JPS6031257B2 - Anion selective electrode - Google Patents

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to an anion-selective electrode, particularly an anion-selective electrode equipped with a polymer resin sensitive membrane suitable for measuring anions in biological samples. Regarding sex electrodes.

[Background of the Invention] Ion-selective electrodes are used to determine ion concentration through a reaction that occurs between the ion to be measured and the sensitive surface when the electrode is immersed in a test sample solution. It is also becoming widely used in the field of clinical testing.

Among ion-selective electrodes for clinical tests, ion-sensitive groups and plasticizers are dispersed in a polymeric resin material to form a polymeric resin sensitive membrane, and this sensitive membrane is used as a container-shaped member in which a reference liquid is stored. Polymer membrane electrodes for measuring cations such as sodium and potassium and anions such as chlorine have been put into practical use. Polymer membrane-type anion-selective electrodes, such as chloride ion electrodes, operate stably when measuring serum samples, and therefore have good correlation with chloride counters, which are said to have high measurement accuracy. However, when a urine sample is measured, a measurement value that is 20 to 40% higher than the measurement value using a chloride counter is obtained, and there is a problem in that the reproducibility of the measurement is poor. As a result of the inventors' experiments, it is assumed that the reason for the large analytical error in the measurement values of the anion-selective electrode for urine samples is likely to be due to the relatively large amount of anionic organic components contained in the urine samples. Ta.
[Object of the invention] The object of the present invention is to be easy to manufacture,
An object of the present invention is to provide an anion-selective electrode that has small measurement errors and excellent responsiveness for urine samples.

[Summary of the invention]

In the present invention, the container-like member in which the internal electrodes are housed is formed of polyvinyl chloride, the sensitive film is formed of polyvinyl chloride containing a quaternary ammonium salt, the sensitive film in the parentheses is joined to the container-like member, An outer layer made of a cellulose-based polymer membrane permeable to inorganic ions is formed on the outer surface of the sensitive membrane, and this outer layer and the sensitive membrane are welded and bonded, and the thickness of the outer layer is 50 mm thinner than that of the sensitive membrane. m or less.

In a preferred embodiment of the present invention, the sensitive membrane is formed by dispersing a quaternary ammonium salt containing 1 to 4 alkyl chains having 7 to 1 carbon atoms in polyvinyl chloride. The molecular membrane is formed from acetylcellulose having 1 to 3 acetyl groups.

The sensitive membrane and the cellulose polymer membrane are welded together. [Embodiments of the Invention] The configuration and measurement performance of an embodiment based on the present invention will be described below.

FIG. 1 is a longitudinal sectional view of an anion selective electrode according to an embodiment of the present invention.

A container-shaped body 2 made of polyvinyl chloride, for example, a cylindrical tubular shape.
The upper end is sealed with a lid 5, and the reference liquid 3 is inside.
It accommodates. A linear electrode 4 is inserted into the reference liquid 3. 6 is a lead wire.

A membrane 1 is formed at the lower end of the body 2.

The membrane 1 has a relatively thick inner layer la and a thin outer layer lb, with the inner layer la being in contact with the reference liquid 3. When measuring a test sample, the electrode shown in FIG. 1 is immersed near its tip in the test sample liquid, and at this time the outer layer lb comes into direct contact with the test sample liquid. Here, an example of an electrode for measuring chloride ions in a biological sample liquid will be explained.

The inner layer la contains 1 to 4 alkyl chains having 7 to 1 carbon atoms.
A quaternary ammonium salt such as silidodecyl ammonium chloride is dispersed in polyvinyl chloride. To form the inner layer la at the end of the main body 2, firstly, 20 to 25% by weight of tridodecylammonium chloride and 75 to 8% by weight of hydrophobic polyvinyl chloride are mixed.
The mixture is mixed so as to be dissolved in the solvent tetrahydrofuran, and the solution is poured into a container with a shallow flat bottom to remove the solvent and form a plate-like membrane. Next, a size corresponding to the size to be bonded to the electrode is cut out from this plate-like membrane, and the cut-out piece is welded and bonded to the main body 2 made of the same material as the membrane base material using tetrahydrofuran. Since the sensitive membrane serving as the inner layer is made of the same polyvinyl chloride as the container-shaped main body 2,
Easy to bond and difficult to peel off. In the next step, the inner layer l
An outer layer lb is bonded to the outer surface of a.

