JPS617461A - Ion selection electrode for potassium ion analysis and manufacture thereof - Google Patents

Abstract

PURPOSE:To reduce electric potential drift, by using a crystal consisting of mixture of potassium and sodium salts, as an electrolytic salt for electrolytic layer formation of an ion selecting electrode for potassium ion analysis. CONSTITUTION:An ion selection electrode is composed of supporting body, dielectric metallic layer, layer containing water-unsoluble salt of this metal and electrolytic salt, anion in common with anion of the water-unsoluble salt and alkali-metal cation and it is formed practically by precipitation of a binder- nonincluding electrolytic layer and an ionselection layer in this order. The ion selection electrode for potassium ion analysis is composed of an electrolytic salt crystal in which said electrolytic layer includes potassium ion salt and sodium ion salt and this is a crystal of the mean crystal diameter of 50mum and less formed by coating of aqueous solution or aqueous organic solvent solution containing potassium/sodium mixture electrolytic salt over a water-unsoluble salt layer and then drying by a running heating gas at the temperature of 40 deg.C and above.

Description

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

[Background of the Invention] Ion-selective electrodes are measuring instruments for botensiometrically measuring ion concentrations mainly in body fluids such as aqueous fluids, blood, and serum. This is disclosed in, for example, Japanese Patent No.-142584.

That is, the ion-selective electrode consists of a support, a conductive metal layer (
a layer containing a water-insoluble salt of the metal (e.g., silver chloride); an electrolyte salt with an anion and a cation (e.g., potassium ion, sodium ion) common to the anion of the water-insoluble salt; It has a basic structure in which an electrolyte layer containing (eg, potassium chloride, sodium chloride)' and a binder, and an ion selection layer 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-bearing bridge and spotting the standard solution and sample solution on each of the ion selective layers A and B, measure the potential difference between the conductive metal layers A and H after -W time has elapsed. Then, a method is used in which the concentration of the electrolyte contained in the sample solution is calculated from a previously prepared calibration curve and this potential difference. Similar measurements can also be performed using electrically isolated ion-selective electrode pairs.

As mentioned above, ion-selective electrodes basically have a simple structure and are obtained as microchips, so the amount of sample required is extremely small. Very useful for measuring quantities. Further, since the ion selective electrode has a simple and minute structure as described above, it also 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 in this case, the unit cost of the ion-selective electrode increases, making it difficult to use and discard it. , and sensitivity is also likely to decrease.

As an improved technique to avoid problems such as potential drift as described above, an electrolyte layer is formed by vapor deposition of an electrolyte or coating and drying of 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 potential drift of conventionally known ion-selective electrodes, it is desirable to further reduce the potential drift in order to improve the accuracy of measurements using ion-selective electrodes. ). In other words, when an electrolyte layer is formed by coating and drying an electrolyte aqueous solution, the electrolyte salt crystals produced tend to be large.
Problems arise in that the electrolyte distribution in the electrolyte layer tends to become non-uniform and the thickness of the electrolyte layer tends to increase, both of which 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 low vapor deposition efficiency. Therefore, it cannot be said to be advantageous for industrial operation.

The inventor has proposed that on a layer containing a water-insoluble salt of a conductive metal,
Applying an aqueous potassium salt solution substantially free of binder and then drying it under heated gaseous liquid flow.
By forming an electrolyte layer made of potassium salt crystals with a relatively small average crystal diameter, they have already completed an invention that makes it possible to reduce the potential drift of the resulting ion-selective electrode, and have filed a patent application. This method produced a potassium salt with a smaller crystal size than conventionally known potassium salts, thereby improving the stability of the potassium ion-selective electrode. However, even potassium salts obtained by such methods still tend to have larger crystal sizes than sodium salts obtained by similar methods, and further improvements in this regard are desired. .

