CA1324418C - Reference electrode - Google Patents
Reference electrodeInfo
- Publication number
- CA1324418C CA1324418C CA000541808A CA541808A CA1324418C CA 1324418 C CA1324418 C CA 1324418C CA 000541808 A CA000541808 A CA 000541808A CA 541808 A CA541808 A CA 541808A CA 1324418 C CA1324418 C CA 1324418C
- Authority
- CA
- Canada
- Prior art keywords
- reference electrode
- ion
- electrode according
- water
- liquid
- 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.)
- Expired - Fee Related
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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
-
- 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
Abstract
ABSTRACT OF THE DISCLOSURE
A miniature, solid-state long-life reference electrode in which the amount of outflow of an internal electrolyte containing a halogen ion is reduced includes a conductor on the periphery of which is formed a sintered body consisting of a silver halide and silver oxide, a water-containing gel enveloping the conductor and including a halogen ion electrolyte, and a hollow tubular body closed by a liquid-junction portion comprising a porous ceramic, or by a partitioning wall having an ion permeable portion of a predetermined diffusion coefficient and volume. In another embodiment, the tubular body of the reference electrode is partitioned by a partitioning wall having an ion permeable portion of a predetermined diffusion coefficient and volume.
A miniature, solid-state long-life reference electrode in which the amount of outflow of an internal electrolyte containing a halogen ion is reduced includes a conductor on the periphery of which is formed a sintered body consisting of a silver halide and silver oxide, a water-containing gel enveloping the conductor and including a halogen ion electrolyte, and a hollow tubular body closed by a liquid-junction portion comprising a porous ceramic, or by a partitioning wall having an ion permeable portion of a predetermined diffusion coefficient and volume. In another embodiment, the tubular body of the reference electrode is partitioned by a partitioning wall having an ion permeable portion of a predetermined diffusion coefficient and volume.
Description
:`
132~418 - -?I~LE OF THE INVENTION
REFER~NCE ELECTRODE
BAC~GROUND OF THE INVENTION
1 Field of the Invention:
5This invention relates to a reference electrode and, more particularly, to a reference electrode used in mea~uring ion concentration, gas concentration and the e Further, the invention relaees to a reference elec~rode capable of operating ~tably for an extended 10 period of time in a biologi~al system or circulating ;~
circuit system . .
132~418 - -?I~LE OF THE INVENTION
REFER~NCE ELECTRODE
BAC~GROUND OF THE INVENTION
1 Field of the Invention:
5This invention relates to a reference electrode and, more particularly, to a reference electrode used in mea~uring ion concentration, gas concentration and the e Further, the invention relaees to a reference elec~rode capable of operating ~tably for an extended 10 period of time in a biologi~al system or circulating ;~
circuit system . .
2. CQscription o the Prior Art Examples of reference electrodes (also referred to a~ -co~parison Qlectrodes) ~nown in the art include ~atùrated 15~ calomel el-ctrod-J and ilver/silver chloride electrode~ -;
These reference electrodes are readily available on the mar~et and coqprise a glass tube accommodating a aaturated potassium or sodium chIoride solution and an electrodQ. Formed in the di~tal end portion of the tube 20~ i8 a liquid-~unction portion through which the solution of potas~ium or sodlum chloride is allowed to flow out 132~18 When a measurement is to be taken in a living body or body fluid, use of the saturated calomel electrode is hazardous since the electrode relies upon mercury. In such cases, therefore, the silver/silver chloride electrode is employed. However, the outflow of the potassium or sodium chloride solution in the latter electrode has a great effect upon a living body. For this reason, the liquid-junction portion is formed of a porous material to reduce the amount of outflow~
Nevertheless, fully satisfactory results are not obtained.
Another disadvantage of the conventional reference electrode is that the electrode is used in a living body or in a circuit system through which a body fluid circulates, the potential of the electrode is rendered unstable by changes in temperature. Though a potential which remains stable for a long period of time can be obtained -~ `
by adding a large quantity of potassium or sodium chloride crystals to the internal liquid chamber of the 20 electrode or adopting a porous body as the ` `
liquid-junction portion, these expedients make it difficult to miniaturize the electrode.
Anotber type of reference electrode is adapted to ``
..
enable replenishment of the sodium chloride which has -flowed out. Such an electrode enjoys a comparatively long ervice lif-l. However, in ord~r to allow this referonce ~ .
electrode to operate stably for an extended period of time in a biological system or circulating circuit and to ~; ...
,~ .
`: ':
1324~8 be integrated with any of a variety of sensors such as an ion sensor, the electrode is required to be of the solid-state type, small in size and possessed of a long life. However, a solid-state electrode of this kind does not enable the electrolyte to be replenished or replaced, and an expedient must be devised that reauces the amount of electrolyte outf low .
SUMMARY OF THE INVENTION
Accordingly, an object of the present invention is to provide a miniature, solid-state reference electrode which can be used safely in vivo or in a body fluid and stably, for an extended period of time, in vivo or in a circulating circuit, and which will not respond to the pH
of a specimen or be influenced by a temperature.
According to the invention, the reference electrode includes a liquid-~unction portion formed of a porous -ceramic, an electrode portion composed of an electrical conductor, which comprises platinum or silver, and a `
sintered body formed on the periphery of the conductor and containing silver halide and silver oxide. The electrode portion is enveloped by a water-containing gel containing a halogen ion electrolyte.
More specifically, the reference electrode of the present invention comprises: an electrode portion having an elec~rical conductor consisting of platinum or silver, ; ~ ~ and a sintered body formed on the periphery of the conductor and consisting of silver halide and silver ':
; oxide; a water-containing gel enveloping the electrode portion and containing halogen ion; a hollow tubular body accommodating the water-containing gel and having one end closed ~y a liquid-junction portion comprising a porous ceramic and its other end liquid-tightly ~ealed by a plug; and a conductor wire connected to the conductor and extended to pass tbrough the plug liquid tightly.
The porous ceramic has voids through which at least -halogen ions are capable of passing. ~-Since the liquid-junction portion is formed of a -porous ceramic, outflow Erom the source of halogen ion supply is ~uppressed, thereby enhancing the safety of the reference electrode. Furthermore, since the electrode portion includes the sintered body comprising silver halide and silver oxide formed on the periphery of the platinum or silver conductor and, moreover, since the ~ater-containing gel contains halogen ion, the potential of the electrode exhibits little dependence upon temperature. In addition, the reference electrode of the 20 invention ha-q a simple structure, is readily manufactured ~ -and can be reducèd in size. The reference electrode is ~ell-suited for mea~uring the concentration of body fluid constituents ~here sterilization by heat i~ required.
In another aspect of the invention, a reference electrode comprises: an electrode portion comprising an olectrical conductor consisting of platinum or silver, and a silver halide and silver oxide formed on the periphery of the conductor; a water-containing gel ~ ;
, ^ .: ,,:- '`:
.~ . .
.. .t - ~ h . .
~ 132~418 enveloping the electrode portion and containing a halogen ion electrolyte; an ion impermeable partitioning wall partitioning the water-containing gel into at least two portions; an ion permeable portion, which is permeable to the ions constituting the electrolyte, running through the partitioning wall and having a predetermined diffusion coefficient and volume; a hollow insulative tube acc~mmodating the water-containing gel and having one end closed by a liquid-junction portion comprising a first plug and its other end liguid-tightly sealed by a ~.
second plug; and a conductor wire connected to the .
conductor and extended to the exterior of the hollow insulative tube by being passed through the second plug liguid tightly. .
In still another aspect of the invention, a reference electrode comprises: an electrode portion comprising an electrical conductor consisting of platinum or silver, and a sil~er halide and silver oxide formed on the periphery of the conductor; a water-containing gel 20 . enveloping the electrode portion and containing a halogen ion electrolyte; an ion impermeable partitioning wall partitioning the water-containing gel into at least two - portion~s a first ion penmeable portion, which is pen~eable to the ions constituting the electrolyte, :~
running through the partitioning wall and having a pr deten~ined diffusion coefficient and volume; a hollow ~.:
insulative tube accommodating the water-containing gel aAd.having one end clo~ed~by a liquid-junction portion .
.
i -6- 132~18 -~ comprising a first plug and its other end liquid-tightly sealed by a second plug; a second ion permeable portion, which is permeable to the ions constituting the electrolyte, running through the liquid-junction portion and having a predetermined diffusion coefficient and volume; and a conauctor wire connected to the conductor and extended to the exterior of the hollow insulative tube by being passed through the second plug liquid tightly.
Preferred embodiments of the invention are as , -.. . .
follows:
1. The diffusion coefficient of the ion permeable portion ranges from 10 7 to 10 10 cm2/sec and the volume tbereof ranges from 0.01 to 6 mm3.
2. The ion permeable portion comprises an ion exchange resin layer.
These reference electrodes are readily available on the mar~et and coqprise a glass tube accommodating a aaturated potassium or sodium chIoride solution and an electrodQ. Formed in the di~tal end portion of the tube 20~ i8 a liquid-~unction portion through which the solution of potas~ium or sodlum chloride is allowed to flow out 132~18 When a measurement is to be taken in a living body or body fluid, use of the saturated calomel electrode is hazardous since the electrode relies upon mercury. In such cases, therefore, the silver/silver chloride electrode is employed. However, the outflow of the potassium or sodium chloride solution in the latter electrode has a great effect upon a living body. For this reason, the liquid-junction portion is formed of a porous material to reduce the amount of outflow~
Nevertheless, fully satisfactory results are not obtained.
