JP2018205034A - Anion selective electrode and method for manufacturing the same - Google Patents

Abstract

To provide an anion selective electrode having high ion selectivity and having a short time until potential is stable, and a method for manufacturing the same.SOLUTION: An anion selective electrode comprises: an electrode housing 22 having a space for putting an internal solution; an inner electrode 24 contacting the internal solution; a first surface 21a; a second surface 21b positioned on the side opposite to the first surface; and an anionic exchange membrane 21 arranged between the internal solution 23 and a sample solution. A part of a second surface of an anion sensitive film is exposed so as to contact the sample solution, and at least a part of the second surface of the anion sensitive film is coated with an epoxy amine resin 26.SELECTED DRAWING: Figure 9

Description

  The present invention relates to an anion selective electrode and a method for producing the same.

  The ion-selective electrode is used in a wide range of fields such as water quality analysis and medical field because it can selectively quantify a specific ion concentration in the liquid. In particular, in the medical field, since there is a close relationship between the metabolic reaction of living organisms and ion concentration, by quantifying specific ions contained in biological samples such as blood and urine, hypertension symptoms, kidney diseases, Neurological disorders can be diagnosed. Since it is necessary to analyze a large number of specimens continuously in a clinical test, a high-throughput automatic analyzer equipped with an ion-selective electrode or an electrolyte concentration measuring apparatus is routinely used.

  As measurement items, cations such as sodium ion and potassium ion and anions such as chlorine ion are mainly measured. With regard to cations, neutral carrier molecules have been found that selectively capture specific cations such as crown ethers and valinomycin but have no charge per se. Generally, membranes containing these neutral carrier molecules are used for ion-sensitive membranes of cation-selective electrodes such as sodium and potassium, and the ion-sensitive membrane has high ion selectivity. On the other hand, with regard to anions, there is no neutral carrier suitable for an ion selective electrode of an automatic analyzer that requires high throughput and quick response, and ion sensitive membranes of various configurations are used.

  For example, Patent Document 1 describes a chloride ion sensitive membrane based on an anion exchange membrane and having a surface coated with a condensate of metaphenylenediamine and formaldehyde.

  Patent Document 2 describes an anion sensitive membrane based on an epoxy resin containing quaternary ammonium ions.

  Further, Non-Patent Document 1 discloses that an anion-sensitive membrane based on an epoxy resin containing a quaternary ammonium ion has a time (preconditioning time) of 3 hours until the measurement potential is stabilized by adding a plasticizer. It has been disclosed to shorten to several minutes from the above.

Japanese Patent No. 3812049 Japanese Patent Laid-Open No. 2003-215087

Anal. Chem. 2004, 76, 4217-4222

  Blood, which is an analysis target of the automatic analyzer, contains a large amount of bicarbonate ions as anions in addition to chloride ions. For example, when a chloride ion selective electrode is used to quantify the chloride ion concentration, the sensitivity to bicarbonate ions is low and the sensitivity to chloride ions is high, that is, the chloride ion selectivity is important. Low carbonate ion selectivity is required. Although there is a method of reducing the influence of interfering ions by correcting by calibration or concentration calculation, higher ion selectivity is required to measure the chlorine ion concentration more accurately.

  As in Non-Patent Document 1, the ion selectivity of the ion sensitive membrane based on epoxy resin is excellent, but it takes time until the measurement potential is stabilized after the ion sensitive membrane is mounted on the apparatus. . Actually, in the automatic analyzer, since the measurement starts several minutes to several tens of minutes after mounting the electrode, it is better that the time until the potential is stabilized is faster. Non-Patent Document 1 shows that the time until potential stabilization can be shortened by adding a plasticizer or a solvent as a membrane component. However, a low molecular weight component such as a plasticizer or a solvent is immobilized in the membrane. Therefore, there is a concern that the components may escape during storage or use and the electrode performance may change.

  On the other hand, ion sensitive membranes based on ion exchange membranes have a high density of fixed charges and are easily hydrated. Therefore, for this ion-sensitive membrane, the time until the potential is stabilized is short, but the ion selectivity is poor. Therefore, in patent document 1, ion selectivity is improved by coat | covering with the condensate of metaphenylenediamine and formaldehyde. Although it has sufficient performance as an ion-selective electrode for automatic analyzers, the ion selectivity and long-term stability of the ion-selective electrode can be improved in order to further improve the analysis accuracy and reliability of ion concentration measurement. Improvement was necessary.

  Therefore, hereinafter, an anion selective electrode having high ion selectivity and a short time until the potential is stabilized and a method for manufacturing the same will be disclosed.

  For example, in order to solve the above-mentioned problem, the configuration described in the claims is adopted. The present application includes a plurality of means for solving the above problems. To give an example, an electrode housing having a space for containing an internal liquid, an internal electrode in contact with the internal liquid, a first surface, and the first And an anion exchange membrane disposed between the internal liquid and the sample liquid, and the internal liquid is the anion exchange A part of the first surface of the membrane is in contact, a part of the second surface of the anion exchange membrane is exposed so as to be in contact with the sample solution, and the anion exchange membrane is There is provided an anion selective electrode having an ion exchange resin membrane, wherein at least a part of the second surface of the anion exchange membrane is coated with an epoxyamine resin.

  According to another example, the step of closing the opening provided in the electrode housing and arranging the anion exchange membrane on the electrode housing so as to be in contact with the sample solution, The anion exchange membrane has an anion exchange resin membrane, a step of arranging, a step of filling the inside of the electrode housing with an internal liquid, and an internal electrode attached to the electrode housing so as to be in contact with the internal liquid A step of applying an epoxyamine resin to the surface of the anion exchange resin membrane in contact with the sample solution before or after the placing step, and the epoxy And a method of manufacturing an anion selective electrode comprising curing an amine resin.

  According to the present invention, it is possible to provide an anion selective electrode having high ion selectivity and a short time until the potential is stabilized, and a method for producing the same. Further features related to the present invention will become apparent from the description of the present specification and the accompanying drawings. Further, problems, configurations and effects other than those described above will be clarified by the description of the following examples.

