JP3288812B2 - Ion-selective electrode - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ion-selective electrode for electrochemically measuring the amount of ions in an aqueous solution.
The present invention relates to a structure of an internal electrode of an ion selective electrode.

[0002]

2. Description of the Related Art An ion-selective electrode using an ion-sensitive membrane is provided with an internal solution or an internal gel on the opposite side of the surface of the ion-sensitive membrane from which the sample comes into contact, and is composed of silver / silver chloride or the like via these. A first type of ion-selective electrode in electrochemical contact with the internal electrode to be formed, and silver / silver chloride without internal solution or internal gel on the side of the ion-sensitive membrane opposite to the side in contact with the sample. There is a second type of ion-selective electrode that makes direct electrochemical contact with the internal electrode composed of the above. Since the second type of ion-selective electrode does not use an internal liquid, it has a feature that the structure is simple and easy to miniaturize as compared with the internal liquid type, and there are many known examples. For example, according to JP-A-58-86449, a flow cell type ion-selective electrode is obtained by forming a sensitive film on the inner surface of a cylindrical internal electrode. JP-A-63-37251 also reports a flow cell type ion-selective electrode having a similar structure. In order to improve the stability of the ion selective electrode of the flow cell type and the accuracy of the measurement, a method of installing an ion sensitive membrane so as to project in a convex shape with respect to the flow path is disclosed in JP-A-61-180133. It is reported in the gazette.

[0003]

When the ion-sensitive membrane is installed so as to protrude in a convex shape with respect to the flow path, if the convex portion has a smooth curved surface, the ion-sensitive membrane is prevented while the sample solution is not retained. Since the sample exchange on the surface can be accelerated, it is effective for speeding up the response. However, there is a problem that it is not easy to form the sensitive film in such a three-dimensionally complicated shape, for example, a convex portion with a smooth curved surface. The simplest way to solve this problem is to form the flow cell with a resin such as polyvinyl chloride and cut the flow cell along a curved surface protruding from the flow path. By forming the sensitive film separately and utilizing its flexibility, it can be adhered to the curved cutting surface from the opposite side of the flow path. Further, an ion-selective electrode can be formed by bonding a plate-like internal electrode from behind. But,
Since a metal plate with sufficient mechanical strength (and a plate-like internal electrode based on it) is poor in flexibility, the curved surface of the cut surface and the shape of the internal electrode must be precisely matched to allow the gap between the sensitive film and the internal electrode. In addition, there is a problem that a gap is easily formed in the film, which causes poor adhesion at the time of manufacture, or that the sensitive film is easily peeled off as it is used repeatedly. As a method of solving this problem, a gap generated when the internal electrode is reduced in cross-sectional area, the periphery thereof is covered with a polymer material which is a base material of the ion-sensitive film, and the internal electrode is bonded to the ion-sensitive film. It is conceivable to increase the adhesiveness and prevent peeling.However, this method sacrifices the effective contact area of the internal electrode to increase the adhesion and adhesiveness, and when using a sensitive film with high impedance For example, there is a problem that noise is easily generated. In the present invention, in view of the above problems, without reducing the effective contact area of the ion-sensitive membrane and the internal electrode in contact with the ion-sensitive membrane in the ion-selective electrode, the high adhesion between the internal electrode and the ion-sensitive membrane, It is an object of the present invention to provide an ion-selective electrode that can be achieved even when the sensitive membrane has a complicated shape, for example, a concave-convex surface.

[0004]