Another disadvantage of the conventional reference electrode is that the electrode is used in a living body or in a circuit system through which a body fluid circulates, the potential of the electrode is rendered unstable by changes in temperature. Though a potential which remains stable for a long period of time can be obtained -~ `
by adding a large quantity of potassium or sodium chloride crystals to the internal liquid chamber of the 20 electrode or adopting a porous body as the ` `
liquid-junction portion, these expedients make it difficult to miniaturize the electrode.
Anotber type of reference electrode is adapted to ``
..
enable replenishment of the sodium chloride which has -flowed out. Such an electrode enjoys a comparatively long ervice lif-l. However, in ord~r to allow this referonce ~ .
electrode to operate stably for an extended period of time in a biological system or circulating circuit and to ~; ...
,~ .
`: ':
1324~8 be integrated with any of a variety of sensors such as an ion sensor, the electrode is required to be of the solid-state type, small in size and possessed of a long life. However, a solid-state electrode of this kind does not enable the electrolyte to be replenished or replaced, and an expedient must be devised that reauces the amount of electrolyte outf low .
SUMMARY OF THE INVENTION
Accordingly, an object of the present invention is to provide a miniature, solid-state reference electrode which can be used safely in vivo or in a body fluid and stably, for an extended period of time, in vivo or in a circulating circuit, and which will not respond to the pH
of a specimen or be influenced by a temperature.
According to the invention, the reference electrode includes a liquid-~unction portion formed of a porous -ceramic, an electrode portion composed of an electrical conductor, which comprises platinum or silver, and a `
sintered body formed on the periphery of the conductor and containing silver halide and silver oxide. The electrode portion is enveloped by a water-containing gel containing a halogen ion electrolyte.
More specifically, the reference electrode of the present invention comprises: an electrode portion having an elec~rical conductor consisting of platinum or silver, ; ~ ~ and a sintered body formed on the periphery of the conductor and consisting of silver halide and silver ':
; oxide; a water-containing gel enveloping the electrode portion and containing halogen ion; a hollow tubular body accommodating the water-containing gel and having one end closed ~y a liquid-junction portion comprising a porous ceramic and its other end liquid-tightly ~ealed by a plug; and a conductor wire connected to the conductor and extended to pass tbrough the plug liquid tightly.
The porous ceramic has voids through which at least -halogen ions are capable of passing. ~-Since the liquid-junction portion is formed of a -porous ceramic, outflow Erom the source of halogen ion supply is ~uppressed, thereby enhancing the safety of the reference electrode. Furthermore, since the electrode portion includes the sintered body comprising silver halide and silver oxide formed on the periphery of the platinum or silver conductor and, moreover, since the ~ater-containing gel contains halogen ion, the potential of the electrode exhibits little dependence upon temperature. In addition, the reference electrode of the 20 invention ha-q a simple structure, is readily manufactured ~ -and can be reducèd in size. The reference electrode is ~ell-suited for mea~uring the concentration of body fluid constituents ~here sterilization by heat i~ required.
In another aspect of the invention, a reference electrode comprises: an electrode portion comprising an olectrical conductor consisting of platinum or silver, and a silver halide and silver oxide formed on the periphery of the conductor; a water-containing gel ~ ;
, ^ .: ,,:- '`:
.~ . .
.. .t - ~ h . .
~ 132~418 enveloping the electrode portion and containing a halogen ion electrolyte; an ion impermeable partitioning wall partitioning the water-containing gel into at least two portions; an ion permeable portion, which is permeable to the ions constituting the electrolyte, running through the partitioning wall and having a predetermined diffusion coefficient and volume; a hollow insulative tube acc~mmodating the water-containing gel and having one end closed by a liquid-junction portion comprising a first plug and its other end liguid-tightly sealed by a ~.
second plug; and a conductor wire connected to the .
conductor and extended to the exterior of the hollow insulative tube by being passed through the second plug liguid tightly. .
In still another aspect of the invention, a reference electrode comprises: an electrode portion comprising an electrical conductor consisting of platinum or silver, and a sil~er halide and silver oxide formed on the periphery of the conductor; a water-containing gel 20 . enveloping the electrode portion and containing a halogen ion electrolyte; an ion impermeable partitioning wall partitioning the water-containing gel into at least two - portion~s a first ion penmeable portion, which is pen~eable to the ions constituting the electrolyte, :~
running through the partitioning wall and having a pr deten~ined diffusion coefficient and volume; a hollow ~.:
insulative tube accommodating the water-containing gel aAd.having one end clo~ed~by a liquid-junction portion .
.
i -6- 132~18 -~ comprising a first plug and its other end liquid-tightly sealed by a second plug; a second ion permeable portion, which is permeable to the ions constituting the electrolyte, running through the liquid-junction portion and having a predetermined diffusion coefficient and volume; and a conauctor wire connected to the conductor and extended to the exterior of the hollow insulative tube by being passed through the second plug liquid tightly.
Preferred embodiments of the invention are as , -.. . .
follows:
1. The diffusion coefficient of the ion permeable portion ranges from 10 7 to 10 10 cm2/sec and the volume tbereof ranges from 0.01 to 6 mm3.
2. The ion permeable portion comprises an ion exchange resin layer.
3. The ion permeable portion comprises an anion ~xchange resin layer and a cation-exchange resin layer.
~. ~he ion penmeable portion comprises a hollow fiber filled with the water-containing gel containing the `
halogen ion electrolyte. `
S. The hollow fiber comprises an ion permeable ~
hydrophilic polymer or an ion permeable hydrophobic -"
polymer.
-~ 25 Thus, in accordance with the invention, there is~
provided a miniature, solid-state reference electrode which can be used safely in vivo or in a body fluid and , ~ stably, for an extended perlod of time, in vivo or in a ` ", ;':.
` 1~2~18 , - circulating circùit, and which will not respond to the pH
of a specimen or be influenced by a fluctuation in temperature.
Other advantages of the reference electrode according to the invention are as follows:
1. Potential is stable without being influenced by the pH of a solution or by the Co2 and 2 concentration of the solution.
2. Since there is no temperature coefficient, there is no influence from fluctuations in t~mperature.
3. The electrode has a long life despite its small si~e. The electrode is particularly suitable for extended use in a circulating circuit. ~"
~. ~he ion penmeable portion comprises a hollow fiber filled with the water-containing gel containing the `
halogen ion electrolyte. `
S. The hollow fiber comprises an ion permeable ~
hydrophilic polymer or an ion permeable hydrophobic -"
polymer.
-~ 25 Thus, in accordance with the invention, there is~
provided a miniature, solid-state reference electrode which can be used safely in vivo or in a body fluid and , ~ stably, for an extended perlod of time, in vivo or in a ` ", ;':.
` 1~2~18 , - circulating circùit, and which will not respond to the pH
of a specimen or be influenced by a fluctuation in temperature.
Other advantages of the reference electrode according to the invention are as follows:
1. Potential is stable without being influenced by the pH of a solution or by the Co2 and 2 concentration of the solution.
2. Since there is no temperature coefficient, there is no influence from fluctuations in t~mperature.
3. The electrode has a long life despite its small si~e. The electrode is particularly suitable for extended use in a circulating circuit. ~"
4. The electrode is simple in structure and readily manufactured.
5. Since the electrode has a solid-sta~e structure, it can be used in any attitude whatsoever.
Other features and advantages of the present invention will be àpparen~ from the following description 20 t~en in con~unction with the accompanying drawings, in ```~``-; wbi d li~e reference character~ designate the same or similar parts throughout the figures thereof.
BRI~F D~SCRIPTION OF THE DRAWINGS
ig. 1 is a sectio,nal view illuatrating a reference ~ "
25 electrode according to Bxample~ 1 tb`rough 6 of-the ` "
pre ent invention;
Fig. 2 is a schematic view of a measuring apparatus ` ~or measuring the characteristics of the reference : ' ~''`
~`` ` 1~24418 ` electrode according to Examples 1, 2, 5 and 6 of the present invention;
Fig. 3 is a graph illus~rating characteristics of the reference electrode according to Examples 1 and 2 of the present invention;
Fig. 4 is a schematic view of a measuring apparatus for measuring the characteristics of the reference electrode according to Examples 3 and 4 of the present invention; -;
Fig~ 5 is a sectional view illustrating a reference ;`~
electrode according to Examples 7 ~hrou~b 9 of the : `
present invention;
Fig. 6 a circuit diagram illustrating a circuit for measuring the performance of the reference electrode according to Examples 7 through 9 of the present invention; ~ `
Fig. 7 is a sectional view illustrating a reference electrode according to an exa~ple used for comparison `
purposes; and Figs. 8 and 9 are sectional views of reference electrodes according respectively to Examples 10 and 11 of the present invention.
DESCRIPTION OF THE PREFERRED BMBODIMENTS
Preferred embodiments of the present invention will now be described with reference to the drawings.
As sho~n in Fig. lt a reference electrode 10 in accordance with the invention has an insulative hollow tubular body 11 such as a Teflon*tube or the like. One ~
.~j. ` . .