It is a front view of the flow type anion selective electrode of one Example. It is a schematic diagram of the A-A 'cross section of FIG. FIG. 3 is a schematic diagram of a B-B ′ cross section of FIG. 2. It is sectional drawing which concerns on the structure of the ion sensitive film | membrane of one Example. It is sectional drawing which concerns on the structure of the ion sensitive film | membrane of one Example. 6 is a cross-sectional view relating to a configuration of an ion-sensitive film of Comparative Example 1. FIG. 6 is a cross-sectional view relating to a configuration of an ion-sensitive film of Comparative Example 2. FIG. 10 is a cross-sectional view relating to a configuration of an ion sensitive membrane of Comparative Example 3. FIG. It is sectional drawing concerning the stick-type anion selective electrode of one Example. It is an evaluation result of the slope sensitivity regarding Examples 1-3 and Comparative Examples 1-2. Chloride for Comparative Examples 1-2 and Example 1 to 3 (Cl ^-) bicarbonate ion to (HCO ₃ ^-) is the measurement results of the selectivity. It is the result of having measured the electrical resistance value regarding the electrode of Example 2, Comparative Example 2, and Comparative Example 3. It is an experimental result of the potential stability immediately after mounting the electrode of Example 2, Comparative Example 2 and Comparative Example 3 in the apparatus. It is the result of having evaluated the slope sensitivity after implementing a load test about the electrode of Example 3 using control serum. It is the result of having evaluated bicarbonate ion selectivity, after implementing a load test about the electrode of Example 3 using control serum. It is an evaluation result of bicarbonate ion selectivity of the stick type electrode of Example 4.

  Embodiments of the present invention will be described below with reference to the accompanying drawings. The accompanying drawings illustrate specific embodiments consistent with the principles of the invention, but are for the purpose of understanding the invention and are not to be construed as limiting the invention in any way. .

[First embodiment]
FIG. 1 is a front view of a flow type anion selective electrode of one embodiment. 2 is a schematic diagram of the AA ′ cross section of FIG. 1, and FIG. 3 is a schematic diagram of the BB ′ cross section of FIG.

  The flow type anion selective electrode of the present embodiment includes an electrode housing 10. The electrode housing 10 includes an internal liquid space 11 serving as a space for containing an internal liquid (hereinafter referred to as internal gel 16) and a flow path 12 that penetrates the electrode housing 10. The sample liquid to be measured passes through the flow path 12. The internal liquid space 11 is filled with an internal gel 16 containing an electrolyte. The electrode housing 10 includes an internal electrode 13 so as to be in contact with the internal gel 16. The internal electrode 13 is bonded to a lid 18 for confining the internal gel 16 in the internal liquid space 11.

  An ion sensitive membrane 17 is disposed between the internal liquid space 11 and the flow path 12 through which the sample liquid passes. The ion sensitive membrane 17 is disposed so as to be in contact with the sample solution passing through the flow path 12. The internal gel 16 is isolated in the electrode housing 10 by the ion sensitive film 17 so as not to contact the sample solution passing through the flow path 12. Further, the electrode housing 10 has a packing 15 in the vicinity of the entrance / exit of the flow path 12 so as to be connected to the flow path of the device or another electrode.

  In addition, the anion selective electrode of a present Example is mounted in an automatic analyzer, for example, and the internal electrode 13 is connected with the apparatus side wiring. Thereby, the automatic analyzer can measure the potential generated according to the concentration of the measurement target ion contained in the sample solution, and can analyze the concentration of the measurement target ion.

  FIG. 4 is an enlarged schematic view of the portion C in FIG. 3 and shows the layer structure of the ion sensitive film 17 that is characteristic of this embodiment. Below, the manufacturing method of the anion selective electrode of a present Example is demonstrated.

  First, an anion exchange resin membrane having immobilized cations is prepared. In this example, the ion sensitive membrane 17 uses an anion exchange resin membrane (anion exchange membrane 1) as a base material. In this example, the anion exchange resin membrane is a strongly basic anion exchange membrane having benzyltrimethylammonium groups, and includes a PVC-based synthetic fiber cloth as a reinforcing material. In addition, the cation immobilized on the anion exchange resin membrane is a quaternary ammonium ion.

  The anion exchange membrane 1 has a first surface 1a and a second surface 1b located on the opposite side to the first surface 1a. A liquid having a viscosity of 30 Pa · s is uniformly applied to the second surface 1 b of the anion exchange membrane 1 with a mixture of an epoxy main agent and an amine curing agent. Therefore, the ion sensitive membrane 17 has the anion exchange membrane 1 and the epoxyamine resin layer 5 applied on the surface thereof. In this example, the epoxy amine resin layer 5 is a polymerization reaction product containing an epoxy main agent and an amine curing agent.

  The ion sensitive film 17 is disposed so that the applied epoxyamine resin layer 5 is in contact with the electrode housing 10. At this time, the ion-sensitive film 17 and the electrode housing 10 are brought into close contact with each other so as to block the opening provided in the electrode housing 10 (that is, the opening serving as the flow path 12), and the conditions of 40 ° C. and 12 hours are satisfied. The epoxy amine resin layer 5 is cured with At this time, since the epoxyamine resin layer 5 is also disposed at the bonding portion between the electrode housing 10 and the anion exchange membrane 1, the anion exchange membrane 1 and the electrode housing 10 can be bonded together.

  Then, the internal gel 16 is filled in the internal liquid space 11 of the electrode housing 10 (see FIGS. 2 and 3). The internal gel 16 is isolated in the electrode housing 10 by the ion sensitive membrane 17 so as not to contact the sample solution passing through the flow path 12. At least a part of the first surface 1 a of the anion exchange membrane 1 is in contact with the internal gel 16. On the other hand, a part of the epoxyamine resin layer 5 on the second surface 1 b of the anion exchange membrane 1 is exposed so as to be in contact with the sample solution passing through the flow path 12. In this example, the epoxyamine resin layer 5 is disposed on the second surface 1b of the anion exchange membrane 1 so as to cover the entire opening portion on the channel 12 side. The epoxy amine resin layer 5 does not necessarily cover the entire opening portion on the flow channel 12 side, and even if it covers at least part of the opening portion on the flow channel 12 side, the effects of the present embodiment described below will be described. Can be expected. Then, the lid 18 is welded to the upper part of the internal liquid space 11, and the internal electrode 13 is attached to the lid 18 so as to be in contact with the internal gel 16.

  In addition, in order to suppress the transpiration of moisture in the internal gel 16, the first surface 1a of the anion exchange membrane 1 on the side opposite to the flow path 12 may be coated with an epoxyamine resin, which has the same effect as electrode performance. Is demonstrated.