An object of the present invention is to use a thin metal wire as a material of an internal electrode, to form an internal electrode by combining the thin wires in a two-dimensional or three-dimensional manner, and to make at least a part of the internal electrode ion-sensitive. The structure is buried inside the film. That is, in an ion-selective electrode including an ion-sensitive membrane, an internal electrode bonded to the ion-sensitive membrane, and a lead wire connected to the internal electrode, a plurality of metal wires are planarly or three-dimensionally formed. To put it more specifically, an internal electrode having a basic skeleton of a member obtained by combining a plurality of wires in a lattice or mesh shape is used. In addition, a basic skeleton may be obtained by combining a plurality of wire members in a planar, three-dimensional, lattice-like or mesh-like shape. The wire constituting the internal electrode is composed of a core made of metal and a surface material made of a salt of this metal, and the metal of the core material of the wire is silver, and the metal salt of the surface material of the wire is silver bromide. , Silver chloride or silver iodide. At least a part of the internal electrode is buried inside the ion-sensitive membrane. Further, each component (ion-sensitive membrane, internal electrode, lead wire, and external terminal) is held in a flow cell having a flow path for supplying a sample solution to the ion-sensitive membrane to form a flow cell-type ion-selective electrode, and the moisture is retained. A member having a function is provided inside the flow cell, and water vapor is supplied from the moisturizing member to the ion-sensitive membrane. In another configuration of the ion-selective electrode, the internal electrode and the ion-sensitive membrane are not directly contacted,
Either a configuration separated by a hydrophilic member, or at least a part of the internal electrode is brought into contact with the ion-sensitive membrane,
Alternatively, it is configured to be buried inside. A hydrated hydrophilic member is provided in at least a part of the gap between the internal electrodes, and the hydrated hydrophilic member is brought into contact with at least a part of the ion-sensitive membrane. As the hydrated hydrophilic member, a hydrated hydrophilic polymer is used, and a hydrated hydrophilic polymer in which a water-soluble salt is dispersed is used.

[0005]

The internal electrode made of a thin wire member obtained by combining thin metal wires in a plane or three-dimensionally has a tensile strength and a rupture strength which are generally lower than those of a metal plate made of the same metal and having the same thickness. The repulsion (elastic force) is extremely low. This is because, in the case of an internal electrode made of a thin wire member, even when a force is applied from the outside, each wire (thin wire) can be relatively easily displaced and rotated to a more stable position and angle. Therefore, even if the ion-sensitive membrane has a complicated shape such as a curved surface, for example, a concave surface or a convex surface, it can be easily deformed and adapted to the shape, and the ion-sensitive film and the internal electrode may be incompatible. It is possible to achieve high adhesion between the ion-sensitive film and the internal electrode without causing a problem such as generation of a gap and separation due to the gap. Of course, when using a member in which a thin metal wire is combined in a two-dimensional or three-dimensional manner as a material for the internal electrode, a wire (thin wire)
Although the gap between them does not become an effective contact area as it is, instead of making the mesh contact the ion-sensitive membrane only at the end face, by burying it deeper inside the ion-sensitive membrane, the end face on the film side of each wire Not only the side surface but also, in some cases, the opposite surface can be brought into contact with the ion-sensitive membrane, so that an extremely large effective contact area can be secured. Therefore, by using a member in which thin metal wires are combined two-dimensionally or three-dimensionally as a material of the internal electrode, and having a structure in which at least a part of the internal electrode obtained from these members is embedded in the ion-sensitive membrane, Even if the ion-sensitive membrane of the selective electrode has a complicated shape, it is possible to ensure consistency with the shape of the ion-sensitive membrane without reducing the effective contact area of the internal electrode in contact with the ion-selective electrode. And high adhesion can be achieved.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. (First Embodiment) FIG. 1 is a sectional view showing a first embodiment of an ion selective electrode to which the present invention is applied. A flow cell 2 through which a sample flows is formed in the flow cell 1, and accommodates an ion-sensitive membrane 3, internal electrodes 4, lead wires 5, and external terminals 6. The network-shaped internal electrode 4 is buried inside the ion-sensitive membrane 3, and FIG. 1 shows only a cross section of a thin line constituting the network. Next, a method for producing the ion-selective electrode according to the present embodiment will be described. As the internal electrode 4, a member obtained by knitting a silver wire having a diameter of 0.05 mm into a mesh as shown in FIG. 2 was used, and a silver wire having the same diameter was used as the lead wire 5. First, the two were joined by spot welding, and then the surface of the silver wire in contact with the ion-sensitive film 3 was electrolyzed into silver bromide. In this method, a part of the surface of the lead wire 5 also becomes silver bromide by electrolysis, but the part where the surface becomes silver bromide functions as an internal electrode. Instead, it acts as an internal electrode 4. The internal electrode 4 thus formed
Was embedded in the ion-sensitive membrane 3 according to the following procedure. Valinomycin as a potassium ion-sensitive substance, potassium tetra (paraphenyl chloride) boron as an additive, dioctyl adipate as a plasticizer, and polyvinyl chloride having an average degree of polymerization of about 1000 as a base material, each in a weight ratio of 1,
Weigh with 0.3, 66, 33, tetrahydrofuran 4m
L (milliliter) was added and mixed and dissolved to obtain a stock solution for film formation. When a glass ring having a diameter of 30 mm was placed on a glass plate and half of the stock solution for film formation was poured into the glass ring and allowed to stand, tetrahydrofuran was evaporated and an ion-sensitive membrane (lower membrane) was obtained.