As a result of further developing the technical concept of reducing potential drift by forming the electrolyte layer described above from an electrolyte salt with a small crystal size, the inventors have discovered that even an ion-selective electrode for potassium ion analysis , the use of a mixture of potassium salt and sodium salt as an electrolyte salt for forming an electrolyte layer does not have any adverse effect on the performance of the ion-selective electrode such as analytical accuracy; It has also been found that crystals consisting of potassium salt can be easily formed with a smaller crystal diameter than crystals consisting of potassium salt alone. The present inventor has also discovered that by utilizing such a phenomenon, it is possible to further reduce the potential drift of the ion selective electrode for potassium ion analysis.

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

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 the analysis of potassium ions provided by the present invention includes: (I) a support, (II) a conductive metal layer, (III) a layer containing a water-insoluble salt of the metal, (rv) the water-insoluble salt. An electrolyte salt crystal (preferably an average crystal diameter of 50 gm or less, more preferably an average crystal diameter of 0.1 to 40 gm) containing an anion common to the anion of the salt and a cation including potassium ions and sodium ions is the above-mentioned water-insoluble It is characterized in that an electrolyte layer densely spread without substantially containing a binder on a salt-containing layer, and (V) a potassium ion selective layer are integrated in this order.

The above-mentioned ion-selective electrode is manufactured by applying an aqueous solution or an aqueous organic solvent solution containing potassium salts and sodium salts onto a layer containing the water-insoluble salt, and then heating the coated layer to 40°C or higher under flowing conditions. It can be produced by using a method of drying by contacting with heated gas, thereby forming an electrolyte layer consisting of the electrolyte salt crystals that are densely expanded on the layer containing the water-insoluble salt. .

[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 alkali metal cations and substantially containing no binder and an ion-selective layer are integrated in this order is already known. Yes (Japanese Unexamined Patent Publication No. 57-1785
Publication No. 2). In the ion selective electrode of the present invention, the structure other than the electrolyte layer and the materials of each layer are as follows:
It 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 Application Laid-open No. 52-142584 and No. 52-142584.
Examples include JP 7-17852 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 vapor deposition. For example, when the conductive metal layer is a metal silver layer, the layer containing the water-insoluble metal salt is
The silver chloride layer can be formed by chemically oxidizing and chlorinating the surface portion of the silver layer, or by applying and drying a dispersion containing silver chloride and a binder to the surface of the metal silver layer. 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 of the ion-selective electrode of the present invention is a potassium ion-selective layer made of a hydrophobic organic binder containing a potassium ion carrier. Examples of potassium ion carriers include palinomycin, cyclic polyether, tetralactone, and Lidoactin, enninatine, potassium tetraphenylporate, and derivatives thereof can be mentioned. As the hydrophobic organic binder, natural polymeric substances, derivatives thereof, or synthetic polymeric substances that can form a thin film can be used, examples of which include cellulose ester, polyvinyl chloride, vinyl chloride/vinyl acetate copolymer. , polyvinylidene chloride, polyacrylonitrile, polyurethane, polycarbonate, and the like.

The characteristic requirements of the ion selective electrode for potassium ion analysis of the present invention are that the electrolyte layer is composed of electrolyte salt crystals containing a salt of potassium ions and a salt of sodium ions, and that the electrolyte layer does not substantially contain a binder. , and the average diameter of the crystal particles densely spread on the layer containing the water-insoluble salt of the metal constituting the conductive metal (hereinafter abbreviated as water-insoluble salt layer) is below a specific value (50 m or less, Preferably 0.1~
40 gm, more preferably 0.2 to 10 pm) of electrolyte salt crystals.

In the present invention, the term "the electrolyte salt crystals are densely spread" means that the electrolyte salt crystals are hydrated to such an extent that a substantially stable interfacial potential is generated between the water-insoluble salt layer, the electrolyte salt crystals, and the ion-selective layer. This means that they are distributed over insoluble chlorine, and not all electrolyte salt crystals need to be arranged adjacent to each other.

