JPH01197647A - Ion sensitive film - Google Patents

Abstract

PURPOSE:To improve the sensitivity of an ion selective electrode to chlorine ions by forming the sensitive film of a polymer and a straight chain org. compd. ion-bonded thereto as main constituting components. CONSTITUTION:The sensitive film has an ion exchange group or the polymer having the ion exchange group and one straight chain hydrophobic group contg. two or three long chain hydrophobic groups or rigid parts in the chain. This ion sensitive film consists of said polymer and the org. compd. having the ion exchange group of the charge opposite to the charge of the polymer as well as the straight chain alcohol of >=10C as the main constituting components. Further, this ion sensitive film consists of the film-like material in which the anion exchange group exists at the ratio in excess of the ratio of the cation exchange group and in which the straight chain alcohol exists at a ratio of 10-150wt.% of the total weight of the polymer and the org. compd. The sensitivity of the ion selective electrode to the chlorine ions is thus improved.

Description

[Detailed description of the invention] [Field of professional application] The present invention is directed to ion selectivity for measuring the activity of ions in a solution! It relates to an ion-sensitive membrane used for electrodes. Specifically, it is an ion-sensitive membrane that can significantly improve the sensitivity of an ion-selective electrode to chlorine ions.

[Prior art and problems to be solved by the invention] In recent years, ion-selective electrodes have been applied for medical purposes to detect ions dissolved in biological fluids such as blood and urine, such as sodium ions, potassium ions, and chlorine. Many attempts are being made to quantify ions, etc.

This is a method for diagnosing various conditions such as hypertension, kidney disease, and neurological disorders by measuring the concentration of specific ions in the living body, which is closely related to the metabolic reactions of the living body. It is.

In general, ion selectivity is 1! As shown in Figure 1, the part of the pole that is immersed in the sample solution (generally the lower part) is the ion-sensitive membrane
The activity of ions in a solution can be measured using such an ion-selective electrode, which is basically constructed by providing an internal electrolyte 23 and an internal reference electrode 24 in a cylindrical container 21 consisting of 2. FIG. 2 shows a typical structure of an ion measuring device for this purpose. That is, the ion-selective electrode 11 is immersed together with the salt bridge 12 in the sample solution 13, and the other end of the salt bridge is immersed together with the reference electrode 14 in the saturated potassium chloride solution 16. Also, a liquid junction may be provided instead of a salt bridge. The potential difference between both electrodes is read by an electrometer 15, and the ionic activity of a specific ion species in the sample solution can be determined from the potential difference. The performance of the ion-selective electrode used in such an ion measuring device is determined by the ion-sensitive membrane used therein.

Conventionally, various membranes have been proposed as ion-sensitive membranes for selectively detecting anions, particularly chloride ions. for example.

a) Solid formed film mainly composed of silver chloride b) A film formed by mixing a polymer such as polyvinyl chloride, a sensitive substance such as a quaternary ammonium salt, and a plasticizer c) Trimethylammonio group, pyridinio group, etc. Membranes such as ion exchange membranes made of polymers having ion exchange groups are known. However, in an ion-selective electrode using an ion-sensitive membrane of the type (,), if bromide ions, cyanide ions, thiocyanate ions, etc. are present in the solution, the membrane surface will undergo chemical changes due to the influence of these ions. Therefore, it is difficult to stabilize the potential, and in extreme cases, potential measurement may become impossible. Furthermore, in the measurement of various biological fluids, etc., they are easily affected by proteins, etc., and also have the drawback that the potential is not stable. An ion-selective electrode using an ion-sensitive membrane of the type (b) has the drawback that the response is slow and the sensitive substance in the membrane gradually dissolves into the solution, resulting in a short lifetime.

Ion-selective electrodes using type (C) ion-sensitive membranes have long lifespans because the ionic groups are covalently bonded to the polymers that make up the membranes, and they can be used to remove proteins and other substances contained in biological fluids. It has the advantage of not being easily influenced. However, when the above-mentioned anion exchange membrane is used as an ion-sensitive membrane, the influence of interfering ions other than chlorine ions, such as phosphate ions and bicarbonate ions, is large;
It also has the disadvantage that the potential obtained is unstable.

Therefore, it has been desired to develop an ion-sensitive membrane that provides an ion-selective electrode that can stably measure chloride ions in biological fluids with high sensitivity.

[A precautionary measure to resolve the problem]

The present inventors have conducted extensive research to develop an ion-sensitive membrane that can solve these problems. As a result, by using a film-like material whose main components are a specific polymer, a specific organic compound, and a long-chain linear alcohol as an ion-sensitive membrane, it has a long life and a chlorine-containing property. The present inventors have discovered that an ion-selective electrode capable of measuring ions with high sensitivity and stability can be obtained, and have completed the present invention.

That is, the present invention provides (1) a polymer having an anion exchange group or a cation exchange group and (ii) a polymer containing two or three long chain hydrophobic groups or a rigid portion in the chain. An organic compound having one linear hydrophobic group and an ion-exchangeable group having an opposite charge to that of the above-mentioned polymer, and (iii) a linear alcohol having 10 or more carbon atoms as the main constituents, and the negative The ion-exchangeable group is present in an excess amount relative to the cation-exchangeable group, and the linear alcohol is present in an amount of 10 to 10% relative to the total amount of the polymer (1) and the organic compound (ii). It is an ion-sensitive membrane consisting of a film-like substance present at a ratio of 150 to 150.

It is a polymer having one anion exchange group or a cation exchange group, which is a main component of the ion-sensitive membrane of the present invention. As the above-mentioned anion exchange group, a known basic group can be used, and as the cation exchange group, a known acidic group can be used without particular restriction. Here, acidic or basic means Brønsted acid or Brønsted base, and acidic groups generally include sulfonic groups, carboxylic groups, phosphoric acid groups, phenolic hydroxyl groups, and their salts, and basic groups include In general, amino groups, substituted amino groups, quaternary ammonio groups, and salts thereof are preferably used.