Next, the internal electrode 4 formed by the above-described procedure is
Is placed on the ion-sensitive membrane (lower membrane) in this glass ring so that the flat mesh side is on the bottom and the side with the lead wire is on the upper side. The side was brought into close contact. When the remaining half of the stock solution is gradually poured from above, this stock solution becomes an ion-sensitive membrane (lower membrane).
Flows between the electrode and the internal electrode, between the mesh of the internal electrodes, and on the internal electrode, and after partially re-dissolving the upper surface of the ion-sensitive film (lower film), the tetrahydrofuran evaporates to become the ion-sensitive film 3. . Since the ion-sensitive film thus obtained has the same composition in the lower film and the portion thereabove, there is actually no distinction between the upper and lower layers, and the ion-sensitive film is formed integrally. This ion-sensitive membrane has a thickness of about 150 μm between the glass surface and the lower end of the mesh of the internal electrode, and a thickness of about 100 μm within the mesh.
m, formed over three layers of about 100 μm from the upper end of the internal electrode, with the internal electrode incorporated therein. Next, the composite member composed of the ion-sensitive membrane 3, the internal electrode 4, and the lead wire 5 was removed from the glass plate and the glass ring, and a portion having a diameter of about 5 mm including the lead wire portion was cut into a disk shape. As described above, the substrate was adhered to the flow cell 1 with tetrahydrofuran such that the surface in contact with the glass plate faced the flow channel 2. Lastly, after soldering the end of the lead wire to the external terminal 6 made of a silver wire, the portion of the flow cell other than the entrance and exit of the flow channel 2 was sealed to prepare a flow cell for potassium ions. Note that the welded portion between the lead wire 5 and the internal electrode 4 may have an irregular shape, so that the ion-sensitive membrane 3 is not located at the portion in contact with the flow channel 2 but at the bonding surface with the flow cell or at the outside thereof. Is preferred. In this way, a part of the ion-sensitive membrane 3 is exposed to the flow channel 2 and can come into contact with the sample flowing through the flow channel 2.

Next, the operation of this embodiment will be described.
When the sample solution is sent into the flow channel 2 of the flow cell 1 according to the present embodiment and is brought into contact with the ion-sensitive membrane 3, the membrane potential (E ₁ ) corresponding to the activity of potassium ions in the sample solution becomes equal to the sample solution. It occurs between the ion-sensitive membrane. Potential outputted to the external terminal 6 (E) is a membrane potential (E _1), although the sum of the potentials generated (E ₂₎ between the ion-selective membrane and the inner electrode, the latter (E ₂ ) Can be regarded as constant and its effect can be ignored. By measuring a potential difference between the reference electrode and the external terminal 6 using a reference electrode connected to the flow cell 1, a potential corresponding to the activity of potassium ions in the sample solution is observed. If a calibration curve is prepared by measuring a standard solution, the activity of potassium ions in a sample of unknown concentration can be determined. In this embodiment, the flow cell 1
The channel 2 was obtained by integrally molding a flow cell by a molding method using hard polyvinyl chloride as a material for the above. However, the material of the flow cell does not need to be limited to polyvinyl chloride, and any material having high adhesiveness to the ion-sensitive membrane and appropriate hardness can be used. The method of forming the flow path is not limited to integral molding with a mold,
It may be formed by joining a plurality of members. As the ion-sensitive membrane 3 of the present embodiment, a polymer-supported liquid membrane-type ion-sensitive membrane using valinomycin as a sensitive substance was used, but other ion-sensitive membranes can of course be used. Sensitive substances are cyclic or non-cyclic antibiotics such as nonactin, monactin, monensin, synthetic ionophores such as various crown ethers, dibutylphenanthroline, phenyl phosphate, non-cyclic diamine, ion exchange such as quaternary ammonium salts and various phosphates. Body ligands and the like can be used, and as a plasticizer, in addition to dioctyl adipate,
Various dicarboxylic acid esters, nitrobenzene, acetophenone and derivatives thereof, and alkyl alcohols having 10 or more carbon atoms can be used. As an additive, in addition to tetra (para-chlorophenyl) boron, tetraphenylboron, tetra (bistrifluoromethylphenyl)
Boron salts and the like can be used. Also as a parent agent,
In addition to polyvinyl chloride, polycarbonate, silicone resin, epoxy resin, and the like can be used.