Furthermore, in the present invention, it is preferable for the electrolyte layer to be thin, but if the particle size of the electrolyte salt crystals is small, the electrolyte salt crystals forming the electrolyte layer may overlap in a direction perpendicular to the surface of the ion selective electrode. Probably not.

That is, in the present invention, by densely spreading potassium and sodium electrolyte salts with small crystal sizes on the surface of the water-insoluble layer without using a binder, the electrolyte can be spread evenly and densely on the surface of the water-insoluble layer. An electrolyte layer is formed which is dispersed and has a thin layer thickness. A potassium ion selective electrode having such an electrolyte layer has a fast response speed, and the occurrence of potential drift is extremely suppressed. 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 reasons for this, besides the densification and reduced thickness of the electrolyte layer, are due to the fact that the electrolyte salt in the form of small crystals defined in the present invention is partially engaged with the water-insoluble salt layer. It can be considered that

In particular, when the water-insoluble salt layer is a silver chloride layer, the silver chloride layer exhibits a relatively porous surface, so the engagement between the electrolyte salt crystals and the water-insoluble salt layer (silver chloride layer) appears prominently. It is estimated to be.

Furthermore, since the electrolyte layer of the present invention is composed of crystal particles having an appropriate microparticle size, poor adhesion and adhesion between the electrolyte layer and the ion selective layer, which often occur in electrolyte layers containing a wood-philic binder, are improved. The occurrence of these phenomena is substantially not observed; the potassium/sodium mixed electrolyte salt crystal with a small crystal size as defined in the present invention has a surface of a water-insoluble salt layer as known so far. cannot be obtained by simply applying an aqueous solution of an electrolyte salt to the surface and drying it in the air.

In other words, in a known method in which an aqueous electrolyte salt solution containing potassium chloride and sodium chloride is applied onto a water-insoluble salt layer and left at room temperature, the crystal size (average crystal size) of the precipitated crystals is generally relatively small. growing. 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 uniformity of electrolyte layer thickness, which causes potential drift. Moreover, since both the electrolyte layer and the ion-selective layer are necessarily thick, the response time in analysis becomes long.

On the other hand, after coating an aqueous solution or an aqueous organic solvent solution containing a potassium/sodium mixed electrolyte salt on the water-insoluble salt layer, the coated layer is heated at 40°C or above (
When dried by contacting with gas heated to a temperature of preferably 80°C to 200°C), the average densely expanded crystal size is usually about 50 gm or less (preferably about 0 gm).
．． An electrolyte layer consisting of the electrolyte salt crystals (1 to 40 μm) is formed on the layer containing the water-insoluble salt. The electrolyte layer made of such small-diameter crystals has improved uniformity of electrolyte distribution and uniformity of the thickness of the electrolyte layer, and also ensures that electrolyte salt crystals remain even when the thickness of the ion-selective membrane is reduced. Since it is coated with an ion-selective membrane, the occurrence of potential drift is reduced, thereby improving the measurement accuracy of analysis, and by making the ion-selective membrane thinner, the manufacturing cost of the ion-selective electrode can be reduced, which is economically advantageous.

The content of potassium salt in the electrolyte salt crystal constituting the electrolyte layer of the present invention relative to the entire electrolyte layer is preferably in the range of 0.08 to 0.75 expressed as a weight ratio.

If the potassium salt content exceeds 0.75, it tends to be difficult to form electrolyte salt crystals with the desired small crystal diameter, whereas even if the potassium salt content is lower than 0.08, Further reduction in crystal diameter cannot be expected, and potential drift is likely to be adversely affected.

The concentration of the electrolyte salt aqueous solution or aqueous organic solvent solution used to produce the electrolyte layer of the present invention is not particularly limited, but is usually about 0.5 to about 25% by weight, preferably about 0.5 to about 25% by weight. 15% by weight, most preferably about 0.5 to about 1
An electrolyte salt solution in the range of 0% by weight is used. In order to improve manufacturing efficiency, it is desirable to use a highly concentrated solution; however, forming electrolyte salt crystals from an aqueous organic solvent solution has the advantage that crystals with small crystal diameters can be easily obtained. be. Examples of aqueous organic solvents used for this purpose include lower alcohols such as methanol, ethanol, and propatool; ketones such as acetone and methyl ethyl ketone; and mixtures of water and ethers such as diethyl ether. .

