JP3175021B2 - Method and apparatus for stabilizing the potential of a pH measurement electrode - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention generally relates to a pH measuring electrode for measuring the pH of a solution, and more particularly, to a method in which the electrode potential of a pH measuring electrode using a metal oxide or a metal as a pH-sensitive film is reduced to the original potential in a short time. The present invention relates to a potential stabilizing method and device for returning to a state.

[0002]

2. Description of the Related Art As is well known, a pH measuring electrode having a hydrogen ion selective sensitive membrane is used for measuring the pH of a solution, and a typical example thereof is a glass electrode using glass as a pH sensitive membrane. For special solutions such as high-temperature solutions and special applications, pH measurement electrodes using a metal such as platinum or a metal oxide such as titanium oxide as a pH-sensitive film are used. Usually, when measuring pH, the above-mentioned pH measuring electrode is used as a working electrode, and this working electrode is dipped in a solution to be measured (solution to be measured) together with a reference electrode such as a calomel electrode or a silver-silver chloride electrode. Then, from the potential difference between the two electrodes, p
The H value is determined.

[0003] Glass electrodes have very good stability and high measurement accuracy, and thus are widely used for measuring the pH of various solutions. However, glass electrodes are fragile and difficult to handle because they are fragile, and there are limitations on the solutions that can be used because of poor chemical resistance. In addition, pH meter and other p
As the demand for miniaturization of the H measuring device has increased, there has been a drawback that it is difficult to miniaturize the glass electrode due to the manufacturing technology due to the high film resistance value.

[0004] For this reason, various pH measurement electrodes capable of eliminating these defects have been studied, and pH measurement electrodes using the above-mentioned metals and metal oxides as pH-sensitive films have been proposed.

A pH measuring electrode using a metal oxide as a pH-sensitive film generally shows that the oxidation-reduction equilibrium potential of the metal oxide at the interface with the solution changes depending on the hydrogen ion concentration in the solution. but it is intended to be used, there are problems in terms of stability, for example, concentration 10 ^-1 to 10 ⁰ M ascorbic acid,
When affected by coexisting substances such as ferrocyan and ferricyan, the electrode potential often fluctuates. Similarly, in the case of a pH measurement electrode using a metal as a pH sensitive film, the potential of the electrode often fluctuates due to the influence of coexisting substances.

Conventionally, the pH measuring electrode whose electrode potential fluctuates must be immersed in a standard solution having a constant pH (for example, pH 6.86) until the electrode returns to the original potential state. It took a minimum of 10 hours to return to, and many took 1 day (24 hours) to 2 days (48 hours).

[0007]

However, if it takes as long as 10 hours or more to restore the potential of the pH measuring electrode, the pH measuring electrode cannot be used during that time, which is extremely inefficient. Also, it may not return at all depending on how it was affected. If the electrode potential fluctuates, the asymmetry potential increases, so that calibration with a pH meter becomes impossible, and it must be discarded as a defective product.

Accordingly, one object of the present invention is to provide a potential stabilizing method capable of returning a fluctuated electrode potential of a pH measuring electrode using a metal oxide or metal to a pH-sensitive film to an original potential state in a short time. It is to provide.

Another object of the present invention is to stabilize the potential of a pH measuring electrode which can return a changed electrode potential to an original potential state in a short time by using a metal oxide or a metal as a pH-sensitive film. It is to provide a chemical conversion device.

[0010]

The above object is achieved by the method and apparatus for stabilizing the potential of a pH measuring electrode according to the present invention. In summary, the present invention provides a method of immersing a plurality of pH measuring electrodes using a metal oxide or a metal having a fluctuating electrode potential as a pH-sensitive membrane in a constant pH solution in a state where they are electrically short-circuited to each other. This is a method for stabilizing the potential of a pH measurement electrode.

Alternatively, the present invention provides a pH measurement electrode using a metal oxide or metal having a fluctuated electrode potential as a pH-sensitive film, and using the same metal oxide or metal as the pH-sensitive film of the pH measurement electrode as an inner electrode. A method for stabilizing the potential of a pH measurement electrode, comprising immersing a reference electrode to be used in a solution having a constant pH same as the internal liquid of the reference electrode in a state of being electrically short-circuited with each other.