In this embodiment, the inner electrode 4 has a diameter of 0.1 mm.
A member obtained by knitting a 05 mm silver wire in a mesh shape was used as a material, and the surface was converted into silver bromide by electrolysis, and then used. However, the method of forming the internal electrode is not limited to this. The metal of the material is silver, gold, platinum, iridium, rhodium, ruthenium, copper,
In addition to the simple substance of nickel, an alloy between these simple substances or an alloy of these simple substances and mercury can be used. The shape of the metal is not only a mesh-shaped member obtained by knitting the wire, but also a comb-like shape as shown in FIG. 3 or a grid-like shape as shown in FIG. Or these may be combined two-dimensionally or three-dimensionally. If the thickness of the wire is sufficiently small, it may be used as it is.If the wire diameter is large, it may be used after rolling to reduce the thickness of the mesh, and in this case, annealing is performed to restore flexibility. It is preferable to use it afterwards. For the surface layer of the internal electrode, it is preferable to use a salt of a metal ion of the internal electrode material and an anion, but silver halide and silver sulfide such as silver chloride and silver bromide, and mercury halide and mercury sulfide. Is preferred, and silver bromide is particularly preferred. As a method for forming the surface layer, electrolysis is a simple and reliable method. Alternatively, a salt may be separately obtained by a precipitation method and then pressed on the surface of the internal electrode. In this embodiment, the lead wire has a diameter of 0.0
Although a 5 mm silver wire was used, metals of other shapes can be used without any problem. However, it is preferable to use the same kind of metal as that used for the internal electrode. The connection method between the lead wire and the internal electrode is preferably spot welding, but other connection methods such as lapping and soldering can be used as long as electrical connection between them can be ensured. Further, a part of a wire constituting the mesh may be used as a lead wire as it is.

In this embodiment, the internal electrode 4 is used as the ion sensitive membrane 3
Although it was embedded in and integrally formed, the method of integrally forming is not limited to the above-described method. Similarly, in a second forming method that is preferably used, an internal electrode is suspended in a glass ring placed on a glass plate in parallel with the glass plate with a gap of about 100 μm above the glass plate. When a stock solution for forming an ion-sensitive membrane is injected from above, the stock solution flows into the gaps, between the meshes of the internal electrodes, and onto the internal electrodes, and when the solvent, tetrahydrofuran, evaporates, the internal electrodes are embedded therein. The ion-sensitive membrane in the state is integrally formed. As a third formation method, it is also possible to divide the stock solution for film formation into halves and bond the ion-sensitive membranes having a thickness of half obtained from each to the inner and outer electrodes. As a solvent for this bonding, tetrahydrofuran or a tetrahydrofuran solution of a sensitive film material is suitably used. As a fourth forming method, a method in which all the stock solutions for film formation are poured into the ring at once, and then the internal electrodes are pushed into the inside of the ion-sensitive film is also possible. On this occasion,
The internal electrode can be pushed as it is before the solvent tetrahydrofuran evaporates from the stock solution for film formation, but even after the evaporation, the solvent is added again from the top of the membrane or the solvent is added to the internal electrode. By pressing after the adhesion, the surface of the film can be melted and the internal electrode can be embedded therein. In this embodiment, an ion-sensitive membrane in which the internal electrode thus formed is embedded is bonded to the periphery of the opening in the flow channel of the flow cell to obtain an ion-selective electrode. It is not limited to this. As another bonding method, for example, an ion-sensitive film may be bonded in advance to the flow cell, and the internal electrode may be bonded to the ion-sensitive film by the third or fourth method described above.

Next, the effects specific to the present embodiment will be described. By embedding the internal electrode inside the ion-sensitive membrane as in this embodiment, most of the surface of the fine wires constituting the internal electrode, except for a very small portion where the fine wires are in contact with each other, Can contact the ion-sensitive membrane. As described above, since the contact area between the two can be kept large, the interface impedance can be minimized, and even if a sensitive film having a high impedance is used, high-precision measurement with little noise is possible. Further, in this embodiment, high adhesion between the ion-sensitive membrane and the internal electrode can be achieved. In the present invention, the internal electrode does not necessarily need to be buried inside the ion-sensitive membrane, and it is possible to contact the ion-sensitive membrane with only a part of the wire constituting the internal electrode. In this embodiment, in which almost all surfaces of the internal electrode are in contact with the sensitive film, the adhesion between the internal electrode and the sensitive film is of course extremely high. Therefore, even when used repeatedly, the two hardly peel off.

