JPS5832155A - Ion sensor - Google Patents

Abstract

PURPOSE:To make a minute sensor eliminating the need to provide with a room standard liquid, by covering a polymer film derived from an aromatic compound containing nitrogen atoms or a hydroxy aromatic compound on the surface of a tip end disk of an electrically conductive substance. CONSTITUTION:An ion sensor is made by covering the circumference of an optionally shaped, e.g. rod-shaped, electrically conductive substance 11 by an insulating material 13 and covering and fixing a prescribed polymer film 12 on the surface of a tip end disk. The film 12 is made of an aromatic compound containing nitrogen atoms or a hydroxy aromatic compound. The aromatic compound containing nitrogen atoms is shown by formula (I). Where, Ar is an aromatic nucleus, R is a substituent, m is 0 or an integer of >=1 and n is an integer of >=1 and then, m+n not exceed the number of effective valence. But, Ar may be 0 in case of a heterocyclic compound containing nitrogen atoms. Also, the hydroxy aromatic compound is shown by formula (II). Where, Ar is an aromatic nucleus, R is a substituent and l is 0 or the effective valence of Ar.

Description

Detailed Description of the Invention 10. Background Technical Field of the Invention The present invention relates to an ion sensor, and more particularly to an ion sensor in which a polymer film is directly deposited on the surface of a conductor, and the ion concentration in a solution is measured by an electrode. Concerning what is measured by potential or current response.

Prior Art and Problems Conventionally, hydrogen electrodes and quinhydrone electrodes have been known as electrodes for measuring the concentration of ions such as hydrogen ions in solutions, but today glass electrodes are widely used in terms of their wide range of application and accuracy. It is starting to be used. The principle of measurement using this positive electrode is to separate two solutions with different hydrogen ion concentrations, one as a reference solution, with a thin glass membrane.
It consists of measuring the potential difference created on both sides of this glass membrane.

That is, in the case of a glass electrode, it is necessary to provide a reference liquid chamber, and therefore miniaturization is difficult.

Furthermore, in a solution containing a sticky substance, the sticky substance adheres to the glass membrane, making it difficult to measure - and causing poor reproducibility of electrode potential response. Furthermore, the resistance of the glass film of the glass electrode is as large as 10 to 100 MΩ, so that an ordinary potentiometer cannot be used alone to measure -, and an amplifier with high input impedance is required.

■1 Purpose of the Invention Therefore, the purpose of the present invention is to provide an ion sensor that measures the concentration of ions in a solution, which does not require a reference liquid chamber, and which can therefore be miniaturized. .

To achieve this objective, the present invention uses a technique that has rarely been used in the past: chemically modifying the conductor surface with a polymer, which is completely different from the concept of conventional glass electrodes. . This chemical modification technique makes the conductor selectively permeable to dissolved ionic species, prevents surface corrosion and dissolution, and responds to the ion concentration in solution by changes in electrode potential or current. Demonstrating New Functions 7 This invention utilizes the responsiveness to ion concentration among the functions of a conductor chemically modified with a polymer.

That is, the ion sensor of the present invention is formed by directly depositing a polymer film derived from a nitrogen-containing aromatic compound or a hydroxy aromatic compound on the surface of a conductor.

Preferably, the polymer film has a low impedance and is obtained by electrolytic oxidative polymerization.

The nitrogen-containing aromatic compound has the formula %formula%) () (where Ar is an aromatic nucleus, R is a substituent, and m is 0 or 1
or more and n is an integer of 1 or more, and 111+n
does not exceed the effective valence number of Ar. However, when Ar is a nitrogen-containing heterocycle, n #-1:0 may be used. Specific examples include kelt, 1,2-diaminobenzene, aniline, 2-aminobenzotrifluoride, 2-aminopyridine, 2,3-diaminopyridine,
At least one member selected from the group consisting of 4,4'-diaminodiphenyl ether, 4,4'-methylene dianiline, tyramine, N-('o-hydroxypencyl)aniline, and pyrrole. In addition, polymer films obtained by polymerization in advance, dissolved in a solvent, applied and dried on the surface of a conductor, can be made of polyaromatic amide or an expanded polymer film.
There are aromatic imides. Ion sensors having polymeric films derived from these nitrogen-containing aromatic compounds are suitable for use as voice sensors.

