JPH11132991A - Ion selective electrode and its manufacturing - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a reliable ion selective electrode that has superior breakdown voltage characteristics and can be stably used for a long time. SOLUTION: In an ion selective electrode using an ion selective sensitive film 4 containing an ion exchange polymer, a buffer member 5 is arranged between the ion selective sensitive film 4 and an electrode body 1. Preferably, a macromolecular elastic body, especially, synthetic rubber, is contained in the buffer member 5. It is ideal to use one of chloroprene rubber, nitrile rubber, and styrene-butadiene rubber as the synthetic rubber, thus absorbing external pressure fluctuation and internal stress by the buffer member and hence obtaining the electrode with high mechanical strength.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an ion-selective electrode, and more particularly to an ion-selective electrode suitable for measuring anions such as chloride ions in biological fluids.

[0002]

2. Description of the Related Art Various types of anion-selective electrodes used for the analysis of chloride ions and the like in biological fluids have been reported. The first known technique is to use a fourth substance as a sensitive substance in a polymer support membrane (or liquid membrane) such as polyvinyl chloride.
There is a polymer-supported membrane type electrode using a sensitive membrane supporting a quaternary ammonium salt or the like. As a second known technique, an electrode or the like using an anion exchange membrane containing a polymer to which a quaternary ammonium salt is covalently bound as a sensitive membrane has been reported. For example, Toshihiko Imato et al., Analytical Chemistry, 1980
Year, Vol. 52, pp. 1893-1896. This electrode uses an ion-exchange membrane in which a quaternary ammonium salt acting as a sensitive substance is covalently bonded to a styrene-divinylbenzene polymer, and this membrane is sandwiched by a Teflon holder and used in a glass cell. ing. Japanese Patent Publication No. 2-13262 (third known technology) discloses that a sensitive membrane formed by impregnating the surface of an anion exchange membrane with a low molecular weight anion such as an alkylbenzene sulfonate is applied to the tip of an electrode body. There is a description that the ion selectivity of the electrode is improved by using such an electrode.

[0003]

The so-called liquid film type sensitive membrane according to the first known technique has a high flexibility, so that when it is used in a flow cell type electrode, when it is used in a flow cell type electrode, the pressure from the sample solution flowing through the flow path is reduced. Although it has the characteristics of being highly durable against pressure and being able to achieve high ion selectivity relatively easily even when exposed to the pressure, the stability of the slope sensitivity is sometimes low due to elution of the sensitive substance. Is left. Further, the electrode according to the second known technique has a problem that the elution of the sensitive substance from the sensitive membrane is small and the stability of the slope sensitivity is high, but the selectivity is rather low and the electrode is easily affected by coexisting interfering ions. . Furthermore, the so-called ion-exchange resin membranes in the second and third known techniques generally have lower flexibility than the liquid membrane type sensitive membrane in the first known technique. In particular, it has been found that when used as a sensitive membrane of a flow cell type electrode, there is a problem that the membrane is easily damaged by pressure or internal stress from a sample solution or the like in the flow channel.

An object of the present invention is to provide an ion-selective electrode using a membrane containing a polymer having an ion-exchange group covalently bonded thereto as an ion-selective sensitive membrane, which has good pressure resistance, is resistant to breakage, and has a long life. An object of the present invention is to provide a highly reliable ion selective electrode that can be used stably.

[0005]