Second Embodiment Next, a second embodiment according to the present invention will be described.
The embodiment will be described with reference to FIG. FIG. 5 is a sectional view of the ion-selective electrode according to the present embodiment. The shape and operation of each component are the same as in the first embodiment,
The second embodiment is different from the first embodiment in that the internal electrode 4 is not completely buried inside the ion-sensitive membrane 3 and a part of the internal electrode 4 is exposed on the opposite side of the flow path 2. Different from the example. Since not all of the internal electrodes are embedded in the ion-sensitive film, the third method, namely, the internal electrode, of the four types of bonding methods of the internal electrode and the ion-sensitive film described in the first embodiment, The method of bonding the ion-sensitive membrane from the front and back cannot be used. The first method can be realized by adjusting the amount of the undiluted solution for film formation used in the first and second-stage pouring so that the surface of the internal electrode is not completely covered. The second method can be realized by adjusting the position where the internal electrode is hung and the amount of the stock solution for film formation, and the fourth method can be realized by adjusting the depth of pushing the internal electrode. As an effect peculiar to the present embodiment, since it is not necessary to keep the thickness of the internal electrode equal to or less than the thickness of the ion-sensitive film, a mesh-like structure made of a metal wire having a relatively large diameter and which is relatively easily available. The member can be used as an internal electrode. Also, since it is not necessary to embed all the internal electrodes in the ion-sensitive membrane, the degree of freedom regarding the thickness of the ion-sensitive membrane and the distance between the internal electrode and the flow path is increased, which facilitates manufacture. is there.

(Third Embodiment) Next, a third embodiment according to the present invention will be described.
The embodiment will be described with reference to FIG. FIG. 6 is a sectional view of the ion-selective electrode according to the present embodiment. This embodiment is different from the first and second embodiments in that a moisturizing member 7 for evaporating water vapor is held inside the flow cell 1. As the moisturizing member, a hydrophilic organic polymer impregnated with moisture, such as agarose, polyvinyl alcohol, polyacrylamide, polysulfonated styrene, or inorganic silicate is favorable. The effect peculiar to the present embodiment is that water vapor evaporating from the moisturizing member can be efficiently supplied to the ion-sensitive membrane through the gap between the mesh-like internal electrodes, and water is necessary for the ion-sensitive membrane to operate stably. Even in such a case, it is to store and operate stably.

(Fourth Embodiment) Next, a fourth embodiment of the present invention will be described.
The embodiment will be described with reference to FIG. FIG. 7 is a sectional view of the ion-selective electrode according to the present embodiment. In this embodiment, the hydrophilic member 8 is provided in the gap between the internal electrodes 4 by the ion-sensitive membrane 3.
The third embodiment differs from the third embodiment in that the third embodiment is provided so as to be in contact with the third embodiment. The hydrophilic member 8 is composed of a hydrophilic polymer and a small amount of water of hydration, or composed of a hydrophilic polymer, a water-soluble salt and a small amount of water of hydration, and It is obtained by evaporating excess water from an aqueous solution of (a water-soluble salt).
In the present embodiment, polyvinyl alcohol was used as the hydrophilic polymer.In addition, gelatin, agarose, polyacrylamide, polyvinylpyrrolidone, polyhydroxyethyl methacrylate, hydroxyethyl polyacrylate, polyacrylic acid, etc. It is preferably used.
Of course, these may be used alone or in combination. Further, as the above water-soluble salt,
Although potassium bromide was used, in addition, sodium chloride, potassium chloride, sodium bromide, ammonium chloride, tetramethylammonium chloride, sodium tetraphenylborate and the like are preferably used. Of course, these may be used alone or in combination. As a cation constituting the water-soluble salt, an alkali metal ion, an alkaline earth metal ion, an ammonium ion, or various quaternary ammonium ions may be used alone or in combination of two or more. As the anion, various halide ions, nitrate ions, nitrite ions, thiocyanate ions, perchlorate ions, sulfate ions, monohydrogen phosphate ions, or various tetraarylborate ions may be used alone or in combination. . Further, as cations of water-soluble salts, alkali metal ions, alkaline earth metal ions,
Ammonium ions or various quaternary ammonium ions are used alone or in combination, and various halide ions, as anions of water-soluble salts,
Among the nitrate ion, nitrite ion, thiocyanate ion, perchlorate ion, sulfate ion, monohydrogen phosphate ion, or various tetraarylborate ions, the internal electrode in the fifth embodiment described later is formed. Ions other than the anion of the metal salt used as the intermediate material or the surface layer material of the wire can be used alone or in combination.
Further, in this embodiment, since a part of the internal electrode is in direct contact with the ion-sensitive membrane, the water-soluble salt is not always an essential element, and operates normally even if it is omitted. The effect peculiar to the present embodiment is that when the hydrophilic member 8 is in direct contact with the ion-sensitive membrane, moisture is easily held in the hydrophilic member, and when the ion-sensitive membrane needs moisture to operate stably. However, the ion sensitive membrane can be stably stored and operated. Further, when a water-soluble salt is added to the hydrophilic member, the hydrophilic member becomes conductive, so that there is also an effect that the transmission of the electrode potential is facilitated.

