JPH11194115A - Ion sensor and ion sensor plate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an ion sensor which comprises an ion sensing membrane of uniform composition, by a method wherein component of a plasticizer to be contained in the ion sensing membrane is set at a specific wt.% to the total. SOLUTION: An ion sensor plate body 5 which comprises at least a pair of a sample-liquid measuring electrode 2a comprising an ion sensing membrane 2d as a coating membrane for specific ions and a reference electrode as a set is installed. A measuring circuit is connected to the ion sensor plate body 5. The concentration of specific ions in a sample liquid can be measured. The ion sensing membrane 2d contains at least a matrix, a plasticizer which plasticizes the matrix and an ion sensing substance. In the ion sensing membrane 2d, the plasticizer in 65 to 80 wt.% is contained. As a result, the potential stabilizing effect of a potential stabilizing substance or an ionophore contained in the ion sensing membrane 2d acts with good efficiency, an initial characteristic at the beginning of its manufacture is good, and an irregularity in the characteristic is small. Consequently, the measuring accuracy of an ion sensor can be enhanced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ion sensor for various kinds of ions for examining blood and the like, and more particularly to a disposable simple ion sensor plate of parts thereof.

[0002]

2. Description of the Related Art Several ion sensor plates have been conventionally proposed as disposable simple inspection ion sensor plates. As one of them, a differential type multi-ion sensor connects a multi-ion sensor plate to a measurement circuit and simultaneously measures a number of different ion concentrations. The multi-ion sensor plate has a structure as shown in FIG. A pair of a sample liquid measurement electrode 2a and a reference electrode 2b, which are formed by etching a copper electrode formed on a glass epoxy substrate 1 by electrolytic silver plating, are provided as a pair, and silver at the opposite end of each electrode is provided. A silver chloride layer 4a, 4b is provided on the plating layer, and a multi-ion sensor plate main body 5 is provided in which the ends of the respective electrodes facing away from each other are external electrodes, and further communicates with each set of silver chloride layers 4a, 4b. Through holes 6a to 6e, 6'a to 6'e, and a liquid junction portion 7 of an elongated hole corresponding to tips of two flow passages of an upper cell, which will be described later, for bringing a sample liquid and a reference liquid into contact with each other; Each pair Poles 2a, 2b
The embankment body 9 made of a polyester film having through holes 8a and 8b communicating with the external electrode portion is joined to the multi-ion sensor plate main body 5. Various different ion-sensitive membrane solutions containing various ion-sensitive substances such as a macrocyclic compound called ionophao or an ion-exchange resin through the respective through holes 6a to 6e and 6'a to 6'e of the bank body 9. Is dropped and dried to form ion-sensitive films on the silver chloride layers 4a and 4b, thereby providing a total of five different ion-sensitive films. The joined body of the ion sensor plate body 5 and the bank body 9 is connected to a lower cell 1 made of a transparent acrylic resin plate.
The upper cell 12 made of a transparent acrylic resin is bonded to the lower cell 10 with a double-sided adhesive tape, and the above-described bonded body is mounted. Upper cell 12
Are the through holes 6a to 6e, 6'a to 6 '
Flow paths 13 and 14 formed of concave grooves communicating with e are provided in two parts by partition walls. One end of each flow path is provided with a sample liquid input section 15 and a reference liquid input section 16. At the ends, air vent grooves 13a and 14a, each of which is a narrow groove, communicating with the air outlet grooves 13a and 14a, are arranged in an L-shape and symmetrically, and the front ends are provided at the front ends of the sample liquid inlet 15 and the reference liquid inlet 16, respectively. Terminal insertion holes 18a and 18b for inserting terminals of a measuring instrument (not shown) corresponding to the exposed ends of the external electrodes of the sample liquid measurement electrode 2a and the reference electrode 2b are formed. It is provided.

When a multi-ion sensor plate having such a structure is used, a sample liquid and a reference liquid are injected into a sample liquid input section 15 and a reference liquid input section 16 by a syringe or the like, respectively. Liquid is circulated,
While being supplied to the ion-selective electrodes in the through holes 6a to 6e and 6'a to 6'e, the sample liquid and the reference liquid come into contact at the liquid junction 7. In this state, insert the terminal of the measuring instrument into the terminal insertion hole 1
The ionic components of the sample solution are measured by inserting the sample solution into each of the external electrodes 8a and 18b, and the concentrations of a total of five types of ions are measured by one injection of the sample solution and the reference solution.