SUMMARY OF THE INVENTION The present invention has been made in the course of pursuing the problems of the prior art ion-selective electrodes, and comprises the steps of forming a membrane containing a polymer having ion-exchange groups covalently bonded thereto. In the ion selective electrode used as the membrane, the above object is achieved by disposing a buffer member made of an elastic body between the ion selective sensitive membrane and the electrode body. The configuration of the present invention will be described in detail below. The ion-selective electrode using the ion-selective sensitive membrane containing the ion-exchange polymer of the present invention has a feature in that a buffer member is disposed between the ion-selective sensitive membrane and the electrode body,
The cushioning member preferably contains a polymer elastic body, and particularly preferably contains a synthetic rubber. As the synthetic rubber, any of chloroprene rubber, nitrile rubber, and styrene-butadiene rubber is suitable. A multi-ion sensor provided with a plurality of ion-selective electrodes according to the present invention, and a biochemical component analyzer provided with these multi-ion sensors and measuring anion concentration are also characterized. Further, the method for producing an ion-selective electrode using an ion-selective sensitive membrane containing an ion-exchange polymer according to the present invention includes a step of forming a buffer member between the ion-selective sensitive membrane and the electrode body. In this step, a synthetic rubber-based adhesive or a solvent diluted solution thereof is applied to the electrode body, and before the adhesiveness is lost, an ion-selective sensitive membrane is brought into close contact with the application site to form a buffer member. It is characterized in that, after applying a synthetic rubber-based adhesive or its solvent diluted solution to the electrode body and drying, a part of the dried substance is re-dissolved by the solvent, or the dried substance is heated. The present invention is characterized in that a buffer member is formed by partially adhering an ion-selective sensitive membrane to a portion to be melted.

[0006]

[0007]

Embodiments of the present invention will be described below. In the following description, the symbol L indicates a unit of liter.

(Embodiment 1) FIG. 1 is a sectional view showing the configuration of a cylindrical anion-selective electrode according to Embodiment 1 of the present invention.
An internal solution 2 containing 10 mmol / L sodium chloride (NaCl) is housed inside the electrode body 1, and an internal electrode 3 made of silver silver chloride (AgCl) is immersed in the internal solution 2. An ion-selective sensitive membrane 4 is formed at an end of the electrode body 1 via a buffer member 5. The method for forming the ion-selective sensitive membrane 4 and the buffer member 5 and the method for manufacturing the anion-selective electrode will be described in detail below. The ion-selective sensitive membrane 4 is a kind of a so-called anion exchange resin membrane containing a polymer having an anion exchange group covalently bonded as described above. Hereinafter, the ion-selective sensitive membrane 4 in this embodiment
Will be described in detail. First, a so-called base film constituting the basic skeleton of the film was synthesized as follows.
Chloromethylstyrene and divinylbenzene were copolymerized in the presence of acrylonitrile-butadiene rubber as a reinforcing material and a woven support (polymer fiber). Specifically, 82% by weight of chloromethylstyrene and 10% by weight
Was mixed with 5% by weight of acrylonitrile-butadiene rubber, and 3% by weight of benzoyl peroxide was added to obtain a paste-like mixture. This mixture was kneaded into a woven fabric (Tevilon cloth) made of polyvinyl chloride manufactured by Teijin Co., Ltd., and the surface was covered with a polyester film.
Heat for 16 hours. In this manner, a base film having a main skeleton of a copolymer of chloromethylstyrene and divinylbenzene was formed. In this polymer, a benzyl chloride group derived from chloromethylstyrene is covalently bonded to the skeleton of the polymer.

Next, the base film was treated with an aqueous base solution to bond hydroxyl groups to the polymer. In this example, a 1 mol / L aqueous solution of potassium hydroxide was used as an aqueous base solution, and the base film was immersed in the aqueous solution and reacted at 60 ° C. for 2 hours. After the reaction, it was sufficiently washed with water and dried. By this reaction, a part of the benzyl chloride group covalently bonded to the polymer in the base film is converted into a benzyl hydroxide group, or in other words, a benzyl hydroxide group. Therefore, the hydroxyl group was fixed to the benzene ring of the copolymer of the base film through a single methylene group by a covalent bond. Thus, a base film having a hydroxyl group covalently bonded to a polymer was formed.

Next, a tertiary amine was reacted with the hydroxyl-bonded base film to bond a quaternary ammonium group to the polymer. Since tributylamine was used as the tertiary amine in this example, the quaternary ammonium group produced was benzyltributylammonium chloride. More specifically, the base film having the hydroxyl groups bonded thereto is made of a 20 mol / L methanol solution of 1 mol / L of tributylamine.
L and reacted at 50 ° C. for 72 hours. After the reaction,
Washed with methanol and then alternately with 1N hydrochloric acid and 0.5N ammonia. By this reaction, the remaining benzyl chloride groups in the polymer in the base film into which the hydroxyl groups have been introduced are converted into benzyltributylammonium chloride groups, and since this onium group is immobilized on the polymer by a covalent bond, an anion Acts as an exchange group. As described above, an anion exchange membrane containing a polymer having a covalently bonded tributylammonium group as an anion exchange group and having a hydroxyl group covalently bonded to the same polymer was formed. used.