The polymer having an ion-exchangeable group is not particularly limited and any known polymer may be used, but in consideration of the strength and stability of the ion-sensitive membrane, it is generally desirable to use a polymer having a molecular weight of 5.000 or more. In addition, the amount of ion-exchangeable groups contained in the polymer varies depending on the type thereof, the linear organic compound described below, etc., and cannot be absolutely limited, but is generally 0.1
It is desirable that the meq is 79 or more, preferably 1.0 meq/9 or more.

As the monomer used to obtain the polymer having an ion-exchangeable group, the monomers having an ion-exchangeable group described above can be used without any restriction.

Examples of monomers that are generally suitably used are as follows. That is, monomers having a carboxyl group such as acrylic acid, methacrylic acid, maleic acid, fumaric acid, itaconic acid, crotonic acid, cinnamic acid, glutamic acid, aspartic acid; styrene sulfonic acid, vinyl sulfonic acid, alkenesulfonic acid, t- Monomers with sulfonic acid groups such as butylacrylamide sulfonic acid; monomers with phosphoric acid groups such as vinylphosphonic acid, acryloyloxyalkylphosphonic acid, methacryloyloxyalkylphosphonic acid; phenolic monomers such as vinylphenol; lysine, ethyleneimine, Cationic monomers such as vinylpyridine and dimethylaminopropylmethacrylamide, or substituted derivatives obtained by substituting these monomers with substituents, are preferably used.

Further, the vinyl monomer that can be copolymerized with the monomer having an ion exchange group is not particularly limited, and known ones can be used. Typical examples that are generally preferably used include, for example, olefin compounds such as ethylene, propylene, and butene; halogen derivatives of olefin compounds such as vinyl chloride and hexafluoropropylene; and diolefins such as butadiene and intadiene. Compounds and their derivatives; aromatic vinyl compounds such as styrene and vinylnaphthalene; vinyl ester compounds such as vinyl acetate; methyl acrylate, ethyl methacrylate, 2-
Examples include acrylic acid and methacrylic acid derivatives such as hydroxyethyl methacrylate, acrylamide, and methacrylamide; unsaturated nitrile compounds such as acrylonitrile; and vinyl ether compounds such as methyl vinyl ether.

The general formula of a polymer having an ion-exchangeable group that is generally preferably used in the present invention is as follows.

■ A polymer having a carboxyl group. However, R is a hydrogen atom, an alkyl group, or a carboxymethyl group, group or aryl group), M is a hydrogen atom, a metal atom, or a lower ammonium. C is an integer of O to 2, and a, l) are O or 1. Here, when a is 0 ke b=l, c=o,
R is a hydrogen atom, and when a is 1, b=o, c=0~
2. R is a hydrogen atom, an alkyl group or a carboxymethyl group.

■ Polymer having sulfonic acid group R1 -C-CH2-CI] 7--, +'d SO, M However, R〃 is a hydrogen atom or an alkyl group, and Y (however, e is a positive integer) , M is a hydrogen atom, a metal atom or a lower ammonium, and d is 0 or 1.

■ Polymer having a quaternary ammonio group R/I/ -C-CH2- ■ H3 However, R'' is a hydrogen atom or an alkyl group, and 2 is -C
O+CH2+g (where g is a positive integer), and X is a halogen atom or an atomic group forming a stable anion.

Above - maximum m, in (ii) and ("III), R, R
The alkyl group represented by ', R' and R' is not limited to the number of carbon atoms and any group can be used, but
Generally, those having 1 to 4 carbon atoms are preferred. In addition, in the above-maximum [ll] and (III), e and g may be positive integers;
Preferably, it is an integer of 4.

As a method for producing the above-described polymer having an ion-exchangeable group, a method of homopolymerizing the above-described monomers having an ion-exchangeable group or copolymerizing two or more monomers is generally adopted. Furthermore, a polymer having an ion-exchangeable group can also be obtained by copolymerizing the above-described monomer having an ion-exchangeable group with a copolymerizable vinyl monomer. Furthermore, a method of introducing an ion-exchange group into a polymer by chemically reacting it with a polymer capable of introducing an ion-exchange group is often suitably employed. For example, by hydrolyzing a single or copolymer of carboxylic acid anhydrides such as maleic anhydride and itaconic anhydride, a method of obtaining a polymer having a carboxyl group, or by subjecting polyvinyl alcohol to a sulfuric acid esterification reaction. Examples include methods for obtaining polymers having sulfonic acid groups.

As the polymer having an ion-exchangeable group in the present invention, in addition to the synthetic polymers synthesized as described above, natural polymers having an ion-exchangeable group can also be used. Examples of natural polymers having ion-exchangeable groups that are generally used in the present invention include alginic acid, sodium alginate, carboxymethyl cellulose, heharin, chondroitin sulfate, and derivatives thereof.

In the present invention, the polymer having an anion exchange group or a cation exchange group can be used as long as it satisfies the above conditions.
There is no problem in using a mixture of more than one species.

Another main component of the ion-sensitive membrane of the present invention has two or three straight chain hydrophobic groups, or one straight chain hydrophobic group containing a rigid part in the chain, and the above-mentioned It is an organic compound (hereinafter abbreviated as a linear organic compound) having an ion exchange group with an opposite charge to the ion exchange group of the polymer.

In the above-mentioned linear organic compound, the linear hydrophobic group is preferably a linear alkyl group having 10 to 30 carbon atoms or a halodane-substituted group thereof, from the viewpoint of the water resistance of the resulting ion-sensitive membrane and the ease of obtaining raw materials.

Note that the linear hydrophobic group referred to in the present invention is not limited to a completely linear group, but also includes a branched group having up to 2 carbon atoms.

One embodiment of the linear organic compound of the present invention has two or three linear hydrophobic groups. If there is only one straight-chain hydrophobic group, the water resistance of the ion-sensitive membrane will not be sufficient, and if there are four or more, it will be difficult to manufacture.

Further, one embodiment of the linear organic compound of the present invention has one linear hydrophobic group containing a rigid portion in the chain.

In the present invention, the rigid moiety refers to the groups shown in the following (1), (2) and (2).