Further, the present invention relates to an electrode accommodating portion for accommodating a plurality of pH measuring electrodes using a metal oxide or metal as a pH-sensitive film, a solution having a constant pH contained in the electrode accommodating portion, Means for electrically short-circuiting the plurality of pH measurement electrodes housed in the housing part to each other, immersing the plurality of pH measurement electrodes in the solution having a constant pH in the electrode housing part, and A potential stabilizing device for a pH measuring electrode, wherein the electrodes are electrically short-circuited to each other to stabilize the electrode potential of each pH measuring electrode.

Alternatively, the present invention provides a method for converting a metal oxide or metal to p
An electrode storage portion for storing a pH measurement electrode to be an H-sensitive film, a comparison electrode using the same metal oxide or metal as the pH-sensitive film of the pH measurement electrode as an inner electrode, and the electrode storage portion accommodated in the electrode storage portion. A solution having the same pH as the internal solution of the reference electrode, and a means for electrically short-circuiting the pH measurement electrode and the comparison electrode housed in the electrode housing part to each other, wherein the pH measurement electrode and A potential stabilizing device for a pH measurement electrode, characterized in that a reference electrode is immersed in the solution having a constant pH, and the electrodes are electrically short-circuited to each other to stabilize an electrode potential of the pH measurement electrode.

[0014]

Embodiments of the present invention will be described below in detail with reference to the accompanying drawings.

As a result of various studies on metal oxides, the present inventors have found that iridium oxide, which is chemically stable, is not attacked by acids including hydrofluoric acid, and has a low film resistance, is sensitive to pH. Was confirmed, and this iridium oxide film was formed on a metal substrate such as platinum or tantalum having a predetermined shape and dimensions by, for example, reactive sputtering, thereby producing a pH measurement electrode using the iridium oxide film as a pH-sensitive film.

(Example 1) Four iridium oxide pH measurement electrodes having the above structure were prepared and used for measuring the pH of a solution in which a substance affecting the iridium oxide pH measurement electrode coexisted. The electrodes were immersed in a neutral phosphate solution as a standard solution, and their electrode potentials were measured. The potentials of the respective electrodes were 281, 321, 256, and 3, respectively.
It fluctuated greatly to 85 mV. For the measurement of the electrode potential, a silver-silver chloride electrode (Satu. KCl-Ag / AgCl, our product HS-205C) was used as a reference electrode in contact with a saturated potassium chloride solution.

Next, as shown in FIG. 1, these four p
H measurement electrodes 1 to 4 are connected to their lead wires (lead wires).
In a state where the electrodes 1a to 4a were electrically connected to each other and the electrodes were electrically short-circuited, the electrodes were immersed in the same neutral phosphate solution 5 at pH 6.86 and left for 1 hour. After standing, the above pH6.
86, while immersed in neutral phosphate solution 5, the potential of each electrode was measured using a silver-silver chloride electrode contacted with the saturated potassium chloride solution as a reference electrode. The potentials were 261, 261, 261, and 261 mV, respectively. When the four electrodes 1 to 4 were immersed in a phthalate solution as a standard solution of pH 4.01, and the potential of each electrode was measured using the same comparative electrode, the potential of the electrodes 1 to 4 was measured. Are 430, 429, 4 respectively
30, and 430 mV. The results are shown in Table 1 below.

[0018]

[Table 1]

As is evident from Table 1 above, when the four electrodes were electrically short-circuited to each other and immersed in a neutral phosphate solution of pH 6.86 for 1 hour, the four iridium oxides which fluctuated greatly changed. It can be seen that the electrode potentials of the pH measurement electrodes 1 to 4 become almost the same in a short time of 1 hour, and return to almost the original potential state and are stabilized. Also, the slope per pH was in agreement with the theoretical value. In this way, the potential of the pH measurement electrode of iridium oxide returns to almost the original state in a short time,
What stabilizes is that since iridium oxide is a semiconductor metal oxide, current flows by electrically short-circuiting each other,
It is considered that the effect of equilibrium occurs.

(Example 2) Five iridium oxide pH measuring electrodes having the same structure as in the above-mentioned Example 1 were prepared and used for measuring the pH of a solution in which a substance affecting the iridium oxide pH measuring electrode coexisted. Thereafter, the electrodes were immersed in a neutral phosphate solution, which is a standard solution of pH 6.86, and their electrode potentials were measured. The potentials of the respective electrodes were 270, 282,
235, 258 and 282 mV. For the measurement of the electrode potential, a silver-silver chloride electrode (Satu. KCl-Ag / AgCl, our product HS-205C) which was brought into contact with the same saturated potassium chloride solution as in Example 1 was used as a comparative electrode.

