JPS60237351A - Ion selection electrode and manufacture therefor - Google Patents

Abstract

PURPOSE:To reduce the response time for measurement by arranging an electrolytic layer made up of an electrolytic crystal with the crystal diameter of 60mum or less which is developed tightly on a layer containing a non-water soluble salt with respect to metal of an electrode. CONSTITUTION:An aqueous solution containing an electrolytic salt is applied on a layer containing a non-water soluble salt with respect to metal used in a conductive metal layer. Then, the coated layer is dried by being brought into contact with a flowing gas heated up to over 40 deg.C. Thus, an electrolytic layer is formed on a layer containing a water-soluble salt in such a manner as to be made up of an electrolytic crystal with the crystal diameter of 60mum or less tightly developed thereby making the potential stable at a very short time.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of the Invention] The present invention relates to an ion selective electrode and a method for making the same. More specifically, the present invention relates to an ion-selective electrode suitable for use in potentiometrically measuring potassium ions and a method for producing the same.

[Background of the Invention] Ion-selective electrodes are measuring instruments for potentiometrically measuring ion concentrations mainly in body fluids such as aqueous fluids, blood, and serum, and the basic structure thereof has already been disclosed in JP-A-52 ．． This is disclosed in, for example, Japanese Patent No.-142584. That is, an ion-selective electrode includes a support, a conductive metal layer (e.g., a vapor-deposited silver layer), and a water-insoluble salt of the metal (e.g., silver chloride).
an electrolyte layer comprising an anion of the water-insoluble salt, an electrolyte salt (e.g., potassium chloride, sodium chloride), a common anion and a cation (e.g., potassium ion, sodium ion), and ion. It has a basic configuration in which the selection layers are integrated in this order.

When using the ion-selective electrode (half-cell) with the above-mentioned basic configuration for actual ion concentration measurement, two ion-selective electrodes A and B are used as a set, and each ion-selective layer A and B is After connecting with a water-carrying bridge and spotting the standard solution and sample solution on each of the ion-selective layers A and H, the potential difference between the conductive metal layers A and H after a certain period of time is measured. A method is used in which the concentration of the electrolyte contained in the sample liquid is calculated from a calibration curve prepared in advance and this potential difference. However, similar measurements can also be carried out using a pair of ion selective electrodes electrically insulated by a scratch groove as disclosed in Japanese Patent Application Laid-Open No. 58-156848.

As mentioned above, the ion selective electrode basically has a simple structure and is obtained as a microchip, so the amount of sample required is extremely small. Very useful for measuring quantities. Furthermore, since the ion selective electrode has a simple and minute structure as described above, it has the advantage of being disposable.

However, on the other hand, a minute ion selective electrode has a problem in that its measurement accuracy tends to be insufficient. This is due to the fact that the ion-selective electrode is prone to potential fluctuations (potential drift) during measurement. One possible measure to reduce potential drift is to thicken each functional layer of the ion-selective electrode, but this increases the unit price of the ion-selective electrode, making it difficult to use it disposablely. Sensitivity also tends to decrease.

As an improved technique to avoid problems such as potential drift as described above, the electrolyte layer is formed by forming an electrolyte base layer or by coating and drying an electrolyte aqueous solution to form an electrolyte layer that does not substantially contain a binder. An invention has already been proposed (Japanese Unexamined Patent Publication No. 17852/1983). Although this invention has made it possible to reduce the occurrence of potential drift in conventionally known ion selective electrodes, it is desirable to further reduce potential drift in order to improve the accuracy of measurements using ion selective electrodes. In other words, when an electrolyte layer is formed by applying and drying an electrolyte aqueous solution, the electrolyte crystals produced are large, so the electrolyte distribution in the electrolyte layer tends to be uneven, and the thickness of the electrolyte layer tends to increase. These problems occur, and both become factors that impede improvement in measurement accuracy. On the other hand, the method of forming an electrolyte layer by vapor deposition of an electrolyte is difficult to use when the vapor pressure of the electrolyte is low, and special care is required in the vapor deposition operation for electrolytes that easily decompose at high temperatures, resulting in a reduction in vapor deposition efficiency. is not advantageous for industrial operation.

[Summary of the Invention] The present invention provides an ion-selective electrode suitable for use in analysis for potentiometrically measuring potassium ions, in which the occurrence of phenomena that cause measurement errors such as potential drift is reduced. The main purpose is

Further, a main object of the present invention is to provide an ion selective electrode for potassium ion analysis that has a shortened response time during measurement.