As described above, the ion-selective sensitive membrane according to this embodiment has, as a main component, a substituted methylstyrene-divinylbenzene copolymer as a skeleton, and a part of the substituted methylstyrene has a hydroxyl group, and the remaining Substituents are anion exchange groups in the form of tributylammonium groups, and further include acrylonitrile-butadiene rubber, which imparts mechanical strength to the membrane, and polyvinyl chloride cloth as a woven support. However, the object of the present invention is not limited to this configuration, but can be achieved by other similar configurations. For example, as the basic skeleton of the polymer of the main component, a copolymer such as chloromethylstyrene-styrene-divinylbenzene, chloromethylstyrene-butadiene, styrene-divinylbenzene, styrene-isoprene, or polysulfone can be used. Even if chloromethylstyrene is not used as a raw material for copolymerization, generally, if the polymer has a benzene ring, a chloromethyl group can be introduced into the benzene ring by a chloromethylation reaction, and the above chloromethylstyrene copolymer can be used. Can be used as well. When a chloromethyl group is introduced as described above, a polymer having a hydroxyl group covalently bonded, which is a feature of the present invention, is obtained by reacting the chloromethyl group with an alkali or water. Further, a benzyltrialkylammonium group, which is an ion exchange group, can be introduced into the polymer by a quaternization reaction in which a tertiary amine reacts with the chloromethyl group, and an anion exchange membrane can be obtained. As the tertiary amine used in the quaternization reaction, various tertiary amines such as trimethylamine, triethylamine, tripentylamine, and tripropylamine can be used in addition to the above tributylamine. As the reinforcing material, various polymer elastic materials can be used in addition to acrylonitrile-butadiene rubber. As the woven support, various materials such as tetron, vinylon, and glass fiber can be used in addition to the mesh-shaped polyvinyl chloride cloth. Although not used in the present embodiment, various plasticizers, additives and the like can be included as needed.

Next, a method of manufacturing the cushioning member 5 in this embodiment will be described in detail. A chloroprene rubber-based adhesive (product name 57) manufactured by Cemedine, which is one of synthetic rubber-based adhesives.
5) was diluted 4-fold with 1,2-dichloroethane. This is applied to the end face of the electrode body 1 and dried in the air. By repeating this twice, the buffer member 5 mainly composed of chloroprene rubber was formed on the end face of the electrode body 1. This buffer member 5 is provided with tetrahydrofuran (TH
When a small amount of F) was dropped, the chloroprene rubber was swollen by THF to recover the adhesiveness, that is, reactivated. The ion-selective sensitive membrane 4 was adhered to the reactivated buffer member 5 and pressed, so that the ion-selective sensitive membrane 4 was bonded to the electrode body 1 via the buffer member 5. Internal liquid 2 in electrode body 1
And the internal electrode 3 were housed to produce an anion-selective electrode. In this embodiment, a chloroprene rubber-based adhesive is used as the buffer member 5, but the material of the buffer member 5 is not limited to this, and any material having elasticity can be suitably used.
Other synthetic rubber adhesives include nitrile rubber adhesives and styrene-butadiene rubber adhesives. Nitrile rubber adhesives are excellent in heat resistance and oil resistance and are therefore effective in maintaining electrode stability. The chloroprene rubber-based adhesive (product name 575) is an adhesive obtained by dissolving chloroprene rubber, which is a polymer elastic material, as a main raw material in toluene or n-hexane. Even if an adhesive dispersed in water is used as the latex, the cushioning member can be similarly formed. In addition, various adhesives based on polymer elastic bodies other than those described above can be used. In addition to materials developed and marketed as adhesives, polymer elastics,
Various materials including a polymer elastic body can also be used as the buffer member 5. Also in this case, the buffer member 5 can be formed by the same method as described above, and an anion-selective electrode can be formed. Also,
In the present embodiment, THF was used to reactivate the adhesive, but a solvent that dissolves the polymer constituting the adhesive and has little influence on the others can be used in the same manner.