~ *trade-mar~ ~
132~18 g end of the tubular body 11 is closed by means of a liquid-junction portion 12 consisting of a porous ceramic. Any porous ceramic permeable to ions applied for generation of a potential at an electrode section, described below, can be used. Examples of these ions are hydrogen ion and halogen ion. Especially preferred as the porous cera~ic is a sintered mixture of zirconium silicate (~rSiO4) and carbon. Specifically, a sintered body can be formed by preparing a mixture o zirconium silicate powder and carbon powder at a weight ratio o~
from 100:1 to 100:50, compacting the mixture into a predetermined shape, e.g. a disk-shaped configuration, and sintering the mixture at a temperature of from 800C
to 1300C. This liquid-junction portion comprising the sintered body of ~irconiu~ silicate and carbon will not be in~luenced by the pH of a liquid specimen. In add}tion, a silver chloride complex eluted by halogen ion will not deposit on this liquid-junction portion and clog the same. This assures that a stable potential will be obtained.
The hollo~ tubular body 11 accommodates an electrode section 14 compriæing a wire-like conductor 15 consisting of platinum or silver, and a sintered body 16 formed about the conductor 15. The sintered body 16 contains a 2S silver halide, particularly æilver chloride,-and silver oxide. The sintered body 16 can be formed by preparing a mixture of silver halide powder and silver oxide powder at a weight ratio of from 95:5 to 5:95, compacting the ~ ;
- 1i ' . :
`` 1324418 --1 o--mixture onto the periphery of the conductor 14 to coat the same, and then sintering the mixture at a temperature of from 300C to 500 &.
- The interior of the hollow tubular body 11 is filled with a water-containing gel 17 enveloping the electrode section 14. Examples of the water-containing gel 17 that can be used include polyvinyl alcohol, polyacryl amide, agar-agar, gelatin, a natural high polymer, mannan or ` `
starch.
The water-containing gel 17 contains a halogen ion, of which sodium chloride is the most suitable source of -supply since any outflow into a liquid biological specimen will have almost no harmful effects.
Ordinarily, the sodium chloride is contained in the gel ~-}5 17 at a ratio of from 0~1 mo~/~ to 4.52 mo~/~. "`
Preferably, a trace amount (e.g. 0.0002 wt~ to 0.001 wt~) o~ sil~er chloride is added to the water-containing gel 17. `
The end of the hollow tubular body 11 opposite the liquid-junction portion 12 is liguid-tightly sealed by an in-ulative plug 13 penetrated liquid tightly by a conduc-tor wire 18, whereby the electrode section 14 is led out to the exterior of the tubular body 11. The insulative plug 13 preferably comprises a silicon bonding agent, an epoxy resin or the li~e. Preferably, the conductor wire . .
18 constitutes a portion of the conductor 15.
(Examples 1 and 2, and Comparison Examples 1 and 2j `;-Two examples of the reference electrode 10 having the ' ~ ~
324~18 ..construction shown in Fig. 1 were prepared as follows:
A mixture consisting of loo parts by weight of 2irconium silicate powder and 30 parts by weight of carbon powder was compressed to be molded into a disk having a diameter of 1 mm, and the disk was sintered in an electric furnace at a temperature of 1200C for 1 hr to fabricate the liquid-junction portion 12. A mixture consisting o~ 60 parts by weight of silver chloride powder and 40 parts by weight of silver oxide powder was compressed into a cylindrical body to coat the distal end portion of a platinum wire having a diameter of 0.2 mm.
This was then sintered in an electric furnace at a ~ .
temperature of 400C for 15 min to fabricate the electrode section 14 having the conductor wire 18. `
15The liquid-junction portion thus fabricated was inserted into the distal end portion of the tubular body 11, consisting of a heat-shrinkable Teflon tube having a .
diameter of about 1 mm, the electrode section 14 was inserted into the tube 11, and the tube 11 was filled 20 ~ith the gel 17, consisting of agar-agar, containing -~
sodium chloride in the proportions shown in the Table :
hereinbelow. The plug 13, consisting of epoxy resin, was ..
inserted into the other end of the tube 11, thereby completing the fabrication of the reference electrode 10. .:
TABL~ 1 :
Reference ~lectrode NaCl Concen ation ~mo~7~~
Example 2 Saturated . .
ComDarison ~xample 1 (apProximate 4.52 moQ/~) Comparison ExamPle 2 _ 1 ..
' ;'' 132~418 .~ -12-(Experiment 1) The apparatus sbown in Fig. 2 was used to examine the ~emperature dependence of the potential exhibited by the reference electrodes fabricated in accordance with - -Examples 1 and 2.
The apparatus of Fig. 2 included identically constructed cells A and B each having an isothermal :
jacket within which an isothermal solution was circulated by respective isothermal solution circulating devices 21 10 and 22. T~e cells A and B were respectively filled with ..
50 mM phosphate buffer solutions 23 and 24 each containing 0~154 M sodium chloride at pH 7.4. Each reference electrode 10 of the present invention was immersed in the buffer solution 23 of cell A, and a readily available saturated sodium chloride calomel electrode thereinafter referred to as an ~SSCE") 25 was immersed in the buffer solution 24 of cell B. A liquid junction ~as formed between the two cells by a saturated sodium chloride agar-agar salt bridge 26, and magnetic stirrer~ 27, 2~ were provided with the cells A, B. The potential difference between the reference electrode 10 `` ..
and SSC~ 25 ~a~ measured by a potentiometer 29.
The solution temperature in cell B was held constant at 25 & by the isothermal circulating device 21, and the :
25 ~olution temperature in cell A was held constant at 20C, :~
30C, 37C and 40 &. m e potential difference at each of : -these latter four temperatures was measured by ~;
potentiometer 29. The results are as shown in Table 2 ' ` -. -13- 132~18 and Fig. 3.
Reference Electrode Potential Difference (mV) Exam~ 1 -22.47 -21.28 -20.32 -20.02 Example 2 -41.06 -40.82 -40.35 -40 74 Com~arison Example 1 38.01 42.87 45.90 46 89 Comparison EXample 2 1.37 3.96 5.77 6.6 These results show the reference electrode of the present embodiment develops a poten~ial having little dependence upon temperature, and that temperature dependence decreases with an increase in the concentration of the sodium chloride in the agar-agar.
In particular, it is sa~e to say that potential is entirely independent of temperature when the sodium chloride concentration reaches saturation. Accordingly, the reference electrode will operate stably even in a system attended by changes in te~perature. :.
~Examples 3 and 4, and Comparison Examples 3 and 4) Reference electrodes were fabricated through a procedure similar to that used in Example 2 except for the fact that the proportions of the silver chloride and . -~ilver oxide constituting the sintered body of the electrode section were ~aried as shown in Table 3.
~ Reference Electrode AgCl ~wt~) A - - :
: ExamPle 3 80 20 ~xamDle 4 _ _ 60 _40 . .
: Comparison ~xam~le 3 _ 40 60 .`:
ComDarison Example 4 20 _ tFxperiment No. 2) As shown in Fig. 4, a cell 31 was filled with '~ .
'~;'`'' `' ' 132~418 agar-agar gel ~2 containing saturated concentrations of sodium chloride and silver chloride, a reference .
electrode 34 in accordance with each of the Examples 3, 4 ``
and Reference Examples 3, 4 was immersed in the gel 32, an aqueous saturated sodium chloride solution 33 was introduced onto t~e gel 32, a readily available SSCE 35 was immersed in the sodium chloride solution 33, and the potential difference across the ele~trodes 34, 35 was measured by a potentiometer 36. The aqueous saturated sodium chloride solution 33 was then removed, the cell 31 containina; ~ aqar-agar gel 32 inclusive of the electrode ' to autoclave sterilization at 121C fo .,~ .~ the potential difference was measure ~ potentiometer 36 as before. The results ;.
15 are as .~lown in Table 4. ;;
TABLE ~ : `
Reference Electrode Potential Differ~ After ~Q _Ex~mple 3 _ _ Sterilisation -42 03- `:`
-41'58 -4~'81 Comparison _ a~ple 3 _ 41 62 -483 13 Co~parison Bxample 4 -41.8~r--- ~136~r -These results show that the reference electrodes of :-25 Examples 3 and ~ are almost entirely unaffected by .:
autoclave sterili2ation, and that reference electrodes having a sintered body containing no less than 60 wt% -. .
silver chloride exhibit stable potentials before and after sterili~ation. `~.
~Examples S and 6, and Comparison Examples 5 and 6) Reference electrodes were fabricated through a .
:
-15- 1 3 2 ~ ~1 8 procedure similar to that used in Example 2 except for the fact that a silver wire having a diameter of 0.2 mm was used as the conductor and the mixture ratios of the ` silver chloride and silver oxide were varied as shown in Table 5.
Reference ~lectrode AgCl (wt~ ) Ag2o (wt~) ExamDle 6 60 40 Comparison ~xample 5 40 60 Comparison Example 6 20 80 (~xperiment No. 3) In a measurement system similar to that used in Example 1, the pH dependence of tbe potentials developed `
lS by the reference electrodes of Examples 5, 6 and 3, 4 and ~` `
of Comparison Examples 3, 4 and 5, 6 were measured while :
varying the pH of the buffer solution. The results are as shown in Table 6. :
Referënce Potential Reference Potential ~lectrode Diff. (mV) Electrode ~ Diff ~mv) Ex. 5 = 0.077x~H-42.98 Ex. 3 0.459x~H-41.45 Ex. 6 0.015xpH-41.63 Ex. 4 0.220xpH-40.79¦
ComD . EX . 5 O.O9~xDH-41.47 ¦Comp. Ex. 3 O.219xpH-41.40 2S Comp~ Ex. 6 0.034xpH-41.26 Comp. Ex. 4 0.135xpH-40.84 These results show that using the silver wire instead of the platinum wire as the conductor provides a greater reduction in pH dependence, and that reference electrodes having a sintered body containing no less than ~.