Since the anion on the other side of the potassium/sodium ion of the electrolyte salt forming the electrolyte layer of the present invention needs to be the same as the anion of the salt contained in the water-insoluble salt, the electrolyte salt constitutes the entire ion-selective electrode. are selected taking into consideration. In general, 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 or consists of silver chloride, so In many cases, a combination of potassium chloride and sodium chloride is used as the electrolyte salt.

However, if the anion of the water-insoluble salt contained in the water-insoluble salt layer is an anion other than chlorine ion, such as bromide ion, iodide ion, sulfonium ion, or carboxylate ion, potassium salt and sodium salt used in the electrolyte layer The anion of should of course be chosen to match it.

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

[Example 1] Polyethylene terephthalate film (thickness mini 188
A metallic silver layer (vapor deposited silver layer) with a thickness of about 800 nm was formed by vacuum evaporation on Bm (size 30 mm x 1000 mm). Then, both ends of this vapor-deposited silver layer were
- Protect both ends of the poly composition disclosed in Japanese Patent Publication No. 102146 by coating it in liquid form with cysts,
Further, the center portion of the deposited silver layer was cut away using a cutting tool to provide an insulating portion in the shape of a shallow T, XU-shaped groove.

Next, the uncoated portion of the vapor-deposited silver layer of the laminate was treated with a treatment solution containing hydrochloric acid and potassium dichromate (an aqueous solution containing hydrogen chloride and potassium dichromate of 36 mmol/vertical and 16 mmol/solid, respectively). The contact treatment was carried out for about 60 seconds. After this treatment was completed, the laminate was washed with water and dried to obtain a film-like silver/silver chloride electrode (a laminate consisting of a support, a conductive silver layer, and a silver chloride layer).

An aqueous organic solution of potassium chloride and sodium chloride in the amounts shown in Table 1 was applied onto the above-mentioned silver fist silver chloride electrode film.
A solution prepared by dissolving 42.5 g (2.5 g of acetone + 20 g of ethanol + 20 g of water) was applied, and then an air flow at a temperature of 80°C was brought into contact with the coated layer for 3 minutes at a wind speed of 1.5 m/sec to form the coated layer. was dried. The weight of the coated layer after drying was approximately 2.3 g/m'. When this dried coating layer (electrolyte layer) was observed under a microscope, fine crystals containing potassium chloride and sodium chloride having the crystal diameter shown in Table 1 were found to be densely spread on the silver chloride layer.

Table 1 Sample NaC1/KCI KClwtX Average crystal size 1 tree 2;82Bg10.148g 5 Approximately 7pm2 2.678g/0.298g 10
Approximately 8gm3 2.380g10.595g 2
0 about 10107z 1.11 g/l, 39
g 513 approx. 35 p, m5 pieces 0.50 g
/2.0Q g 80 Approximately 7o well m6 0.25
g/ 2.25 g 80 approx. 8oILm7 zero
〇 g/ 2.50 g 100 Approx. 80 g
Note) Sample 2.3.4 is a sample according to the present invention, and Sample 1.
5.6.7 (sample with wood) is a comparison sample. Note that the above sample 4 is an electrolyte salt crystal containing equimolar amounts of MCI and Na0.

An ion-selective electrode for potassium ion analysis was prepared by attaching 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 25 pLm.