The hydroxy aromatic compound may be represented by the formula % (6) (where Ar is an aromatic nucleus, each RFi substituent, and t is the effective valence number of 0 to Ar). Specific examples include phenol, dimethylphenol, trioxypyridine, 0- and m-benzyl alcohol No.
dibenzaldehyde in lm- and p-hydro, 0- and m-hydroxyacetophenone, o-lm- and p-hydroxypropiophenone 7% 0-1 n- and p-benzophenol, 0-1 m- and p-hydroxybenzophenone , 0-lm- and p-calgexyphenol, diphenylphenol, 2-methyl-8-hydroquinoline, 5-human nx-1,4-su7toquinone, 4-(p-hydroxyphenyl)-2- Butanone, 1
．． These include 5-2hydroxy-1,2,3,4-tetrahydronaphthalene, bisphenol At, and mixtures thereof. In addition, in the case of pre-polymerized nonapolymer films, the polymer film is dissolved in a solvent and coated on the surface and dried to form polyferrylene oxide, polycarbonate, etc. specifically polyphenylene oxide derivatives, polydiphenyl
Phenylene oxide, polydimethylphenylene oxide, I liquor 1. Examples include kenate derivatives.

Note that the term polymer used in this specification includes both homopolymers and interpolymers (eg, copolymers, terpolymers, etc.).

10 Detailed description of the invention The present invention will be described in detail below with reference to the accompanying drawings.

As shown in FIG. 1, the ion sensor of the present invention has an arbitrary shape, for example, a rod-like conductor of 1.10 Mflal, coated with an insulator 13 such as lyolefin or XXXX, and a predetermined polymer film 12 on the surface of the cask at the tip. It is made by attaching and fixing. The conductor 11 is made of a conductive material, preferably platinum or the like. The polymer film 12 deposited on the surface of the conductor disk 11 is made of a polymer of a nitrogen-containing aromatic compound. Such nitrogen-containing aromatic compounds have, for example, the general formula (where Ar is an aromatic nucleus, R is a substituent, m is O or 1
or more, and n is an integer of 1 or more, and m + n
does not exceed the effective valence number of Ar. However, when Ar is a nitrogen-containing heterocycle, n may be O. The aromatic nucleus Ar may be monocyclic (for example, benzene nucleus, pyridine nucleus) or polynuclear (for example, quinoline nucleus, naphthoquinone nucleus, bisphenol nucleus).

N-substituted derivatives of compounds of the formula (-) may also be used.

Examples of the substituent R include an alkyl group such as a methyl group,
Halogenated alkyl group, aryl group example evaphenyl group,
Arylcarnonyl group and arylcarnonyl group 1 (-〇-R'), hydroxyalkyl group (-R"0) (
), cargexyl group, aldehyde group, hydroxyl group, etc.

Specific examples of such nitrogen-containing aromatic compounds include:
1.2-diaminobenzene, aniline, 2-aminopenzotrifluoride, 2-aminopyridine, 2.3-diaminopyridine, 1,4'-diaminodiphenyl ether, 4,4'-methylenenoaniline, tyramine, N −(
o-hydroxybenzyl)aniline and pyrrole. Polymers obtained by prior polymerization include pre-aromatic amides and imides, such as polyamide/imide compounds such as 4,4'-diaminodiphenyl ether and 4,4'-diaminodiphenylmethane derivatives, and bis-cyclo-(2, 2,2)-Octo-Tsene-2,3,
5,6-titracarnic dianhydride is converted to acid chloride by reacting with thionyl chloride.

was obtained by reacting it with 4,4'-diaminophenyl ether. Lyamide polymer (Kobayashi et al., octane (12)
1929-32 (1980)).

Alternatively, polymeric membrane 12 may be derived from hydroxyaromatic compounds. Such hydroxyaromatic compounds may have, for example, the general formula (where Ar is an aromatic nucleus, each R is a substituent, and l is 0
to the effective valence number of Ar). The aromatic nucleus Ar may be monocyclic (for example, penze/nucleus, pyridine nucleus) or polynuclear (for example, quinoline nucleus, naphthoquinone nucleus, bisphenol nucleus). The substituent R is the same as described for formula (A).