An object of the present invention is to provide an ion-selective electrode particularly suitable for analyzing potassium ions in body fluids.

Furthermore, another object of the present invention is to provide a method for manufacturing an ion-selective electrode for potassium ion analysis in which the occurrence of phenomena that cause measurement errors such as potential drift is reduced and the response time is shortened. It is something to do.

The ion selective electrode suitable for analyzing potassium ions provided by the present invention includes a support, a conductive metal layer, a layer containing a water-insoluble salt of the metal, an anion common to the anion of the water-insoluble salt, and potassium ions. In an ion-selective electrode, an electrolyte layer consisting of an electrolyte salt substantially free of paint and an ion-selective layer are integrated in this order,
The electrolyte layer is characterized in that the electrolyte crystals having a crystal diameter of 60 μm or less are densely spread on the layer containing the water-insoluble salt.

The above-mentioned ion-selective electrode is produced by coating an aqueous solution containing an electrolyte salt on a layer containing the water-insoluble salt, and then bringing the coated layer into contact with a flowing gas heated to 40°C or higher. The electrolyte layer can be produced by forming an electrolyte layer on the layer containing the water-insoluble salt so as to be made of the electrolyte crystals having a crystal diameter of 60 pm or less, which are dried and expanded by this process.

[Detailed Description of the Invention] The basic composition of the ion-selective electrode provided by the present invention is a support, a conductive metal layer, a layer containing a water-insoluble salt of the metal, and an anion common to the anion of the water-insoluble salt. As mentioned above, an ion-selective electrode in which an electrolyte layer consisting of an electrolyte salt of ions and potassium ions and substantially containing no binder and an ion-selective layer are integrated in this order is already known (particularly Publication No. 17852/1983). In the ion selective electrode of the present invention, a structure other than the electrolyte layer,
The material of each layer can be selected according to known techniques. Examples of publications disclosing the structure, materials, etc. of ion-selective electrodes include the above-mentioned Japanese Patent Laid-Open No. 5
Examples include JP 2-142584, JP 57-17852, and JP 58-211648.

For example, a film (or sheet) made of a plastic material such as polyethylene terephragm can be used as the support. As a conductive metal layer,
A typical example is a layer made of metallic silver laminated on the surface of a support by a method such as thin coating. For example, when the conductive metal layer is a metal silver layer, the layer containing the water-insoluble metal salt is
It can be formed by chemically oxidizing and chlorinating the surface portion of the silver layer to form a silver chloride layer, or by applying a dispersion containing silver chloride and a binder to the surface of the metal silver layer and drying it. The electrolyte layer provided on the layer containing the water-insoluble salt described above is a characteristic layer of the present invention, and can be formed by the method described later.

The ion-selective layer is a layer consisting of a hydrophobic organic binder containing an ion carrier consisting of an organic substance. Examples of ion carriers include palinomycin, cyclic polyethers, tetralactones, macrolidoactin, enninatin, potassium tetraphenylfolate, and derivatives thereof. 6°. 52.7. As the material, natural polymeric substances, derivatives thereof, or synthetic polymeric substances capable of forming a thin film can be used, such as cellulose ester, polyvinyl chloride, vinyl chloride, etc. - Vinyl acetate copolymer, polyvinylidene chloride, polyacrylonitrile, polyurethane, polycarbonate, etc. can be mentioned. Note that the ion selective layer may be formed from an ion exchange resin,
In that case, the ion exchange resin is appropriately selected depending on the type of ion to be analyzed.

The characteristic structure of the ion-selective electrode of the present invention is that the electrolyte layer containing a salt of potassium ions substantially does not contain a binder, and the layer containing a water-insoluble salt of a metal constituting the conductive metal (hereinafter referred to as water-insoluble The diameter of the crystals densely developed on the insoluble salt layer is below a certain value (60 gm or less, preferably 50-0.1 pm, more preferably 40-0.5 pm,
m) consists of electrolyte crystals.

In the present invention, "the electrolyte crystals are densely spread" means that the electrolyte crystals form a layer between the water-insoluble salt layer and the ion-selective layer to such an extent that they do not substantially come into contact with each other. It does not necessarily mean that all electrolyte crystals are arranged adjacent to each other.