Next, these five pH measuring electrodes were adjusted to pH
Dipped in a phthalate solution as a standard solution of 4.01;
The electrode lead wires of the electrodes were electrically connected to each other, short-circuited, and left for 1 hour. After standing, the potential of each electrode was measured using a silver-silver chloride electrode in contact with the saturated potassium chloride solution as a reference electrode while immersed in the phthalate solution of pH 4.01. The potentials of the electrodes are 425, 426, 430, 426, and 42, respectively.
6 mV. In addition, these five electrodes are connected to the above pH.
When the electrodes were immersed in 6.86 neutral phosphate solution and the potential of each electrode was measured using the same reference electrode, the potentials of these electrodes were 258, 261, 260, 260, and 258 mV, respectively. . The results are shown in Table 2 below.

[0022]

[Table 2]

As is evident from Table 2 above, the potential of the five iridium oxide pH measuring electrodes which fluctuated greatly was determined by the pH
It can be seen that even when immersed in the 4.01 phthalate solution, it becomes almost the same in a short time of one hour, and returns to almost the original potential state and is stabilized. In addition, 1pH
The slope per hit also agreed with the theoretical value.

From Tables 1 and 2 above, the solution in which the pH measuring electrode is immersed may be a solution having a constant pH. If the electrodes are short-circuited and immersed in the solution having a constant pH for a short time, It can be understood that the electrode returns to the substantially uniform and stable original electrode potential.

Each of the pH measuring electrodes having a fluctuating electrode potential, or the pH measuring electrode having a fluctuating electrode potential and a reference electrode are electrically short-circuited with each other and then dipped in a solution having a constant pH. After that, they may be electrically short-circuited to each other.

(Embodiment 3) In this embodiment, the pH measurement electrode
This is a method for stabilizing the electrode potential when iridium oxide is used not only for the H-sensitive film but also for the inner electrode of the reference electrode. As shown in FIG. 2, the reference electrode 10 is a double junction type having junctions 11 a and 12 a for the inner cylinder 11 and the outer cylinder 12, respectively. The inner electrode immersed in the internal liquid 13 in the inner cylinder 11 is used. 14, iridium oxide is used. As shown in an enlarged manner in FIG. 3, the inner pole 14 includes a conductive electrode support 21 having a predetermined shape and dimensions,
The electrode support 21 is formed on one surface of the support 21 and an iridium oxide film 22 formed by, for example, sputtering. The electrode support 21 is formed on the bottom surface of the support tube 16 coaxially arranged in the inner cylinder 11. The iridium oxide film 22 is supported in a state of being completely immersed in the internal liquid 13 in the inner cylinder 11 by being attached in a liquid-tight state in the formed through hole.

The electrode support 21 functions as a support for the iridium oxide film 22 and may be made of any conductive material such as aluminum, platinum, tantalum, titanium, and iridium. A plate-shaped tantalum metal plate is used, and an iridium oxide film 2 is used.
The entire surface other than the surface where 2 is applied is electrically insulated by the insulating film 24. Further, a lead wire 23 is electrically connected to an upper end portion of the electrode support 21 which does not contact the internal liquid 13,
The lead wire 23 passes through the support tube 16 and is connected to an input jack of a measurement processing circuit (not shown).

Although the insulating film 24 does not exist between the iridium oxide film 22 and the electrode support 21 in FIG. 3, the insulating film 24 is first deposited on the entire surface of the electrode support 21. The iridium oxide film 22 is, for example, deposited by sputtering to remove the insulating film therebetween, and the iridium oxide film 22 is electrically and strongly connected to the electrode support 21. Therefore, it is not necessary to remove the insulating film at the portion where the iridium oxide film is to be formed from the electrode support 21 in advance.

The electrode support 21 may be an insulating plate made of an inorganic material such as sapphire, glass, ceramics, or a plastic material such as polyvinyl chloride (PVC) or fluororesin. In this case, the upper part of the iridium oxide film 22 is disposed in the support tube 16, and the lead wire 23 is connected to the upper end of the iridium oxide film 22. On the other hand, as the insulating film 24, tantalum pentoxide (Ta ₂ O ₅ ), alumina (Al ₂ O ₃ ), silicon dioxide
Insulating oxides such as (SiO ₂ ) and silicon nitride (Si ₃ N ₄ ), and plastic materials such as nitride and fluororesin can be used. The insulating film 24 may use a natural oxide film, or may be formed using a manufacturing method such as a vacuum thin film manufacturing technique such as sputtering or CVD, a thermal oxidation, or a dip coating method using a metal alkoxide as a material. . In addition,
The shape and dimensions of the electrode support 21 can be arbitrarily selected. For example, various shapes of supports such as a rod, a cylinder, and a rectangular tube can be used. Also, as the metal oxide,
In addition to iridium oxide, for example, metal oxides such as palladium oxide and titanium oxide can be used. Of course, reference electrode 1
The inner pole 14 of 0 may be of any configuration.