As described above, the present embodiment employs a novel structure in which a buffer member is disposed between an ion-selective sensitive membrane based on an ion exchange resin membrane and an electrode body. It is as follows. First, the surface of the ion-exchange resin membrane including the woven support has irregularities reflecting the structure of the woven fabric. Therefore, when the ion-exchange resin membrane is directly adhered to the electrode body using THF or the like, the two do not contact uniformly. Since the bonding area is small, the bonding strength is generally low. On the other hand, as in the present embodiment, when a cushioning member is provided between the two, it penetrates between the two and fills the gap at the time of bonding, so that the uniformity of contact between the two is improved by mediation of the cushioning member, The bonding area and bonding strength increase, and the mechanical stability increases. Second,
When the ion exchange resin membrane and the electrode body are directly bonded,
The joining portion is a mechanically fragile portion in which the two members are mixed unevenly. Here, for example, a stress is generated between the two members due to a residual strain due to an applied pressure at the time of bonding, a thermal expansion or contraction, a swelling due to moisture or THF, or a contraction due to drying. Easily breaks. On the other hand, when an elastic cushioning member is provided between the two as in this embodiment, the stress is dispersed by the deformation of the cushioning member, and when the stress is eliminated, the original shape is restored. As described above, since the cushioning member is flexibly deformed in response to the stress and its fluctuation, the mechanical stability of the joint is enhanced. Third, when the ion exchange resin membrane and the electrode body are directly adhered to each other and a pressure is applied from the outside, for example, from a sample solution or the pressure fluctuates, stress is concentrated on a joint portion and destruction there is liable to occur. On the other hand, if a buffer member is provided between the two as in the present embodiment, even if an external force or a stress generated by the rotation is applied, the buffer member is dispersed by the displacement of the buffer member, and the original shape is restored when the external force is eliminated. I do. As described above, since the cushioning member is deformed flexibly in response to the external force and its fluctuation, breakage hardly occurs at the joint. That is, an effect peculiar to this embodiment is that an electrode having high mechanical stability against external pressure, internal stress, and the like can be provided.

(Embodiment 2) Next, an anion selective electrode according to Embodiment 2 of the present invention will be described. This embodiment is similar to the first embodiment, but slightly different in the form of the electrodes, the structures and compositions of the ion-selective sensitive membrane 4 and the buffer member 5, and the bonding method. FIG. 2 is a cross-sectional view showing a configuration of a flow cell type anion-selective electrode of Example 2 of the present invention. In this embodiment, a flow cell type electrode body 1 'shown in FIG. 2 was used instead of the cylindrical electrode body 1 shown in FIG. Also,
As the ion-selective membrane, a commercially available ion-exchange membrane was used, and a chemically modified ion-selective membrane was used to enhance its selectivity. This is mainly different from the first embodiment in that heat is used. Hereinafter, a method of manufacturing the ion-selective sensitive membrane 4 in this embodiment will be described in detail. As a commercially available anion exchange resin membrane, SELEMION manufactured by Asahi Glass Co., Ltd.
An anion exchange membrane of ASV type strong basic monovalent ion selective permeability was used. In order to improve the chloride ion selectivity of the ion exchange resin membrane, a film made of a dense condensate was further provided on the membrane surface by the following procedure. In a 5.5 mol / L methanol solution of metaphenylenediamine (MPDA), 192 mg of the above anion exchange membrane fragment (area 16
00 square millimeters) was soaked overnight. After removing this film from the immersion liquid to remove excess MPDA, the film was put into 10 mL of a mixed solution of formalin: concentrated hydrochloric acid: water = 5: 1: 25, and a condensation reaction was performed at a temperature of 5 ° C. for 20 minutes. After being washed several times with water, it was dried to obtain a film subjected to the first-stage condensation treatment.
(The second stage condensation treatment will be described later).

Next, a method of manufacturing the cushioning member 5 in this embodiment will be described in detail.