Potassium ion VYNS* 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) 50 mg Note)
VYNS: Vinyl chloride/vinyl acetate copolymer manufactured by Union Carbide [Evaluation of ion selective electrode] The two liquid receivers are made of plastic film with holes. Next, a bridge made of spun polyester yarn was attached to the liquid receiver so as to communicate the holes, thereby preparing an electrode device for potassium ion analysis. 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), 12a and 12b are 'evaporated silver layers (the evaporated silver layer is formed by cutting grooves that reach a part of the support surface as shown in the figure), and has two areas. ), 13a, 13b
14 represents a silver chloride layer, 14 represents an electrolyte layer, and 15 represents a potassium ion selective layer. The liquid receiver is indicated by 16 for the mask, the holes for the liquid receiver by 17a, 17b and the bridge by 18.

One liquid receiver has the potash plate 2 as a potassium ion-containing standard solution placed in the hole 17a, and the other liquid receiver has the hole 17b.
Caliplate 1 (C:AL, 1) was used as a sample solution.
, Caliprate 2 (C:AL, 2), or Caliprate 3 (CAL, 3) was spotted, and the simultaneous reproducibility of the values was determined by a differential method according to a conventional method.

The results are shown in Table 2.

Table 2 CAL, I CAL, 2 CAL, 3 (mV
/decade) 1 tree 3. lEl 5.21
8.94 63.62 1.71 1.25
1.11 59.23 2.0? 1.33.
0.84 58.84 +, l[l 1
．． 15 0.74 511.45 Thu 1. H1,H
1,22 Go, 8 6 Tree 1.40 2.13 1.93 Bo,
47 wood 0.83 1', 24 +, 81 5
111.8 edition) Sample 2.3.4 is a sample according to the present invention,
Samples 1.5.6.7 (wooden samples) are comparative samples.

Practically speaking, it is desirable that the CV value, which indicates "variation" in sample liquid measurement, be within about 3 to 4%, and the slope should be close to the standard value of 59 + sV/decade, so based on the above results, Sample 1 (comparative sample)
It can be seen that the performance is inferior compared to other samples. In addition, for samples 5.6.7 (comparative samples) that have electrolyte layers formed from electrolyte salt crystals with large crystal diameters, abnormal values of ±50 mV or more than the expected value occurred the following number of times in 50 measurements for each. .

Sample 5: 1 time, Sample 6: 1 time, Sample 7: 2 times.On the other hand, abnormal values occurred for Samples 2 to 4 having electrolyte layers formed from electrolyte salt crystals having a crystal diameter according to the present invention. was not seen at all.

[Example 21 Sample of Example 1? , a potassium chloride/sodium chloride mixed electrolyte layer similar to 3.4, and a potassium ion selective layer having the same composition as Example 1 except that potassium tetrakis parachlorophenylborate was not included as the potassium ion selective layer. An ion selective electrode for ion analysis was prepared. Sample No. 2 was examined for simultaneous reproducibility and the occurrence of abnormal values in the same manner as in Example 1. Regarding the simultaneous reproducibility, it was found that the simultaneous reproducibility was substantially the same as that of Sample 4.5.6 of Example 1. No abnormal values were observed in any of the samples.

C Example 3 Samples 2 to 4 of the film-like silver/silver chloride electrode (reference electrode) and the ion-selective electrode for potassium ion analysis prepared in Example 1 were cut at the cutting groove portions, and
The liquid receiver as shown in the figure was connected using a mask and a bridge. - Spotting Caliprate 2 as a potassium ion-containing standard solution on the reference electrode, and spotting Caliprate 1, 2, or 3 as a sample solution on the ion-selective electrode, and changing the potential over time according to the known direct method. was measured. The results are shown in FIG.

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

[Example 4] In the same manner as in Example 3, the reference electrode and the ion-selective electrode for potassium ion analysis (Samples 2 to 4) were cut at the cutting grooves, and the liquid receivers as shown in Fig. 1 were cut. Connected using a mask and bridge.

Both potassium ion and sodium ion are 2 each
．． The standard solution contained 8 meq/b and 99 meq/m, and both potassium ion and sodium ion were 2.8 meq/41 and 179 meq/b, respectively.
The potential difference was measured in the same manner as in Example 3 using the liquid containing 1.1 as the test liquid. The obtained potential difference is 0.3-2.0
It was mV. This value indicates that the influence of sodium ions in the potassium ion measurement operation is approximately 0.05 to 0.2 meq/
Therefore, it was confirmed that the presence of a considerable amount of sodium ions does not pose an obstacle in actual potassium ion measurements.