By the way, in the structure in which an ion-sensitive film is directly provided without having an internal electrolyte aqueous solution layer on the surface of silver chloride as described above, the ion-sensitive film is made of, for example, a polyvinyl chloride resin as a matrix (substrate). To this is added a salt, such as an ionophore, which selectively reacts with the ion to be detected, or a salt such as an anion eliminator that eliminates the interference of anions from the sample solution and the reference solution, to prepare a solution of the mixture. In this case, a plasticizer is also mixed and used at the same time in order to maintain flexibility so that the coating film does not peel off from the base or cracks or the like do not occur. The plasticizer in the ion-sensitive membrane can be added to these liquids when using the sample solution or reference solution, or when using the cleaning solution when the ion sensor plate with the ion-sensitive membrane is used repeatedly. When the elution amount increases, the ionophore and the added salt also elute with the elution, and the performance of the ion-sensitive membrane is reduced. Is 35% by weight of a polyvinyl chloride resin and 60 to 65% by weight of a plasticizer, based on the whole film.

[0005]

However, in a method of forming an ion-sensitive film by dropping a solution of a mixture therefor using, for example, a tetrahydrofuran solvent, a method of forming an ion-sensitive film by applying the solution to the surface of the coating film when air-drying is performed. Convection occurs inside the film, resulting in a so-called “yuzu skin-like” surface state, and the coated film loses fluidity and solidifies as it is, making it impossible to maintain the uniformity of the film. Also, due to insufficient plasticization of the polyvinyl chloride resin of the matrix, the ion-sensitive film could not sufficiently wet and spread on the underlying silver chloride layer, and the contact area with the underlying layer became small, and the same In order to stabilize the dissociation equilibrium (AgX = Ag ⁺ + X ⁻ ) of silver halide such as silver chloride in addition to the above components in the ion-sensitive membrane, at least one of the components constituting this equilibrium is proposed. When one kind of substance or a substance that dissociates it is added, when the same ionophore used in the ion-sensitive membrane is excessively added, or when the above Ag is added.
X = Ag ⁺ + X ^- Displacement equilibrium effectively replaces eg A
g-TPB = Ag ⁺ + TPB ⁻ (TPB is tetrakisphenylborate) When an anion eliminator such as TPB is excessively added to the ion-sensitive membrane in order to control the stabilization of the dissociation equilibrium, the dissociation equilibrium is stabilized. In other words, the effect of stabilizing the potential generated at the interface between the silver halide layer of the electrode and the ion-sensitive film cannot be sufficiently exhibited. As described above, when the film composition of the ion-sensitive film becomes non-uniform and the contact area with the substrate is not sufficient, the measured value of the ion concentration to be detected in the sample liquid varies, and the measurement accuracy is satisfactory. Can not get. In particular, since the measured potential of the electrodes of the ion sensor body and the ion sensor plate at the beginning of manufacture, that is, the initial characteristics vary, and high measurement accuracy cannot be obtained, the initial characteristics are corrected or only those within the standard are selected. It is necessary to carry out sorting, which is inevitably disadvantageous in terms of productivity in terms of cost.

A first object of the present invention is to provide an ion sensor and an ion sensor plate having an ion-sensitive film having a uniform composition. A second object of the present invention is to provide an ion sensor and an ion sensor plate having an ion-sensitive film capable of increasing a contact area with a base. A third object of the present invention is to provide an ion sensor and an ion sensor plate in which the potential stabilizing effect of the potential stabilizer contained in the ion-sensitive membrane works efficiently.
A fourth object of the present invention is to provide an ion sensor and an ion sensor plate which have good initial characteristics at the time of manufacture, have small variations, and have high measurement accuracy. A fifth object of the present invention is to provide an ion sensor and an ion sensor plate with good productivity. A sixth object of the present invention is to provide a single-use disposable simple ion sensor and an ion sensor plate that are less affected by the dissolution of a plasticizer or the like in a sample liquid or a reference liquid, and are used only once.