A nitrile rubber adhesive (product name: Hybon 2) manufactured by Hitachi Chemical Co., Ltd., which is one of synthetic rubber adhesives.
047) was diluted 4-fold with 1,2-dichloroethane. This was applied to the portion of the electrode body 1 'where the ion-selective sensitive membrane was to be placed (hereinafter referred to as the membrane bonding surface) and dried in air. This operation was repeated twice to form a buffer member 5 mainly composed of nitrile rubber on the film bonding surface of the electrode body 1 '. When a hot air heater of about 150 ° C. was provided in the vicinity of the buffer member 5 and heated, the nitrile rubber was plasticized by the hot air from the heater to recover the adhesiveness, that is, reactivated. The membrane subjected to the first-stage condensation treatment is placed on the reactivated buffer member 5 and pressed, and further heated by a 100 ° C. heater, so that the ionic membrane is electroded through the buffer member 5. Adhered to body 1 '. Next, the second stage condensation treatment of the film will be described. The same formalin hydrochloride aqueous solution as used in the first-stage condensation treatment was allowed to flow through the flow path of the electrode body 1 'to which the above-mentioned film was adhered at room temperature for 1 hour. The condensation reaction was further carried out from the flow channel side. After sufficiently washing with water, the second stage condensation treatment was completed. As described above, the ion-selective sensitive membrane 4
I got The internal liquid 2 and the internal electrode 3 were housed in this body with a membrane to produce an anion-selective electrode. In addition, in order to facilitate the adhesion of the membrane and to facilitate the contact between the adhered membrane and the sample solution, the adhesion surface of this membrane protrudes in a smooth curved surface with respect to the flow path as shown in FIG. Is provided. In the present embodiment, the radiant heat from the electric heater is used as the method of reactivation by heat, but it is needless to say that the heat may be reactivated by another method. For example, methods such as heat conduction by direct connection with a heater, high-frequency (microwave) induction heating, ultrasonic welding, and heating using a high-temperature inert gas flow are also possible. Also, as in Example 1, reactivation using a solvent is also possible.

The advantages specific to this embodiment are as follows.
Since the flow cell type electrode body is used, the amount of the sample is small, and the exchange of the sample is easy, so that a plurality of samples can be measured continuously and the throughput is high. Since the membrane is projected into the flow path in a curved surface, the sample in the flow cell flow path is in good contact with the ion-selective sensitive membrane, and retention is unlikely to occur. When the MPDA treatment is performed, the flexibility of the film generally decreases, and when the film is curved as described above, the adhesiveness tends to further decrease. However, due to the action of the cushioning member provided between the body and the membrane, the stress of the membrane is dispersed, breakage at the bonded portion is prevented, and mechanical stability is improved.
Further, if the MPDA condensation treatment is completely performed, the adhesiveness is significantly reduced. Therefore, the first-stage condensation treatment is performed at a low temperature for a short time before the adhesion, and the adhesion is performed at a stage where the adhesiveness is not impaired. Performs the second stage condensation treatment at room temperature for a long time,
A sufficient amount of MPDA was coated on the membrane. As a result, both the workability and the adhesiveness and selectivity were satisfied. In a flow cell, pressure fluctuations are generally large in order to quickly exchange samples in the flow channel, but the buffer member receives external pressure fluctuations, so that the membrane bonding part is not broken and mechanical stability is improved. I do. By using a nitrile rubber-based material with high chemical resistance as the buffer member, even if a large number of complex biological samples containing various chemical substances are measured, including the treatment solution for the second-stage condensation, Characteristics are kept stable.
Further, by using a nitrile rubber-based material having high heat resistance, the characteristics can be stably maintained even if a reactivation method by heat is used. The adoption of a thermal reactivation method prevents the dissolution, deformation and denaturation of the body and membrane, and reduces the risk of fire and the danger of toxicity to the human body associated with the use of organic solvents. effective.