(Fifth Embodiment) Next, a fifth embodiment of the present invention will be described.
The embodiment will be described with reference to FIGS. FIG.
FIG. 9 is a cross-sectional view of an ion-selective electrode according to the present embodiment, and FIG. 9 is a cross-sectional view of a wire constituting an internal electrode in the present embodiment. As shown in FIG. 9, in the present embodiment, a core material 9 made of silver is used as a wire constituting the mesh-like internal electrode 4,
The fourth embodiment is different from the first to fourth embodiments in that an intermediate member 10 made of silver bromide and a surface member 11 made of a hydrophilic member are used. The ability of such hydrated hydrophilic members to replace the internal solution in conventional ion selective electrodes has been reported by Smith et al.
Analytical Chemistry, 4th
Vol. 5, No. 9, pp. 1782-1784 (1973)
As shown in FIG. 8, the hydrated polymer material (hydrophilic member) described in this document was used as the surface material of the internal electrode in the ion-selective electrode of this example as shown in FIG. Also works fine. However, in the above document, a linear internal electrode is used, and no consideration is given to the structure of the internal electrode (such as a mesh) which is a feature of the present invention.
In the present embodiment, as the hydrophilic member forming the surface material 11,
Although a dispersion in which potassium chloride is dispersed in polyvinyl alcohol is used, another hydrophilic polymer and another water-soluble salt may be combined as in the fourth embodiment. However, in this embodiment, since the surface material 11 needs to have conductivity, the water-soluble salt cannot be omitted. In the case where a hydrophilic member is used as a surface layer material as an internal electrode as in this embodiment, contact between the internal electrode and the sensitive film may become unstable, but in this embodiment, it is shown in FIG. As described above, the adhesion between the internal electrode and the sensitive film was secured by bonding and fixing the end of the internal electrode to a part of the flow cell. The effect peculiar to the present embodiment is that, since the hydrophilic surface layer material 11 is in direct contact with the sensitive film, moisture is easily held in the surface layer material 11, and water is required to make the ion-sensitive film act stably. Even in this case, the ion-sensitive membrane can be stably stored and operated.

(Sixth Embodiment) Next, a sixth embodiment of the present invention will be described.
Will be described with reference to FIG. FIG. 10 is a sectional view of the ion-selective electrode according to the present embodiment. This embodiment is a combination of the fourth embodiment and the fifth embodiment. As a wire constituting the mesh-shaped internal electrode 4, a core material 9 made of silver as shown in FIG. A material composed of an intermediate material 10 made of bromide and a surface material 11 made of a hydrophilic member was used, and a hydrophilic member 8 was provided between the internal electrodes 4 so as to be in contact with the ion-sensitive membrane 3. The points are different from the third embodiment. In the present embodiment, as the hydrophilic member 8 and the surface layer material 11, as in the fifth embodiment, a material obtained by dispersing potassium chloride in polyvinyl alcohol is used, so that there is practically no distinction between the two. Of course, the fourth,
As in the fifth embodiment, another hydrophilic polymer and another water-soluble salt may be combined, and different materials may be used for both. Also in the present embodiment, at least the surface material 11 needs to have conductivity, so that the water-soluble salt cannot be omitted from the surface material 11. In this embodiment, FIG.
As shown in No. 0, by adhering and fixing the end of the internal electrode to a part of the flow cell, the adhesion between the internal electrode and the sensitive film was ensured. The effect peculiar to the present embodiment is that, since the hydrophilic member 8 and the hydrophilic surface material 11 are in direct contact with the sensitive film, moisture is easily held in the surface material 11 and the ion sensitive film is made to act stably. Even if you need water,
That is, the ion-sensitive membrane can be stably stored and operated. In the fourth embodiment, the fifth embodiment, and the sixth embodiment, the moisturizing member 7 is used as in the third embodiment, but the first embodiment, the second embodiment, and the like are used. Similarly, the moisturizing member can be omitted.