When such a comparative electrode 10 having iridium oxide as the inner electrode 14 is used, as shown in FIG. 2, the pH of the iridium oxide with the electrode potential fluctuated.
The measurement electrode 30 and the comparison electrode 10 are connected to the inner cylinder 1 of the comparison electrode 10.
1 is immersed in a solution 15 having the same pH as that of the internal liquid 13 injected into the inside 1, and the lead wire 31 of the pH measurement electrode 30 and the lead wire 23 of the comparison electrode 10 are electrically connected to connect both electrodes to each other. Short-circuit electrically and leave for a predetermined time. In the present embodiment, the pH measurement electrode 30 of iridium oxide having an electrode potential of 320 mV and the reference electrode 10 of 247 mV in a neutral phosphate solution which is a standard solution of pH 6.86 are electrically short-circuited to each other. It was immersed in the same solution 15 as the constant pH internal solution 13 injected into the inner cylinder 11 of the comparative electrode 10 and left for 1 hour. Thereafter, this pH measuring electrode 30 was immersed in the above-mentioned neutral phosphate solution of pH 6.86, and its electrode potential was measured.
Met.

As described above, when the same metal oxide as that of the pH measurement electrode is used for the inner electrode of the reference electrode, the pH is changed to the same solution as the internal solution injected into the inner cylinder of the reference electrode.
By immersing the measurement electrode and the reference electrode, electrically short-circuiting the two electrodes and leaving the electrodes for a short time, the fluctuation of the electrode potential of the pH measurement electrode can be restored to almost the original state and stabilized. .

An example of the iridium oxide pH measuring electrode 30 is shown in FIG. This pH measurement electrode 30
A conductive electrode support 32 having a predetermined shape and dimensions, and a pH-sensitive film 33 made of, for example, an iridium oxide film formed on one surface of the support 32 by sputtering.
And the electrode support 3 supporting the pH-sensitive membrane 33.
The pH-sensitive film 33 is supported by the support tube 34 by fixing 2 to the bottom surface of the support tube 34 made of glass, for example. In this embodiment, the electrode support 32 has a diameter of 2 mm,
A platinum disk having a thickness of 0.2 mm was used, and a platinum lead wire 31 was connected to the platinum disk.
The surface of the platinum electrode plate to which the lead wire 31 is connected is brought into contact with the end surface of the glass support tube 34 by being inserted into a lead wire insertion hole formed on the end surface of the glass support tube 34 of the measurement electrode 30, and heated to form platinum. The disk was fused to the end face of the glass support tube 34.
At this time, the lead wire insertion hole was closed, and the lead wire 31 was sealed on the end face of the glass support tube 34. Next, after the oxide film on the surface is sufficiently removed by acid cleaning, a circular sensitive film forming portion having a diameter of 1 mm is left at the center of the surface of the platinum disk.
The remaining part is masked, put into a film forming chamber of a sputtering apparatus, and an Ir target is sputtered at a voltage of 0.8 KV for 100 minutes in an oxidizing atmosphere to form an iridium oxide film. The iridium oxide film is masked and placed in an alkaline solution.
After immersion for a time, an oxide film (insulating film) 35 was formed on the entire exposed surface of the platinum disk except for the iridium oxide film portion.

In another embodiment, a tantalum disk having a thickness of 0.5 mm and a diameter of 4 mm is used as the electrode support 32, and tantalum pentoxide formed by natural oxidation on the entire surface of the tantalum disk. This film was used as an insulating film 35, and an iridium oxide film having a diameter of 3 mm was deposited on the tantalum disk having the insulating film by sputtering using a masking material to form a pH-sensitive film 33 having a thickness of about 1000 °.

In FIG. 4, the insulating film 35 is provided between the pH-sensitive film 33 of iridium oxide and the electrode support 32 of a platinum disk.
However, an insulating film 35 is first applied to the entire surface of the electrode support 32, and the insulating film therebetween is removed by applying a metal oxide film of iridium oxide, for example, by sputtering. The metal oxide film is electrically and strongly connected to the electrode support 32. Therefore, it is not necessary to remove the portion of the insulating film where the metal oxide film is to be formed from the electrode support 32 in advance.