[0007]

In order to solve the above-mentioned problems, the present invention provides (1) at least one pair of a sample liquid measuring electrode having a coating film of an ion-sensitive film of a specific ion and a reference electrode. In an ion sensor provided with an ion sensor plate main body having a set, a measurement circuit is connected to the ion sensor plate main body so that a specific ion concentration of a sample liquid can be measured, wherein the ion-sensitive membrane plasticizes the matrix and the matrix. It is an object of the present invention to provide an ion sensor which contains at least a plasticizer and an ion-sensitive substance, and contains 65 to 80% by weight of the plasticizer in the ion-sensitive film. The present invention also provides (2) an ion sensor plate main body in which at least one pair of a sample liquid measurement electrode having a coating film of an ion-sensitive film and a reference electrode is provided on a substrate; A closed fluid passage for supplying the specimen liquid to the reference electrode and a closed fluid passage for supplying the reference liquid to the reference electrode are respectively formed on the substrate surface, and a specimen liquid input section and a reference liquid input section communicating with the respective flow paths. And a liquid junction provided in the ion sensor plate main body and supplied to the respective flow passages for liquid-junction of a reference liquid and the ion-sensitive membrane is a matrix and the matrix To provide an ion sensor plate containing at least a plasticizer for plasticizing the compound and an ion-sensitive substance, and containing 65 to 80% by weight of the plasticizer in the ion-sensitive film.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A joined body of a multi-ion sensor plate main body 5 and a bank 9 shown in FIG.
a to 6e, 6'a to 6'e, for example, through holes 6a, 6'a
In addition, polyvinyl chloride resin, plasticizer, ion sensitive material,
Addition salts such as an anion eliminator such as Na-TPB and K-KTPB, if necessary, stabilize the dissociation equilibrium such as the above-mentioned silver halide if necessary, and prepare the silver halide layer of the electrode and the ion-sensitive membrane. The above-mentioned dissociation equilibrium constituent of silver halide which stabilizes the potential generated at the interface or a substance which dissociates the ions thereof, or a potential stabilizing substance of an anion elimination agent added in excess, or these anion elimination agents and other A resin solution for an ion-sensitive membrane of a specific ion containing the same kind and an excessive amount of ionophore etc. of the same type as that used for the ion-sensitive membrane used in combination with at least one of the potential stabilizing substances. 65-80% by weight, preferably 65% by weight, of the plasticizer based on the whole ion-sensitive membrane after drying)
A resin solution of about 78% by weight, more preferably 70-75% by weight is dropped and dried to form an ion-sensitive film of specific ions, thereby forming an ion-sensitive electrode. FIG. 1 shows a cross-sectional view around the electrode on the side that supplies the sample liquid. In the figure,
1 is a glass epoxy substrate, 2a is a sample liquid measuring electrode, 4a
2 is a silver halide layer, and 3 is not shown in FIG. 2. Except for a part of a portion of the silver halide layer such as a silver chloride layer, which faces the through hole 6a, and an outer end of the electrode (external electrode). Insulating film covering the surface of the multi-ion sensor plate main body 5 except for the corresponding portions in actuality, 4c is a window, 9c
Is a bank, 6a is a through hole, and 2d is an ion sensitive membrane. Further, other through holes 6b and 6'b, 6c and 6'c, 6d and 6 '
In the same manner as described above, different resin solutions for ion-sensitive films are dropped on d, 6e and 6'e, and dried to form ion-sensitive electrodes on which different specific ion-sensitive films are formed.

Next, as in the case of FIG. 2, the joined body of the multi-ion sensor plate main body 5 and the bank body 9 is inserted into the recesses 10a and 10b of the lower cell 10 made of a transparent acrylic resin plate. Then, the upper cell 12 made of a transparent acrylic resin is joined with a double-sided adhesive tape, and the above joined body is mounted. The sample liquid and the reference liquid are respectively injected into the sample liquid input section 15 and the reference liquid input section 16 of the multi-sensor plate having such a structure by a syringe or the like, and the flow paths 13 and 14 are provided.
The respective liquids are circulated through the through holes 6a to 6a.
6e, 6'a to 6'e are supplied to the ion-sensitive electrodes, and both are brought into contact at the liquid junction 7 so that electrical conduction can be achieved. Then, by inserting the terminals of the measuring instrument (not shown) into the terminal insertion holes 18a and 18b and bringing them into contact with the external electrodes of the electrodes, five different ion concentrations in the sample liquid can be measured.