■ Divalent groups consisting of at least two aromatic rings connected directly or via carbon-carbon multiple bonds, carbon-nitrogen multiple bonds, nitrogen-nitrogen multiple bonds, ester bonds, amide bonds, etc. Specific examples of such groups include divalent groups such as .

■ A divalent group in which two aromatic rings have multiple bonds or a single bond between multiple atoms, and the rotation of the bond is energetically constrained. Specific examples of such groups include: For example, CH.

Examples include divalent groups such as.

■ A divalent group in which aromatic rings form a condensed ring, and when this condensed ring is stacked between multiple molecules, the rotation of the condensed rings is sterically constrained to each other. Examples include divalent groups such as the following.

The number of carbon atoms in the straight chain hydrophobic group of a straight chain organic compound having one straight chain hydrophobic group containing a rigid part in the chain is as follows: It means the number of carbon atoms in the removed part. The bonding portion between the rigid portion and the linear hydrophobic group is generally a carbon-carbon single bond, an ester bond,
Ether bonds are preferred.

Limiting the number of straight-chain hydrophobic groups containing a rigid part to one is because if there are more than two, it will be extremely difficult to mix with the polymer and the subsequent molding process, and it will also cause problems with the formation of the ion-sensitive membrane. This is because points in stability often occur, which is undesirable.

In the present invention, the linear organic compound has an ion exchange group having an opposite charge to the ion exchange group of the polymer having an ion exchange group, as well as the above linear hydrophobic group. This is necessary to improve the stability of the formed film in water. As such an ion exchange group, the same ion as the ion exchange group in the polymer is applied.

In particular, when the ion exchange group of the polymer is a cation exchange group, the ion exchange group of the linear organic compound is a quaternary ammonium group or a salt thereof. It is preferred because of its excellent properties. Further, the number of ion-exchangeable groups contained in the linear organic compound of the present invention is preferably one from the viewpoint of moldability of the resulting ion-sensitive membrane.

The linear organic compound of the present invention is not particularly limited as long as it satisfies the above requirements, and any known compound can be used. Representative ones that are generally suitably used are specifically shown below.

■ However, R and R are the same or different straight chain alkyl groups having 12 to 30 carbon atoms or halodane substituted products thereof, R5, R4
are the same or different alkyl groups having 1 to 4 carbon atoms, or substituted products thereof with a halogen atom and/or a hydroxyl group.

(2) However, R and R are the same as above, A is or 1, and k is a positive integer. ), h, and i are positive integers. R, R.

R5 is the same as described for R3 and R4 above.

■ However, R, R, R, R, R and A are the same as above.
t is 1 or 2, m is 0 or 1.

However, R1, R2, R3, R4 and R5 are the same as above, and n is a positive integer.

■ However, R3, R' and R5 are the same as above, R6 is an alkyl group having 4 to 30 carbon atoms, an alkyloxy group, or an alkyloxycarbunyl group, or a halodane substituted product thereof, and D is It is 1. ) E is (-CH2+, or -o+ca2+, Te).

(However, q+r is a positive integer.) ■! I However, R' t R2 is the same or different carbon number 6-30
is a straight-chain alkyl group or a halodane-substituted derivative thereof.

Above - maximum 1: B), CDI and [E], k, n
, q and r may be any positive integer, but generally they are preferably 1-16 from the viewpoint of easy availability of raw materials. In addition, in the above-mentioned maximum [B], h and l can be positive integers without any restriction, but in general, 1.
It is preferable that it is 4.

Furthermore, the above-maximum (A), (B), [:C]
, CD).

[E] and [F), R', R2, R3# R'
# Examples of the halogen atom in the halogen-substituted alkyl group represented by R5 and R6 include fluorine, chlorine, bromine, and iodine atoms.

The linear organic compound constituting the ion-sensitive membrane of the present invention may be a mixture of two or more as long as it has an ion-exchange group with an opposite charge to the ion-exchange group of the polymer having an ion-exchange group. There is no problem.

It is also possible to construct an ion-sensitive membrane using only the above-mentioned polymers and linear organic compounds having ion-exchangeable groups, which have high responsiveness to chloride ions to interfering ions such as carbonate ions. .

In the present invention, by adding a linear alcohol having 10 or more carbon atoms (hereinafter simply referred to as linear alcohol) to the above components, the selective response to chlorine ions is further improved, and the durability is improved. This made it possible to obtain an excellent ion-sensitive membrane. That is, when the number of carbon atoms in the linear alcohol is less than 10, the resulting ion-sensitive membrane has poor water resistance, and the effect of improving selective response by adding alcohol disappears in a very short period of time. Moreover, the need for linearity is to improve compatibility with other constituent components, to fully exhibit the effect of addition of alcohol, and to not reduce the strength of the ion-sensitive membrane.

The linear alcohol of the present invention is not particularly limited as long as it satisfies the above conditions, and any known one can be used. in general,
Considering the water resistance of the resulting ion-sensitive membrane and the ease of obtaining raw materials, linear alcohols having 16 to 18 carbon atoms are preferably used.

In the ion-sensitive membrane of the present invention, the linear alcohol is contained in a proportion of 10 to 150% by weight based on the total amount of the polymer and the linear organic compound. If the linear alcohol content is 10% by weight or less, the effect of improving the ion selectivity of the resulting ion-sensitive membrane may not be sufficient.

Furthermore, if the content is 150% by weight or more, the resulting ion-sensitive membrane may have insufficient water resistance and strength.

The ion-sensitive membrane of the present invention has the above-mentioned polymer having an ion-exchangeable group and the above-mentioned linear organic compound as main components, and the ion-sensitive membrane exhibits high responsiveness (selectivity) to chloride ions. In order to achieve this, it is necessary that the anion exchange groups exist in excess of the cation exchange groups. The ratio of anion exchange groups to cation exchange groups in the ion-sensitive membrane (
anion exchange group/cation exchange group) in an equivalent ratio of more than 1; 2. The range below OO, preferably 1.05=
A range of 1.50 is preferably adopted. Incidentally, the amount of ion-exchangeable groups can be determined from elemental analysis values. If the ratio of anion exchange groups to cation exchange groups in the ion-sensitive membrane is smaller than the above range, high responsiveness to chloride ions cannot be obtained, and if the ratio is larger than the above range. In some cases, the ion-sensitive membrane is not easily dissolved in water, making it impractical.