Specific examples of such hydroxy aromatic compounds include phenol, dimethylphenol (e.g. 2,6-
and 3,5-dimethylphenol), 2-13- and 4-hydroxypyridine, o- and m-benzyl alcohol, o-lm- and p-hydroxybenzaldehyde, o-lm- and p-hydroxyacetophenone, o”” , m- and p-hydroxypropiophenone, o-lm- and p-benzophenol, o”-1
m- and p-hydroxybenzophenone so-1m-
and p-cal? 2-methyl-8-hydroquinoline, 5
-Hydroxy-1-4-naphthoquinone, 4-(p-hydroxyphenyl)-2-fmethane, 1,5-dihydroxy-1,2,3,4-tetrahydronaphthalene, bisphenol A, and the like. Examples of polymers obtained by pre-polymerization include polyphenylene oxide, boria m-ethylene oxide conductor, boridiphenyl, phenylene oxide, polydimethylphenylene oxide, polycargonate, and the like.

In order to deposit the polymer film of the nitrogen-containing aromatic compound or hydroxy aromatic compound on the surface of the conductor 11, the nitrogen-containing aromatic compound or hydroxy aromatic compound is applied to the conductor 11 by electrolytic oxidation polymerization. A method of polymerizing on the surface, a method of dissolving a pre-synthesized electropolymer in a solvent and fixing the solution to the conductor surface by dipping/coating and drying, and a method of chemically processing, physically processing or irradiating the polymer film. A method of directly fixing it to the conductor surface through treatment can be adopted.

The most convenient of the above deposition methods is by electrolytic oxidative polymerization. In this electrolytic oxidative polymerization, a nitrogen-containing aromatic compound (preferably a hydroxy aromatic compound) is electrolytically oxidized and polymerized in a suitable solvent to deposit a polymer film on the surface of a conductor desired as a working electrode. For example, 1.2--
/aminobenzene, 2-aminopenzotrifluoride okara 4. The electrolytic oxidative polymerization of t'-noaminodiphenylmethane is carried out in a phosphate buffer solution at pH 7, the polymerization of aniline is carried out in an acetonitrile solution containing pyridine and sodium perchlorate, and the polymerization of 4,4'-diaminodiphenyl ether is carried out in a perchloric acid buffer solution. The polymerization of virol was carried out in an acetonitrile solution containing sodium or a methanol solution containing sodium hydroxide, and tetrabutylammonium hexafluorophosphate (nu4N (pp6)
The electrolytic oxidative polymerization of hydroxy aromatic compounds is carried out in an acetonitrile solution containing (abbreviated as ) in an alkaline solvent such as methanol.

The polymer film deposited by electrolytic oxidation polymerization has extremely good adhesion stability and has a smooth film surface.

There is no particular limit to the thickness of the polymer film, but it is between 0.01μ and t.
Ai of 1 degree is appropriate.

y.Specific Functions of the Invention The functions of the covered electrode having the above structure will be explained in detail below. ,・su・((1) Response as an ion sensor k when measuring the - of the sample solution using the ion sensor shown in Fig. 1 is as shown in the tsz diagram.
A sample solution 22 whose medium K pH is to be measured is added, and the ion sensor 23 of the present invention and a silver-silver chloride electrode, a calomel electrode, etc. as a reference electrode 24 are immersed in this solution. And the potential difference of the ion sensor 23 with respect to the reference electrode 2a (
electromotive force) is measured with a potentiometer 26. At this time, it is preferable to stir the sample solution 22 with a stirrer 25, and read the - of the sample solution from a correlation diagram of electromotive force and - prepared in advance. Note that when blowing gas, a gas blowing pipe 21 is used.

The relationship between the electromotive force and - by the ion sensor of this invention shows a linear relationship with a slope of 59 mV/- in one wide area, and is expressed by the formula (ζ, where E is the electromotive force (mV) and E is a constant potential. (mV
), R is a gas constant, T is an absolute temperature, F is a Faraday constant, and [H+] is a hydrogen ion concentration).

However, the sample solution is measured in an open system or in an oxygen stream. Furthermore, when the electromotive force is measured in a hydrogen gas stream, the value changes greatly to a negative potential value, but it satisfies Nernst's equation for hydrogen ions.

(2) Selective membrane permeation of ionic species and control electrode The coated membrane exhibits selectivity for membrane permeation of ionic species in solution. Convective gel tanmetry using a rotating disk electrode is effective for this measurement. This is because the amount of mass transport of ionic species onto the electrode can be controlled by the rotation speed of the disc electrode, so we investigated the dependence of the critical current value of the lutamogram on the rotation speed for electrodes with and without a coating film. Then, the membrane permeability of each chemical species can be evaluated. This behavior varies depending on the type of coating membrane and dissolved ionic species, but in general, the thicker the coating membrane is, the more the ionic species permeation is inhibited, and the larger the volume of the dissolved ionic species, the more the membrane permeation is suppressed. .