60 wt% silver chloride are almost entirely independent of pH.
Though not indicated in the above-described Examples, ~ .
`. 132~18 r it will be apparent from the Examples that follow that the liquid-junction portion is not limited to a porous ceramic obtained by compacting a mixture of zirconium silicate powder and carbon powder and sintering the mixture in an electric furnace. The liquid-junction portion can be a plug provided with an ion permeable portion having a predeterminea diffusion coefficient and :
vol ume.
(Examples 7 through 9) Fig. 5 illustrates the structure of a reference electrode 60 according to an Example 7. The reference electrode 60 includes a hollow insulative tubular body 51 ~
in one open end of wbich is fixedly secured a plug 52 ~ `
serving as a liquid-junction portion. The tubular body 15 51 preferably is made of Teflon, and the plug 52 `
comprises a porous ceramic filter~ The latter can be fabricated by compacting powders of zirconium silicate and carbon at a mixture ratio of 100:30, followed by -sintering the mixture at 1200C for 1 hr.
Accommodated within the hollow tubular body 51 is an ion permeable portion comprising a cation exchange layer 53 and an anion exchange layer 54 which are fixedly secured ~ithin the eubular body by a urethane resin `
forming a partitioning wall 55 that divides into two 25 portions a water-containing gel 56 filling the tubular `-body. The cation layer 53 has a length of 15 mm, a width of 1 mm and a thickness of 0.2 mm, the main chain whereof is a fluorocarbon. An example is Nafion 117*
~trade-mar~
.~t ~ 1324418 1 7 ~
r~ (manufactured by Dupont), having a diffusion coefficient of 7 x 10 8 cm2/sec. The anion exchange layer 54 has a length of 15 mm, a width of 1 mm and a thickness of 0.3 mm, the main chain whereof is a fluorocarbon. An example is MA-43 (manufactured by Toyo Soda K.K.), having a diffusion coefficien~ of 6 x lo 8 cm2/sec. About 2 mm of the ion-exchange layers ~3, 54 are left exposed to the gel 56 at each end thereof.
The ion-exchange layers 53, 54 and the partitioning 10 wall 55 compri~ing the urethane resin partition the -interior of the tubular body 51 into cells a and b f illed with the gel 56. The latter is agar-agar gel containing saturated sodium chloride as an electrolyte. A
silver/silver chloride electrode S7 having a conductor ~"
15 wire 59 is inserted into the cell b and secured therein `~
by a urethane resin. A plug 58 is formed at this end of the tubular body, namely at the end opposite the plug 52 serving as the liquid-junction portion. The conductor `~
~ire 59 is passed throu~h the plug 58 to lead the 20 electrode 57 to the exterior of the tubular body. Thi s ~ .
corpletes the fabrication of the electrode 60 having the structure shown in Fig. 5.
The ion diffusion coefficient (D) of the electrolyte ` in the ion penmeable section comprising the ion-exchange 251~ lay-r- 53, S4 preferably is 10 7 - 10 10 cm2/sec, especially 10 8 - 10 9 cm2jsec, at 25C. The volume ` ```
;preferred for the ion permeable section is 0.01 - 6 mm3. -The~plug 52 serving as the liquid-junction portion is .: , permeable to ion mole~ules having a size on the order of 1 - 50 A. This means that the plug 52 will not pass molecules whose size exceeds the above mentioned range.
As shown in Table 7, reference electrodes having both the cation- and anion-exchange layers, the cation-exchange layer alone and the anion-exchange layer alone.
~xample Ion-Exchange LaYer Used 7 Cation- and anion-exchan~_3~yers in parallel 8 An~on-exchanqe layer onlv 9 _ Cation-exchange layer oniv Where the ion migration mechanism will now be described using the reference electrode of Example 7, ~ which is shown in Fig. 5~ `
The following equilibrium reaction takes place in cell b at the silver/silver chloride electrode:
AgC~ + e ---> Ag+C~
As a result of this reaction, the ~ollowing electrode potential E is generated:
~ = ~ + RT/F-~nta -) ~here ~ represents the potential of the silver/silver chloride electrode, ac- is the activity of chlorine ion, ac ~ r x lc~ 1 (note that IC~ 1 represents the C~ ion concentration and ~ represents the activity coefficient), R stands for the gas constant, F the Faraday constant and T ehe thermodynamic temperature.
Step 1: As a result of a difference in concentration between the liquid specimen and the gel in cell a, Na+
ion and/or C~ ion migrate through the specimen.
,~
', 'J; ' ~
- 132~418 step 2: As a result of a difference in concentration between cell a and cell b, Na+ ion ana/or CQ- ion in cell b migrate to cell a.
Accordingly, if the concentration of Cl in cell b 5 could be held constant, the electrode would be usable permanently. Owing to the migration of cl ion, however, lifetime is curtailed. This embodiment of the invention is adapted to hold the concen~ration of C~ ion in cell b constant.
~Experiments 4 through 61 As shown in Fig. 6, reference electrodes 60 fabricated in accordance with Examples 7 through 9 were immersed in a 50 mM phosphate buffer solution having a pH
of 7.4. ~he electrodes were withdrawn from the solution after 0, 25, 45, 161 and 288 hr and then immersed `
together with a readily available SSCE 61 in a phosphate buffer solution 62 (p~ 7.4, 50 mM) containing 0.154 N
sodium chloride. Potential with respect to the SSCE 61 was measured. The results are as shown in Table 8.
Al~ost no difference among the reference electrodes of Example~ ~, 8, 9 ua~ noticed after 45 hr of ~mmersion.
After 161 hr of immersion, however, the potential of ~xample 8 shifted in the positive direction and that of Exa~ple 9 shifted iD the negative direction. In Example 7, on the other hand, the effects of the cation-exchange layer and anion exchange layer offset each other an no potential shift of the magnitudes was observed. Thus, a highly stable potential was obtained.
:'., .
`~- `` 1324418 ~ 10 _1 0 ~)_1 ~D
_ ~ C u~ o~ N o ¦-- ~t Vl N n~ N ~ :
~O ~ ~ ~
~ _ _ _ ~ C ~ ~. :, .
: ~ ' . .. -V~ 0 ' ' "
1324~18 As a comparison example, a reference electrode having a double-junction structure shown in Fig. 7 was fabricated using a porous ceramic filter as the plug 52 - and the partitioning wall 52a serving as the 5 liquid-junction portion. The potential of this reference `
electrode with respect to the SSCE 61 was measured after 0, 20, 45, 101 and 288 hr through the same method as that employed in Examples 7 through 9. The results are as shown in ~able 8. It was found that the reference electrode having this structure develops a sudden rise in potential after 288 hours, indicating that the electrode cannot withstand long use.
The above results show that use of the cation- and anion-exchange layers of the kind employed in Example 7 provided a reference electrode in which the outflow of chloride ion is prevented, whereby there is obtained a stable potential over an extended period of time. `
(Example 10~
As shown in ~ig. 8, a reference electrode was fabricated using a plug 52b having a capillary tube 80b in place of the plug 52 serving as the liquid-~unction portion. In addition, the ion permeable section employed a capillary tube 80a in place of the ion-exchange layer ~ `
:. :` .
53, 54.- Other portions identical with those shown in Fig. 7 are designated by like reference characters.
A hollow fiber of regenerated cellulose having a --length of 25 mm, an inner diameter of 203 pm, an outer diameter of 255 pm and a diffusion coefficient of 5 x ,'.~' '.,.' .' .
- 1~2~l8 1O-7 cm2/sec was used as the capillary tubes 80a, b. The lower capillary tube 80 was fixed in the lower hollow insulative tubular body 51 by a urethane bonding agent.
The other capillary tube 80 was passed through and secured within the partitioning wall 55 and the plug 52b.
Introduced under pressure from the other end of the hollow insulative tubular body 51 was agar-agar gel (agar-agar concentration: 2 wt~ containing saturated sodium chloride, whereby the interior of the tubular body 51 and the interiors o~ the regenerated cellulose hollow fibers were filled with the agar-agar gel. Another method whic~ can be used is to dip the end por~ion not having the regenerated cellulose hollow fiber secured thereto into the aforementioned agar-agar gel ana then lower the pressure inside the cellulose hollow fibers and tubular body 51 to fill them with the gel~ Next, the silver/silver chloride electrode 57 was inserted into the tubular body 51 to complete the fabrication of the reference electrode.
(~periment 7) The abovementioned reference electrode was dipped in a 50 ~M phosphate buffer solution of pH 7.4 and was ~ithdrawn after 20, 45, 161 and 2~8 hr. Then, as shown in Fig. 6, the electrode wais immeræed together with the readily available SSCE 61 in the 50 mM phosphate buffer solution 62 tpa 7.4) con~aining 0.154 M sodium chloride.
Potential with respect to the SSCE 31 was measured. The concentration of chlorine ion which flowed out into the 132~18 50 mM phosphate buffer solution from the reference electrode was measured by colorimetry. The results are shown in Table 8 in the same manner as the results of Experiments 4 through 6.
It is evident from the results that the reference electrode using the regenerated cellulose hollow fibers exhibited little chlorine ion outflow and a stable potential over an extended period of time.