In the present invention, the ratio of the anion exchange group to the cation exchange group in the ion-sensitive membrane can generally be adjusted by the mixing ratio of the polymer having the ion exchange group and the linear M machine compound. . Moreover, the ion-sensitive membrane of the present invention is
In addition to the polymer having an ion exchange group and the linear organic compound, a hydrophobic compound having an anion exchange group may be used as long as it does not adversely affect the resulting ion-sensitive membrane. The above-mentioned compound needs to be hydrophobic in order to improve the stability of the obtained ion-sensitive membrane in water. Typical hydrophobic compounds having an anion exchange group that are preferably used are specifically shown below.

R' (However, 13, R4, R5 are the same or different alkyl groups having 1 to 4 carbon atoms, or substituted products thereof with halogen atoms and/or hydroxyl groups, n is an integer of 10 to 20, is a halodane atom or an atomic group forming a stable anion.) (However, R6 is an alkyl group having 6 to 20 carbon atoms or a phenyl group, and X is the same as X above.) When using a hydrophobic compound having an ion-exchange group, the ratio of the anion of the hydrophobic compound to the anion-exchange group of the main component should be determined, taking into consideration the stability of the resulting ion-sensitive membrane in water. Equivalence ratio of exchangeable groups (hydrophobic compound having anion exchange group/anion exchange group as main component)
is preferably in the range of 0.05 to 0.5.

Note that the amount of anion exchange groups in the above-mentioned hydrophobic compound is also subject to the ratio to the cation exchange groups in the ion-sensitive membrane of the present invention.

The method for producing the ion-sensitive membrane of the present invention is not particularly limited, and any method may be used. in general.

As a preferred production method, after producing a composition (hereinafter abbreviated as ion exchange composition) whose main components are the polymer having the ion exchange group and the long chain organic compound,
An example of this method is to add and mix a linear alcohol to the mixture and form it into a film.

By using the above method, the effect of alcohol fA 71111 on the ion-sensitive membrane is further improved.

The method for producing the above-mentioned ion-exchangeable composition is not particularly limited, but a suitable production method includes, for example, a polymer having an ion-exchangeable group and a linear organic compound having an oppositely charged ion-exchangeable group. There is a method of dissolving or suspending them in the same or different solvents, mixing them, and collecting the resulting precipitate. When the solvents used here are the same, water or a mixed solvent with an organic solvent that is compatible with water, such as a water/methanol mixed solvent, a water/ethanol mixed solvent, a water/acetone mixed solvent, etc. are generally preferred. It is. When different solvents are used for the polymer and the linear organic compound, water is generally preferred as the solvent for the polymer. As a solvent for linear organic compounds, water, methanol, ethanol, 2-propanol, acetone, ethyl acetate, ethyl ether, benzene, chloroform, methylene chloride, tetrahydrofuran, dimethylformamide,
Trimethylacetamide, acetonitrile and the like are preferably used. In the case of solvents that are not miscible with each other, it is generally effective to form an emulsion by stirring vigorously during mixing to obtain a precipitate.

Generally, the precipitate obtained by the above method is poorly soluble in water. This is considered to be because the polymer having an ion exchange group and the linear organic compound having an opposite charge form an ion pair. This is also supported by the fact that in the precipitate, a considerable amount of the counterions of the constituent components before mixing disappeared.

Furthermore, if necessary, a polymer having an ion exchange group, a linear organic compound having an ion exchange group, or a hydrophobic compound having an anion exchange group may be added to the precipitate obtained by the above method. An may also be added and mixed so that the anion exchange group is in excess in equivalent ratio to the cation exchange group. Although the above mixing method is not particularly limited, a method of dissolving each of these components in a soluble solvent and then evaporating the solvent is preferably employed. The soluble solvent used here varies depending on the solubility of each component, but it is generally preferable to use dimethylformamide, dichloromethane, chloroform, tetrahydrofuran, dichloroethane, and chlorobenzene.

The ion exchange composition thus produced and used in the present invention is generally a colorless, white or pale yellow solid. Although it is sparingly soluble in water, organic solvents such as dimethylformamide, chloroform, dichloromethane,
It dissolves in dichloroethane, tetrahydrofuran, chlorobenzene, etc. at room temperature to 100°C.

In the ion-exchangeable group acid obtained by the above production method,
The method of adding and mixing the linear alcohol and forming it into a film-like material is not particularly limited, and any method may be used. Examples of generally preferred methods are as follows.

(2) A method of obtaining a film-like material by dissolving the ion-converting composition of the present invention and a linear alcohol in a soluble solvent, casting the solution onto a suitable substrate, and then removing the solvent. The solvent used here is not particularly limited as long as it dissolves the ion exchange composition of the present invention and the linear alcohol, but the soluble solvents described in the above-mentioned method for producing the ion exchange composition are preferably used. It will be done. To remove the above-mentioned solvent, air drying, heat drying, reduced pressure drying, etc. are generally used without particular limitation.

(2) A method of dissolving an ion-exchange composition and a linear alcohol in a soluble solvent, removing the solvent, and forming a film by heating and stretching.

The soluble solvent used here varies depending on the solubility of each component, but generally dimethylformamide, dichloromethane, chloroform, tetrahydrofuran, dichloroethane, chlorobenzene, 1,1,2.2
-Tetrachloroethane is preferably used. To remove the above-mentioned solvent, air drying, heat drying, reduced pressure drying, etc. are generally used without particular limitation. The temperature during the above heating molding is
A value near the softening point of the ion exchange composition is adopted, and although it varies depending on the type of ion exchange composition, generally 50~
A range of 200°C is selected.

The thickness of the ion-sensitive membrane of the present invention is not particularly limited, but it is generally in the range of 0.1μ to 5μ, preferably 5 to 1000μ to provide the ion-sensitive membrane with membrane strength sufficient for practical use. It's good to be able to do it.