  In this embodiment, the anion exchange membrane 1 is a highly cross-linked polystyrene membrane having a quaternary ammonium ion as an anion exchange group, and a fabric of PVC (polyvinyl chloride) yarn is used as a reinforcing material. The film is used. However, the present invention is not limited to this membrane, and the effects described below can be exhibited as long as the ion exchange membrane has fixed cations at a high density.

  The anion-selective electrode manufactured by such a method has a cured product of an epoxy main agent and an amine-based curing agent at the bonded portion between the anion exchange membrane 1 and the electrode housing 10, and an anion. The surface exposed to the flow path 12 of the exchange membrane 1 is also covered with a cured product of an epoxy main agent and an amine curing agent. As described above, since the epoxyamine resin layer 5 is disposed at the bonding portion between the electrode housing 10 and the anion exchange membrane 1, the anion exchange membrane 1 and the electrode housing 10 can be firmly bonded. . In addition, the layer structure composed of the anion exchange membrane 1 and the epoxyamine resin layer 5 is a high performance (slope sensitivity, ion selectivity, initial potential stability, low electricity) required for an automatic analyzer as an ion sensitive membrane. Resistance, specimen load tolerance). Specific electrode performance will be described later. In this way, a simple method of forming the epoxyamine resin layer 5 on the surface of the anion exchange membrane 1 and adhering the anion exchange membrane 1 and the electrode housing 10 to each other with a high performance anion selective electrode. Manufacture is possible.

  In this example, a mixture mainly composed of bisphenol A liquid epoxy resin was used as the epoxy main agent, but not limited thereto, and other glycidyl ethers, glycidyl amines, glycidyl esters, and the like may be used. Moreover, the material used as an epoxy main ingredient may contain the plasticizer and other additives. As the amine curing agent, a mixture mainly composed of polyamideamine was used, but aliphatic polyamines, alicyclic polyamines, aromatic polyamines, aliphatic polyamines, modified polyamines and the like may be used. In addition, the material used as the amine curing agent may contain a curing accelerator and other additives.

  As described above, according to the present embodiment, the anion selective electrode suitable for an automatic analyzer that performs continuous measurement at a high throughput, with high performance (ion selectivity, slope sensitivity, low electrical resistance, and specimen load resistance). An anion selective electrode having initial potential stability) can be provided. Moreover, the anion selective electrode of a present Example can be manufactured by a simple process.

[Second Embodiment]
The present example is a flow type anion selective electrode shown in FIGS. 1 to 3 similar to that described in the first example. FIG. 5 is an enlarged schematic view of a portion C in FIG. 3 and shows a layer structure of the ion sensitive film characteristic of this embodiment.

  The manufacturing method of the anion selective electrode of a present Example is demonstrated. First, an anion exchange membrane 1 having an immobilized cation is prepared. The anion exchange membrane 1 is dipped in a solution in which metaphenylenediamine is dissolved in a solvent, and then dipped in a mixed solution of formaldehyde and an inorganic acid. Thereby, a condensate of metaphenylenediamine (MPDA) and formaldehyde is formed inside and on the surface of the anion exchange membrane 1. This condensation layer 2 is referred to as MPDA condensation layer 2.

  A liquid having a viscosity of 30 Pa · s (25 ° C.) is uniformly applied to the surface of the anion exchange membrane 1 on which the MPDA condensation layer 2 is formed with a mixture of an epoxy main agent and an amine curing agent. Thereby, for example, the epoxyamine resin layer 5 is formed on the surface of the MPDA condensation layer 2 on the second surface 1b side of the anion exchange membrane 1. Thus, the ion sensitive membrane 17 of this example has a layer structure in which the MPDA condensation layer 2 is disposed between the anion exchange membrane 1 and the epoxyamine resin layer 5.

  The ion sensitive film 17 is disposed so that the epoxyamine resin layer 5 is in contact with the electrode housing 10. At this time, the ion-sensitive film 17 and the electrode housing 10 are brought into close contact with each other so as to block the opening provided in the electrode housing 10 (that is, the opening serving as the flow path 12), and the conditions of 40 ° C. and 12 hours are satisfied. The epoxy amine resin layer 5 is cured with When the curing temperature is higher than 80 ° C., the anion exchange membrane 1 and the electrode housing 10 may be damaged. Therefore, it is better to use a material that can be cured at the lowest possible temperature. Therefore, the curing temperature in the step of curing the epoxyamine resin layer 5 is preferably 80 ° C. or lower.

  Then, the internal gel 16 is filled in the internal liquid space 11 of the electrode housing 10 (see FIGS. 2 and 3). The internal gel 16 is isolated in the electrode housing 10 by the ion sensitive membrane 17 so as not to contact the sample solution passing through the flow path 12. A part of the epoxyamine resin layer 5 on the second surface 1b side of the anion exchange membrane 1 is exposed so as to be in contact with the sample solution passing through the flow path 12. Then, the lid 18 is welded to the upper part of the internal liquid space 11, and the internal electrode 13 is attached to the lid 18 so as to be in contact with the internal gel 16.

  In addition, in order to suppress the transpiration of moisture in the internal gel 16, the first surface 1a side of the anion exchange membrane 1 on the side opposite to the flow path 12 may be coated with an epoxyamine resin, and the electrode performance is the same. The effect is demonstrated.

  In this embodiment, the anion exchange membrane 1 is a highly cross-linked polystyrene membrane having a quaternary ammonium group as an anion exchange group, and a fabric of PVC (polyvinyl chloride) yarn is used as a reinforcing material. The film is used. However, the present embodiment is not limited to this membrane, and the effect of the present embodiment can be achieved as long as the ion exchange membrane has a high density of immobilized cations.

  In the anion selective electrode manufactured by such a method, a cured product of an epoxy main agent and an amine curing agent exists between the anion exchange membrane 1 and the electrode housing 10, and an anion exchange is performed. The surface exposed to the flow path 12 of the film 1 is also covered with a cured product of an epoxy main agent and an amine curing agent. Thus, the presence of the epoxy resin between the anion exchange membrane 1 and the electrode housing 10 allows the anion exchange membrane 1 and the electrode housing 10 to be firmly bonded. Further, since the anion exchange membrane 1 is covered with the MPDA condensation layer 2, the ion selectivity is improved as compared with the anion exchange membrane 1 itself. Furthermore, in the anion selective electrode of the present embodiment, since the epoxyamine resin layer 5 exists on the surface of the MPDA condensation layer 2, the slope sensitivity and the ion selectivity are improved. Specific electrode performance will be described later.

