removable encasing member is glass tubing cladded to a porous ceramic plug member.
10. A reference electrode according to Claim 9, in which the length of the porous member is in the range from 1 to 5 millimetres and the glass tubing has a length from 10 to 20 millimetres.
1 1. A reference electrode according to any one of Claims 1 to 10 characterised by the use in an immersed position in a solution contained within a shippable container.
1 2. A reference electrode substantially as described with reference to Figures 3 to 7 of the accompanying drawings.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US21878880A | 1980-12-22 | 1980-12-22 |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| GB2089997A true GB2089997A (en) | 1982-06-30 |
| GB2089997B GB2089997B (en) | 1985-06-26 |
Family
ID=22816517
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB8137794A Expired GB2089997B (en) | 1980-12-22 | 1981-12-15 | Replaceable junctions for reference electrodes |
Country Status (3)
| Country | Link |
|---|---|
| CH (1) | CH661595A5 (en) |
| DE (1) | DE3148440A1 (en) |
| GB (1) | GB2089997B (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR2541462A1 (en) * | 1983-02-17 | 1984-08-24 | Texaim | Miniature electrochemical reference electrode |
| WO2002103344A1 (en) * | 2001-06-19 | 2002-12-27 | Invensys Systems, Inc. | A replaceable reference junction including an ion-barrier for an electrochemical sensor |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5861457A (en) * | 1981-10-07 | 1983-04-12 | Yokogawa Hokushin Electric Corp | Ph meter sensor |
| DE3333660A1 (en) * | 1983-09-17 | 1985-04-11 | Fraunhofer-Gesellschaft zur Förderung der angewandten Forschung e.V., 8000 München | Electrode for electrochemical methods of measurement |
Family Cites Families (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| AT321868B (en) * | 1972-10-16 | 1975-04-25 | List Hans | ELECTROCHEMICAL ELECTRODE ARRANGEMENT |
| CH620298A5 (en) * | 1977-11-01 | 1980-11-14 | Proton Ag | Measuring electrode for measuring ions in solutions |
-
1981
- 1981-12-08 DE DE19813148440 patent/DE3148440A1/en active Granted
- 1981-12-15 GB GB8137794A patent/GB2089997B/en not_active Expired
- 1981-12-16 CH CH804481A patent/CH661595A5/en not_active IP Right Cessation
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR2541462A1 (en) * | 1983-02-17 | 1984-08-24 | Texaim | Miniature electrochemical reference electrode |
| WO2002103344A1 (en) * | 2001-06-19 | 2002-12-27 | Invensys Systems, Inc. | A replaceable reference junction including an ion-barrier for an electrochemical sensor |
Also Published As
| Publication number | Publication date |
|---|---|
| DE3148440C2 (en) | 1992-05-14 |
| DE3148440A1 (en) | 1982-09-16 |
| CH661595A5 (en) | 1987-07-31 |
| GB2089997B (en) | 1985-06-26 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PE20 | Patent expired after termination of 20 years |
Effective date: 20011214 |