The ion-sensitive membrane of the present invention generally often exhibits liquid crystallinity as its basic property. The temperature range in which liquid crystallinity is exhibited is usually within the range of 0 to 200°C. Liquid crystallinity is generally confirmed by measurement using a differential scanning calorimetry needle. If it is a liquid crystal, the amount of heat associated with the transition from solid to liquid crystal is observed at a certain temperature, and that temperature is called the solid-liquid crystal transition temperature. Therefore, the ion-sensitive membrane of the present invention is desirably used at a temperature below the solid-liquid crystal transition temperature, more preferably at least 10° C. lower than the solid-liquid crystal transition temperature.

When used at a temperature higher than the solid-liquid crystal transition temperature, the selectivity for various anions, especially divalent anions, may decrease and the electrode life may also be shortened.

In order to improve the selectivity of the ion-sensitive membrane of the present invention to chlorine ions, it is preferable to immerse the ion-sensitive membrane used in water at a temperature equal to or higher than its solid-liquid crystal transition temperature for 1 minute or more. This operation improves the selectivity of chloride ions to hydrogen carbonate ions in the ion-sensitive membrane, and by using this as the sensitive membrane of an ion-selective electrode, chloride ions can be measured with high sensitivity. The applied potential is also often stable.

In the ion-sensitive membrane of the present invention, the repeated use durability of the ion-sensitive membrane can be significantly improved by the presence of a fibrous material in the ion-sensitive membrane. That is, the ion-sensitive membrane of the present invention does not elute constituent substances in the liquid to be measured and has a long life, but ion selectivity decreases when repeatedly immersed in the liquid and dried in air. It may decrease. The present inventors have discovered that by allowing fibrous materials to exist in the ion-sensitive membrane, the ion selectivity can be reduced without reducing the ion selectivity.
It has been discovered that such a phenomenon can be prevented.

In addition, by mixing fibrous materials into the ion-sensitive membrane, it is possible to improve the mechanical strength of the ion-sensitive membrane, and it is also possible to improve the operability when using this as an ion-selective electrode. Can be done.

The material of the fibrous material is not particularly limited as long as it can be molded into a fibrous shape, and known materials can be used.

Examples of materials that are generally preferred are listed below. That is, glasses such as borosilicate glass and silica glass, polyvinyl chloride, sodium polyacrylate,
Synthetic polymers such as polyethylene, polypropylene, polyno-92 phenylene terephthalamide, 6,6-nylon,
Natural polymers such as cotton, silk, and cellulose are preferably employed. The diameter of the fibrous material is 0.1 μrn to 10 μrn.
A range greater than 0 is preferably adopted. When the diameter is as small as 0.1μ, the improvement in film strength is not remarkable;
If it is larger than μm, the responsiveness of the ion-sensitive membrane tends to deteriorate. The length of the fibrous material is 1 μm to 1 μm.
A range of 0 is preferably adopted. When the length is as small as 1 μm, the membrane strength is not significantly improved, and when the length is longer than 1 μm, the responsiveness of the ion-sensitive membrane tends to deteriorate.

The method of mixing the fibrous material into the ion-sensitive membrane of the present invention is not particularly limited, and any method may be used. To give an example of a generally preferred method, after dissolving the ion exchange composition of the present invention and a linear alcohol in a soluble solvent, fibrous materials are dispersed in the solution and cast on a suitable substrate. After that, the ion-sensitive membrane can be obtained by a method such as removing the solvent. The solvent used here is not particularly limited as long as it dissolves the ion exchange composition of the present invention and the linear alcohol, but the soluble solvents described in the above-mentioned method for producing the ion exchange composition are preferably used. used. To remove the above-mentioned solvent, air drying, heat drying, reduced pressure drying, etc. are generally used without particular limitation. Further, as a method for dispersing the fibrous material in the solution, stirring, shaking, ultrasonic irradiation, etc. can be used without particular limitation.

When a fibrous material is mixed into the ion-sensitive membrane of the present invention,
The mixing ratio of the fibrous material and the ion exchange composition (fibrous material/ion exchange composition, weight ratio) is 0.01 to 0.3.
A range of is suitable. The mixing ratio of the above fibrous material is 0.01
When it is smaller, the improvement in membrane strength is not significant, and when it is larger than 0.3 kg, the responsiveness of the ion-sensitive membrane tends to deteriorate.

〔effect〕

Since the ion-sensitive membrane of the present invention is mainly composed of a polymer and a linear organic compound ionically bonded to the polymer, there is almost no elution of constituent substances, and the membrane has a long life. In addition, the ion-sensitive membrane of the present invention has extremely high responsiveness of chloride ions to various interfering ions such as bicarbonate ions present in biological fluids such as blood and urine. By using it as an ion-sensitive membrane, it is possible to very accurately quantify chlorine ions in biological fluids such as blood, urine, etc., and its industrial value is extremely large.

Further, by having a fibrous material present in the ion-sensitive membrane, the durability for repeated use can be significantly improved, the strength is also improved, and handling becomes easier.

As the ion-selective electrode to which the ion-sensitive membrane of the present invention can be applied, any one having a known structure can be employed without particular limitation.

Generally, an internal standard electrode,
A structure containing an internal electrolyte is preferable. For example, a typical embodiment is the structure shown in Figure 11g1 above. That is, the ·r on-selective electrode in the gi diagram is the electrode cylinder 2
The container is made up of an ion-sensitive J [22 attached to the bottom of the container, the inside of which is filled with a folding liquid 23, and an internal reference electrode 24 is provided. Note that 25 is a QIJ ring for liquid sealing.

In the electrode, materials other than the ion-sensitive membrane are not particularly limited, and conventional materials may be used without limitation. For example, the material of the electrode cylinder may be polyvinyl chloride, polymethyl methacrylate, etc. The liquid may be a sodium chloride aqueous solution, a potassium chloride aqueous solution, etc. The internal base or single electrode may be a conductive material such as platinum, gold, or graphite, or a sparingly soluble metal chloride such as silver-silver chloride, mercury-mercury chloride, etc. is used.