(Embodiment 3) Next, an anion-selective electrode according to Embodiment 3 of the present invention will be described. This embodiment is similar to the second embodiment, but the structures and compositions of the ion-selective sensitive membrane 4 and the buffer member 5 and the bonding method are slightly different. That is, this embodiment is mainly different in that an adhesive having a long tack life is used as a cushioning member and the adhesive is adhered without reactivation. Hereinafter, a method of manufacturing the ion-selective sensitive membrane 4 in this embodiment will be described in detail. As a commercially available anion-exchange resin membrane, an anion-exchange membrane having strong basic monovalent ion selective permeation, manufactured by Asahi Glass Co., Ltd., was used. In order to improve the chloride ion selectivity of the ion exchange resin membrane, a polymer having a charge of the opposite sign was further entangled on the membrane surface. As a raw material for the ion-selective sensitive membrane 4, an anion-exchange membrane having a selective permeation of a strong basic monovalent ion was used as in the above-mentioned case. Also,
Sodium styrenesulfonate was used as a monomer for forming a cation exchange group having the opposite sign. Sodium p-styrenesulfonate 47mg manufactured by Tokyo Chemical Industry
(0.23 mmol), 167 mg (1.6 mmol) of special grade styrene monomer manufactured by Wako Pure Chemical Industries, and 58 mg (0.5%) of divinylbenzene for chemical use (55%, isomer mixture) manufactured by the company.
(45 mmol) was dissolved in 10 mL of methanol, and 54 mg (area of about 451 square millimeters) of the above-mentioned ASV-type strongly basic monovalent ion-permeable anion exchange membrane fragment was immersed in this solution. This is Kanto Chemical's special grade AIBN
After adding and mixing 10 mL of a 0.9 mg methanol solution, the mixture was refluxed at 70 ° C. for 1.5 hours. The membrane was taken out from the cooled reaction solution and washed with methanol and water to obtain an ion-selective sensitive membrane 4. As described above, in this embodiment, the copolymer of sodium styrenesulfonate was used as the polymer having the opposite sign to the ion exchange resin membrane main body. Polymers based on monomers can likewise be used. next,
A method for manufacturing the cushioning member 5 in the present embodiment will be described in detail. A chloroprene-modified phenol resin-based adhesive (product name: Hibon 1420) manufactured by Hitachi Chemical Co., Ltd., which is one of synthetic rubber-based adhesives, was diluted twice with toluene. This was applied to the film bonding surface of the electrode body 1 'and dried for 3 minutes or more. The tack life of this adhesive (about 100
Within minutes, the ion-selective sensitive film 4 was placed on the coated surface and pressed to adhere the ion-selective sensitive film 4 to the electrode body 1 'via the adhesive. When the volatile components volatilize from the adhesive, a buffer member 5 mainly composed of chloroprene-modified phenol resin is formed between the electrode body 1 ′ and the ion-selective sensitive membrane 4. The internal liquid 2 and the internal electrode 3 were accommodated in this, and an anion-selective electrode similar to FIG. 2 was produced. The specific effect of this embodiment is that many parts are common to those of the first and second embodiments, but the manufacturing operation is easy because the reactivation of the adhesive is not required.