As for other functionality, it is possible to modify the electrode surface by directly coating the electrode surface with polymer J[K, which may contribute to improving the electrode catalytic ability and preventing surface corrosion and dissolution. have. In addition, the coating film has the functionality as an anchor for introducing an appropriate substituent to the conductor surface.If the electrode surface does not have an appropriate substituent that can be compounded with an organic substance, etc., the electrode surface first is coated with a polymer having substituents such as aldehyde or amine.

The coated film can be used as a reactive substituent in graft polymerization reactions, etc., and can be used as a substrate for immobilizing a target compound, and can also be used to modify the coated film. If the substituent of the coating film is a ligand such as pyridine, the film has coordination bonding ability, and if the substituent has a charge such as sulfonic acid or quaternized giridine, the film has coordination bonding ability. It has the properties of a polymer electrolyte and has the ability to accumulate and fix oppositely charged ionic species. Therefore, these coated membrane electrodes have the effect of pre-concentrating trace amounts of dissolved ionic species, and then oxidize or reduce them at the electrode, which can then be detected by electric current, making them useful as electrodes for detecting trace amounts of ionic species. have sex. In addition, by inserting a third chemical species into the coating film, which is an insulator, it can be improved and modified into a conductive film.

In addition, by applying an electrode potential, the redox state of the reactive active species in the membrane can be changed, and the color of the membrane can be changed, colored or bleached.

Examples of this invention will be shown below.

Example 1 The circumference of the platinum wire was insulated with T-xxxx, and the disk surface was pretreated by the following method before electrolysis. First, it was smoothed by polishing with silicon car guid paper and alumina powder (0.3 μm), washed with dilute aqua regia, and then with distilled water.
Soak in acetic acid solution of M. Next, using a normal three-electrode H-type cell with this electrode as the working electrode, a platinum mesh as the counter electrode, and a saturated calomel electrode as the reference electrode, the voltage applied to the electrode was varied from -0.6v to +1. After ovO, the electrode surface is activated by reciprocating about 10 times and then washed with distilled water, then with methanol, and dried.

To prepare the electrode coating film, the pretreated working electrode described above was immersed in the same electrolytic cell as described above, and the electrolytic oxidation polymerization reaction was carried out on the surface of the platinum disk at 10 m, M4.4'-diaminodiphenyl ether, Q The electrolyte was thoroughly deoxygenated with alyne gas before electrolysis. 4. After confirming that the oxidation reaction of the 4'-diaminodiphenyl ether monomer is occurring at the platinum electrode, the applied voltage is kept at +1.20° (vs. saturated calomel electrode), and constant electrolysis is performed for 10 minutes to remove the electrode surface. was coated with an oxidized polymer.

Thereafter, the electrode surface was washed three times or more with distilled water to produce a polymer-coated chemically modified electrode. Figure 3 is a cyclic deltangram showing the start of the oxidative polymerization reaction, and the difference in C-reactive current between the first scanning oxidation wave (curve a) and the second scanning wave (curve b) is due to the This is due to the formation of a deposited film.

Curves C and d are the third and fourth scan waves.

Note that the potential scanning speed was 74 mV/sec.

The function of the fabricated coated membrane electrode as a sensor was investigated. -1 Using a buffer solution containing a total phosphoric acid concentration of 50 mM as the measurement solution, oxidize the solution with IJ and perchloric acid. From OO to to, o.

The range K11il has been adjusted. The coated membrane electrode was immersed in this sample solution, and the electromotive force was measured using a saturated calomel electrode as a reference electrode. A plot of this measured electromotive force and a value measured using a commercially available glass electrode is shown in FIG. 4 by a straight line a (open system). The slope of this straight line was a linear relationship satisfying the Nernst equation in a region from 2.0 to 11.0, and the slope was 54 mV/pH. This measurement was conducted in an open system where the sample solution was left in the air.

When measuring while blowing oxygen gas and alden gas into the sample solution, the responses shown by straight lines and straight lines C in Figure 4 were obtained, and the slopes of the straight lines were 54 mV/pH and 4 mV/pH, respectively.
It was 6 mV/pH. In addition, in a hydrogen gas flow, the value of electromotive force changes greatly to a negative potential value in a region from 2.0 to 9.0, but it satisfies the Nernst relation of 59 my/, ) I (straight line). d).