[Example 5] KCul, 11g and NaCJLl, 39g at 42.5
An ion-selective electrode for potassium ion analysis was prepared in the same manner as in Example 1 using a K Cl / Na C equimolar electrolyte salt solution prepared by dissolving it in water. Regarding this ion-selective electrode, the simultaneous reproducibility of its value was determined by the differential method in the same manner as in Example 1 using Kaliplate 1.2 or 3, and the results obtained for Sample 4 of Example 1 were obtained. Similar results were obtained.

[Brief explanation of the drawing]

FIG. 1 shows a potassium ion selective electrode equipped with a bridge for carrying out evaluation by the differential method. FIG. 2 is a graph showing the time change in the potential of the ion selective electrode for potassium ion analysis of the present invention measured by the direct method in Example 2. '11: Support, 12
a, 12b: Vapor deposited silver layer, 13a, 13b: Silver chloride layer, 1
4: Electrolyte layer, 15: Potassium ion selective layer, 16: Liquid receiver is mask, 17a, 17b: Liquid receiver is hole, 18 nibridge (twisted thread bridge) Figure 1 Figure 2 (min.) Procedural amendment document 1980 11 Month 1st

Claims (1)

[Claims] 1. (I) support, (II) conductive metal layer, (III) layer containing a water-insoluble salt of the metal, (IV) an anion common to the anion of the water-insoluble salt. and (V) potassium ions; and (V) potassium ions; and (V) potassium ions. An ion selective electrode for potassium ion analysis in which selective layers are integrated in this order. 2. The electrolyte salt crystal according to claim 1, wherein the potassium salt is contained in a weight ratio of 0.08 to 0.75 with respect to the entire electrolyte layer. Ion selective electrode. 3. The ion selective electrode according to claim 1, wherein the electrolyte salt crystal has an average crystal diameter of 50 μm or less. 4. The average crystal diameter of the electrolyte salt crystal is 0.1 to 40 μm.
The ion selective electrode according to claim 1, characterized in that the ion selective electrode falls within the range of . 5. The ion selective electrode according to any one of claims 1 to 4, wherein the electrolyte salt crystal is a crystal consisting essentially of potassium chloride and sodium chloride. 6. The conductive metal layer is a metal silver layer, the layer containing a water-insoluble salt of the metal is a silver chloride layer, and the electrolyte salt crystal is a crystal consisting of sodium chloride and potassium chloride. An ion selective electrode according to any one of claims 1 to 4. 7. (I) Support, (II) Conductive metal layer, (III) Layer containing a water-insoluble salt of the metal, (IV) Anion common to the anion of the water-insoluble salt, potassium ion, and sodium ion (V
) A method for manufacturing an ion selective electrode for potassium ion analysis, in which potassium ion selective layers are integrated in this order, wherein the electrolyte layer contains the electrolyte salt on a layer containing the water-insoluble salt. After applying the aqueous solution, the applied layer is dried by contacting with a flowing gas heated to 40°C or higher, whereby the electrolyte salt crystals that are densely spread on the water-insoluble salt layer are removed. 1. A method for manufacturing an ion selective electrode, characterized in that the electrode is manufactured by a step of forming a layer. 8. The electrolyte salt crystal according to claim 7, wherein the potassium salt is contained in a weight ratio of 0.08 to 0.75 with respect to the entire electrolyte salt. A method for manufacturing an ion selective electrode. 9. The method for producing an ion selective electrode according to claim 7, wherein the electrolyte salt crystal has an average crystal diameter of 50 μm or less. 10. The average crystal diameter of the electrolyte layer crystal is 0.1 to 40μ
8. The method for manufacturing an ion selective electrode according to claim 7, wherein the ion selective electrode is in a range of m.