(~xample 11) As shown iR Fig. 9, a reference electrode was fabricated having the ion-exchange layers provided between the cells a and b and the plug 5~b provided with the capillary tube 80 comprising a regenerated cellulose `
hollow fiber~ This reference electrode exhibited a 15 stable potential over an extended period of time, just as --the reference electrode of 2xample 10~
It should be noted that the cation- and anion-exchange layers and the regenerated cellulose hollow fibers can be plural in number. Also, the ele~trolyte is ~ ;
not limited to chlorine compounds such as sodium chloride and potassium chloride mentioned in the foregoing examples, and other halide compounds can be used if "
desired. The technical concept of the invention resides in a reference electrode which, while fulfilling its ~ -function as a reference electrode, exhibits less outflow of ions to a liquid specimen. To this end, the amount of - -ion permeation (diffusion coefficient, etc.) is set -within a predetermined range. The method of achieving -;;
' .
.' ,'''.' ` ~
;
132~418 ` this is not limited to that of the foregoing examples.
As many apparently widely different embodiments of the present invention can be made without departing from the spirit and scope thereof, it is to be understood that the invention is not limited to the specific embodiments thereof except as defined in the appended claims.
.
:
' '; ~ ~ ` ' . ~ , .
.
Other features and advantages of the present invention will be àpparen~ from the following description 20 t~en in con~unction with the accompanying drawings, in ```~``-; wbi d li~e reference character~ designate the same or similar parts throughout the figures thereof.
BRI~F D~SCRIPTION OF THE DRAWINGS
ig. 1 is a sectio,nal view illuatrating a reference ~ "
25 electrode according to Bxample~ 1 tb`rough 6 of-the ` "
pre ent invention;
Fig. 2 is a schematic view of a measuring apparatus ` ~or measuring the characteristics of the reference : ' ~''`
~`` ` 1~24418 ` electrode according to Examples 1, 2, 5 and 6 of the present invention;
Fig. 3 is a graph illus~rating characteristics of the reference electrode according to Examples 1 and 2 of the present invention;
Fig. 4 is a schematic view of a measuring apparatus for measuring the characteristics of the reference electrode according to Examples 3 and 4 of the present invention; -;
Fig~ 5 is a sectional view illustrating a reference ;`~
electrode according to Examples 7 ~hrou~b 9 of the : `
present invention;
Fig. 6 a circuit diagram illustrating a circuit for measuring the performance of the reference electrode according to Examples 7 through 9 of the present invention; ~ `
Fig. 7 is a sectional view illustrating a reference electrode according to an exa~ple used for comparison `
purposes; and Figs. 8 and 9 are sectional views of reference electrodes according respectively to Examples 10 and 11 of the present invention.
DESCRIPTION OF THE PREFERRED BMBODIMENTS
Preferred embodiments of the present invention will now be described with reference to the drawings.
As sho~n in Fig. lt a reference electrode 10 in accordance with the invention has an insulative hollow tubular body 11 such as a Teflon*tube or the like. One ~
.~j. ` . .
~ *trade-mar~ ~
132~18 g end of the tubular body 11 is closed by means of a liquid-junction portion 12 consisting of a porous ceramic. Any porous ceramic permeable to ions applied for generation of a potential at an electrode section, described below, can be used. Examples of these ions are hydrogen ion and halogen ion. Especially preferred as the porous cera~ic is a sintered mixture of zirconium silicate (~rSiO4) and carbon. Specifically, a sintered body can be formed by preparing a mixture o zirconium silicate powder and carbon powder at a weight ratio o~
from 100:1 to 100:50, compacting the mixture into a predetermined shape, e.g. a disk-shaped configuration, and sintering the mixture at a temperature of from 800C
to 1300C. This liquid-junction portion comprising the sintered body of ~irconiu~ silicate and carbon will not be in~luenced by the pH of a liquid specimen. In add}tion, a silver chloride complex eluted by halogen ion will not deposit on this liquid-junction portion and clog the same. This assures that a stable potential will be obtained.
The hollo~ tubular body 11 accommodates an electrode section 14 compriæing a wire-like conductor 15 consisting of platinum or silver, and a sintered body 16 formed about the conductor 15. The sintered body 16 contains a 2S silver halide, particularly æilver chloride,-and silver oxide. The sintered body 16 can be formed by preparing a mixture of silver halide powder and silver oxide powder at a weight ratio of from 95:5 to 5:95, compacting the ~ ;
- 1i ' . :
`` 1324418 --1 o--mixture onto the periphery of the conductor 14 to coat the same, and then sintering the mixture at a temperature of from 300C to 500 &.
- The interior of the hollow tubular body 11 is filled with a water-containing gel 17 enveloping the electrode section 14. Examples of the water-containing gel 17 that can be used include polyvinyl alcohol, polyacryl amide, agar-agar, gelatin, a natural high polymer, mannan or ` `
starch.
The water-containing gel 17 contains a halogen ion, of which sodium chloride is the most suitable source of -supply since any outflow into a liquid biological specimen will have almost no harmful effects.
Ordinarily, the sodium chloride is contained in the gel ~-}5 17 at a ratio of from 0~1 mo~/~ to 4.52 mo~/~. "`
Preferably, a trace amount (e.g. 0.0002 wt~ to 0.001 wt~) o~ sil~er chloride is added to the water-containing gel 17. `
The end of the hollow tubular body 11 opposite the liquid-junction portion 12 is liguid-tightly sealed by an in-ulative plug 13 penetrated liquid tightly by a conduc-tor wire 18, whereby the electrode section 14 is led out to the exterior of the tubular body 11. The insulative plug 13 preferably comprises a silicon bonding agent, an epoxy resin or the li~e. Preferably, the conductor wire . .
18 constitutes a portion of the conductor 15.
(Examples 1 and 2, and Comparison Examples 1 and 2j `;-Two examples of the reference electrode 10 having the ' ~ ~
324~18 ..construction shown in Fig. 1 were prepared as follows:
A mixture consisting of loo parts by weight of 2irconium silicate powder and 30 parts by weight of carbon powder was compressed to be molded into a disk having a diameter of 1 mm, and the disk was sintered in an electric furnace at a temperature of 1200C for 1 hr to fabricate the liquid-junction portion 12. A mixture consisting o~ 60 parts by weight of silver chloride powder and 40 parts by weight of silver oxide powder was compressed into a cylindrical body to coat the distal end portion of a platinum wire having a diameter of 0.2 mm.
This was then sintered in an electric furnace at a ~ .
temperature of 400C for 15 min to fabricate the electrode section 14 having the conductor wire 18. `
15The liquid-junction portion thus fabricated was inserted into the distal end portion of the tubular body 11, consisting of a heat-shrinkable Teflon tube having a .
diameter of about 1 mm, the electrode section 14 was inserted into the tube 11, and the tube 11 was filled 20 ~ith the gel 17, consisting of agar-agar, containing -~
sodium chloride in the proportions shown in the Table :
hereinbelow. The plug 13, consisting of epoxy resin, was ..
inserted into the other end of the tube 11, thereby completing the fabrication of the reference electrode 10. .:
TABL~ 1 :
Reference ~lectrode NaCl Concen ation ~mo~7~~
Example 2 Saturated . .
ComDarison ~xample 1 (apProximate 4.52 moQ/~) Comparison ExamPle 2 _ 1 ..
' ;'' 132~418 .~ -12-(Experiment 1) The apparatus sbown in Fig. 2 was used to examine the ~emperature dependence of the potential exhibited by the reference electrodes fabricated in accordance with - -Examples 1 and 2.
The apparatus of Fig. 2 included identically constructed cells A and B each having an isothermal :
jacket within which an isothermal solution was circulated by respective isothermal solution circulating devices 21 10 and 22. T~e cells A and B were respectively filled with ..
50 mM phosphate buffer solutions 23 and 24 each containing 0~154 M sodium chloride at pH 7.4. Each reference electrode 10 of the present invention was immersed in the buffer solution 23 of cell A, and a readily available saturated sodium chloride calomel electrode thereinafter referred to as an ~SSCE") 25 was immersed in the buffer solution 24 of cell B. A liquid junction ~as formed between the two cells by a saturated sodium chloride agar-agar salt bridge 26, and magnetic stirrer~ 27, 2~ were provided with the cells A, B. The potential difference between the reference electrode 10 `` ..
and SSC~ 25 ~a~ measured by a potentiometer 29.
The solution temperature in cell B was held constant at 25 & by the isothermal circulating device 21, and the :
25 ~olution temperature in cell A was held constant at 20C, :~
30C, 37C and 40 &. m e potential difference at each of : -these latter four temperatures was measured by ~;
potentiometer 29. The results are as shown in Table 2 ' ` -. -13- 132~18 and Fig. 3.
Reference Electrode Potential Difference (mV) Exam~ 1 -22.47 -21.28 -20.32 -20.02 Example 2 -41.06 -40.82 -40.35 -40 74 Com~arison Example 1 38.01 42.87 45.90 46 89 Comparison EXample 2 1.37 3.96 5.77 6.6 These results show the reference electrode of the present embodiment develops a poten~ial having little dependence upon temperature, and that temperature dependence decreases with an increase in the concentration of the sodium chloride in the agar-agar.
In particular, it is sa~e to say that potential is entirely independent of temperature when the sodium chloride concentration reaches saturation. Accordingly, the reference electrode will operate stably even in a system attended by changes in te~perature. :.
~Examples 3 and 4, and Comparison Examples 3 and 4) Reference electrodes were fabricated through a procedure similar to that used in Example 2 except for the fact that the proportions of the silver chloride and . -~ilver oxide constituting the sintered body of the electrode section were ~aried as shown in Table 3.
~ Reference Electrode AgCl ~wt~) A - - :
: ExamPle 3 80 20 ~xamDle 4 _ _ 60 _40 . .