From this, the coated membrane electrode exhibits extremely excellent electrode characteristics for measuring hydrogen ion concentration. The accuracy and stability of the equilibrium electrode potential (electromotive force) response is good, and the potential shows a constant value within 5 to 15 minutes, and then maintains a constant value within a range of ±2 mV even after several hours.

Furthermore, even if we examine the electromotive force response to hydrogen ions after immersing this electrode in a phosphate buffer solution with m = 7.0 for one week, it satisfies the Nernst equation as shown by the straight line e in Figure 4. , the durability of the film is extremely good. In addition, similar measurements were carried out in the presence of copal (II) ions, nickel (IF) ions, iron (n) ions, or zinc (ions) in the sample solution. It was not affected and changed only due to changes in hydrogen ion concentration in the solution.
The measurement results for pH=4.0) are shown in FIG. Note that even when alkaline earth metal ions such as calcium (II) were present in the sample solution, the equilibrium potential was not affected by the ions.

Example 2 A coating film was formed on the surface of a platinum disk electrode by an electrolytic oxidative polymerization reaction of aniline in an acetonitrile solvent containing 10 mM aniline, phosphorus, 20 mM pyridine, and 0.1 M sodium perchlorate. An electrode coating film was created by the same method as in Example 1, that is, the electrolytic oxidation polymerization reaction method. The response of this coated membrane electrode as a sensor was investigated, and 2
．． A linear relationship was obtained with a slope of 52 mV/pH in one region from 0 to 9.0 ma. The electrode potential showed a constant value in 5 to 10 minutes, and then stabilized within a range of ±2 mV for several hours.

Although the durability of this coating film is extremely good, when the sample solution contained transition metal ions, the equilibrium potential was affected by the concentration of these ion species.

Example 3 A coating film was formed on the surface of a platinum disk electrode by electrolytic oxidative polymerization reaction of 1.2-cyaminobenzene at 10 mM 1.2
-diaminobenzene, 50mM phosphate buffer (pH=7)
．． 00) was held inside. The relationship between the equilibrium potential (electromotive force) of this coating film 1° electrode and - almost satisfied the Nernst relation, and a linear relationship of 54 mV/- was satisfied in the - range from 2.0 to 9.0. . However, this measurement was conducted in an open system where the sample solution was left in the air. When measuring while blowing oxygen gas and argon gas into the sample solution, the slope of each straight line was 57.
rnV/pH and 54 mV/pH satisfied the y-Nernst relation. Further, in a hydrogen gas flow, the value of the electromotive force changes greatly to a negative potential value, but the Nernst relational expression of 52 mV/pH was satisfied.

From this, the coated membrane electrode exhibits extremely excellent electrode characteristics for measuring hydrogen ion concentration. The electrode potential shows a constant value within 5 to 15 minutes, and remains constant within a range of ±2 mV even after 40 hours.

The durability of this coating film is extremely good. Furthermore, even if the sample solution coexists with transition metals, the equilibrium potential is not affected by these transition metal ion species, and it can be used as a sensor in the solution.

Further, the AC impedance measurement results of the coated membrane electrode obtained in this example are shown in the table. It is recognized that a sensor with extremely low impedance, with little change in resistance and capacitance components before and after coating with a polymer film, has been provided. The measurement conditions were as follows: platinum was used as an electrode in a 50 mM IJ acid buffer solution with −=7.0.

Example 4 A coated membrane electrode was prepared in the same manner as in Example 1 in a nitrile solution. Is the electrolytic oxidative polymerization of pyrrole in this case applied voltage +0.8? The cat electrode, which had been subjected to constant potential electrolysis for 10 minutes using a saturated calomel electrode, was washed with water and methanol in that order, and dried. The prepared electrode coating film exhibits a purple color.

