JPH05340916A - Coated wire type ion-selective electrode - Google Patents

Abstract

PURPOSE:To enable repetitive use of an expensive silver/silver chloride electrode by making it possible to bring an ion-sensitive film into close contact with the silver/silver chloride electrode and to detach it from the electrode simply, and to simplify maintenance by using an ion-selective electrode not using an internal electrolytic solution. CONSTITUTION:A macromolecular support film type film is used for an ion- sensitive film 2 and a macromolecular hollow body 1 is bonded to the ion- sensitive film 2. A silver/silver chloride electrode is fixed inside the body so that it can be held in a state of being brought into close contact with the ion- sensitive film 2, and the surface of the silver/silver chloride electrode which comes into contact with the ion-sensitive film 2 is made a curved surface.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ion electrode, and more particularly to an ion electrode for measuring ions such as sodium, potassium, chlorine and hydrogen in a biological fluid.

[0002]

2. Description of the Related Art Conventionally, an ion selective electrode has an internal reference liquid containing a certain amount of specific ions to be measured and an internal reference electrode as a potential detection lead wire for measuring the potential difference inside and outside the ion sensitive membrane. The ionic activity in the sample was measured by interposing it between the ion-sensitive membranes and determining the difference in the interface potential between the ion-sensitive membrane and the internal standard solution and the interface potential between the ion-sensitive membrane and the sample solution. However, since these ion-selective electrodes use an internal electrolytic solution, it is difficult to downsize the electrodes and maintenance is complicated.

For this reason, various types of coated wire type electrodes have recently been studied. This is the one in which the surface of a lead wire for detecting a metallic potential such as platinum is directly coated with an ion sensitive film made of a polymer. As an application example of this, a planar type ion electrode is described in JP-A-58-48844. This is one in which a solid polymer ion sensitive membrane is provided on a support plate to enable repeated measurement of the reference electrode, and an opening for inserting the reference electrode is provided in the support plate.

[0004]

In the conventional coated wire type ion selective electrode, the surface of the lead wire for potential detection is coated with an ion sensitive film by a brush or the like, or the lead wire is made of platinum or gold. It was a planar type in which a metal plate was electrically connected and an ion-sensitive film was laminated on the surface of the metal plate. These electrodes have an ion-sensitive film that is formed by applying a liquid ion-sensitive substance dissolved in a solvent to a lead wire or a metal plate connected to the lead wire and drying it. The mold electrode has a problem that the adhesion between the metal conductor and the ion sensitive film is poor. The air bubbles in the ion-sensitive film and the poor stability of the conductor-ion-sensitive film interface affect the signal potential drift and response speed of the ion-selective electrode. In the present invention, the signal potential is stabilized by mechanically improving the adhesion between the conductor and the ion sensitive film.

[0005]

In order to achieve the above object, the present invention provides a flat plate-shaped metal conductor surface interposed between a lead wire for potential detection and an ion-sensitive film to form a curved surface for polymer ion-sensitivity. A film is used, and a support made of a polymer insulator is adhered to the film, and the support is fixed to a metal conductor or a potential detection lead wire.

[0006]

[Function] The curved surface of the metal conductor in contact with the ion-sensitive film is convex toward the ion-sensitive film side, and when the ion-sensitive film support is fixed to the metal conductor, the ion-sensitive film and the metal conductor surface are mechanically separated. Adheres well. Therefore, the contact between the ion-sensitive film and the metal conductor interface is more stable than in the conventional method in which the ion-sensitive film is simply laminated on the surface of the metal conductor, so that the drift can be reduced and the service life is extended.

[0007]

1 is a cross-sectional view of a chloride ion electrode according to a first embodiment of the present invention. An ion-sensitive film 2 containing polyvinyl chloride is bonded to one end of a cylindrical hollow body 1 made of hard polyvinyl chloride by using an organic solvent such as tetrahydrofuran in advance. On the other hand, one end surface of a cylindrical silver 3 having an outer diameter equal to the inner diameter of the hollow body 1 is processed into a hemispherical shape, and a silver chloride layer 4 is formed on the surface. A lead wire 5 for potential detection is provided on the end face opposite to the surface on which the silver chloride layer 4 is formed.
Are electrically connected by soldering or the like. The hollow body 1 is fitted into the hollow body 1 so that the silver chloride layer 4 comes into close contact with the ion-sensitive film 2 from the other end of the hollow body 1 as shown by an arrow 6. A degassing groove 7 for exhausting air between the silver chloride layer 4 and the ion sensitive film 2 is provided on the side surface of the cylindrical silver 3.

FIG. 2 is a cross-sectional view of a chloride ion electrode according to the second embodiment of the present invention. An ion sensitive membrane 2 containing polyvinyl chloride is bonded to one end of the hollow body 1. On the other hand, one end surface of a cylindrical silver 3 having a diameter equal to or smaller than the inner diameter of the hollow body 1 is processed into a hemispherical shape, and a silver chloride layer 4 is formed on the surface thereof. A lead wire 5 for potential detection is connected to the opposite end surface of the silver chloride layer 4. After inserting the silver 3 into the hollow body 1 so that the silver chloride layer 4 on the surface is in contact with the ion-sensitive membrane, a silicone rubber packing 9 having an opening 8 for taking out the lead wire to the outside of the hollow body is provided inside the hollow body. The silver 3 is fixed so as to be in close contact with the ion sensitive film 2.