: Comparison ~xam~le 3 _ 40 60 .`:
ComDarison Example 4 20 _ tFxperiment No. 2) As shown in Fig. 4, a cell 31 was filled with '~ .
'~;'`'' `' ' 132~418 agar-agar gel ~2 containing saturated concentrations of sodium chloride and silver chloride, a reference .
electrode 34 in accordance with each of the Examples 3, 4 ``
and Reference Examples 3, 4 was immersed in the gel 32, an aqueous saturated sodium chloride solution 33 was introduced onto t~e gel 32, a readily available SSCE 35 was immersed in the sodium chloride solution 33, and the potential difference across the ele~trodes 34, 35 was measured by a potentiometer 36. The aqueous saturated sodium chloride solution 33 was then removed, the cell 31 containina; ~ aqar-agar gel 32 inclusive of the electrode ' to autoclave sterilization at 121C fo .,~ .~ the potential difference was measure ~ potentiometer 36 as before. The results ;.
15 are as .~lown in Table 4. ;;
TABLE ~ : `
Reference Electrode Potential Differ~ After ~Q _Ex~mple 3 _ _ Sterilisation -42 03- `:`
-41'58 -4~'81 Comparison _ a~ple 3 _ 41 62 -483 13 Co~parison Bxample 4 -41.8~r--- ~136~r -These results show that the reference electrodes of :-25 Examples 3 and ~ are almost entirely unaffected by .:
autoclave sterili2ation, and that reference electrodes having a sintered body containing no less than 60 wt% -. .
silver chloride exhibit stable potentials before and after sterili~ation. `~.
~Examples S and 6, and Comparison Examples 5 and 6) Reference electrodes were fabricated through a .
:
-15- 1 3 2 ~ ~1 8 procedure similar to that used in Example 2 except for the fact that a silver wire having a diameter of 0.2 mm was used as the conductor and the mixture ratios of the ` silver chloride and silver oxide were varied as shown in Table 5.
Reference ~lectrode AgCl (wt~ ) Ag2o (wt~) ExamDle 6 60 40 Comparison ~xample 5 40 60 Comparison Example 6 20 80 (~xperiment No. 3) In a measurement system similar to that used in Example 1, the pH dependence of tbe potentials developed `
lS by the reference electrodes of Examples 5, 6 and 3, 4 and ~` `
of Comparison Examples 3, 4 and 5, 6 were measured while :
varying the pH of the buffer solution. The results are as shown in Table 6. :
Referënce Potential Reference Potential ~lectrode Diff. (mV) Electrode ~ Diff ~mv) Ex. 5 = 0.077x~H-42.98 Ex. 3 0.459x~H-41.45 Ex. 6 0.015xpH-41.63 Ex. 4 0.220xpH-40.79¦
ComD . EX . 5 O.O9~xDH-41.47 ¦Comp. Ex. 3 O.219xpH-41.40 2S Comp~ Ex. 6 0.034xpH-41.26 Comp. Ex. 4 0.135xpH-40.84 These results show that using the silver wire instead of the platinum wire as the conductor provides a greater reduction in pH dependence, and that reference electrodes having a sintered body containing no less than ~.
60 wt% silver chloride are almost entirely independent of pH.
Though not indicated in the above-described Examples, ~ .
`. 132~18 r it will be apparent from the Examples that follow that the liquid-junction portion is not limited to a porous ceramic obtained by compacting a mixture of zirconium silicate powder and carbon powder and sintering the mixture in an electric furnace. The liquid-junction portion can be a plug provided with an ion permeable portion having a predeterminea diffusion coefficient and :
vol ume.
(Examples 7 through 9) Fig. 5 illustrates the structure of a reference electrode 60 according to an Example 7. The reference electrode 60 includes a hollow insulative tubular body 51 ~
in one open end of wbich is fixedly secured a plug 52 ~ `
serving as a liquid-junction portion. The tubular body 15 51 preferably is made of Teflon, and the plug 52 `
comprises a porous ceramic filter~ The latter can be fabricated by compacting powders of zirconium silicate and carbon at a mixture ratio of 100:30, followed by -sintering the mixture at 1200C for 1 hr.
Accommodated within the hollow tubular body 51 is an ion permeable portion comprising a cation exchange layer 53 and an anion exchange layer 54 which are fixedly secured ~ithin the eubular body by a urethane resin `
forming a partitioning wall 55 that divides into two 25 portions a water-containing gel 56 filling the tubular `-body. The cation layer 53 has a length of 15 mm, a width of 1 mm and a thickness of 0.2 mm, the main chain whereof is a fluorocarbon. An example is Nafion 117*
~trade-mar~
.~t ~ 1324418 1 7 ~
r~ (manufactured by Dupont), having a diffusion coefficient of 7 x 10 8 cm2/sec. The anion exchange layer 54 has a length of 15 mm, a width of 1 mm and a thickness of 0.3 mm, the main chain whereof is a fluorocarbon. An example is MA-43 (manufactured by Toyo Soda K.K.), having a diffusion coefficien~ of 6 x lo 8 cm2/sec. About 2 mm of the ion-exchange layers ~3, 54 are left exposed to the gel 56 at each end thereof.
The ion-exchange layers 53, 54 and the partitioning 10 wall 55 compri~ing the urethane resin partition the -interior of the tubular body 51 into cells a and b f illed with the gel 56. The latter is agar-agar gel containing saturated sodium chloride as an electrolyte. A
silver/silver chloride electrode S7 having a conductor ~"
15 wire 59 is inserted into the cell b and secured therein `~
by a urethane resin. A plug 58 is formed at this end of the tubular body, namely at the end opposite the plug 52 serving as the liquid-junction portion. The conductor `~
~ire 59 is passed throu~h the plug 58 to lead the 20 electrode 57 to the exterior of the tubular body. Thi s ~ .
corpletes the fabrication of the electrode 60 having the structure shown in Fig. 5.
The ion diffusion coefficient (D) of the electrolyte ` in the ion penmeable section comprising the ion-exchange 251~ lay-r- 53, S4 preferably is 10 7 - 10 10 cm2/sec, especially 10 8 - 10 9 cm2jsec, at 25C. The volume ` ```
;preferred for the ion permeable section is 0.01 - 6 mm3. -The~plug 52 serving as the liquid-junction portion is .: , permeable to ion mole~ules having a size on the order of 1 - 50 A. This means that the plug 52 will not pass molecules whose size exceeds the above mentioned range.
As shown in Table 7, reference electrodes having both the cation- and anion-exchange layers, the cation-exchange layer alone and the anion-exchange layer alone.
~xample Ion-Exchange LaYer Used 7 Cation- and anion-exchan~_3~yers in parallel 8 An~on-exchanqe layer onlv 9 _ Cation-exchange layer oniv Where the ion migration mechanism will now be described using the reference electrode of Example 7, ~ which is shown in Fig. 5~ `
The following equilibrium reaction takes place in cell b at the silver/silver chloride electrode:
AgC~ + e ---> Ag+C~
As a result of this reaction, the ~ollowing electrode potential E is generated:
~ = ~ + RT/F-~nta -) ~here ~ represents the potential of the silver/silver chloride electrode, ac- is the activity of chlorine ion, ac ~ r x lc~ 1 (note that IC~ 1 represents the C~ ion concentration and ~ represents the activity coefficient), R stands for the gas constant, F the Faraday constant and T ehe thermodynamic temperature.
Step 1: As a result of a difference in concentration between the liquid specimen and the gel in cell a, Na+
ion and/or C~ ion migrate through the specimen.
,~
', 'J; ' ~
- 132~418 step 2: As a result of a difference in concentration between cell a and cell b, Na+ ion ana/or CQ- ion in cell b migrate to cell a.
Accordingly, if the concentration of Cl in cell b 5 could be held constant, the electrode would be usable permanently. Owing to the migration of cl ion, however, lifetime is curtailed. This embodiment of the invention is adapted to hold the concen~ration of C~ ion in cell b constant.
~Experiments 4 through 61 As shown in Fig. 6, reference electrodes 60 fabricated in accordance with Examples 7 through 9 were immersed in a 50 mM phosphate buffer solution having a pH
of 7.4. ~he electrodes were withdrawn from the solution after 0, 25, 45, 161 and 288 hr and then immersed `
together with a readily available SSCE 61 in a phosphate buffer solution 62 (p~ 7.4, 50 mM) containing 0.154 N
sodium chloride. Potential with respect to the SSCE 61 was measured. The results are as shown in Table 8.
Al~ost no difference among the reference electrodes of Example~ ~, 8, 9 ua~ noticed after 45 hr of ~mmersion.
After 161 hr of immersion, however, the potential of ~xample 8 shifted in the positive direction and that of Exa~ple 9 shifted iD the negative direction. In Example 7, on the other hand, the effects of the cation-exchange layer and anion exchange layer offset each other an no potential shift of the magnitudes was observed. Thus, a highly stable potential was obtained.
:'., .
`~- `` 1324418 ~ 10 _1 0 ~)_1 ~D
_ ~ C u~ o~ N o ¦-- ~t Vl N n~ N ~ :
~O ~ ~ ~
~ _ _ _ ~ C ~ ~. :, .
: ~ ' . .. -V~ 0 ' ' "
1324~18 As a comparison example, a reference electrode having a double-junction structure shown in Fig. 7 was fabricated using a porous ceramic filter as the plug 52 - and the partitioning wall 52a serving as the 5 liquid-junction portion. The potential of this reference `
electrode with respect to the SSCE 61 was measured after 0, 20, 45, 101 and 288 hr through the same method as that employed in Examples 7 through 9. The results are as shown in ~able 8. It was found that the reference electrode having this structure develops a sudden rise in potential after 288 hours, indicating that the electrode cannot withstand long use.
