JPH01250750A - Sensitive film for sodium ion selecting electrode - Google Patents

Abstract

PURPOSE:To measure an Na ion accurately while removing the hindrance by a K ion and the like by a method wherein a sensitive film for an electrode is made to contain at least one kind of calix(4)arene compound expressed by a specific formula as a neutral carrier. CONSTITUTION:The title film is formed by incorporating at least one kind of calix(4)arene compound expressed by the formula as a neutral carrier. The calix(4)arene compound has an Na ion selecting property about 250 times as large as a K ion selecting property, and accordingly the Na ion is measured accurately while the hindrance by the K ion is removed without fail. In addition, this compound has a large fat-soluble property and, accordingly, it is solved surely and held in an organic solution in a sensitive film for an electrode and reluctant to flow out of the film. Therefore the lifetime of the film can be prolonged.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a novel sensitive membrane for a sodium ion selective electrode that is widely used in fields such as medicine and environmental chemistry.

[Prior art and problems to be solved by the invention] In general, an ion-selective electrode is an electrode that indicates the concentration of a specific ion in a solution by the membrane potential shown by the membrane electrode, and is used for pH measurement. A typical example is a glass electrode.

By the way, the sodium ion concentration in living organisms is closely related to the metabolic reactions of living organisms, and measurement of this ion concentration in living organisms is often used in hemodialysis, as well as in the diagnosis of various diseases such as hypertension symptoms and renal disease. However, conventionally, spectral methods such as tip analysis have been mainly used for this measurement. However, this type of spectral method requires large equipment and takes time to measure, making it unsuitable for use in diagnostic settings. There is a strong demand for the development of equipment. For this reason, methods using glass electrodes have been proposed, but glass electrodes have the drawbacks of being easily damaged, expensive, and having a relatively short lifespan.

On the other hand, a liquid film electrode has also been proposed in which the antibiotics palinomycin and monensin form stable complexes with alkali metal ions and are dissolved in an aromatic organic solvent as a so-called neutral carrier. However, palinomycin shows higher selectivity for potassium ions than sodium ions, and although monensin forms a complex with sodium ions, it is easily interfered with by coexisting ions such as potassium ions, so both It is difficult to use as a sensitive membrane for ion selective electrodes.

In this way, in order to be a practical sodium ion-selective electrode, it must be highly selective for sodium ions without being substantially affected by the interfering effects of potassium ions and ammonium ions that often coexist with sodium ions. It is necessary to have excellent reproducibility and a sufficiently short response time. Conventionally, a practical sodium ion selective electrode that satisfies these requirements is bis-12-
Those using a membrane containing a Crown-4 compound (Toshiyuki Shono et al., J, E 1 electroana1. Che
132 +99 (1982)) and one using a membrane containing an acyclic amide compound (W, SIM
on et al., He1v, Chim.

Acta, 59, 2417 (1976)) is only known.

The present invention has been developed in view of the above circumstances, and has extremely high selectivity for sodium ions. Therefore, it is possible to accurately measure sodium ions by eliminating interference caused by potassium ions, etc., and has a long membrane life. The object of the present invention is to provide a sensitive membrane for a sodium ion selective electrode that can stably maintain a constant concentration of 81 g over a long period of time.

[Means and effects for solving the problem] That is, in order to achieve the above object, the present invention has the following general formula (1) [However, R is an alkyl group or an allyl group, and R' is CI (,
Monosubstituted acetate residue or C0OR'
It is a monosubstituted acetamide residue represented by H,C0N(R'')2 (where R'' represents a hydrocarbon chain with a length of 04 or more and rich in hydrophobicity). A sensitive membrane for a sodium ion selective electrode is provided, which is characterized in that it contains at least one type of Caritas [4] arene compound represented by the following as a neutral carrier.