The response of this coated electrode as a sensor was investigated.
A straight line with a slope of 48 mV/pH was obtained in one region from 9.0 to 9.0. The electrode potential showed a constant value in 5 to 30 minutes, and after that, it was stable within the range of ±2 mV for several hours.When measuring while blowing oxygen and argon gas into the sample solution, it was 57. mV/pH (2,0<:4×1G), 48 mV
/pH (-2.0 < pH < 9.0), the potential reached a constant value in 20 to 40 minutes, and then remained at ±2 for several hours.
It was stable in the mV range. Next, similar results were obtained when the hydrogen ion concentration was measured after immersing this electrode in phosphate buffer (p) [=7.0] for 5 days. The durability of this coating film was extremely good, and even when the sample solution contained transition metal ions, there was no effect on the equilibrium potential.

Example 5 A coating film of 2-aminopyrinone was formed on the surface of a platinum disk electrode using an electrolytic oxidation polymerization method in the same manner as in Example 3 in 10 mM 2-aminopyrinone and 50 mM phosphate buffer (PH = 7.OO). This was done by A linear relationship was satisfied between the equilibrium potential (electromotive force) and pH of this coated membrane electrode, and 48 mV/- was obtained in one region from 2.0 to 11.0. However, the measurement was carried out in an open system where the sample solution was left in the air - when measuring while blowing oxygen and argon gas into the sample solution, the pH was 159 mV and 48 mV, respectively.
/P)I (however, each 2.00<pH<11.0
0, 2no<pH<.

10.5). The value of electromotive force in the case of hydrogen gas injection shows a remarkable potential value of eclipse, but s 9 mV
/pH, all Nernst relations were satisfied.

From this, the coated membrane electrode exhibits electrode characteristics that allow measurement of hydrogen ion concentration.

The equilibrium potential shows a constant value within 5 to 20 minutes, and even after several hours, it maintains a constant value within a range of ±2 mV. Furthermore, after immersing this electrode in a phosphate buffer solution with m = 7.0 for about 10 days, the electromotive force response to hydrogen ions was investigated, and a similar response was obtained, indicating that the membrane of the present invention has extremely good durability. .

Examples 6 and 7 2.3-Noaminopyridine and 2-aminopenzotrifluoride were oxidatively polymerized on a platinum surface in the same manner as in Example 3 to produce a polymer-coated electrode. Using these coated electrodes, we investigated the hydrogen ion concentration of the measurement solution, the equilibrium potential response, and the effects of gas injection (oxygen, Alton, hydrogen, etc.) on the hydrogen ion concentration measurement. I got the result.

Table 2 Example 8 1.

Biscyclo(2,2,2)-oct-7-nin-2゜3
, 5.6-Chitrakal? dimethyl sulfoxide (0 MO) at a concentration of 0.04 wt.
8), the tip of the platinum electrode was immersed in the solution, and then taken out from the solution and air-dried for several hours at room temperature to produce a coated electrode.

The relationship between the equilibrium potential (electromotive force) in the measurement solution and - satisfies a linear relationship, and in the range of pH 2, oo to to, oo (J 46 mV/- was obtained. When oxygen gas was blown p)12.
It is 46 mV/pH in the range from 0 to 7.00, but about 25 mV/pH on the alkaline side (7,00<pH<10.Oo).
mV/pH.

↓ When argon is injected, 2.5<:pH<10.0
In the range of 32 mV/pkig, the electromotive force value in the case of hydrogen gas injection shows a significantly negative potential value,
The Nernst relation for pH was satisfied (2.0<:
pH<9.0).

The equilibrium potential shows a constant value within 10 minutes and remains constant within a range of ±2 mV even after several hours.

In addition, after immersing this electrode in a phosphate buffer solution of −=7.0 for a day and night, we measured the change in hydrogen ion concentration.The results satisfied a linear relationship and showed a slope of 31 mV/−.The value of the slope changed and Changes over time were observed.

When 1 mM iron(2) ions coexist in the sample solution, the equilibrium potential is affected by this ion species.

Example 9 In the following example, several redox chemical species are used as examples to demonstrate that the coating film on the electrode has selective membrane permeation properties with respect to ionic species in a solution. We also show that the membrane has the function of preventing direct contact between dissolved ionic species and the electrode surface. As a measurement method, 1. Convection rutammetry using a rotating disk electrode was used. First, phenol will be described as a representative compound of phenol derivatives. Rotating platinum disk electrode (area 4.4 x 10-s
j) The electrolytic solution for creating the electrolytic polymerized film of phenol on the top is 10mM phenol and 30mM in methanol solvent.
of sodium hydroxide, and was sufficiently deoxidized with aldine gas before electrolysis. The applied voltage was stopped at 1.0 Kelt (versus saturated calomel electrode), and constant electrolysis was carried out for 3 minutes to coat the electrode surface with the oxidized polymerization product. Convective gel tamograms for hydrogen reduction waves were investigated using this coated membrane electrode in a -:3.00 aqueous solution containing 0.2 M CCF3C00N as a supporting electrolyte (rotation speed 491 stlm, applied voltage scanning rate 5 mm/s). ), the limiting current value (curve b) corresponding to the reduction reaction of hydrogen ions is significantly smaller than the limiting current value obtained with a platinum electrode without a coating film. (96 tens in Figure 6). This shows that the coating film only allows a certain amount of hydrogen ions to pass through.