  The anion exchange membrane 1 covered with the MPDA condensation layer 2 in the present embodiment can also sufficiently satisfy the performance required for the automatic analyzer. Therefore, even if a part of the surface in contact with the sample solution is not covered with the epoxyamine resin layer 5, sufficient electrode performance is exhibited, so that an electrode with stable performance can be manufactured.

  In this example, a mixture mainly composed of bisphenol A liquid epoxy resin was used as the epoxy main agent, but not limited thereto, and other glycidyl ethers, glycidyl amines, glycidyl esters, and the like may be used. Moreover, the material used as an epoxy main ingredient may contain the plasticizer and other additives. As the amine curing agent, a mixture mainly composed of polyamideamine was used, but aliphatic polyamines, alicyclic polyamines, aromatic polyamines, aliphatic polyamines, modified polyamines and the like may be used. In addition, the material used as the amine curing agent may contain a curing accelerator and other additives.

[Third embodiment]
The present example is a flow type anion selective electrode shown in FIGS. 1 to 3 similar to that described in the first example. FIG. 5 is an enlarged schematic view of a portion C in FIG. 3 and shows a layer structure of the ion sensitive film characteristic of this embodiment.

  The manufacturing method of the anion selective electrode of a present Example is demonstrated. First, an anion exchange membrane 1 having an immobilized cation is prepared. The anion exchange membrane 1 is dipped in a solution in which metaphenylenediamine is dissolved in a solvent, and then dipped in a mixed solution of formaldehyde and an inorganic acid. Thereby, a condensate of metaphenylenediamine (MPDA) and formaldehyde is formed inside and on the surface of the anion exchange membrane 1. This condensation layer 2 is referred to as MPDA condensation layer 2.

  A liquid having a viscosity of 1.5 Pa · s (25 ° C.) is uniformly applied to the surface of the anion exchange membrane 1 on which the MPDA condensation layer 2 is formed with a mixture of an epoxy main agent and an amine curing agent. Thereby, for example, the epoxyamine resin layer 5 is formed on the surface of the MPDA condensation layer 2 on the second surface 1b side of the anion exchange membrane 1.

  The ion sensitive film 17 is disposed so that the epoxyamine resin layer 5 is in contact with the electrode housing 10. At this time, the ion-sensitive film 17 and the electrode housing 10 are brought into close contact with each other so as to block the opening provided in the electrode housing 10 (that is, the opening serving as the flow path 12), and the conditions of 40 ° C. and 12 hours are satisfied. The epoxy amine resin layer 5 is cured with

  Thereafter, the internal gel 16 is filled in the internal liquid space 11 of the electrode housing 10. The internal gel 16 is isolated in the electrode housing 10 by the ion sensitive membrane 17 so as not to contact the sample solution passing through the flow path 12. A part of the epoxyamine resin layer 5 on the second surface 1b side of the anion exchange membrane 1 is exposed so as to be in contact with the sample solution passing through the flow path 12. Then, the lid 18 is welded to the upper part of the internal liquid space 11, and the internal electrode 13 is attached to the lid 18 so as to be in contact with the internal gel 16.

  In addition, in order to suppress the transpiration of moisture in the internal gel 16, the first surface 1a side of the anion exchange membrane 1 on the side opposite to the flow path 12 may be coated with an epoxyamine resin, and the electrode performance is the same. The effect is demonstrated.

  In this embodiment, the anion exchange membrane 1 is a highly cross-linked polystyrene membrane having a quaternary ammonium group as an anion exchange group, and a fabric of PVC (polyvinyl chloride) yarn is used as a reinforcing material. The film is used. However, the present embodiment is not limited to this membrane, and the effect of the present embodiment can be achieved as long as the ion exchange membrane has a high density of immobilized cations.

  In the anion selective electrode manufactured by such a method, a cured product of an epoxy main agent and an amine curing agent exists between the anion exchange membrane 1 and the electrode housing 10, and an anion exchange is performed. The surface exposed to the flow path 12 of the film 1 is also covered with a cured product of an epoxy main agent and an amine curing agent. Thus, the presence of the epoxy resin between the anion exchange membrane 1 and the electrode housing 10 allows the anion exchange membrane 1 and the electrode housing 10 to be firmly bonded. Further, since the anion exchange membrane 1 is covered with the MPDA condensation layer 2, the ion selectivity is improved as compared with the anion exchange membrane 1 itself. Furthermore, in the anion selective electrode of this example, since the epoxyamine resin layer 5 exists on the surface of the MPDA condensation layer 2, the performance (slope sensitivity, ion selection) required for the automatic analyzer as the ion sensitive membrane 17 is obtained. , Initial potential stability, low electrical resistance, and specimen load resistance). Specific electrode performance will be described later.

  The anion exchange membrane 1 covered with the MPDA condensation layer 2 in the present embodiment can also sufficiently satisfy the performance required for the automatic analyzer. Therefore, even if a part of the surface in contact with the sample solution is not covered with the epoxyamine resin layer 5, sufficient electrode performance is exhibited, so that an electrode with stable performance can be manufactured. Further, in this example, since an epoxyamine resin having a lower viscosity than that in Example 2 is used, it is easy to apply uniformly to the film surface, and an electrode having high performance can be manufactured more stably. The viscosity of the epoxyamine resin used as the epoxyamine resin layer 5 is preferably 30 Pa · s (25 ° C.) or less, more preferably less than 10 Pa · s (25 ° C.).

  In this example, a mixture mainly composed of bisphenol A liquid epoxy resin was used as the epoxy main agent, but not limited thereto, and other glycidyl ethers, glycidyl amines, glycidyl esters, and the like may be used. Moreover, the material used as an epoxy main ingredient may contain the plasticizer and other additives. As the amine curing agent, a mixture mainly composed of polyamideamine was used, but aliphatic polyamines, alicyclic polyamines, aromatic polyamines, aliphatic polyamines, modified polyamines and the like may be used. In addition, the material used as the amine curing agent may contain a curing accelerator and other additives.