Hydrophilic acetyl cellulose having 1 to 3 acetyl groups is suitable for the membrane base material of the outer layer. Acetylcellulose is dissolved in tetrahydrofuran to a weight ratio of 2 to 3% to form a liquid, and the lower end of the main body 2 to which the inner layer la is fixed is immersed in the solution and then pulled up to evaporate the tetrahydrofuran.

During this bonding, the surface layer of the PVC sensitive membrane is slightly dissolved by tetrahydrofuran, which is a solvent for the acetylcellulose solution, and a thin layer of a mixture of PVC and acetylcellulose appears at the interface. As a result, a thin layer of the outer layer lb is formed on the inner layer la, but in order to form the outer layer lb, it is also possible to use a method in which a tetrahydrofuran solution in which acetyl cellulose is dissolved is made into a mist and then sprayed onto the inner layer la and dried. good. When the two layers are welded and bonded in this manner, the thickness of the outer layer lb is 10 to 15 rm. The outer layer lb of the membrane 1, in which the inner layer and the outer layer are integrated, allows inorganic ions with a relatively small hydrated ion radius to permeate well, but organic ionic proteins with a large hydrated ion radius have poor permeability. It is presumed that only inorganic ions are selectively detected by la.

The inner layer, the sensitive membrane, and the outer layer, the acetyl cellulose layer, are deposited and bonded to each other by melting at the bonding surfaces, so that no voids are created between the inner layer and the outer layer.

If there are gaps, liquid will enter and reduce responsiveness, but this does not occur in the example of the present invention. Moreover, since the bonding strength is high, it is difficult to peel off. Since the outer layer is made of a cellulose polymer membrane and is hydrophilic, anions in the sample liquid easily enter the inner layer. Therefore, it works to improve responsiveness. If the outer layer is a hydrophobic material, the response speed will be reduced. On the other hand, the inner sensitive membrane is made of polypinyl chloride and is hydrophobic, so it prevents liquid from penetrating too much into the membrane. Next, an anion selective electrode according to another embodiment of the present invention will be explained.

In preparing the inner layer la of the membrane 1 shown in FIG.
%, 5-15% phenyl alkyl alcohol by weight
, polyvinyl chloride is dissolved in tetrahydrofuran to a weight ratio of 60 to 79%. That is, in addition to the tridodecylammonium chloride and polyvinyl chloride used in the previous example, phenylalkyl alcohol was used to form the inner layer.
The manufacturing methods of a and the outer layer lb are the same as in the previous example.
According to this example, the selective sensitivity to inorganic ions is the same as that of the previous example, and the response speed is also faster than that of the previous example.

Figures 2 and 3 compare the measured values obtained when the present invention is applied, that is, the chloride ion electrode obtained in the first example, and when the present invention is not applied, that is, the single-layer membrane electrode. .

Figure 2 shows the correlation between an electrolytic chloride counter widely used for clinical testing and an electrode before applying the present invention (subsequent ion-selective electrode), and Figure 3 shows the correlation between an electrolytic chloride counter widely used for clinical tests and an electrode to which the present invention was applied. The correlation between electrodes and chloride counters is shown. These data are the results of measurements for 24 urine samples from patients. Note that both the vertical and horizontal axes of the figure are the displayed values of meters. It is understood that when the present invention is applied, the correlation with the chloride counter, which has high measurement accuracy, will be significantly improved. FIG. 4 shows the relationship between the first and second measured values of chloride ions in a urine sample for confirming the reproducibility of measured values by the electrode to which the present invention is applied.

In this way, even if the sample is urine, high analytical accuracy can be obtained by applying the present invention. FIG. 5 compares the response speed of a conventional electrode and an electrode to which the present invention is applied when measuring chloride ions for a urine sample, and the measured value 11 of the chloride counter is shown for reference.

The vertical axis is the meter display value of each measuring device, and the machine axis is the response time from when the electrode was immersed in the urine sample liquid. The value 12 measured by the conventional electrode is not stable past 3 sands and drifts much higher than the value measured by the chloride counter. Measured value 13 of the electrode to which the present invention is applied stabilizes in about 11 seconds.