(Embodiment 4) A multi-ion sensor of the present invention will be described with reference to FIG. FIG. 3 is a cross-sectional view illustrating a configuration of a multi-ion sensor according to Embodiment 4 of the present invention. A flow path is formed in the flow cell type electrode body 1 ″, an opening is provided to project in a curved shape to the flow path, and a plurality of ion-selective responsive elements are formed along the curved surface via the buffer member 5. The films 8, 8 ', 8 ", etc. are adhered. An internal electrode 7 is formed on the surface of the individual ion-selective sensitive membrane opposite to the flow path with an internal electrolyte layer 6 interposed therebetween. As the internal electrolyte layer 6, a polymer gel containing an electrolyte such as sodium chloride or the like is used. Examples of suitable polymer gels include polyvinyl alcohol, polyethylene glycol, agarose, and the like. Further, a moisturizing material typified by polyhydric alcohols may be added to these for use. As the internal electrode 7, a curved plate-like electrode made of silver-silver chloride or the like can be used, and a mesh-like electrode that can be easily bent or adhered can also be used. Although not shown, a lead wire or the like is connected to this internal electrode to take out a signal outside the multi-ion sensor. The individual ion-selective sensitive membranes, internal electrolyte layers, and internal electrodes are formed so as to be electrically insulated from each other, and thus function as independent ion-selective electrodes. When a polymer gel having a low water content, that is, a solid internal electrolyte layer is used as the internal electrolyte layer 6, each ion-selective electrode can be regarded as a solid ion sensor. In this example, an ion-selective sensitive membrane having the same composition as the ion-selective sensitive membrane in Example 2 was used as the ion-selective sensitive membrane of one independent ion-selective electrode. In response to anions, the performance of the electrode itself is similar to that of Example 2. Of course, ion selective sensitive membranes of other compositions according to the present invention may be used. In this example, as another independent ion-selective electrode, an ion-selective electrode using an ion-selective sensitive membrane for sodium ions and potassium ions is formed in the same flow cell type electrode body, and in addition to these, for chlorine ions or A reference electrode 9 using an ion-selective sensitive membrane for potassium ions was also formed on the same flow cell type electrode body, and a multi-ion sensor capable of comprehensively measuring three items of anions, sodium ions, and potassium ions was formed. The advantage unique to this embodiment is that the integrated and formed plural independent ion-selective electrodes and the reference electrode require a small sample amount, reduce the size of the electrodes, and reduce the size and cost of the entire measuring device. There are things that can be done and handling is easy.

(Embodiment 5) Next, a biochemical component analyzer according to the present invention will be described with reference to FIG. FIG. 4 is a diagram schematically illustrating a configuration of a biochemical component analyzer according to Embodiment 5 of the present invention. In the biochemical component analyzer of this embodiment, the anion-selective electrode 10 and the reference electrode 11 shown in Embodiment 2 are held in the flow cell 12, and the liquid sending device 13 and the valves 14, 1
5, a sampling mechanism 16, a measurement control device 17, a reference electrode solution 18, an internal standard solution 19, an external standard solution 20, a measurement sample solution 21, and other types of electrodes 22 and the like.
Next, an outline of the operation of this device will be described. Liquid sending device 1
3. By the operation of the valves 14 and 15, the reference electrode solution 18 is sent to the reference electrode 11 in the flow cell 12, and the internal standard solution 19 is sent to the anion-selective electrode 10 as a sample solution.
They merge in the flow cell 12 to form a liquid junction. Then, an electromotive force is generated between the reference electrode 11 and the anion-selective electrode 10 in accordance with the activity of the target ion in the internal standard solution 19, and is measured. Next, the sampling mechanism 1
6, the external standard solution 20 or the measurement sample solution 21 is measured as a sample solution in the same procedure. Based on a calibration curve created using the measured values of the external standard solution 20,
The activity of the target ion contained in the measurement sample solution 21 is calculated, and output such as display and printing is performed. The above measurement and control are automatically performed by the measurement control device 17 based on the instruction of the measurer. Although the anion-selective electrode according to the second embodiment is used here as the anion-selective electrode 10, other anion-selective electrodes according to the present invention can be used. Example 4 was replaced with an anion-selective electrode 10, a reference electrode 11, another type of electrode 22, a flow cell 12, and the like.
A similar biochemical component analyzer can be configured using the multi-ion sensor according to the above. Next, effects of the present invention will be described. FIG. 5 shows a conventional example and Examples 1 to 5 of the present invention.
FIG. 3 is a diagram showing evaluation results of durability of the ion-selective electrode with respect to pressure fluctuation according to No. 3; That is, the pressure (+/- 2
kg / cm ² ) for 100 hours continuously, and it is a result of testing whether the adhesion between the ion-selective sensitive membrane and the body is not broken. When this bond is broken, the slope sensitivity decreases. Therefore, five individuals were evaluated for each electrode, and FIG. 5 shows the proportion of the electrodes that maintained the slope sensitivity even after the load test. For comparison, a test was also performed under the same conditions for a conventional electrode that did not include a buffer member. FIG.
As is clear from the above, as compared with the electrode according to the conventional method, the electrode according to each embodiment of the present invention has a higher ratio of the electrode whose slope sensitivity is maintained even under the load of the pressure fluctuation. In other words, it is clear that the pressure resistance is good, the material is hardly damaged, and can be used stably for a long period of time.