Further, in the present invention, it is desirable that the electrolyte crystals forming the electrolyte layer do not substantially overlap in the direction perpendicular to the surface of the ion selective electrode, and therefore the thickness of the electrolyte layer approximately corresponds to the average diameter of the electrolyte crystals. This is desirable.

That is, in the present invention, by densely spreading such an electrolyte salt with a small crystal size on the surface of the water-insoluble layer without using a binder, the electrolyte can be distributed uniformly and densely on the surface of the water-insoluble layer. , a thin electrolyte layer is formed. An ion selective electrode having such an electrolyte layer has a fast response speed, and the occurrence of potential drift can be suppressed in a non-destructive manner. Further, phenomena such as interlayer separation caused by peeling of the electrolyte layer, which tends to be a problem in an electrolyte layer without a binder, hardly occur. The reason for this, besides the homogenization and reduced thickness of the electrolyte layer, is that the electrolyte salt in the form of small crystals defined in the present invention is partially engaged with the water-insoluble salt layer. I can think of things. In particular, when the water-insoluble salt layer is a silver chloride layer, since the silver chloride layer exhibits a relatively porous surface, the electrolyte salt and the water-insoluble salt layer (silver chloride layer) are significantly bound together.

Furthermore, since the electrolyte layer of the present invention is composed of crystal grains with an appropriate particle size and is substantially a single-particle layer, poor adhesion between the electrolyte layer and the ion-selective layer, which is observed in an electrolyte layer containing a hydrophilic binder, can be avoided. Problems such as poor adhesion have been improved, and the occurrence of these phenomena is hardly observed.

According to the inventor's studies, potassium electrolyte salt crystals with a small crystal size as specified in the present invention can be obtained by simply applying an aqueous solution of an electrolyte salt to the surface of a water-insoluble salt layer as known so far. , this cannot be obtained by methods such as air drying.

That is, in a known method in which an aqueous solution of a potassium electrolyte salt such as potassium chloride or potassium bromide is applied onto a water-insoluble salt layer and left at room temperature, the crystal diameter (average crystal size) of the precipitated crystals The crystal diameter is generally 70 Kawada or more, and is usually about 70 to 100 gm. An electrolyte layer composed of such large crystals spread over a water-insoluble salt layer is inferior in terms of uniformity of electrolyte distribution and thickness of the electrolyte layer, which causes potential drift. However, since the electrolyte layer inevitably becomes thicker, the response time in analysis becomes longer.

On the other hand, after applying an aqueous solution containing an electrolyte salt on the water-insoluble salt layer, the applied layer is brought into contact with a flowing gas heated to 40°C or higher (preferably 50 to 200°C). When dried, the densely developed crystals have a diameter of 50 gm or less (usually 40-0.1A1.m).
An electrolyte layer consisting of the electrolyte crystals is formed on the layer containing the water-insoluble salt. An electrolyte layer made of crystals with such a small S diameter improves the uniformity of electrolyte distribution and the uniformity of the thickness of the electrolyte layer, thereby reducing the occurrence of potential drift and thus improving the measurement accuracy of analysis. will improve.

There is no particular restriction on the concentration of the electrolyte salt aqueous solution used to produce the electrolyte layer of the present invention, but it is usually about 0.5 to
An aqueous electrolyte salt solution ranging from about 20% by weight, preferably from about 0.5 to about 15% by weight, and most preferably from about 0.5 to about 10% by weight is used. Note that in order to improve manufacturing efficiency, it is desirable to use a highly concentrated solution.

Since the anion on the other side of the potassium ion in the electrolyte salt forming the electrolyte layer of the present invention needs to be the same as the anion in the salt contained in the water-insoluble salt, the electrolyte salt should be selected in consideration of the overall configuration of the ion-selective electrode. and be selected. Generally, the conductive metal layer of an ion selective electrode is often composed of metallic silver, and the layer containing a water-insoluble salt of the metal often contains silver chloride, so potassium chloride is inevitably used as the electrolyte salt. is often used. However, the anion of the water-insoluble salt contained in the water-insoluble salt layer is a bromine ion.

If the anion is an anion other than a chloride ion, such as an iodide ion, a sulfonium ion, or a carboxylate ion, the anion of the potassium salt used in the electrolyte layer must be selected to match the anion.

Next, Examples and Comparative Examples of the present invention will be shown.