Figure 6 shows a urine sample with a chloride concentration of 15 skin M.
This figure shows the relationship between the thickness of the acetylcellulose membrane and the degree of reduction in measurement error.
It was possible to almost completely eliminate the influence of interfering components above the limit.

However, as the film thickness increases, the response speed becomes slower, and in particular, if the film thickness exceeds 100 m, the response speed becomes so slow that it cannot be put to practical use. Therefore, for practical purposes, the film thickness is desirably 30 to 50 m. FIG. 7 shows the results of a study to determine whether the performance of an electrode to which the present invention is applied is reduced by immersing it in water and then drying it.

When conventional single-layer membrane electrodes are dried after being immersed in water, the membrane shrinks and does not function stably as an electrode, making it impractical. As can be understood from the results in FIG. 7, if the present invention is applied, the performance will hardly deteriorate even after immersion in water and drying. The results shown in FIG. 7 were obtained by soaking the electrode in water for 15 days and then drying it naturally in the air for 11 days, measuring urine samples of various concentrations, and comparing the results with the measurement results of a chloride counter. Since it is now possible to use the electrode even after it has been immersed in water and dried, it is possible to eliminate the troublesome maintenance required to keep the electrode constantly moistened, which improves ease of handling.
FIG. 8 is a correlation diagram between the results of measuring liquid hydrogen ions in a human serum sample using an electrode to which the present invention is applied and the values measured by a chloride counter.

Highly accurate measurement is also possible for serum samples. [Effects of the Invention] In the present invention, since the container-like member and the sensitive film (inner layer) are formed of the same polyvinyl chloride, they can be easily joined together simply by using a solvent, and the effect is achieved that they are difficult to separate. be done.

And since the inner layer and outer layer are welded and joined,
It is possible to prevent liquid from entering between the two layers, resulting in far more responsiveness. Moreover, the inner layer is made of hydrophobic polyvinyl chloride, and the outer layer is made of a hydrophilic and inorganic ion-permeable cellulose-based polymer material, and the thickness of the outer layer is less than 50 mm.
It is possible to reduce the measurement error of anions even in urine samples while maintaining high responsiveness.

[Brief explanation of drawings]

FIG. 1 is a diagram for explaining an embodiment of the present invention, FIG. 2 is a diagram showing an example of measured values using a conventional electrode, and FIG. 3 is a diagram showing an example of measured values using an electrode to which the present invention is applied. Figure 4 is a diagram for examining reproducibility, Figure 5 is a diagram comparing response speeds for urine samples, Figure 6 is a diagram showing the relationship between the influence of interfering components and the thickness of the acetyl cellulose membrane, and Figure 7 is a diagram for water immersion. FIG. 8 is a diagram examining performance deterioration due to the electrode after drying, and FIG. 8 is a diagram showing an example of measured values of a serum sample. 1...Membrane, la...Inner layer, lb...Outer layer, 2...Main body, 3...Reference liquid, 4...
...Internal electrode. Leopard figure 2 figure Tsutomu 3 office work 4 figure grandchild figure purple 5 figure hair 2 figure Tsutomu figure

Claims (1)

[Scope of Claims] 1. A reference liquid in which the internal electrodes are immersed is contained in a container-like member, and the container is placed such that a polymer resin sensitive membrane containing an anion-sensitive substance is in contact with the reference liquid. In the anion selective electrode provided in the container-shaped member, the container-shaped member is made of polyvinyl chloride, the sensitive membrane is made of polyvinyl chloride containing a quaternary ammonium salt, and the sensitive membrane is provided in the container-shaped member. An outer layer made of an inorganic ion-permeable cellulose polymer membrane is formed on the outer surface of the sensitive membrane, and this outer layer and the sensitive membrane are welded and bonded, and the thickness of the outer layer is equal to the thickness of the sensitive membrane. 50μ thinner than the film thickness
An anion selective electrode characterized in that the anion selectivity is less than or equal to m. 2. The anion-selective electrode according to claim 1, wherein phenyl alkyl alcohol is dispersed in the sensitive membrane.