The conductive electrode support 32 functions as a support for the pH-sensitive film 33 of a metal oxide film, and can be made of any conductive material such as aluminum, platinum, tantalum, titanium, and iridium. But it is good. As the insulating film 35, tantalum pentoxide (Ta ₂ O ₅ ), alumina (Al ₂ O ₃ ), silicon dioxide (SiO ₂ ), silicon nitride (Si ₃
Plastic materials such as insulating oxides such as N ₄ ), nitrides and fluororesins can be used. The insulating film 35 may use a natural oxide film, or may be formed using a manufacturing method such as a vacuum thin film manufacturing technique such as sputtering or CVD, heat oxidation, or a dip coating method using a metal alkoxide as a material. . Further, as the metal oxide film, a metal oxide such as iridium oxide, palladium oxide, or titanium oxide can be used, and is formed on the electrode support 32 by a vacuum thin film manufacturing technique such as sputtering or CVD.
Of course, the configuration of the pH measurement electrode, the materials used, the manufacturing method, and the like are merely examples, and various modifications and changes can be made as needed.

FIG. 5 is a schematic diagram showing one embodiment of a potential stabilizing device for a pH measuring electrode according to the present invention.
This shows a state where the H measurement electrodes 41 and 42 are housed in the electrode housing part of the adapter 43. A constant pH solution 44 is injected into the adapter 43, and each adapter 43 has a different pH.
Terminals (input jacks) 45 and 46 into which electrode plugs (not shown) attached to the tips of the lead wires 41a and 42a of the measurement electrodes 41 and 42, respectively, are provided.
An on / off switch 47 is connected between these terminals. When the switch 47 is turned on, the two pH measuring electrodes 41 and 42 can be electrically short-circuited.

If the adapter 43 having the above configuration is attached to the pH measuring device (it is convenient to make it detachable), after the measurement is completed, the pH measuring electrode is housed in the adapter 43 and the switch 47 is turned on. By doing so, the pH measurement electrode can be stabilized easily and in a short time, so that the next measurement can be immediately performed, which is very convenient.

In the above embodiment, the adapter 43 is provided with an electrode housing for accommodating two pH measuring electrodes. However, if the electrode housing is configured to be able to accommodate three or more pH measuring electrodes, it is necessary to provide one. Thus, many pH measuring electrodes can be stabilized.
Of course, in this case, all the p stored in the electrode storage section
Short-circuit means are configured so that the H measurement electrodes can be electrically short-circuited to each other. In addition, one or more adapters 43
The configuration may be such that the H measurement electrode and one (or a plurality of) comparison electrodes can be accommodated. In this case, the same constant pH solution as the internal solution of the reference electrode is put in the adapter 43. Furthermore, if the same constant pH solution as the internal solution of the reference electrode is put in the electrode storage portion of the adapter 43, even when a plurality of pH measurement electrodes are stored, the pH measurement electrode and the comparison electrode are stored. However, there is an advantage that the pH measurement electrode can be stabilized quickly.

Since the adapter 43 can be removed,
Remove the adapter 4 to save the measurement electrode.
3 and electrically short-circuited, there is an advantage that trouble during storage is completely eliminated. In addition, when the pH measurement electrode is stored or when aging is insufficient, a good result can be obtained by inserting an appropriate resistor into the short circuit when electrically short-circuiting. If this resistance is a variable resistance of about 0 to gigaΩ, the operation becomes easy and it is convenient. Further, it is a matter of course that the potential stabilizing device may not be of the adapter type, but may be completely separate from the pH measuring device.

Although iridium oxide is used as the metal oxide in each of the above embodiments, the same operation and effect as in the above embodiment can be expected in the case of other metal oxides having similar properties. In addition, the present invention described above can be applied to a pH measurement electrode using a metal such as gold, silver, and platinum as a pH-sensitive film,
Similar effects can be expected.

[0041]

As is apparent from the above description, according to the present invention, a plurality of pH measuring electrodes using a metal oxide or a metal whose electrode potential fluctuates as a pH-sensitive film are electrically short-circuited to each other. In this state, if the electrode is simply immersed in a constant pH solution for a short period of time, or when using a reference electrode having the same metal oxide or metal as the pH-sensitive membrane as the inner electrode, the pH measurement electrode and this reference electrode are electrically connected to each other. In a short-circuited state, simply immersing in a solution with the same pH as the internal solution of the reference electrode for a short time,
Even if these fluctuating electrode potentials of the pH measurement electrode fluctuate significantly, they can be returned to almost the original potential state and stabilized, so that it is very efficient, and
Since it can be restored to a potential state that can be sufficiently calibrated and stabilized, it has a remarkable effect that it can be reused without being discarded as a defective product as in the related art.