[Example 1] Polyethylene terephthalate film (Jl: 1.8
811. A metallic silver layer (vapor deposited silver layer) with a thickness of about 800 nm was formed by vacuum deposition on the sample (dimensions: 30 mm x 100 mm). Then, both ends of this vapor-deposited silver layer were
8-102146, to protect both ends thereof, and remove scratches from the central part of the vapor-deposited silver layer using a canter knife to form a figure-7 groove. An insulated part was provided.

Next, the uncoated portion of the vapor-deposited silver layer of the laminate was treated with a treatment solution containing chloride and potassium dichromate (an aqueous solution containing 36 mmol/liter and 16 mmol/liter of hydrogen chloride and potassium dichromate, respectively). A catalytic oxidation chlorination treatment was carried out for about 60 seconds. After this treatment is completed, this laminate is washed with water and dried to form a film-like silver/silver chloride electrode (support, conductive silver, etc.).
A 3% potassium chloride aqueous solution was coated on the silver 11 silver chloride electrode film-1- described above, and then the coated layer was dried by contacting it with air waves at a temperature of about 150° C. for about 3 minutes using a dryer. The weight of the coated layer after drying is l, Og/m
'Met. When this dried coating layer (electrolyte layer) was observed under a microscope, a large number of potassium chloride microcrystals with a crystal diameter of about 30 gm were found to be densely spread on the silver chloride layer.

An ion selective electrode I for potassium ion analysis was prepared by placing a potassium ion selective layer having the composition shown below on the above electrolyte layer using a conventional method so that the layer thickness was 20 pm.

Potassium on VYNS wood 0.9 g Dioctyl adipate 1.2 g Palinomycin 44 mg Potassium tetrakis parachlorophenylborate 18 mg Methyl ethyl ketone 5 g 1% 5H510 (polysiloxane, methyl ethyl ketone solution) 0.05 g Note) VYNS:
Vinyl chloride-vinyl butyrate copolymer manufactured by Union Carbide [Comparative Example 1] A 3% potassium chloride aqueous solution was applied to a silver/silver chloride electrode film prepared by the same method as in Example 1, and the weight of the coated layer after drying was is 1. og/rrf, and then the coated layer was left at room temperature (about 20'0) for about 5 hours to air dry. When this dried coating layer (electrolyte layer) was observed under a microscope, many potassium chloride crystals with a crystal diameter of about 80 gm were developed on the silver chloride layer.

A potassium ion selective layer was attached on the electrolyte layer by a conventional method in the same manner as in Example 1 to prepare an ion selective electrode (2) for potassium ion analysis.

[Evaluation of ion-selective electrode] The two liquid receivers are made of plastic film with holes.A mask is attached to the surface of the ion-selective electrode by adhesion, and then the liquid receiver is made of polyester spun yarn so that the holes are connected. An electrode device for potassium ion analysis was prepared by attaching a bridge. A schematic diagram showing the configuration of this electrode device for potassium ion analysis is shown in FIG. In FIG. 1, 11 is a polyethylene terephthalate film (support), l 2
13a and 13b are silver chloride layers, 14
1 is a potassium chloride layer, 15 is an ion-selective layer, 16 is a mask, 17a and 17b are liquid receiving holes, and 18 is a bridge.

One of the liquid receivers has the hole 17a dotted with Caliplate 2 as a potassium ion-containing standard solution, and the other liquid receiver has the hole 17a.
Caliprate 1, 2, or 3 was spotted as a sample solution on the plate, and the simultaneous reproducibility of the values was determined by a differential method according to a conventional method. The results are shown in Table 1.

1st table electrode ■ Electrode ■ Displayed value Actual value Kaliprate 1 2.0 3.2 2.8 2,9 2 2.5 3.5 4.9 4.9 3 2.8 3.0 7.9 7 .8 Note: The slope value at Cali plate 1 is 63 mV
It was / decade.

In the above measurements, the expected value (±50 mV) for electrode ① manufactured according to Example 1 was obtained even after 50 measurements.
However, electrode H manufactured according to Comparative Example 1 had a deviation of ±50 m in 50 measurements.
Eight times within the range of V, values deviating from the expected values were obtained.

[Example 2] An ion selective electrode for potassium ion analysis was produced in the same manner as in Example 1 except that the thickness of the ion selective layer was changed from 20 gm to 25 gm.