FIG. 3 is a cross sectional view of a chloride ion electrode according to a third embodiment of the present invention. A thread is machined inside a cylindrical hollow body 1 made of hard polyvinyl chloride. On the other hand, a hemispherical silver 3 is adhered to a support 10 made of an insulating material, which is formed in conformity with the thread inside the hollow body 1, and a silver chloride layer 4 is formed on the surface thereof. A lead wire 5 is connected to the silver 3 and is connected to a detector outside the hollow body through the opening 11 of the support 10. The silver 3 and the support 10 are fixed inside the hollow body 1 by screws, and the silver chloride layer 4 formed on the surface of the silver 3 adheres to the ion sensitive film 2.

FIG. 4 is a cross-sectional view of a multi-ion electrode in which sodium ion, potassium ion and chloride ion electrodes according to a fourth embodiment of the present invention are integrated. Frame 12
The printed circuit board 13 is set in. The lead wire 5 for potential detection is soldered to the metal conductor pin 14, and the hemispherical silver 3 is electrically adhered to the upper portion of the pin 14 with silver paste or the like. The pin 14 is inserted into the hole formed in the printed circuit board 13, and the epoxy filler 15 is injected onto the hole. on the other hand,
The ion sensitive membrane 2 is adhered to the hollow body 1 formed according to the outer diameter of the pin 14 with tetrahydrofuran to form the hollow body 1
It is inserted into the silicon rubber sheet 16 having a hole corresponding to the outer diameter of. The frame 12 and the silicone rubber sheet 16 have engaging portions 17 and 18 for fixing the silicone rubber sheet 16 to the frame 12.

The ion sensitive membrane used in these examples is a polymer supporting membrane in which a ligand is dispersed in a polyvinyl chloride membrane. As a ligand which is an ion-sensing substance, valinomycin is used for potassium ion, biscrown ether is used for sodium ion, and quaternary ammonium salt is used for chlorine ion.

FIG. 5 shows an outline of a flow type blood electrolyte analyzer using the fourth embodiment of the present invention. Sample 19 is
The diluted solution 20 is introduced by the ironing pump 21 into the sensitive portion 22 having the ion sensitive membrane 2 as a part of the flow path.
Ions such as sodium, potassium, and chlorine contained in blood are taken into the sensitive membrane by the ligand in the ion sensitive membrane, causing a change in membrane potential. This change is detected by the potential difference between the electrode made of silver 3 and silver chloride 4 serving as the internal electrode and the comparison electrode 23. The potential is read into the calculator 25 through the amplifier 24, and the concentration of each ion contained in blood is calculated according to the Nernst equation. The calculated ion concentration is displayed or printed out by the display unit 26.

FIG. 6 and FIG. 7 show the results of the evaluation of the fourth embodiment of the present invention using the control serum as the sample, which are related to the chloride ion electrode. FIG. 6 is a correlation diagram of a coated wire type chloride ion electrode using an ion selective electrode using an internal electrolyte as a reference method. Error variance of correlation with standard method (Sy
x) shows a good correlation with 2.0 mmol / l. Figure 7
[Fig. 4] is a diagram showing changes in sensitivity with time. Equivalent to 0.1 mv / h compared to the ion selective electrode using the internal electrolyte
Within the drift, I maintained more than 50mv / decade for 2 months.

[0014]

According to the present invention, since the ion sensitive film can be adhered to the silver / silver chloride electrode and can be easily detached, the expensive silver / silver chloride electrode can be repeatedly used. Moreover, since the electrode is an ion-selective electrode that does not use an internal electrolyte, maintenance is easy.

[Brief description of drawings]

FIG. 1 is a sectional view of a first embodiment of the present invention.

FIG. 2 is a sectional view of a second embodiment of the present invention.

FIG. 3 is a sectional view of a third embodiment of the present invention.

FIG. 4 is a sectional view of a fourth embodiment of the present invention.

FIG. 5 is a system diagram of a blood electrolyte analyzer using the fourth embodiment of the present invention.

FIG. 6 is a characteristic diagram of a chlorine electrode having a constitution of the present invention and a conventional ion selective electrode using an internal electrolytic solution.

FIG. 7 is an explanatory diagram of a change over time in the sensitivity of the chlorine electrode having the configuration of the present invention.

[Explanation of symbols]

1 ... Hollow polymer, 2 ... Ion-sensitive membrane, 3 ... Silver, 4 ... Silver chloride layer, 5 ... Lead wire, 6 ... Arrow, 7 ... Degassing groove.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Watanabe ▲ Yoshi ▼ Yu ▼ 1-280 Higashi-Kengikubo, Kokubunji-shi, Tokyo Inside the Central Research Laboratory, Hitachi, Ltd.

Claims (4)

[Claims] 1. A polymer ion-sensitive membrane, a hollow body made of a polymer insulator adhered under the polymer ion-sensitive membrane and having openings at both ends, and a hollow body installed inside the hollow body. In the ion-selective electrode made of a metal conductor, a surface of the metal conductor in contact with the ion-sensitive film has a convex curved surface on the ion-sensitive film side, and the hollow body made of the polymer insulator is A coated wire type ion-selective electrode having a mechanism for fixing a metal conductor. 2. An ion electrode comprising a metal conductor whose one surface is a curved surface convex to the outside and a solid polymer ion-sensitive film adhered to the curved surface of the metal conductor, and a high electrode around the ion electrode. A coated wire type ion-selective electrode having an ion-sensitive membrane support made of a molecular insulator. 3. The coated wire type ion-selective electrode according to claim 1, wherein the ion-selective electrode has an organic and inorganic electrolyte layer at an interface between the metal conductor and the ion-sensitive film. 4. The hollow body made of the polymer insulator and the ion-sensitive membrane adhered to the hollow body according to claim 1, can be attached to and detached from the metal conductor installed inside the hollow body. Coated wire type ion selective electrode.