The above results show that use of the cation- and anion-exchange layers of the kind employed in Example 7 provided a reference electrode in which the outflow of chloride ion is prevented, whereby there is obtained a stable potential over an extended period of time. `
(Example 10~
As shown in ~ig. 8, a reference electrode was fabricated using a plug 52b having a capillary tube 80b in place of the plug 52 serving as the liquid-~unction portion. In addition, the ion permeable section employed a capillary tube 80a in place of the ion-exchange layer ~ `
:. :` .
53, 54.- Other portions identical with those shown in Fig. 7 are designated by like reference characters.
A hollow fiber of regenerated cellulose having a --length of 25 mm, an inner diameter of 203 pm, an outer diameter of 255 pm and a diffusion coefficient of 5 x ,'.~' '.,.' .' .
- 1~2~l8 1O-7 cm2/sec was used as the capillary tubes 80a, b. The lower capillary tube 80 was fixed in the lower hollow insulative tubular body 51 by a urethane bonding agent.
The other capillary tube 80 was passed through and secured within the partitioning wall 55 and the plug 52b.
Introduced under pressure from the other end of the hollow insulative tubular body 51 was agar-agar gel (agar-agar concentration: 2 wt~ containing saturated sodium chloride, whereby the interior of the tubular body 51 and the interiors o~ the regenerated cellulose hollow fibers were filled with the agar-agar gel. Another method whic~ can be used is to dip the end por~ion not having the regenerated cellulose hollow fiber secured thereto into the aforementioned agar-agar gel ana then lower the pressure inside the cellulose hollow fibers and tubular body 51 to fill them with the gel~ Next, the silver/silver chloride electrode 57 was inserted into the tubular body 51 to complete the fabrication of the reference electrode.
(~periment 7) The abovementioned reference electrode was dipped in a 50 ~M phosphate buffer solution of pH 7.4 and was ~ithdrawn after 20, 45, 161 and 2~8 hr. Then, as shown in Fig. 6, the electrode wais immeræed together with the readily available SSCE 61 in the 50 mM phosphate buffer solution 62 tpa 7.4) con~aining 0.154 M sodium chloride.
Potential with respect to the SSCE 31 was measured. The concentration of chlorine ion which flowed out into the 132~18 50 mM phosphate buffer solution from the reference electrode was measured by colorimetry. The results are shown in Table 8 in the same manner as the results of Experiments 4 through 6.
It is evident from the results that the reference electrode using the regenerated cellulose hollow fibers exhibited little chlorine ion outflow and a stable potential over an extended period of time.
(~xample 11) As shown iR Fig. 9, a reference electrode was fabricated having the ion-exchange layers provided between the cells a and b and the plug 5~b provided with the capillary tube 80 comprising a regenerated cellulose `
hollow fiber~ This reference electrode exhibited a 15 stable potential over an extended period of time, just as --the reference electrode of 2xample 10~
It should be noted that the cation- and anion-exchange layers and the regenerated cellulose hollow fibers can be plural in number. Also, the ele~trolyte is ~ ;
not limited to chlorine compounds such as sodium chloride and potassium chloride mentioned in the foregoing examples, and other halide compounds can be used if "
desired. The technical concept of the invention resides in a reference electrode which, while fulfilling its ~ -function as a reference electrode, exhibits less outflow of ions to a liquid specimen. To this end, the amount of - -ion permeation (diffusion coefficient, etc.) is set -within a predetermined range. The method of achieving -;;
' .
.' ,'''.' ` ~
;
132~418 ` this is not limited to that of the foregoing examples.
As many apparently widely different embodiments of the present invention can be made without departing from the spirit and scope thereof, it is to be understood that the invention is not limited to the specific embodiments thereof except as defined in the appended claims.
.
:
' '; ~ ~ ` ' . ~ , .
.
Claims (23)
1. A reference electrode comprising:
an electrical conductor consisting of platinum or silver;
a sintered body on the electrical conductor formed of a mixture of silver halide and silver oxide;
a water-containing gel enveloping said sintered body and containing a halogen ion electrolyte;
a hollow tubular body accommodating said water-containing gel and having one end closed by a first liquid-junction portion and its other end liquid-tightly sealed by a plug; and a conductor wire connected to the electrical conductor and extended to pass through the plug liquid tightly.
an electrical conductor consisting of platinum or silver;
a sintered body on the electrical conductor formed of a mixture of silver halide and silver oxide;
a water-containing gel enveloping said sintered body and containing a halogen ion electrolyte;
a hollow tubular body accommodating said water-containing gel and having one end closed by a first liquid-junction portion and its other end liquid-tightly sealed by a plug; and a conductor wire connected to the electrical conductor and extended to pass through the plug liquid tightly.
2. The reference electrode according to claim 1, wherein said first liquid-junction portion comprises a porous ceramic including a silicate and carbon.
3. The reference electrode according to claim 1, wherein said water-containing gel is selected from the group consisting of polyvinyl alcohol, polyacrylic amide. agar-agar, gelatin, mannon and starch.
4. The reference electrode according to claim 1, wherein said halogen ion is supplied to said water-containing gel by sodium chloride.
5. The reference electrode according to claim 1, wherein said first liquid-junction portion comprises an ion impermeable wall penetrated by an ion permeable portion permeable to said halogen ion and having a pre-determined diffusion coefficient and volume.
6. The reference electrode according to claim 5, wherein said water-containing gel is selected from the group consisting of polyvinyl alcohol, polyacrylic amide, agar-agar. gelatin, mannon and starch.
7. The reference electrode according to claim 5, wherein said halogen ion is supplied to said water-containing gel by sodium chloride.
8. The reference electrode according to claim 5, wherein the diffusion coefficient of said ion permeable portion ranges from 10-7 to 10-10 cm2/sec and the volume thereof ranges from 0.01 to 6 mm3.
9. The reference electrode according to claim 5, wherein said ion permeable portion comprises an ion exchange resin layer.
10. The reference electrode according to claim 5, wherein said ion permeable portion comprises an anion exchange resin layer and a cation-exchange resin layer.
11. The reference electrode according to claim 5, wherein said ion permeable portion comprises a hollow fiber filled with the water-containing gel containing the halogen ion electrolyte.
12. The reference electrode according to claim 11, wherein said hollow fiber comprises an ion permeable hydrophilic polymer or an ion permeable hydrophobic polymer.
13. The reference electrode according to claim 1, further comprising a second liquid-junction portion partitioning said water-containing gel into at least two portions.
14. The reference electrode according to claim 13, wherein at least one of said first and second liquid-junction portions comprises an ion impermeable wall penetrated by an ion permeable portion permeable to said halogen ion and having a predetermined diffusion coefficient and volume, and the diffusion coefficient of said ion permeable portion ranges from 10-7 to 10-10 cm2/sec and the volume thereof ranges from 0.01 to 6 mm3.
15. The reference electrode according to claim 14. wherein said ion permeable portion comprises an ion exchange resin layer.
16. The reference electrode according to claim 14, wherein said ion permeable portion comprises an anion exchange resin layer and a cation-exchange resin layer.
17. The reference electrode according to claim 14, wherein said ion permeable portion comprises a hollow fiber filled with the water-containing gel containing the halogen ion electrolyte.
18. The reference electrode according to claim 17. wherein said hollow fiber comprises an ion permeable hydrophilic polymer or an ion permeable hydrophobic polymer.
19. The reference electrode according to claim 13, wherein at least one of said first and second liquid-junction portions comprises a porous ceramic including a silicate and carbon.
20. A method of producing a reference electrode comprising:
mixing a silver halide and a silver oxide to form a mixture;
applying the mixture on a surface of an electrical conductor consisting of platinum or silver;
and sintering the mixture.
mixing a silver halide and a silver oxide to form a mixture;
applying the mixture on a surface of an electrical conductor consisting of platinum or silver;
and sintering the mixture.
21. The method according to claim 20, wherein the mixture has no less than 60 wt.% silver chloride and is sintered at 300-500°C.