In this case, the plasticizer in the resin solution for the ion-sensitive membrane is a so-called poor solvent which does not have a high solubility in the polyvinyl chloride resin. The dispersion state of the ionophore and other additives with respect to the plasticizer can be improved, and the solution is dropped to form a coating film. Convection hardly occurs, and the above-mentioned "citrus skin" does not occur, the added ionophore and the added salt, and the dispersed state of the added potential stabilizing substance are also well maintained. Nature is also maintained,
A film having a more uniform composition can be obtained. As described above, the dispersion state of the potential stabilizing substance, the ionophore, and the like is also good. When a film having a uniform composition is formed, the state of penetration of the moisture of the sample liquid and the reference liquid is made uniform, and the dispersion of measured values can be reduced.
In addition, since the ion-sensitive film in which the plasticizer is used in a large amount with respect to the polyvinyl chloride resin has sufficient flexibility and increases the contact area with the underlying silver chloride layer, the ion-sensitive film is contained in the ion-sensitive film. Potential stabilizing substances and ionophores are efficiently controlled to stabilize the chemical equilibrium of silver halide and the like described above, thereby improving initial characteristics, and improving the silver halide layer and the ion-sensitive film. The potential at the interface with the substrate quickly stabilizes, the dispersion of the initial characteristics is small, and the dispersion of the measured values can be reduced. If the initial characteristics are quickly stabilized, the inspection can be performed quickly, and if the variation is small, the yield rate can be improved.

As a potential stabilizing substance, Cl^-Source of supply and
The general formula R_FourN⁺Cl^-(R represents an alkyl group,
The same applies hereinafter. An ammonium salt represented by the general formula R_FourP
⁺Cl^-At least one of the phosphonium salts represented by
And Cl^-Besides Br ^-, I^-But the same effect
These ammonium salts, phosphonium
And a compound corresponding to a salt of the compound. Also on
As the polyvinyl chloride resin described above, vinyl chloride resin,
Vinyl chloride and vinyl acetate, vinyl alcohol, carbox
At least the amount of sil group-containing monomer and other vinyl monomers
May also be used as a copolymer with one kind.
Phthalic acid plasticizers, aliphatic dibasic acid plasticizers,
Ethers of substituted or unsubstituted phenols with higher alcohols
And other plasticizers.

[0012]

Next, an embodiment of the present invention will be described with reference to the drawings. Example 1 A 4 g of DOA (dioctyl adipate) as a plasticizer was added to a 4 g of trioctyl methyl ammonium chloride.
Grade salt ^- was added 0.8mg chlorine (Cl sources), further AgCl (potential stabilizing substance) 10 mg of powder was added and stirred. A supernatant (250 mg) of the mixed solution was separated, and 72 mg of PVC (copolymer of vinyl chloride: vinyl alcohol: vinyl acetate = 90: 6: 4, manufactured by Denki Kagaku Kogyo KK) and valinomycin (ionophore for potassium ion detection) were collected. ) 14 mg, 1.24 mg of K-TCPB (potassium tetrakis (p-chlorophenyl) borate, manufactured by Dojin Chemical Co., Ltd., anion exclusion agent), 250 mg of THF (tetrahydrofuran) as a solvent was added, and the resin solution for the ion-sensitive membrane was added. I do. Table 1 shows the composition of the non-volatile matter excluding THF in the resin solution for an ion-sensitive membrane and the ratio (75% by weight) of DOA in the non-volatile matter. In Table 1, 250 mg of the plasticizer is a value containing a quaternary amine salt or AgCl, but since these are small, even if they are neglected in quantity, they can be approximated to the above 75% by weight (hereinafter, other The same applies to the case of the combination of The resin solution for the ion-sensitive membrane is applied by being dropped onto the silver chloride layers 4a and 4b through the through holes 6a and 6'a as described with reference to FIGS. A potassium ion-sensitive film was formed as the ion-sensitive film 2d. Twenty such multi-ion sensor plates having the structure shown in FIGS.
FIG. 3 shows the results obtained by measuring the potential by the above-described measurement method when an aqueous solution containing 4 mM KCl was used as the sample solution and a predetermined reference solution was used as the reference solution, and the standard deviation σ (mV) was obtained. The actual measured potassium ion concentration is
The measured value of the potential is determined by applying the relationship between the potential and the concentration determined in advance. The same applies hereinafter.