The ion-selective electrode to which the ion-sensitive membrane of the present invention can be applied is not limited to the structure shown in FIG. 1, but may have any structure as long as it has the ion-sensitive membrane. Other preferred examples of ion-selective electrodes include ion-selective electrodes constructed by pasting the ion-sensitive membrane on a conductor such as gold or platinum graphite, or an ion conductor such as silver chloride or mercury chloride. Electrodes, etc.

Moreover, the ion-selective electrode using the ion-sensitive membrane of the present invention can be used in a known method.

For example, the usage mode as shown in FIG. 1 described above is basic. That is, the ion-selective electrode 11 is immersed together with the salt bridge 12 in the sample solution 13, and the other 14 of the salt bridges are immersed together with the reference electrode 14 in the saturated potassium chloride solution 16.

As the above-mentioned reference electrode, generally known ones are employed, and examples of those preferably used include a calomel electrode,
These include silver-silver chloride electrodes, platinum plates, carbon graphite, etc.

〔Example〕

Examples are given below to further specifically explain the present invention, but the present invention is not limited to these Examples.

In addition, the measurement of film strength in the examples of the present invention was performed by the method shown below. That is, outer diameter 8 m, inner diameter 4 x length 20 m
Two pieces of polyvinyl chloride Zeif were adhered to both sides of an 9-diameter ion-sensitive membrane using a cyanoacrylate adhesive. After leaving this at room temperature for 1 hour, attach the metal attachment and crosshead speed 10 m/s.
The tensile film strength was measured using a min tensile tester.

In addition, the repeated use durability of the ion-sensitive membranes in the Examples of the present invention was measured by the method shown below.

That is, an ion-sensitive membrane with a diameter of 8 mm was bonded to one end of a polyvinyl chloride gib with an outer diameter of 8 m, an inner diameter of 4 + m, and a length of 20 mm, using a cyanoacrylate adhesive. This was left in air and water for one day each alternately, and after 30 days, it was observed whether or not any cracks had occurred in the membrane.

Production Example 1 $1 50 mmot of the linear organic compound shown in the table was added to 100 mmot of water.
Ultrasonic dispersion was performed at 0d to obtain a milky white solution. Sodium polystyrene sulfonate (viscosity average molecular weight = 6 million)
Dissolve 50 mmot (monomer unit) in 1000 ml of water.9. The precipitate produced by mixing the two was collected by filtration, soaked in water 5QQ+M for 1 hour, and then in methanol 5QQ.
Al? The mixture was stirred for 1 hour. The precipitate was collected again by filtration and dried under reduced pressure to obtain the first solid substance. The composition ratio (organic compound/polymer, equivalent ratio) of the obtained solid was determined by elemental analysis. The results are summarized in Table 1.

Production Example 2 20 mmol of the compound was ultrasonically dispersed in 5001 ml of water to obtain a milky white solution. 18 mmol of polymer shown in Table 2
(monomer unit) was dissolved in 500 ml of water. The precipitate produced by mixing the two was collected by filtration, stirred in 500ml of water for 1 hour, and then stirred in 5001d of methanol for 1 hour. The precipitate was collected again by filtration and dried under reduced pressure to obtain a white solid in the amount shown in Table 2.

The composition ratio (linear organic compound/polymer, equivalent ratio) of the obtained solid was determined by elemental analysis. The results are summarized in Table 2.

Table 2 Production Example 3 10 mmot of the linear organic compound shown in Table 3 was added to 300 mm of water.
- A milky white solution was obtained by ultrasonic dispersion. 10 mmot (monomer unit) of the polymer shown in Table 3 was dissolved in 300 mm of water. The precipitate produced by mixing the two is filtered,
The mixture was stirred in 500 ml of water for 1 hour and then in methanol for 1 hour. The precipitate was collected again by filtration and dried under reduced pressure to obtain a solid substance. The composition ratio (linear organic compound/N combination, equivalent ratio) of the obtained solid was determined by elemental analysis. The results are summarized in Table 3.

Example 1 The solid matter of Production &1 obtained in Production Example 1 500~ and n-octadecyl alcohol in the amounts shown in Table 4.

and Compound 50 were dissolved in 501 dK of chloroform and cast into a petri dish made of polytetrafluoroethylene (hereinafter abbreviated as PTFE). Chloroform was evaporated at 50° C. and atmospheric pressure to obtain a uniform and transparent film. The equivalent ratio of anion exchange groups and cation exchange groups was determined by elemental analysis. Furthermore, a film not containing n-octadecyl alcohol was also formed in the same manner as Comparative Film 1. The results are summarized in Table 4.

Table 4 After immersing the ion-sensitive membranes of Membranes 1 to 8 and Comparative Membrane 1 shown in Table 4 above in water at 80°C for 5 minutes,
Next, attach it to the electrode as shown in the figure. Using this, the relationship between concentration and potential difference was measured for 91 different anions using the apparatus shown in FIG.

Based on the results obtained, a known method (G, J, Moody
, J.

The selectivity coefficient of chloride ions for each anion was determined using the method described in "Ion Selective Electrode", translated by Tomoshiro Ishiki, Kyoritsu Shuppan, X5-S-J (1977), published by Thomas D., Shinichi Munemori. . The results are shown in Table 5.

Table 5 As can be seen from Table 5, the ion-selective electrode using the ion-sensitive membrane of the present invention has excellent selectivity for chloride ions relative to sulfate ions present in biological fluids, and By adding alcohol, thiocyanate ion,
The selectivity of chlorine ions to perchlorate ions, nitrate ions, etc. is significantly improved, making it suitable for measuring chloride ion concentrations in biological fluids.

Example 2 After dissolving 500In9 of the solid material of Production Flat 1 obtained in Production Example 1, the amount of the linear alcohol shown in Table 6, and the compound 80■ in 501nL of chloroform, PTF was added.
The mixture was cast into a Petri dish manufactured by E. Chloroform was evaporated at 50° C. and atmospheric pressure to obtain a uniform and transparent film. The equivalent ratio of anion exchange groups and cation exchange groups was determined by elemental analysis. Furthermore, a film containing no linear alcohol was also formed in the same manner as Comparative Film 2. The results are summarized in Table 6.