22. The reference electrode according to claim 1, wherein said water-containing gel is a natural high polymer.
23. The reference electrode according to claim S, wherein said water-containing gel is a natural high polymer.
Applications Claiming Priority (4)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP61-160932 | 1986-07-10 | ||
| JP61160932A JPS6318259A (en) | 1986-07-10 | 1986-07-10 | Reference electrode |
| JP61169938A JPS6326566A (en) | 1986-07-21 | 1986-07-21 | Reference electrode |
| JP61-169938 | 1987-07-21 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1324418C true CA1324418C (en) | 1993-11-16 |
Family
ID=26487256
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000541808A Expired - Fee Related CA1324418C (en) | 1986-07-10 | 1987-07-10 | Reference electrode |
Country Status (10)
| Country | Link |
|---|---|
| US (1) | US5071537A (en) |
| EP (1) | EP0313657B1 (en) |
| KR (1) | KR900005480B1 (en) |
| AU (1) | AU596860B2 (en) |
| CA (1) | CA1324418C (en) |
| DE (1) | DE3789898T2 (en) |
| DK (1) | DK126388A (en) |
| ES (1) | ES2005903A6 (en) |
| FI (1) | FI890099A (en) |
| WO (1) | WO1988000700A1 (en) |
Families Citing this family (29)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| AT392848B (en) * | 1988-10-25 | 1991-06-25 | Karl Dr Harnoncourt | ELECTROCHEMICAL SENSOR |
| JP2581833B2 (en) * | 1989-09-11 | 1997-02-12 | 株式会社日立製作所 | Plant operation status monitoring system |
| GB9118300D0 (en) * | 1991-08-24 | 1991-10-09 | Kodak Ltd | Reference half-cell electrode |
| US5384031A (en) * | 1992-04-29 | 1995-01-24 | Diametrics Medical, Inc. | Reference electrode |
| US5516413A (en) * | 1993-09-01 | 1996-05-14 | Westinghouse Electric Corporation | Rugged electrode for electrochemical measurements at high temperatures and pressures |
| US5419826A (en) * | 1994-03-25 | 1995-05-30 | The United States Of America As Represented By The Secretary Of The Navy | Ion-selective reference probe |
| EP0840111B1 (en) * | 1994-10-28 | 2003-05-02 | Fuji Photo Film Co., Ltd. | Method of measuring a silver or halogen ion concentration and an apparatus for the same |
| US5584978A (en) * | 1994-11-15 | 1996-12-17 | Cominco Ltd. | Collection electrode (collectrode) for geo-electrochemical sampling |
| US5505826A (en) * | 1994-11-30 | 1996-04-09 | Haglin; Patrick G. | Hydrophilic anode corrosion control system |
| RU2117281C1 (en) * | 1994-12-15 | 1998-08-10 | Семен Борисович Ицыгин | General-purpose integral ion-selection transducer |
| FR2732466B1 (en) * | 1995-03-31 | 1997-06-06 | Jeulin Sa | ELECTRODE FOR A DEVICE FOR MEASURING SMALL POTENTIALS IN AN AQUEOUS SOLUTION, A NOZZLE FOR MAKING SUCH AN ELECTRODE, AND A METHOD FOR OBTAINING THE SAME |
| US6893552B1 (en) * | 1997-12-29 | 2005-05-17 | Arrowhead Center, Inc. | Microsensors for glucose and insulin monitoring |
| AU4830400A (en) * | 1999-08-04 | 2001-03-05 | Orion Research Inc. | Sealed salt bridge |
| GB2359995B (en) * | 2000-03-09 | 2002-02-13 | Ronald John Trott | Porous body probe electrodes |
| JP3760137B2 (en) * | 2002-03-08 | 2006-03-29 | 株式会社堀場製作所 | Reference electrode |
| DE10243930A1 (en) * | 2002-03-08 | 2003-09-25 | Conducta Endress & Hauser | A reference half-cell useful for a potentiometric measurement cell and useful generally in chemistry. medicine, and in environmental studies |
| US7373195B2 (en) | 2004-07-30 | 2008-05-13 | Medtronic, Inc. | Ion sensor for long term use in complex medium |
| NL1028264C2 (en) * | 2005-02-14 | 2006-08-15 | Hydrion | Membrane module for use in a reference electrode, a reference electrode and method for manufacturing a membrane module. |
| EP1929938A1 (en) * | 2006-12-04 | 2008-06-11 | Sentec AG | Device for measuring partial pressure of carbon dioxide |
| US20080149482A1 (en) * | 2006-12-21 | 2008-06-26 | Healthwatchsystems, Inc. | Reference electrode and reference solutions for use therein |
| US9006738B2 (en) * | 2008-08-25 | 2015-04-14 | Nxp, B.V. | Reducing capacitive charging in electronic devices |
| US8833146B2 (en) * | 2010-04-26 | 2014-09-16 | Southwest Research Institute | Corrosion sensor |
| MY183563A (en) * | 2010-10-29 | 2021-02-26 | Mimos Berhad | Silver and silver chloride reference electrode |
| US20180021563A1 (en) * | 2015-03-09 | 2018-01-25 | Koninklijke Philips N.V. | Iontophoretic device, arrangement and method |
| US10175277B2 (en) | 2015-08-31 | 2019-01-08 | Pgs Geophysical As | Identification of degrading electrodes in a marine electromagnetic survey system |
| US11571567B2 (en) * | 2016-01-05 | 2023-02-07 | Biosensor Laboratories Inc. | Iontophoresis device for drug delivery and method for manufacturing the same |
| CN107238641A (en) * | 2016-03-28 | 2017-10-10 | 梅特勒-托利多仪器（上海）有限公司 | A kind of reference electrode system |
| CN106841342B (en) * | 2017-03-31 | 2018-12-25 | 国家电网公司 | A kind of mercury-nitric acid amino mercury reference electrode and its preparation method and application |
| US20230295810A1 (en) * | 2022-02-22 | 2023-09-21 | Abdeljawad Abusneineh | Cathodic protection polypropylene graphite reference electrode |
Family Cites Families (20)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3833495A (en) * | 1970-09-28 | 1974-09-03 | Gen Electric | Reference electrode half cell |
| US3806439A (en) * | 1972-10-05 | 1974-04-23 | Foxboro Co | Reference electrode construction |
| US3856636A (en) * | 1972-11-30 | 1974-12-24 | Gen Electric | Oxygen sensor |
| CA1071306A (en) * | 1976-02-20 | 1980-02-05 | Ingrid J. Magar | Reference electrode for use at high temperatures and pressures |
| JPS5829868B2 (en) * | 1976-10-13 | 1983-06-25 | 四郎 吉沢 | Silver-silver oxide reference electrode |
| JPS5626250A (en) * | 1979-08-10 | 1981-03-13 | Olympus Optical Co Ltd | Composite chemical sensor |
| US4259164A (en) * | 1979-08-13 | 1981-03-31 | Eastman Kodak Company | Silver/silver halide electrodes comprising chromium or nickel |
| US4282081A (en) * | 1980-07-10 | 1981-08-04 | Graphic Controls Corp. | Double junction reference electrode |
| JPS5924242A (en) * | 1982-08-02 | 1984-02-07 | Terumo Corp | Reference electrode |
| FR2541462A1 (en) * | 1983-02-17 | 1984-08-24 | Texaim | Miniature electrochemical reference electrode |
| US4613422A (en) * | 1984-01-19 | 1986-09-23 | Integrated Ionics Inc. | Ambient sensing devices |
| NL8400649A (en) * | 1984-02-29 | 1985-09-16 | Cordis Europ | REFERENCE ELECTRODE OF THE SECOND ORDER. |
| JPS60231156A (en) * | 1984-04-30 | 1985-11-16 | Kuraray Co Ltd | Liquid junction type reference electrode |
| KR900008847B1 (en) * | 1985-05-27 | 1990-11-30 | 테루모가부시끼가이샤 | Ion senser and method of manufacturing same |
| US4913793A (en) * | 1985-09-10 | 1990-04-03 | Broadley-James Corporation | Reference electrode and method of making same |
| DK626986A (en) * | 1985-12-25 | 1987-06-26 | Terumo Corp | ion sensor |
| EP0235470B1 (en) * | 1986-01-24 | 1992-11-11 | TERUMO KABUSHIKI KAISHA trading as TERUMO CORPORATION | Ion-sensitive fet sensor |
| JPS62180263A (en) * | 1986-02-04 | 1987-08-07 | Terumo Corp | Oxygen sensor |
| JPS62277547A (en) * | 1986-05-26 | 1987-12-02 | Terumo Corp | Gas sensor |
| DE8614220U1 (en) * | 1986-05-26 | 1987-03-26 | Neukum Elektronik Gmbh, 7541 Straubenhardt, De |
-
1987
- 1987-07-09 US US07/298,744 patent/US5071537A/en not_active Expired - Lifetime
- 1987-07-09 EP EP87904557A patent/EP0313657B1/en not_active Expired - Lifetime
- 1987-07-09 WO PCT/JP1987/000491 patent/WO1988000700A1/en active IP Right Grant
- 1987-07-09 KR KR1019880700230A patent/KR900005480B1/en not_active IP Right Cessation
- 1987-07-09 AU AU76909/87A patent/AU596860B2/en not_active Ceased
- 1987-07-09 DE DE3789898T patent/DE3789898T2/en not_active Expired - Fee Related
- 1987-07-10 ES ES8702050A patent/ES2005903A6/en not_active Expired
- 1987-07-10 CA CA000541808A patent/CA1324418C/en not_active Expired - Fee Related
-
1988
- 1988-03-09 DK DK126388A patent/DK126388A/en not_active Application Discontinuation
-
1989
- 1989-01-09 FI FI890099A patent/FI890099A/en not_active Application Discontinuation
Also Published As
| Publication number | Publication date |
|---|---|
| EP0313657A1 (en) | 1989-05-03 |
| AU7690987A (en) | 1988-02-10 |
| EP0313657B1 (en) | 1994-05-25 |
| KR900005480B1 (en) | 1990-07-30 |
| DE3789898D1 (en) | 1994-06-30 |
| DK126388D0 (en) | 1988-03-09 |
| EP0313657A4 (en) | 1991-01-16 |
| WO1988000700A1 (en) | 1988-01-28 |
| DK126388A (en) | 1988-05-10 |
| FI890099A0 (en) | 1989-01-09 |
| DE3789898T2 (en) | 1994-09-08 |
| AU596860B2 (en) | 1990-05-17 |
| ES2005903A6 (en) | 1989-04-01 |
| FI890099A (en) | 1989-01-09 |
| KR880701881A (en) | 1988-11-05 |
| US5071537A (en) | 1991-12-10 |
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| Date | Code | Title | Description |
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| MKLA | Lapsed |