Figure 7 shows the ethylenediaminetetraacetic acid complex (F-(
This is a gel tammogram for the reduction reaction of bromine ion (Br-) and the oxidation reaction of bromine ion (Br-). From the limiting current values of various ions, the coating film does not transmit F. (edta), while it allows a certain amount of Br- You can see that it will pass. In this case, the solution composition for measuring the reduction reaction of F@'7(・dta) is 2 mM Fa'(edta)-0,2MCF3C
O0Na (pH='3.0), and the solution composition for measuring the oxidation reaction of bromide ions was 2.0mMBr-published, 2
M CF5■0Na (pH = 3.0), the platinum disk electrode area is 4.4 x 10-3 layers, and the number of rotations is 9.
It was 23 rpl. Curves a and C show the case of an electrode without a coating film, and curves a and d show the case of an electrode covered with a phenol electrolytic oxidation polymer film.

Example 10. L 1.12. 1 In the following examples, it will be shown that the electrode coating membrane has a selective membrane permeation function for ionic species in a solution.

Example 14 The results of one measurement in liquid liquid are described. A coated electrode was prepared by depositing 4,4'-diaminodiphenyl ether on the surface of a platinum fisk in the same manner as in Example 1. Using this electrode, Carbopol$ K 40 (manufactured by Gutdrich), a thickener based on polyacrylic acid, was used.
The hydrogen and ion concentrations in a solution of 0.1% by weight dissolved in a 5% by weight sodium hydroxide solution were measured, and an electrode equilibrium potential (electromotive force) of about 140 mV versus a saturated calomel electrode was obtained.

This value is approximately - from the relationship between the open system electromotive force and - in Figure 4.
=tO,S.

Similar measurements were made using a positive electrode, but no equilibrium potential response was obtained and negative measurements could not be made.

Example 15 Measurements were carried out in a solution containing almost no electrolyte.

A platinum electrode is immersed in a known volume of rainwater sample solution and used as an electrode for electrolysis to adjust the concentration of hydrogen ions in the sample solution through water electrolysis. The amount of electricity used during electrolysis is read with a coulometer. The total hydrogen ions in the sample solution at this time are the analysis excess hydrogen ion concentration already contained in the sample solution, Q is the amount of electricity used for electrolysis, F is the Faraday constant, and V is the volume of the sample solution. be. If the Nernst equation holds true in electromotive force (E) measurement, then the following equation holds at 25°C.

Therefore, it holds true. When the equilibrium potential was measured using a coated electrode prepared by electrolytic oxidative polymerization of phenol, a linear relationship was satisfied. As a result, the values of F:, o and H8 could be determined. From that ideal value, the - of the rainwater used here is 5
．． I was surprised that it was 0.

Example 16 The electrolytic oxidative polymerization reaction of 4,4'-diaminodiphenyl ether onto the surface of a platinum disk electrode was carried out under different electrolytic conditions from Example 1, namely, a methanol solution containing l OmM 4,4'-diaminodiphenyl ether and 30mM sodium hydroxide. It was done inside.

In this case, a stable golden coating was obtained. The response of this coated membrane electrode as a sensor was good. (2) Specific Effects of the Invention The ion sensor of the present invention described above has the following effects.

(1) A conductor coated with a polymer film derived from a nitrogen-containing aromatic compound or a hydroxy aromatic compound is immersed in a solution, and - can be measured based on the electrode potential response. Therefore, there is no need to provide a reference liquid chamber, the size can be miniaturized to the limited range of processing of the conductor, and only a small amount of measurement sample liquid is required. Also, the potential response speed is fast. Furthermore, one sensor of the present invention can be formed so that it can be inserted into the body.

(2) The conductivity of the polymer film is extremely good, the film resistance is very small, and the impedance is low, so a high input impedance amplifier is not required for measurement.