[Fourth embodiment]
FIG. 9 is a schematic cross-sectional view of the stick-type anion selective electrode of this example. The stick-type anion selective electrode includes an electrode housing 22. The electrode housing 22 has an opening. The anion exchange membrane 21 is disposed so as to close the lower opening of the electrode housing 22. The anion exchange membrane 21 has a first surface 21a and a second surface 21b located on the opposite side to the first surface 21a. The second surface 21b of the anion exchange membrane 21 located outside the stick-type anion selective electrode is covered with an epoxyamine resin layer 26 made of a cured product of an epoxy main agent and an amine curing agent. The opening of the electrode housing 22 constitutes an internal liquid space 27 into which the internal liquid 23 is placed. In the internal liquid space 27, the internal liquid 23 containing an electrolyte is disposed. At least a part of the first surface 21 a of the anion exchange membrane 21 is in contact with the internal liquid 23. Further, the electrode housing 22 includes an internal electrode 24 so as to be in contact with the internal liquid 23. The internal electrode 24 is bonded to a lid 25 for confining the internal liquid 23 in the electrode housing 22.

  In addition, the anion selective electrode of a present Example is mounted in an automatic analyzer, for example, and the internal electrode 24 is connected to the apparatus side wiring. Thereby, the automatic analyzer can measure the potential generated according to the measurement target ion concentration contained in the sample solution, and can analyze the concentration of the measurement target ion.

  The manufacturing method of the anion selective electrode of a present Example is demonstrated. First, an anion exchange membrane 21 having immobilized cations is prepared. As the material of the anion exchange membrane 21, the same material as that of the anion exchange membrane 1 of Examples 1 to 3 described above can be adopted.

  The electrode housing 22 has an opening that opens in the vertical direction in FIG. The anion exchange membrane 21 is bonded to the electrode housing 22 so as to close the lower opening of the electrode housing 22. Next, a mixture of the epoxy main agent and the amine curing agent is applied to at least the surface (second surface 21b) in contact with the sample solution of the anion exchange membrane 21. And the epoxy amine resin layer 26 is hardened on the conditions of 40 degreeC and 12 hours. Thereafter, the internal liquid 23 is filled into the electrode housing 22. The internal liquid 23 is in contact with at least a part of the first surface 21 a of the anion exchange membrane 21. The lid 25 is attached to the upper portion of the electrode housing 22, and the internal electrode 24 is attached to the lid 25 so as to be in contact with the internal liquid 23.

  In this embodiment, the anion exchange membrane 21 is a highly cross-linked polystyrene membrane having a quaternary ammonium group as an anion exchange group, and a fabric of PVC (polyvinyl chloride) yarn is used as a reinforcing material. The film is used. However, the present embodiment is not limited to this membrane, and the effect of the present embodiment can be achieved as long as the ion exchange membrane has a high density of immobilized cations.

  In the anion selective electrode manufactured by such a method, a cured product of an epoxy main agent and an amine-based curing agent also exists at the boundary between the anion exchange membrane 21 and the electrode housing 22, The exposed surface of the ion exchange membrane 21 is also covered with a cured product of an epoxy main agent and an amine curing agent. Therefore, the anion exchange membrane 21 and the electrode housing 22 can be firmly bonded.

  Further, the layer structure composed of the anion exchange membrane 21 and the epoxyamine resin layer 26 has high performance (slope sensitivity, ion selectivity, initial potential stability, low electrical resistance) required for an anion selective electrode as an ion sensitive membrane. , Specimen load tolerance). Specific electrode performance will be described later. As described above, it is possible to manufacture a high-performance and strong electrode by a simple method of applying an epoxyamine resin to the surface of the anion exchange membrane 21. Further, the layer structure composed of the anion exchange membrane 21 and the epoxyamine resin layer 26 has high performance (slope sensitivity, ion selectivity, initial potential stability, etc.) required for an anion selective electrode as an ion sensitive membrane. Low electrical resistance and specimen load tolerance). Specific electrode performance will be described later. As described above, it is possible to manufacture a high-performance and strong anion-selective electrode by a simple method of applying an epoxyamine resin to the surface of the anion exchange membrane 21.

  Note that the MPDA treatment similar to that in the second embodiment may be performed on the anion exchange membrane 21. That is, the MPDA condensation layer may be formed on the surface and inside of the anion exchange membrane 21, and the epoxyamine resin layer 26 may be formed on the surface of the MPDA condensation layer.

  Since the layer structure of the membrane of this example is the same as that of Examples 1-3, the slope sensitivity, ion selectivity, electrical resistance, service life, initial potential stability, etc. as the ion sensitive membrane have the same characteristics. Have.

  In the present embodiment, the bonding process between the anion exchange membrane 21 and the electrode housing 22 and the application and curing process of the epoxyamine resin layer 26 are performed in separate steps, but they may be performed simultaneously. Even if the bonding process between the electrode housing 22 and the electrode housing 22 is performed with an epoxyamine resin, the effect of this embodiment is exhibited.

  In this example, a mixture mainly composed of bisphenol A liquid epoxy resin was used as the epoxy main agent, but not limited thereto, and other glycidyl ethers, glycidyl amines, glycidyl esters, and the like may be used. Moreover, the material used as an epoxy main ingredient may contain the plasticizer and other additives. As the amine curing agent, a mixture mainly composed of polyamideamine was used, but aliphatic polyamines, alicyclic polyamines, aromatic polyamines, aliphatic polyamines, modified polyamines and the like may be used. In addition, the material used as the amine curing agent may contain a curing accelerator and other additives.

[Comparative Example 1]
Comparative Example 1 has the same configuration as that shown in FIGS. 1 to 3, and only the configuration of the ion sensitive membrane is different. Therefore, below, only a different part from Example 1 is demonstrated. FIG. 6 is an enlarged schematic view of a portion C in FIG. 3 and shows the layer structure of the ion-sensitive film of Comparative Example 1.

  A method for producing the anion selective electrode of Comparative Example 1 will be described. First, an anion exchange membrane 1 having an immobilized cation is prepared. The anion exchange membrane 1 is welded to the electrode housing 10 using THF (tetrahydrofuran) which is a low boiling point solvent so as to close the opening provided in the electrode housing 10. Thereafter, the internal gel 16 is filled in the internal liquid space 11 of the electrode housing 10. Then, the lid 18 is welded to the upper part of the internal liquid space 11 and the internal electrode 13 is fixed to the lid 18 so as to be in contact with the internal gel 16.