Examples 2 and 3 In Example 1, the amount of PVC used was 95 mg, 50 m
The multi-ion sensor plates of Examples 2 and 3 were prepared in the same manner as in Examples 1 and 3 having the compositions shown in Table 1 except that the amount was changed to g. The potential was measured in the same manner as in Example 1, and the standard deviation obtained from the measured value is shown in FIG.

Comparative Examples 1 to 3 In Example 1, the amount of PVC used was 350 mg, 23
Except that the amount was 5 mg and 155 mg, the composition was the same as shown in Table 1, and the amount of the plasticizer was 40% by weight, 50% by weight, and 6% by weight, respectively.
Comparative Example 1 having 0% by weight potassium ion sensitive membrane,
A few multi-ion sensor plates were prepared, the potential was measured in the same manner as in Example 1, and the standard deviation obtained from the measured values is shown in FIG.

[0015]

[Table 1]

[0016] Example 4 is a plasticizer NPOE (2-nitrophenyl octyl ether) 2 g quaternary amine salts such as trioctyl methyl ammonium chloride ^- chlorine (Cl sources) 0.
86 mg was added, and 10 mg of powdered AgCl (potential stabilizing substance) was further added, followed by stirring. A supernatant (250 mg) of the mixed solution was separated and added to PVC (vinyl chloride: vinyl alcohol: vinyl acetate = 90: manufactured by Denki Kagaku Kogyo Co., Ltd.).
6: 4 copolymer) 72 mg, bis (12-crown-)
4) (Ionophor for sodium detection) 12.4 mg,
12.4 mg of Na-TPB (sodium tetrakisphenylborate, manufactured by Dojin Kagaku Co., Ltd.) was added, and THF (tetrahydrofuran) 25 as a solvent was further added.
Add 0 mg to make a resin solution for ion-sensitive membrane. Composition of non-volatile matter except THF in the resin solution for ion-sensitive membrane and proportion of NPOE in the non-volatile matter (75% by weight)
Are shown in Table 2. In Table 2, 250 mg of the plasticizer and
The calculation of the weight% of the plasticizer is the same as in Table 1. This ion-sensitive film resin solution is applied by dripping onto the silver chloride layers 4a and 4b through the through holes 6a and 6'a in the same manner as in Example 1, and is naturally dried to form the ion-sensitive film 2d. A sodium ion sensitive membrane was formed. Twenty such multi-ion sensor plates are prepared, and each of them is used as a sample liquid by using each of them at the beginning of manufacture.
FIG. 4 shows the results obtained by measuring the potential by the above-described measurement method when an aqueous solution containing 0 mM NaCl and a predetermined reference solution were used as the reference solution, and determining the standard deviation.

Examples 5 and 6 In Example 4, the amount of PVC used was 95 mg, 50 m
The multi-ion sensor plates of Examples 5 and 6 were prepared in the same manner as in Examples 2 and 3 having the compositions shown in Table 2 except that g was used, and having potassium ion-sensitive membranes of 70% by weight and 80% by weight, respectively. The potential was measured in the same manner as in the above, and the standard deviation obtained from the measured value is shown in FIG.

Comparative Examples 4 to 6 In Example 4, the amount of PVC used was 350 mg, 23
Except that the amounts were 5 mg and 155 mg, the composition was the same as shown in Table 2, and the amount of the plasticizer was 40% by weight, 50% by weight, and 6% by weight, respectively.
Comparative Example 4 having 0% by weight potassium ion sensitive membrane,
The multi-ion sensor plates of Nos. 5 and 6 were prepared, the potential was measured in the same manner as in Example 1, and the standard deviation obtained from the measured values is shown in FIG.