When the same evaluation as above was carried out using this ion selective electrode Natsu, results similar to those obtained when ion selective electrode I was used were obtained.

U Example 3 F A 3% potassium chloride aqueous solution was coated on a silver/silver chloride electrode film prepared by the same method as in Example 1 using a continuous coater, and an air flow was applied to this coated layer at a temperature of 80°C and a wind speed of 2.5 m. /
The contact was made for 3 minutes under the condition of 2 seconds. The weight of the coating layer obtained was 1 -3 g/rn'. This dry coating layer (
When the electrolyte layer) was observed under a microscope, the crystal diameter was approximately 35 mm.
A large number of potassium chloride fine crystals of gm were densely spread on the silver chloride layer.

In the same manner as in Example 1, a potassium ion selective layer was attached on top of the electrolyte layer described above to prepare an ion selective electrode IV for potassium ion analysis.

Regarding the above ion selective electrode IV, ion selective electrode■,
Evaluation was performed using the same differential method as in (2).

The results are shown in Table 2.

Second table electrode rv Display value Actual value Highland Q-It 2.8 6.3 6.2 Highland Q-I 2.3 4.5 4.5 Omega-C2,72
, 62, 6 The ion selective electrode IV did not deviate from the expected value even after 50 measurements.

[Example 4] A film-like silver/silver chloride electrode (reference electrode) and the ion-selective electrode for potassium ion analysis prepared in Example 1 were assembled using a mask and a bridge to form a liquid receiver as shown in Figure 1. Connected.

Caliplate 2 is spotted as a potassium ion-containing standard solution on the reference electrode, and Caliprate 1.2 or 3 is spotted as a sample solution on the ion-selective electrode I, and the time of the potential at that time is determined according to the known direct method. Changes were measured. The results are shown in FIG.

As is clear from FIG. 2, the potential stabilized within a very short time.

[Example 5] Potassium chloride content is 0.5%, 1.0%, 2.0%
, 3.0%, 4.0%, 5.0%, and 10.0% sample solutions using ion selective electrode I for potassium ion analysis.
When measurements were performed using the same direct method as in Example 4, the measured values in all cases were about -230 mV.

A similar measurement was carried out using the differential method; cv=2.0.
A result of ~3.5% was obtained.

[Brief explanation of drawings]