The caritas [4] arene compound of formula (1) used in the present invention has a sodium ion selectivity of about 250 times that of potassium ions, and is equivalent to the bis-12-crown-4 compound used in conventional sensitive membranes. Although the selectivity is approximately 125 times higher, it is extremely thick (therefore, by using the Caritas [4] arene compound of formula (1), the interference of potassium ions can be reliably eliminated and sodium ions can be measured accurately. Also, Caritas [4
] The allene compound has greater fat solubility than the bis-12-crown-4 compound, and is therefore reliably dissolved and retained in the organic solvent in the membrane, and is less likely to flow out of the membrane. For example, when a bis-12-crown-4 compound is used, the membrane life is about 6 months, but when a compound of formula (1) is used, it is about 1 year. . Furthermore, the compound of formula (1) has various advantages as a sensitive membrane material, such as being able to be produced at low cost and with good yield and having a wide quantitative range.

The present invention will be explained in more detail below.

As described above, the sensitive film of the present invention uses the caritas [4] arene compound of formula (1) as a neutral carrier.

In this case, specifically in the compound of formula (1), R=t
-C4H,, R'=CH, ester type where COOC1゜H2□, or R= t -C4Hs rR'
An amide type material such as =CH,C0N(n-C4H,)2 is preferably used. The drawings show examples of the responses of electrodes using ester-type and amide-type calix[4]arene compounds as neutral carriers, respectively.

Although there is no limitation on the method for producing the compound of formula (1), for example, caritas [4] arene synthesized from phenol and formaldehyde is combined with decyl-bromoacetate or N,N
Examples include a method of reacting -dibutyl-chloroacetamide.

The sensitive membrane according to the invention can be used as a solid membrane or a liquid membrane. The solid film is formed by uniformly dispersing the caritas [4] arene compound in a water-insoluble solid organic polymer as a support. Here, the above polymer forms a matrix for supporting the caritas [4] arene compound, which is a neutral carrier, in a film form, and prevents the neutral carrier from eluting into the sample aqueous solution, etc., and also prevents sodium in the sample aqueous solution. Any water-insoluble solid polymer can be used as long as it has a property that allows ions to diffuse into the matrix appropriately.1 Usually, polyvinyl chloride, polymethyl methacrylate, polyvinyl acetate, silicone rubber, paraffin, collodion, etc. One or a mixture of two or more of these can be used. A sensitive membrane using polyvinyl chloride as a support can be prepared by dissolving polyvinyl chloride, a plasticizer, and a Caritas [4] arene compound in an appropriate low-boiling point organic solvent, and then gradually evaporating the solvent in a plate for example. By doing so, it is formed into a film shape.

Plasticizers are used to impart appropriate flexibility to the resulting sensitive film, such as dibutyl phthalate, dioctyl phthalate, dioctyl sebaque-1, 0-nitrophenyl octyl ether, O-fluorophenyl-0-nitro Phenyl ether etc. are used. Any plasticizer for polyvinyl chloride can be used. In addition, like a sensitive film using silicone rubber as a support, Caritas [4] arene compound, silicon monomer, and if necessary, a silane compound for crosslinking the formed film are mixed in an appropriate organic solvent. It can also be produced by dissolving it, polymerizing it into a film, and then removing the solvent from the molded product.

Caritas [4] arene compound in solid film is 0.5~
It is desirable that the amount is 20% by weight, preferably 1 to 15% by weight. If the content of the Caritas [4] arene compound is too small, the response will be poor, and if it is too large, it will not only be difficult to uniformly disperse it in the polymer, but also uneconomical. When a plasticizer is used in combination, such as when polyvinyl chloride is used as a support, the plasticizer is
~80% by weight is suitable. In particular, 50 to 70% by weight is suitable. Note that it is generally desirable to mix 1% by weight or less of a hydrophobic salt, such as dipicrylamine-sodium salt, into the membrane.

In addition, the liquid film is formed by dissolving the Caritas [4] arene compound in a water-insoluble polar organic solvent. , aromatic ether,
Certain organic phosphorus compounds are used. Preferred specific examples include 1-decanol, nitrobenzene, chlorobenzene, bromobenzene, diphenyl ether, 1,
Examples include 2-dichloroethane and di-0-octylphenylphosphonate.

The content of Caritas [4] arene compound in the liquid film is 0
．． It is 5 to 20% by weight, preferably 1 to 10% by weight.