  In this comparative example, the anion-sensitive membrane is a highly cross-linked polystyrene film having a quaternary ammonium group as an anion exchange group, and a fabric of PVC (polyvinyl chloride) yarn serves as a reinforcing material. The membrane is used. The anion selective electrode manufactured by such a method has a structure in which the anion exchange membrane 1 is directly exposed to the flow path 12. Specific electrode performance will be described later.

[Comparative Example 2]
Comparative Example 2 has the same configuration as that shown in FIGS. 1 to 3 and differs only in the configuration of the ion sensitive membrane. Therefore, only the parts different from the second embodiment will be described below. FIG. 7 is an enlarged schematic view of a portion C in FIG. 3 and shows the layer structure of the ion-sensitive film of Comparative Example 2.

  A method for producing the anion selective electrode of Comparative Example 2 will be described. First, an anion exchange membrane 1 having an immobilized cation is prepared. The anion exchange membrane 1 is dipped in a solution in which metaphenylenediamine is dissolved in a solvent, and then dipped in a mixed solution of formaldehyde and an inorganic acid. Thereby, a condensate of metaphenylenediamine (MPDA) and formaldehyde is formed inside and on the surface of the anion exchange membrane 1. This condensation layer 2 is referred to as MPDA condensation layer 2.

  THF (tetrahydrofuran) which is a low-boiling solvent so that the anion exchange membrane 1 on which the MPDA condensation layer 2 is formed closes the opening provided in the electrode housing 10 (that is, the opening serving as the flow path 12). Is welded to the electrode housing 10. Thereafter, the internal gel 16 is filled in the internal liquid space 11 of the electrode housing 10. Then, the lid 18 is welded to the upper part of the internal liquid space 11 and the internal electrode 13 is fixed to the lid 18 so as to be in contact with the internal gel 16.

  In this comparative example, the anion-sensitive membrane is a highly cross-linked polystyrene film having a quaternary ammonium group as an anion exchange group, and a fabric of PVC (polyvinyl chloride) yarn serves as a reinforcing material. The membrane is used. The anion selective electrode manufactured by such a method has a structure in which the MPDA condensation layer 2 is directly exposed to the flow path 12. Specific electrode performance will be described later.

[Comparative Example 3]
Comparative Example 3 has the same configuration as that shown in FIGS. 1 to 3 and differs only in the configuration of the ion sensitive membrane. Therefore, below, only a different part from Example 1 is demonstrated. FIG. 8 is an enlarged schematic view of the portion C in FIG. 3 and shows the layer structure of the ion-sensitive film of Comparative Example 3.

  A method for producing the anion selective electrode of Comparative Example 3 will be described. First, in a state where a round bar having an outer diameter substantially the same as the inner diameter of the flow channel 12 is inserted into the flow channel 12, an opening provided in the electrode housing 10 (that is, an opening serving as the flow channel 12) is formed. Apply a mixture of epoxy base and amine curing agent to close. And the apply | coated mixture is hardened on the conditions of 40 degreeC and 12 hours. Thereby, the arc-shaped epoxyamine resin layer 7 is formed on the upper part of the flow path 12. Thereafter, the internal gel 16 is filled in the internal liquid space 11 of the electrode housing 10. Then, the lid 18 is welded to the upper part of the internal liquid space 11 and the internal electrode 13 is fixed to the lid 18 so as to be in contact with the internal gel 16.

  In this comparative example, a mixture mainly containing bisphenol A type liquid epoxy resin and bisphenol F type liquid epoxy resin is used as the epoxy main agent, and a mixture mainly containing polyamidoamine is used as the amine curing agent. The anion selective electrode manufactured by such a method has a structure in which the epoxyamine resin layer 7 is in contact with the sample solution. Specific electrode performance will be described later.

  A procedure for evaluating the characteristics as a chlorine ion selective electrode for Examples 1 to 3 and Comparative Examples 1 to 3 will be described here.

First, the slope sensitivity was determined from the equation (1) by measuring a known high concentration standard solution and a low concentration standard solution.
SL = (EMF _H -EMF _L ) / (Log C _H -Log C _L ) (1)
SL: Slope sensitivity EMF _H : Measurement electromotive force of a known high concentration standard solution EMF _L : Measurement electromotive force of a known low concentration standard solution C _H : Known concentration value of a high concentration standard solution C _L : Known concentration value of a low concentration standard solution

The slope sensitivity SL corresponds to the following Nernst type 2.303 × (RT / zF).
E = E0 + 2.303 × (RT / zF) × Log (f × C)
(E0: constant potential determined by measurement system, z: valence of ion to be measured, F: Faraday constant, R: gas constant, T: absolute temperature, f: activity coefficient, C: ion concentration)

  Although the slope sensitivity can be calculated from the temperature and the ion valence of the measurement object, the slope sensitivity SL specific to the electrode can be obtained by the above method.

  Moreover, the bicarbonate ion selectivity with respect to a chlorine ion was evaluated by what is called a mixed solution method. The mixed solution method is a method in which interfering ions are added to a standard solution, and the measured concentration value when it is used as a sample solution is obtained from the slope of a straight line plotted against the added concentration.

FIG. 10 shows the evaluation results of the slope sensitivity regarding Examples 1 to 3 and Comparative Examples 1 and 2. FIG. 11 is a measurement result of bicarbonate ion (HCO ₃ ⁻ ) selectivity for chlorine ion (Cl ⁻ ) regarding Examples 1 to 3 and Comparative Examples 1 and 2.

  The slope sensitivity indicates that the larger the absolute value, the better the performance as an electrode, that is, the smaller the value is better in the case of an anion selective electrode. In addition, when used as a chlorine ion selective electrode, it is better that the selectivity for bicarbonate ions, which are interfering ions, is small.

  As shown in FIG. 10, the slope sensitivity was −45.4 for the electrode of Comparative Example 1 having a sensitive membrane that was not treated on the anion exchange membrane 1. In contrast, the slope sensitivity of the electrode of Example 1 in which the surface of the anion exchange membrane 1 was covered with the epoxyamine resin layer 5 was improved to -49.4.

  As shown in FIG. 11, for the electrode of Comparative Example 1, the bicarbonate ion selectivity was 0.47, but for Example 1, the bicarbonate ion selectivity was improved to 0.22. Thus, conventionally, in order to improve the ion selectivity of the ion exchange membrane, a surface treatment such as MPDA treatment has been required. However, as the comparison result between Example 1 and Comparative Example 1 shows, the same effect can be obtained without applying the MPDA treatment by applying the epoxyamine resin layer 5 to the surface of the anion exchange membrane 1 and curing it. Was found to be obtained.