Table 6 The ion-sensitive membranes of Membranes 9 to 14 and Comparative Membrane 2 shown in Table 6 above were immersed in water at 90° C. for 4 minutes, and then attached to electrodes as shown in FIG. 1, respectively.

Using this, the relationship between concentration and potential difference for one variety of anions was measured using the apparatus shown in FIG. The results obtained were based on known methods (G, J, Moody.

The selectivity coefficient of chloride ions with respect to each anion was determined by the method described in "Ion Selective Electrode" by J. D. Thomas, translated by Nobumu Munemori and Tomio Nikishiro, Kyoritsu Shuppan, p. 18 (1977). The results are shown in Table 7.

Table 7 As can be seen from Table 7, the ion-selective electrode using the ion-sensitive membrane of the present invention has excellent selectivity for chloride ions relative to sulfate ions present in biological fluids, and also when alcohol is added. By doing so, the selectivity of chlorine ions with respect to thiocyanate ions, perchlorate ions, nitrate ions, etc. is significantly improved, and it is suitable for measuring the chloride ion concentration in biological fluids.

Example 3 After dissolving the solids 5001n9 obtained in Production Examples 1 to 3, n-octadecyl alcohol 25019, and the compounds shown in Table 8 in chloroform 50g in the amounts shown in Table 8,
It was cast into a petri dish made of PTFE.

Evaporate chloroform at 50°C and atmospheric pressure to obtain a uniform, transparent film. The equivalent ratio of anion exchange groups and cation exchange groups was determined by elemental analysis. The results are summarized in Table 8.

Ion-sensitive membrane 1 of membranes 15 to 30 shown in the 8g8 table above
After immersing in water at 90°C for 3 minutes, each was attached to an electrode as shown in Figure 1 and compared. Using this, we measured the relationship between concentration and potential difference for various anions using the apparatus shown in Figure 2. Based on the obtained results, known methods (G,
J, Moody, J, D.

The selectivity coefficient of chloride ions with respect to each anion was determined by the method described in "Ion Selective Electrode", written by Thomas S., translated by Tomoshiro Munemori, published by Kyoritsu Shuppan, XS (1977). The results are shown in Table 9. The comparative membrane 3 was an ion-sensitive membrane (Analyticml Ch@mlstry) containing polyvinyl chloride, methyltridodecylammonium chloride, and dibutyl phthalate as components.

56.535-538 (1984)]
Table 9 also shows the selectivity coefficients for chloride ions determined in a similar manner.

Table 9 As can be seen from Table 9, the ion-selective electrode using the ion-sensitive membrane of the present invention has excellent selectivity for chloride ions relative to sulfate ions present in biological fluids, and also has a high selectivity for chloride ions when alcohol is added. As a result, the selectivity of chlorine ions with respect to thiocyanate ions, perchlorate ions, nitrate ions, etc. is significantly improved, and it is suitable for measuring the chloride ion concentration in biological fluids.

Example 4 500 Da of the solid obtained in Production Example 1, 50 W1y of the hydrophobic compound shown in Table 10 and 300 Da of n-tadecyl alcohol were mixed with 500 Da of chloroform, and then mixed with P.
It was cast into a TFE petri dish. Evaporate chloroform at 50°C and atmospheric pressure to obtain a uniform, transparent film. Determine the equivalent ratio of anion exchange groups and cation exchange groups by elemental and elementary analysis. The results are summarized in Table 10.

Regarding the ion-sensitive membranes of 11% A31 to 33 shown in Table 110 above, the selectivity coefficients for chlorine ions were measured by the same method as in Example 1. The results are shown in Table 11.

Ml1 Table Example 5 The linear organic compounds and polymers shown in Table 12 were each soaked in water at 500 rnlK. The two were mixed together to form a solid substance, which was collected by filtration and dried under reduced pressure. Obtained solid matter 50
0 Da and 250 Da of n-octadecyl alcohol were cast onto a PTFE Petri dish containing 30 Da of chloroform and 250 Da of n-octadecyl alcohol.

Chloroform f: Evaporated under conditions of 50° C. and atmospheric pressure to obtain a transparent and uniform film.

The equivalent ratio of anionic exchange groups and cation exchange groups of the obtained film was determined by elemental analysis. The results are summarized in Table 12.

Regarding the ion-sensitive membranes Nos. 34 to 39 shown in Table 12 above, the selectivity coefficients for chlorine ions were measured by the same method as in Example 1, and the t0 results are shown in Table 13.

Table 13 Example 6 n-octadecyl alcohol 20019 and production examples 1 to 3
The solid obtained in step 1 and the linear organic compound shown in Table 14 were dissolved in chloroform of fl:5 o at shown in Table 14. The resulting solution has an average diameter of 2 μm and an average length of 1
111 glass fibers were added in the amount shown in Table 13 and dispersed by ultrasonic irradiation. Next, the mixture was cast into a PTFE Petri dish, and chloroform was evaporated at 50°C and atmospheric pressure to obtain a uniform and transparent film. The equivalent ratio of ion-exchangeable groups and cation-exchangeable groups is determined by elemental analysis. The results are summarized in Table 14.

The tensile strength of the ion-sensitive membranes of 1lfiA40-55 shown in Table 14 above was measured. Also, for reference, we have added a sample of the ion-sensitive membrane of 41.8°17-30 that does not contain glass fibers! Next, set the intensity of 6111. The results are summarized in Table 15. Furthermore, I shown in Table 14 above
The repeated use durability of the ion-sensitive membranes with a weight of 40 to 51 g was also measured. The results are also shown in Table 15.

Further, the ion-sensitive membranes A28 to A45 shown in Table 13 above were immersed in water at 80° C. for 5 minutes, and then the selectivity coefficient of chloride ions with respect to each ion was determined in the same manner as in Example 1. The results are shown in Table 16.

Table 15 16th e.

As can be seen from Table 16, the strength of the membrane is significantly improved by incorporating fibers into the ion-sensitive membrane of the present invention. As can be seen from Table 15, even when used as an ion-selective electrode, the selectivity of chloride ions to thiocyanate ions, perchlorate ions, and nitrate ions is good, so chloride ions in biological fluids are Suitable for measuring concentration.