FIG. 1 shows an ion-selective electrode equipped with a bridge for carrying out evaluation by a differential method. FIG. 2 is a graph showing temporal changes in the potential of the ion selective electrode of the present invention measured by a direct method. 11: Support, 12a, 12b near 4 silvered layers. 13a, 13b: Silver I layer, 14: Potassium chloride layer, 1
5: Ion selective layer, 16: Liquid receiver is mask. 17a, 17b: Liquid receiver is hole, 18: Brillant patent applicant Fuji Photo Film Co., Ltd. agent Patent attorney Yanagawa
Yasuo Figure 1 Figure 2 (&) Procedural amendment November 1, 1980 # Manabu Shiga, Director General of the Office of the Chief Administrative Authority, Indication of the case 2, Name of the invention Ion selective electrode and its manufacturing method 3, Person making the amendment Relationship to the case Patent applicant name (520) Fuji Photo Film Co., Ltd. 4, agent address 6, 8th floor, Mitsuya Yotsuya Building, 2-14 Yotsuya, Shinjuku-ku, Tokyo, number of inventions increased by amendment None 7, amendment Subject: Column 8 of the "Detailed Description of the Invention" in the Specification, Contents of the Amendment As shown in the attached document, the "Detailed Description of the Invention" column of the Specification will be amended as follows. (1) Page 10, line 2 to page 4, supplement 1 - "The ion-selective layer is a layer made of hydrophobic organic paint containing an ion carrier made of an organic substance." 11□ r The ion-selective layer is a layer that can select specific ions, and has high electrical resistance and is substantially electrically insulating in a dry state before coming into contact with the sample solution or standard solution. Here, "can select a specific ion" means not only when only a specific ion is selectively transmitted or sensitive to it, but also when a specific ion is excluded from other measurement targets with a sufficient time difference for measurement. This also includes cases where the substance can be selected from the following. Also, depending on the material used for the ion selective layer,
In this specification, when the potential difference corresponding to the change in ion activity in the liquid is measured through ion exchange, and the function equivalent to that of selecting a specific ion is expressed as a result, this specification also refers to [J that can select a specific ion]. . The ion-selective layer must be water-insoluble since both the sample and standard solutions are aqueous static. Further, the ion selective layer may be wood-philic or hydrophobic as long as it is water-insoluble, but it is preferably hydrophobic. The ion selective layer can be provided by a conventionally known method. For example, an ion carrier dissolved in an ion carrier solvent is applied together with a hydrophobic organic paint onto a water-insoluble salt layer, an electrolyte layer, or a conductor layer and dried. The ion carrier concentration is generally 0,05~l
Og/m', the thickness of the ion selective layer is about 3 gm to about 125
μm, preferably about 5 to about 50 m. J (2) On page 10, line 8, insert the following sentence after "I can list the following." Examples of the above-mentioned ion carrier solvents include phthalate, sehecate aromatic or aliphatic ethers and adipates. -Methoxyphenyl phenol ether, dimethyl fucrate, dibutyl phthalate, didodecyl phthalate, dioctyl phenyl phosphonate, sifresyl phosphe-1...bis(2-ethylhexyl)2
Mention may be made of talate, octyl diphenyl phosphonoate, tritolyl phosphate, dioctyl adipate and dibutyl sepacate. Also, many other useful solvents are already known. Isamu (3) p. 10, line 14 to p. 18, correction 1 "Polycarbonate can be mentioned. In addition, the ion-selective layer may be formed from an ion-exchange resin, and in that case, the ion-exchange resin is It is selected as appropriate depending on the type of ion to be analyzed. The ion selective layer consists of
In addition to the above-mentioned Japanese Patent Publication No. 5B-4981, Japanese Patent Publication No. 58
-156848 or US Pat. No. 405338
1ji11 United States4. II Language No. 4171246 U.S. Patent 4
214968 each detailed account and rResearch D
isclosureJQ, Report No. 16113 (
The materials and υ techniques described in the September 1977 issue can be used. Ion exchange substances can also be used as the material for the ion selective layer. In this case, the potential difference response resulting from the change in ion activity 9 caused by ion exchange will be measured. Appropriate ion exchange materials that can be used in the present invention and methods for forming ion selective layers using these materials are disclosed in Japanese Patent Publication No. 52-477.
It is described in Publication No. 17. A typical example of the ion exchange material is trialkylammonium chloride for chlorine ion exchange. "that's all

Claims (1)

[Scope of Claims] 1. Consisting of a support, a conductive metal layer, a layer containing a water-insoluble salt of the metal, an electrolyte salt of an anion common to the anion of the water-insoluble salt and a potassium ion, and substantially In an ion-selective electrode for potassium ion analysis in which an electrolyte layer containing no binder and an ion-selective layer are integrated in this order, the electrolyte layer is densely spread over the layer containing the water-insoluble salt. An ion selective electrode comprising the electrolyte crystal having a crystal diameter of 60 gm or less. 2. The ion selective electrode according to claim 1, wherein the crystal diameter of the electrolyte salt is in the range of 50 to 0.17 zm. 3. The ion selective electrode according to claim 1, wherein the average thickness of the electrolyte layer is approximately the same as the average diameter of the electrolyte. 4. The ion selective electrode according to any one of claims 1 to 3, wherein the electrolyte salt is potassium chloride. 5. Claim 1, wherein the conductive metal layer is a metallic silver layer, the layer containing a water-insoluble salt of the metal is a layer containing silver chloride, and the electrolyte salt is potassium chloride.
The ion selective electrode according to any one of Items 1 to 3. 6゜Support, a conductive metal layer, a layer containing a water-insoluble salt of the metal, an electrolyte salt of an anion common to the anion of the water-insoluble salt and a potassium ion, and substantially containing a binder. In the method for producing an ion-selective electrode for potassium ion analysis in which an electrolyte layer containing a non-containing electrolyte and an ion-selective layer are integrated in this order, the electrolyte layer has an aqueous solution containing the electrolyte salt on top of the layer containing the water-insoluble salt. After applying,
The coating layer is dried by contacting with a flowing gas heated to 40° C. or higher, whereby the electrolyte crystals having a crystal diameter of 60 gm or less are densely spread on the water-insoluble salt layer. A method for manufacturing an ion selective electrode, characterized in that the electrode is manufactured by a step of forming a layer. 7. The method for producing an ion selective electrode according to claim 6, wherein the electrolyte salt is potassium chloride.