[0021]

According to the present invention, fluctuations in external pressure and internal stress are absorbed by the buffer member, and the adhesiveness of the membrane is improved, and an electrode having high mechanical strength can be obtained. That is, in an ion-selective electrode using a membrane containing a polymer having an ion-exchange group covalently bonded as an ion-selective sensitive membrane, it has high pressure resistance, is not easily damaged, and has high reliability that can be used stably for a long period of time. Electrodes can be provided.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a configuration of a cylindrical anion-selective electrode according to a first embodiment of the present invention.

FIG. 2 is a cross-sectional view illustrating a configuration of a flow cell type anion-selective electrode according to a second embodiment of the present invention.

FIG. 3 is a sectional view illustrating a configuration of a multi-ion sensor according to a fourth embodiment of the present invention.

FIG. 4 is a view schematically showing a configuration of a biochemical component analyzer according to Embodiment 5 of the present invention.

FIG. 5 is a diagram showing evaluation results of durability against pressure fluctuation of ion-selective electrodes according to a conventional example and Examples 1 to 3 of the present invention.

[Explanation of symbols]

1, 1 ', 1 "... electrode body, 2 ... internal liquid, 3 ... internal electrode, 4 ... ion selective sensitive membrane, 5 ... buffer member, 6 ... internal electrolyte layer, 7 ... internal electrode, 8, 8', 8 "-... Ion-selective sensitive membrane, 9 ... Reference electrode, 10 ... Anion-selective electrode, 11 ... Reference electrode, 12 ... Flow cell, 13 ... Liquid feeder, 14 ... Valve, 15 ... Valve, 16 ... Sampling mechanism , 1
7: Measurement control device, 18: Reference electrode solution, 19: Internal standard solution, 20: External standard solution, 21: Measurement sample solution, 22
... other types of electrodes.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Yuji Miyahara 1-280 Higashi Koigakubo, Kokubunji-shi, Tokyo Inside Central Research Laboratory, Hitachi, Ltd.

Claims (10)

[Claims] 1. An ion-selective electrode using an ion-selective sensitive membrane containing an ion-exchange polymer, wherein a buffer member is disposed between the ion-selective sensitive membrane and an electrode body. Selective electrode. 2. The ion-selective electrode according to claim 1, wherein said buffer member includes a polymer elastic body. 3. The ion-selective electrode according to claim 2, wherein said elastic polymer is a synthetic rubber. 4. The ion-selective electrode according to claim 3, wherein said synthetic rubber is any one of chloroprene rubber, nitrile rubber, and styrene-butadiene rubber. 5. The ion-selective electrode according to claim 1, wherein said buffer member is formed using a synthetic rubber-based adhesive. 6. A multi-ion sensor comprising a plurality of ion-selective electrodes, comprising the ion-selective electrode according to claim 1. 7. A biochemical component analyzer for measuring anion concentration, which comprises the ion-selective electrode according to claim 1. 8. A biochemical component analyzer for measuring anion concentration, comprising the multi-ion sensor according to claim 6. 9. A method for producing an ion-selective electrode using an ion-selective sensitive membrane containing an ion-exchange polymer,
Forming a buffer member between the ion-selective sensitive membrane and the electrode body, the step comprising: applying a synthetic rubber-based adhesive or a solvent diluent thereof to the electrode body; A portion in which a portion of the dried product is re-dissolved by a solvent, or a portion in which a portion of the dried product is melted by heat, wherein the ion-selective sensitive membrane is adhered to form the buffer member. Of producing an anion-selective electrode. 10. A method of manufacturing an ion-selective electrode using an ion-selective sensitive membrane containing an ion-exchange polymer, wherein a buffer member is formed between the ion-selective sensitive membrane and an electrode body. In the step, applying a synthetic rubber-based adhesive or a solvent diluted solution thereof to the electrode body,
A method for manufacturing an anion-selective electrode, wherein the buffer member is formed by bringing the ion-selective sensitive membrane into close contact with the application site before the adhesive property is lost.