Example 7 9 solids obtained in Preparation 1 500 I! 9 and the hydrophobic compound 50Iky and n-octadecyl alcohol 30019 shown in Table 16? /loloform 50i7. The fibrous material shown in Table 17 was added to the obtained solution in the amount shown in Table 17, and the mixture was dispersed by ultrasonic irradiation. After casting in a PTFE Petri dish, chloroform was evaporated under conditions of 50° C. and atmospheric pressure to obtain a uniform and transparent film (f). The equivalent ratio of anion exchange groups and cation exchange groups was determined by elemental analysis. The results are summarized in Table 17.

The tensile strength of the ion-sensitive membranes shown in Table 17 [456 to 58] was measured and fc. For reference, we also measured the tensile strength of ion-sensitive membranes of MA31-33 that do not contain glass fibers. The results are summarized in Table 18.

In addition, the repeated use durability of the ion-sensitive membranes 56 to 58 shown in Table 17 was also measured. ff11 with the results
It is shown in Table 8.

Further, after immersing the ion-sensitive membranes 456 to 58 shown in Table 17 in water at t-80° C. for 5 minutes, the selectivity coefficient of chloride ions for each ion was determined in the same manner as in Example 1. The results are shown in Table 19.

As can be seen from Table 18, Table 19, and Table 18, by fully incorporating the fibers into the ion-sensitive membrane of the present invention, the membrane strength is significantly improved. It was. As can be seen from Table 19, when used as an ion-selective electrode, the selectivity of chloride ions to thiocyanate ions, perchlorate ions, and chloride ions is good. Suitable for measuring concentration.

Example 8 The ion-sensitive membrane of membrane A1 was immersed in water at 80° C. for 5 minutes and then attached to a pole as shown in FIG.

Using this and using the ratio device shown in Figure 2, 10''-'
The potential difference between a reference electrode (Calomel 1! electrode) and an ion-selective electrode was measured at 20° C. using a 10 M sodium chloride aqueous solution as a sample intoxicant. The relationship between the obtained t potential difference and the chloride ion concentration of the sample solution is shown in FIG. As can be seen from FIG. 3, the ion selective electrode of the present invention has a 10-4
It shows a linear response in the range from M to 10-'M. Also, the potential gradient at this time was 58 mV/decade. This value is calculated directly from the Nernst equation59 mV/de
cade, and it is clear from this result that the ion-sensitive membrane of the present invention has sufficient sensitivity to Pi elementary ions.

Example 9 The ion-sensitive membrane of membrane A1 was immersed in water at 80° C. for 5 minutes, and then attached to an electrode as shown in FIG. Using this and the apparatus shown in Figure 2, the concentration of sodium chloride in the sample solution f
Table 20 shows the values of the output potential when the potential was suddenly changed from 1 m) to 3.1 mM. Figure 4 shows the relationship between the concentration of sodium chloride and the output potential. Fourth
As can be seen from the figure, the ion-selective electrode using the ion-sensitive membrane of the present invention has a 98% response within 4 seconds, allowing rapid measurement. Further, even after repeating the measurement 1500 times, almost no change in the output potential was observed.

Table 20 Application examples Specific films Al~27. obtained in Examples 1 to 3 described above.
The ion-sensitive membranes and comparative membranes 1 to 3 were immersed in water at 80°C, and then attached to electrodes as shown in Figure 1.

Using this, 1.06mM and 3
．． The output potential was measured when 83mM sodium chloride aqueous solution was used as the sample solution, and a calibration curve of chloride ion concentration and output potential was created from the 9U measurement values. On the other hand, as test solutions, sodium chloride 2.13 mM and sodium hydrogen carbonate 0.6
Measure the output potential using an aqueous solution containing 4mM sodium dihydrogen phosphate, 0.64mM sodium sulfate, and determine the chloride ion concentration from the above-mentioned f-line.9. The results are shown in Table 21.

From this result, nine results were obtained using the ion-sensitive membrane of the present invention.

The fixed value on the second side is the actual chloride ion concentration in the test solution2.
13mM, and it is clear that the nine ion selective electrode using the ion-sensitive membrane of the present invention can accurately measure the chloride ion concentration in a solution containing one variety of anions.

Table 21

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing the structure of an example of an ion-selective electrode using the ion-sensitive membrane of the present invention. FIG. 2 is an explanatory diagram of an apparatus for measuring a potential difference using the ion-selective electrode of FIG. FIG. 3 is a diagram showing the relationship between chloride ion concentration and potential difference measured in Example 1. FIG. 4 is a diagram showing the response speed of the ion-selective electrode of the present invention measured in Example 3. Each number in FIG. 1 and FIG. 2 indicates the following content. 11... Ion selective electrode, 12... Salt bridge, 13.
... Sample solution, 14... Reference electrode, 15... Electrometer, 16... Saturated potassium chloride water bath solution, 1
7...Recording type, 21...Electrode cylinder, 22...Ion sensitive membrane, 23...Internal electrolyte, 24...Internal reference electrode, 25...0 ring. Patent applicant: Tokuyama Soda Co., Ltd. Figure 3: Chlorine ion! LIt(r-t) No.! l Flash time - 1 →

Claims (2)

[Claims] (1) (i) A polymer having an anion exchange group or a cation exchange group, and (ii) (a) one containing two or three long chain hydrophobic groups or a rigid part in the chain. an organic compound having a linear hydrophobic group and an ion-exchangeable group having an opposite charge to that of the above-mentioned polymer; and (iii) a linear alcohol having 10 or more carbon atoms as the main constituents; The group is present in an excess amount relative to the cation exchangeable group, and the linear alcohol is present in an amount of 10 to 150% by weight based on the total amount of the polymer (i) and the organic compound (ii). An ion-sensitive membrane consisting of a film-like substance that exists in a certain proportion. (2) The ion-sensitive membrane according to claim 1, wherein a reinforcing agent made of a fibrous material is dispersed in the membrane material.