  Further, as shown in FIG. 10, the slope sensitivity of the electrode of Comparative Example 2 having a sensitive membrane obtained by subjecting the anion exchange membrane 1 to MPDA treatment was −51.1. Moreover, as shown in FIG. 11, with respect to the electrode of Comparative Example 2, the bicarbonate ion selectivity was 0.21. In contrast, with respect to Example 2 and Example 3 in which the epoxyamine resin layer 5 was formed on the surface of the anion exchange membrane 1 subjected to MPDA treatment, the slope sensitivities were -51.1 and -52.8, respectively. . Moreover, regarding Example 2 and Example 3, the bicarbonate ion selectivity was 0.17 and 0.11, respectively. From these results, it was confirmed that the bicarbonate ion selectivity of Examples 2 and 3 was improved as compared with Comparative Example 2. Moreover, it turns out that the slope sensitivity of Example 3 was further improved compared with Example 2.

  The reason why Examples 1 to 3 were improved in electrode performance as compared with Comparative Examples 1 and 2 was that the surface (second surface 1 b) in contact with the sample liquid of the anion exchange membrane 1 was covered with the epoxyamine resin layer 5. It is considered that the ion selectivity possessed by the epoxyamine resin could be obtained. In addition, the difference between Example 2 and Example 3 is due to the difference in the viscosity of the epoxyamine resin before curing, that Example 3 was able to apply the epoxyamine resin uniformly on the surface. it is conceivable that.

  FIG. 12 shows the results of measuring the electrical resistance values for Example 2, Comparative Example 2 and Comparative Example 3. In general, a lower electrical resistance value is suitable for an ion-selective electrode because it is less susceptible to electrical noise. Regarding Comparative Example 3 having only the epoxyamine resin as the ion sensitive film, the electric resistance value was 900 MΩ, which was a high resistance value. On the other hand, regarding the electrode of Comparative Example 2, the electric resistance value was 41 KΩ. Moreover, regarding the electrode of Example 2, it was confirmed that the electric resistance value was 49 KΩ and the resistance was much lower than that of Comparative Example 3.

  In the curing process of the epoxyamine resin, ammonium ions are produced, but it is considered that ammonium ions are present only at a low density. For this reason, it is considered that the ion-sensitive film formed only with the epoxyamine resin of Comparative Example 3 has low conductivity and high resistance. On the other hand, ammonium ions are immobilized at a high density on the anion exchange membrane 1 and have relatively high conductivity. Since Example 2 has the epoxyamine resin layer 5 only on the surface of the anion exchange membrane 1, it is considered that the Example 2 has a low resistance substantially equal to that of Comparative Example 2.

  FIG. 13 shows the results obtained when the electrodes of Comparative Example 2, Comparative Example 3 and Example 2 were respectively mounted on an electrolyte measuring apparatus, and a standard solution having a constant ion concentration was continuously measured every few minutes to several tens of minutes immediately thereafter. Indicates power. In the graph of FIG. 13, the vertical axis represents the measured potential, and the horizontal axis represents the measurement time. “0:00” is a potential measured immediately after each electrode is mounted on the electrolyte measuring device.

  As shown in FIG. 13, in Comparative Example 3, the potential was stabilized after one hour or more had elapsed, whereas in Comparative Example 2, the potential was stable immediately after being mounted on the apparatus. On the other hand, it was confirmed that the potential of Example 2 was quickly stabilized immediately after being mounted on the apparatus, as in Comparative Example 2. This is considered to be related to the familiarity of the ion-sensitive membrane with respect to moisture. The ion-sensitive membrane composed only of the epoxyamine resin of Comparative Example 3 has a low density of ammonium ions and slowly adapts to water, whereas it is implemented with Comparative Example 2 based on the anion exchange membrane 1. In Example 2, since the anion exchange membrane itself has a high density of immobilized ammonium ions, it is easily compatible with water. From this, in the case of Comparative Example 2 and Example 2, it is considered that the potential was stabilized immediately after mounting in the apparatus. It is important that the electrolyte measuring device can start measurement immediately after it is started up. The ion selective electrode of Example 2 has an important characteristic that the potential is quickly stabilized.

  FIG. 14 shows the result of evaluating the slope sensitivity after performing a load test on the electrode of Example 3 using the control serum. FIG. 15 shows the results of evaluating bicarbonate ion selectivity after conducting a load test on the electrode of Example 3 using control serum.

  A total of 12000 specimen loading was performed. As a result, with respect to Example 3, both the slope sensitivity and the bicarbonate ion selectivity were stable, and it was confirmed that the electrode performance hardly changed even when continuous measurement was performed with an automatic analyzer. Similarly, it was confirmed that Example 1 and Example 2 hardly changed in the load test. This is because the surface material in contact with the sample is made of the same material, so the contamination of the membrane surface is considered to be equivalent, and the cation immobilized at high density as the base of the ion sensitive membrane 17 Since the anion exchange membrane 1 having the above is used, the membrane has many chloride ions as counter anions. Therefore, even when interfering ions enter the anion exchange membrane 1 at the time of measurement, it is considered that the influence on the ion response is small. In addition, the ion sensitive membranes 17 of Examples 1 to 3 have sufficient physical strength. From the above, it is considered that the electrode performance stable for the load test could be maintained for all the electrodes of Examples 1 to 3.

  FIG. 16 shows the measurement results of the bicarbonate ion selectivity when the thickness of the epoxyamine resin layer 26 is changed in the stick-type electrode of Example 4.

  As shown in FIG. 16, the bicarbonate ion selectivity was 0.5 when the epoxyamine resin was not applied, whereas the epoxyamine resin layer 26 was applied to the surface of the anion exchange membrane 21. The selectivity was greatly improved from 0.21 to 0.26. When the film thickness was 1 mm or more, a normal potential could not be obtained within a short measurement time of 1 minute after immersion in the measurement liquid. For this reason, the film thickness of the epoxyamine resin on the anion exchange membrane is preferably less than 1 mm.