[Brief description of the drawings]

FIG. 1 is a schematic explanatory view illustrating one embodiment of a method for stabilizing the potential of a pH measurement electrode according to the present invention.

FIG. 2 is a schematic explanatory view illustrating another embodiment of a method for stabilizing the potential of a pH measurement electrode according to the present invention.

FIG. 3 is an enlarged configuration diagram illustrating an example of a comparative electrode.

FIG. 4 is an enlarged configuration diagram showing an example of a pH measurement electrode.

FIG. 5 is a schematic configuration diagram showing one embodiment of a potential stabilizing device for a pH measurement electrode according to the present invention.

[Explanation of symbols]

1-4 pH measuring electrode 5 pH 6.86 neutral phosphate solution 10 Comparative electrode 11 Inner cylinder of comparative electrode 12 Outer cylinder of comparative electrode 13 Internal liquid in inner cylinder 14 Inner electrode of comparative electrode 15 In inner cylinder Solution having the same pH as the internal solution 16 Support tube 21 Electrode support 22 Iridium oxide film 23 Lead wire 30 pH measurement electrode 31 Lead wire 32 Electrode support 33 pH-sensitive film of iridium oxide 34 Support tube 35 Insulation film 41, 42 pH measuring electrode 43 Adapter 44 Constant pH solution 47 Switch

──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Yuko Konno 613 Kitairiso, Sayama-shi, Saitama Toa Denpa Kogyo Co., Ltd. Sayama Plant (56) References JP-A-61-195344 (JP, A) 58-221156 (JP, A) JP-A-61-51554 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G01N 27/416 G01N 27/26 381 G01N 27/30

Claims (7)

(57) [Claims] 1. A method of immersing a plurality of pH measuring electrodes using a metal oxide or a metal having a fluctuating electrode potential as a pH-sensitive film in a constant pH solution in a state of being electrically short-circuited with each other. The method for stabilizing the potential of the pH measurement electrode. 2. A pH measurement electrode using a metal oxide or metal whose electrode potential fluctuates as a pH-sensitive film, and a comparative electrode using the same metal oxide or metal as the pH-sensitive film of the pH measurement electrode as an inner electrode. Are electrically short-circuited to each other,
A potential stabilizing method for a pH measuring electrode, characterized by immersing the electrode in a solution having the same pH as the internal liquid of the comparative electrode. 3. The method according to claim 1, wherein the metal oxide is Ir, Pd, Pt,
3. The potential stabilizing method for a pH measuring electrode according to claim 1, wherein the method is an oxide of a metal selected from the group consisting of Sn, Rh, Ta, Os, Ru, W, and Ti. 4. The method for stabilizing a potential of a pH measurement electrode according to claim 1, wherein the metal oxide is iridium oxide. 5. The method according to claim 1, wherein the immersion time in the solution having a constant pH is about 1 hour.
A method for stabilizing the potential of the H measurement electrode. 6. An electrode accommodating section for accommodating a plurality of pH measuring electrodes using a metal oxide or a metal as a pH-sensitive film, a constant pH solution contained in the electrode accommodating section, and accommodating in the electrode accommodating section. Means for electrically shorting the plurality of pH measurement electrodes to each other, immersing the plurality of pH measurement electrodes in the solution having a constant pH in the electrode housing portion, and electrically connecting the pH measurement electrodes to each other. Characterized in that the electrode potential of each pH measuring electrode is stabilized by short-circuiting
Potential stabilizer for measuring electrode. 7. An electrode housing section for housing a pH measuring electrode using a metal oxide or metal as a pH sensitive film and a comparative electrode using the same metal oxide or metal as the inner electrode as the pH sensitive film of the pH measuring electrode. And a solution having the same pH as the internal solution of the comparison electrode contained in the electrode storage portion, and means for electrically short-circuiting the pH measurement electrode and the comparison electrode stored in the electrode storage portion to each other. And p in the electrode housing.
The H measurement electrode and the reference electrode are immersed in the constant pH solution, and these electrodes are electrically short-circuited to each other to form the p electrode.
A potential stabilizing device for a pH measuring electrode, which stabilizes an electrode potential of an H measuring electrode.