(3) - can be quantitatively and accurately measured in a short time even in solutions containing many types of ion species, especially transition metal ions.

It also works as a sensor in solution systems containing heterogeneous substances, such as suspensions and slurry liquids.

(4) Test RIK Even when oxygen gas, alyne gas, and hydrogen gas are blown into the sample, a linear relationship satisfying the Nernst equation is established, and one measurement of the sample liquid can be performed.

(5) The coating membrane has the function of partially permeating hydrogen ions and bromide ions, selectively permeating only hydrogen ions, and not permeating ti transition metal ions and their complexes. - 1", so it can operate as a sensor even in solutions with low electrical conductivity, such as rainwater.

[Brief explanation of drawings]

Figure 1 is an enlarged sectional view of a part of the ion sensor of the present invention, Figure 2 is a schematic diagram showing one measurement method using the ion sensor of the present invention, and Figure 3 is an electrode oxidation reaction of 4゜4'-diaminodiphenyl ether. FIGS. 4 and 5 are graphs showing the relationship between electromotive force and − of different ion sensors of the present invention. FIGS. 6 and 7 are gel tammograms in which convection is measured by lutammetry. 11... Conductor, I2... Polymer film, 23...-
Sensor, 24... Reference electrode, 26... Potentiometer. Applicant's agent Patent attorney Takehiko Suzue 1 Figure 11 183@

Claims (9)

[Claims] (1) Using an ion sensor that measures ions in a solution using electrode potential or current response, a polymer film derived from a nitrogen-containing aromatic compound or a hydroxyaromatic compound is directly applied to the surface of the conductor. An ion sensor characterized by being attached to. (2) The ion sensor according to claim 1, wherein the polymer membrane has a low impedance. (3) The ion sensor according to claim 1 or 2, wherein the polymer membrane is an electrolytically oxidized polymer membrane. (4) The nitrogen-containing aromatic compound has the formula %) () (where Ar is an aromatic nucleus, R is a substituent, m is O or Fi
an integer greater than or equal to t, and n is an integer greater than or equal to 1, and m +
n does not exceed the effective valence number of Ar. (However, when Ar is a nitrogen-containing heterocycle, n may be 0.) The ion sensor according to any one of claims 1 to 3, wherein n may be 0. (5) The nitrogen-containing aromatic compound is 1,2-diaminobenzene, aniline, 2-aminopenzotrifluoride, 2-
Aminopyridine, 2,3-diaminopyridine, 4.4'
-Noamin diphenyl ether, 4,4'-methylene dianiline, tyramine, N-(0-hydroxybenzyl)
The ion sensor according to claim 4, which is at least one selected from the group consisting of aniline and pyrrole. (6) The ion sensor 0 according to claim 1 or 2, wherein the polymer film is a polyaromatic amide dissolved in a solvent, applied and dried on the surface of the conductor, and the polymer film is a polyaromatic imide. (7) The ion sensor according to any one of claims 4 to 6, which is a pH sensor. (8) Hydroxyaromatic compounds have the formula OH ■ Ar-(6)t (where Ar is an aromatic nucleus, each R is a substituent, and t is 0
3. The ion sensor according to any one of claims 1 to 3, wherein the ion sensor is represented by the effective valence number of Ar. (9) Hydroxyaromatic compounds include phenol, dimethylphenol, hydroxypyridine,
-benzyl alcohol, 0-lm- and p-hydroxybenzaldehyde, O- and m-hydroxyacetophenone, 0-1In- and p-hydroxyacetophenone, 0-lm- and p-benzophenol, 〇-
1m- and p-hydroxybenzophenone, 0-lm
- and p-cal? xyphenol, diphenylphenol, 2-methyl, -8-hydroquinoline, 5-hydroxy-1,4-su7toquinone, 4-(p-hydroxyphenyl)-2-butanone, 1,5-dihydroxy-1,
111. The ion sensor according to claim 8, which is at least one selected from the group consisting of 2,3,4-tetrahydronaphthalene and bisphenol A. The ion sensor according to claim 1 or 2, wherein the ion sensor is coated and dried monophenylene oxide or monolicarbonate. The ion according to any one of claims 1, 2, and 9, which is selected from the group consisting of at least one of phenylene oxide, polydimethylphenylene oxide, and f-licarmenate derivatives. sensor.