  The anion selective electrodes of Examples 1 to 4 described above have an electrode housing for holding an internal liquid therein, an ion sensitive membrane, and an internal electrode. The internal solution is exposed to the flow path so that the first surface of the anion sensitive membrane and a part of the internal electrode are in contact with each other, and the second surface of the anion sensitive membrane is in contact with the sample solution. doing. The anion sensitive membrane is based on an anion exchange resin membrane, and at least a part of the second surface of the anion sensitive membrane is coated with an epoxyamine resin.

  The anion selective electrodes of Examples 1 to 4 described above can be manufactured by the following method. The manufacturing method includes a step of placing an anion exchange membrane in an electrode housing so as to close an opening provided in the electrode housing and come into contact with a sample solution; And a step of disposing an internal electrode in contact with the internal liquid. In the case of Examples 1 to 3, before the step of placing the anion exchange membrane on the electrode housing, a step of applying an epoxyamine resin to the surface of the ion exchange resin membrane on the side in contact with the sample solution, and an epoxyamine resin Curing. In the case of Example 4, after the step of placing the anion exchange membrane on the electrode housing, a step of applying an epoxyamine resin to the surface of the ion exchange resin membrane on the side in contact with the sample solution, and curing the epoxyamine resin And a step of causing.

  According to the above-described embodiment, it has high performance (ion selectivity, slope sensitivity, low electrical resistance, and specimen load resistance), and also has a short time until the measurement potential is stabilized after the electrode is installed in the apparatus. An ion selective electrode can be provided. Moreover, the anion selective electrode of the above-mentioned Example can be manufactured by a simple process. The anion selective electrode of the above-described embodiment is also suitable for an automatic analyzer that performs continuous measurement at a high throughput, and can further improve the analysis accuracy and reliability of ion concentration measurement.

  The present invention is not limited to the above-described embodiments, and includes various modifications. The above embodiments have been described in detail for easy understanding of the present invention, and are not necessarily limited to those having all the configurations described. Also, a part of the configuration of one embodiment can be replaced with the configuration of another embodiment. Moreover, the structure of another Example can also be added to the structure of a certain Example. Further, with respect to a part of the configuration of each embodiment, another configuration can be added, deleted, or replaced.

DESCRIPTION OF SYMBOLS 1 ... Anion exchange membrane 2 ... MPDA condensation layer 5 ... Epoxyamine resin layer 10 ... Electrode housing 11 ... Internal liquid space 12 ... Flow path 13 ... Internal electrode 15 ... Packing 16 ... Internal gel 17 ... Ion sensitive membrane 18 ... Lid 21 ... Anion exchange membrane 22 ... Electrode housing 23 ... Internal liquid 24 ... Internal electrode 25 ... Lid 26 ... Epoxyamine resin layer 27 ... Internal liquid space

Claims (15)

An electrode housing having a space for containing an internal liquid;
An internal electrode that contacts the internal liquid;
An anion exchange membrane having a first surface and a second surface located on the opposite side of the first surface, and disposed between the internal liquid and the sample liquid;
Have
The internal liquid is in contact with a part of the first surface of the anion exchange membrane,
A part of the second surface of the anion exchange membrane is exposed so as to be in contact with the sample solution,
The anion exchange membrane has an anion exchange resin membrane,
An anion selective electrode, wherein at least a part of the second surface of the anion exchange membrane is coated with an epoxyamine resin. The anion selective electrode according to claim 1, wherein
The anion selective electrode, wherein the epoxy amine resin is a polymerization reaction product containing an epoxy main agent and an amine curing agent. The anion selective electrode according to claim 1, wherein
The anion-selective electrode, wherein the epoxyamine resin is disposed at a bonding portion between the electrode housing and the anion exchange membrane. The anion selective electrode according to claim 1, wherein
An anion-selective electrode, wherein the cation immobilized on the anion exchange resin membrane is a quaternary ammonium ion. The anion selective electrode according to claim 1, wherein
An anion-selective electrode, characterized in that a condensate of metaphenylenediamine and formaldehyde is disposed between the anion exchange membrane and the epoxyamine resin. The anion selective electrode according to claim 1, wherein
An anion-selective electrode, wherein the anion-exchange resin membrane is a strongly basic anion-exchange membrane having a benzyltrimethylammonium group and includes a PVC-based synthetic fiber cloth as a reinforcing material. The anion selective electrode according to claim 1, wherein
An anion selective electrode, wherein at least a part of the first surface of the anion exchange membrane is coated with an epoxyamine resin. The anion selective electrode according to claim 1, wherein
An anion selective electrode, wherein the thickness of the epoxyamine resin is less than 1 mm. An anion exchange membrane is disposed on the electrode housing so as to close an opening provided in the electrode housing and to be in contact with a sample solution, and the anion exchange membrane is an anion exchange A step of arranging the resin film;
Filling the inside of the electrode housing with an internal liquid;
Attaching an internal electrode to the electrode housing so as to be in contact with the internal liquid,
Before the placing step or after the placing step,
Applying an epoxyamine resin to the surface of the anion exchange resin membrane that is in contact with the sample solution;
Curing the epoxyamine resin. A method for producing an anion selective electrode. In the manufacturing method of the anion selective electrode according to claim 9,
The method for producing an anion selective electrode, wherein the epoxyamine resin is a polymerization reaction product containing an epoxy main agent and an amine curing agent. In the manufacturing method of the anion selective electrode according to claim 9,
The method for producing an anion selective electrode, wherein the epoxyamine resin has a viscosity of 30 Pa · s (25 ° C.) or less. In the manufacturing method of the anion selective electrode according to claim 9,
The method for producing an anion selective electrode, wherein the curing temperature in the curing step is 80 ° C. or lower. In the manufacturing method of the anion selective electrode according to claim 9,
The step of arranging includes the step of arranging the epoxyamine resin between the anion exchange resin membrane and the electrode housing and bonding the anion exchange resin membrane and the electrode housing. A method for producing an anion selective electrode. In the manufacturing method of the anion selective electrode according to claim 9,
The method for producing an anion selective electrode further comprising a step of coating the surface of the anion exchange resin membrane with a condensate of metaphenylenediamine and formaldehyde before the step of applying the epoxyamine resin. . In the manufacturing method of the anion selective electrode according to claim 9,
The method for producing an anion selective electrode, wherein the anion exchange resin membrane is a strongly basic anion exchange membrane having a benzyltrimethylammonium group, and includes a PVC synthetic fiber cloth as a reinforcing material.

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