[0019]

[Table 2]

In FIGS. 3 and 4, dotted lines are reference lines for improvement, and solid lines are Comparative Examples 3, 6, and 6 in which the plasticizer weight% is 60% by weight.
The standard deviation .sigma. Value obtained in the example when the content is 5% by weight or more is obtained by connecting the standard deviation .sigma. Value obtained in the comparative example when the plasticizer weight% is less than 60% by weight. Is tied. If the standard deviation σ value is smaller than the neighborhood above the improvement reference line, it indicates that the improvement has been made. FIG.
From FIG. 4, it can be said that the plasticizer weight% of 65 to 80% by weight is the improvement range, and the range of the plasticizer weight% of 65 to 78% by weight where the solid line crosses the improvement reference line in FIG.
Of course, the case of FIG. 4 is more preferable, and the range of 70% to 75% by weight of the plasticizer is more preferable in both figures. For these reasons, in the above (1), (2) and other above-mentioned inventions, these limitations may be added.
Further, a method of stabilizing the electrode potential (the potential of the electrode having the silver halide layer) using the ion sensor and the ion sensor plate of the present invention may be adopted.

[0021]

According to the present invention, since the ion-sensitive film contains 65 to 80% by weight of a plasticizer, the ion-sensitive film has an ion-sensitive film having a uniform composition and a large contact area with the substrate.
Potential stabilizing substances contained in the ion-sensitive membrane and the potential stabilizing effect of the ionophore work efficiently, the initial characteristics at the beginning of production are good, the dispersion is small, and therefore not only the measurement accuracy and reliability are high, but also the production The present invention can provide an ion sensor and an ion sensor plate having good properties, and particularly, a single-use disposable ion sensor and an ion sensor which are less likely to be affected even if a plasticizer or the like is dissolved in a sample liquid or a reference liquid. Useful as a plate.

[Brief description of the drawings]

FIG. 1 is a partial sectional view of a multi-ion sensor plate according to one embodiment of the present invention.

FIG. 2 is an exploded perspective view of a multi-ion sensor plate.

FIG. 3 is a graph showing the relationship between the standard deviation of the potential corresponding to the potassium ion concentration and the plasticizer weight% using the multi-ion sensor plate of one embodiment of the present invention.

FIG. 4 is a graph showing a relationship between a standard deviation of a potential corresponding to a sodium ion concentration and a plasticizer weight% using a multi-ion sensor plate according to another embodiment of the present invention.

[Explanation of symbols]

 2a Sample liquid measurement electrode 2b Reference electrode 2d Ion sensitive membrane 5 Multi-ion sensor plate body 7 Liquid junction 13, 14 Flow passage

 ──────────────────────────────────────────────────の Continuing on the front page (72) Inventor Akihiko Mochizuki Taiyo Denki Co., Ltd. 6-16-20 Ueno, Taito-ku, Tokyo

Claims (2)

[Claims] 1. An ion sensor plate main body having at least one pair of a sample liquid measurement electrode having a coating film of an ion-sensitive membrane of a specific ion and a reference electrode is provided, and a measurement circuit is connected to the ion sensor plate main body. In the ion sensor, the specific ion concentration of the sample solution can be measured by using the ion-sensitive membrane, the ion-sensitive membrane contains at least a matrix, a plasticizer for plasticizing the matrix, and an ion-sensitive substance, and the plastic is contained in the ion-sensitive membrane. The agent is 65-80
An ion sensor containing a weight percent. 2. An ion sensor plate body comprising a pair of a sample liquid measurement electrode having a coating film of an ion-sensitive film and a reference electrode and at least one set provided on a substrate, and supplying a sample liquid to the sample liquid measurement electrode. Forming a closed flow path for supplying a reference liquid to the reference electrode and a closed flow path for supplying a reference liquid to the reference electrode, and a sample liquid input unit communicating with each flow path;
An upper cell having a reference liquid inlet, and at least a liquid junction provided in the ion sensor plate main body and supplied to the respective flow passages, and a liquid junction for liquid junction of the reference liquid, wherein the ion-sensitive membrane is An ion sensor plate comprising at least a matrix, a plasticizer for plasticizing the matrix, and an ion-sensitive substance, and 65 to 80% by weight of the plasticizer in the ion-sensitive membrane.