The liquid film is usually held in a porous ceramic or cellulosic support and used as an electrode. A porous film made of a fluororesin, such as a Millipore membrane, is also one of the preferred supports.

〔Effect of the invention〕

The sensitive membrane according to the present invention uses the Caritas [4] arene compound as a neutral carrier, and the above-mentioned Caritas [4] arene compound maintains the sodium ion concentration compared to the conventional one despite the presence of interfering ions such as potassium ions and ammonium ions. It can perform measurements with higher selectivity than conventional membranes, has a short response time, has excellent reproducibility, and has a long membrane life, making it a sensitive membrane for sodium ion-selective electrodes with high practical value. It is something.

Examples are shown below.

[Example 1] 9.7% of the compound of formula (1) synthesized from p-(t-butyl)-caritas[4]-arene and decyl-bromoacetate was used as a solvent. Sensitization using polyvinyl chloride as a support consisting of 35.5% of fluorophenyl-〇-nitrophenyl ether, 24.3% of polyvinyl chloride, and 0.5% of dipicrylamine sodium salt (each % by weight) A membrane was prepared. This sensitive membrane was cut into a circular shape with a diameter of 7 mm, and Ph1lips IS-
Attached to the bottom of the 561 electrode, Ag-AgCQ/1×10M NaCQ/membrane/measurement sample solution/O-I M N
H4N O3/K CQC4M)/Ag-AgCQ
(7) Using the electrode configuration, the activity of sodium ions in the measurement sample solution and the potential difference between the electrodes were measured, and a calibration curve was created.

All measurements, including this one, were made using Corning.
It was carried out using pHmeter 130 at 25@±0.1°C.

The calibration curve is linear over the pNa range of 5 to 1.

That is, it showed a Nernst response. In addition, virtually no influence by pH was observed over the pH range of 3 to 11.

Next, the selectivity coefficient KNaM for the interfering ion M+ is determined by the mixed solution method (for experimental methods, see, for example, G, J.

Moody and J.D.R.Thomas, “Ion Selective Electrode”, co-translated by Makoto Munemori and Kazuo Nikiro, published by Kyoritsu Shuppan in 1978 (
Detailed explanations are given in Chapter 2 of Issuance of Stocks. ), i.e.
The activity of the interfering ion M+ in the measurement sample solution is set to a constant a
The potential difference between the electrodes was measured by changing the activity of sodium ions while maintaining M+, and the activity aN8+ of Natowau 11 ions that no longer exhibited a Nernst response was determined, and this was divided by aM÷.

Therefore, KN8M:aN8+/aM+.

The selection coefficient KNaM for the interfering ion M+ is shown in Table 1.

[Example 2] p-(t-butyl)-caritas[4]-alene and N,N
The above (1) synthesized from -dibutyl-chloroacetamide
) in the formula R'=CH2CON(C4H9).

9.7% of the compound where R = t -C1H, and 65% of bis(2-ethylhexyl) sebacate as the membrane solvent.
A sensitive membrane was prepared using polyvinyl chloride as a support, consisting of 5% polyvinyl chloride, 24.3% polyvinyl chloride, and 0.5% dipicrylamine-sodium salt. The coefficient KNaM was measured.

The results are shown in Table 2.

[Brief explanation of the drawing]

The drawing is a graph showing an example of the response of an electrode using the sensitive membrane of the present invention. Applicant Toshiyuki Shono (and one other person) Representative Patent attorney Takashi Kojima

Claims (1)

[Claims] 1. The following general formula (1) ▲There are mathematical formulas, chemical formulas, tables, etc.▼...(1) [However, R is an alkyl group or an allyl group, and R' is CH_2
Monosubstituted acetate residue or C
It is a monosubstituted acetamide residue represented by H_2CON(R″)_2 (where R″ represents a hydrocarbon chain with a long chain of C_4 or more and rich in hydrophobicity). ] A sensitive membrane for a sodium ion selective electrode, characterized in that it contains at least one calix[4]arene compound represented by the following as a neutral carrier.