[0017]

According to the present invention, as a material for an internal electrode, a member formed by combining thin metal wires in a three-dimensional or three-dimensional manner is used, and at least a part of the internal electrode obtained from these members is embedded in the ion-sensitive membrane. Due to the structure, even if the shape of the ion-sensitive membrane in the ion-selective electrode is complicated, the effective contact area of the internal electrode in contact with the ion-selective electrode is not reduced, By securing the shape to a required shape, high adhesion to the internal electrode can be obtained.

[Brief description of the drawings]

FIG. 1 is a sectional view of an ion-selective electrode according to a first embodiment of the present invention.

FIG. 2 is a perspective view of a mesh-like silver wire which is a raw material of an internal electrode according to the first embodiment of the present invention.

FIG. 3 is a perspective view of a comb-shaped internal electrode having one end fixed.

FIG. 4 is a perspective view of a blind (lattice) internal electrode having both ends fixed.

FIG. 5 is a sectional view of an ion-selective electrode according to a second embodiment of the present invention.

FIG. 6 is a sectional view of an ion-selective electrode according to a third embodiment of the present invention.

FIG. 7 is a sectional view of an ion-selective electrode according to a fourth embodiment of the present invention.

FIG. 8 is a sectional view of an ion-selective electrode according to a fifth embodiment of the present invention.

FIG. 9 is a sectional view of a wire constituting an internal electrode according to the fifth and sixth embodiments of the present invention.

FIG. 10 is a sectional view of an ion-selective electrode according to a sixth embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Flow cell, 2 ... Flow path, 3 ... Ion sensitive membrane, 4 ... Internal electrode, 5 ... Lead wire, 6 ... External terminal, 7 ... Moisturizing member,
8: hydrophilic member, 9: core material, 10: intermediate material, 11: surface material.

──────────────────────────────────────────────────の Continuing on the front page (72) Inventor Kotaro Yamashita 1-280 Higashi-Koikekubo, Kokubunji-shi, Tokyo Inside the Central Research Laboratory, Hitachi, Ltd. (56) References JP-A-6-118052 (JP, A) JP-A-5-340916 (JP, A) JP-A-5-142191 (JP, A) JP-A-5-142188 (JP, A) (58) Field surveyed (Int. Cl. ⁷ , DB name) G01N 27/333 G01N 27/28 321 JICST file (JOIS)

Claims (4)

(57) [Claims] 1. A flow cell having a flow channel through which a sample solution flows.
And a part of the opening from the opening formed in the flow path
Ion exposed and in contact with the sample solution flowing through the flow path
Is a member in which a plurality of metal-sensitive wires and metal wires are
And is deformable, at least partially
An internal electrode embedded in the membrane, the sample solution and the
Between the ion-sensitive membrane and the ions in the sample solution
The membrane potential corresponding to the activity, the ion-sensitive membrane and the internal
An external terminal for outputting the sum of the potential generated between the terminal and the
A lead wire connecting the internal electrode and the external terminal;
An ion-selective electrode comprising: 2. The ion-selective electrode according to claim 1, wherein
All of the internal electrodes are embedded in the ion-sensitive membrane.
An ion-selective electrode characterized in that: 3. The ion-selective electrode according to claim 1,
All of the internal electrodes are embedded in the ion-sensitive membrane.
And a part of the internal electrode is not
Characterized in that it is exposed inside the flow cell.
On-selective electrode. 4. The ion-selective electrode according to claim 3,
And a moisturizing member for evaporating water vapor is provided inside the flow cell.
An ion-selective electrode provided in a part.