JPH0128337B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a solid electrode integrated plate for measuring ion concentration or ion activity and a method for using the same. The present invention relates to a solid electrode integrated plate for measuring ion concentration or ion activity, which is used to potentiometrically measure ion concentration or ion activity in body fluids such as, and methods for using the same.

The electrodes in the solid electrode integrated plate for measuring ion concentration or ion activity of the present invention have the same structure as what is generally called a half cell or a single electrode.

In general, K, Na, Ca〓, Cl,
Measuring the concentration of inorganic ions such as HCO ₃ is clinically important, and methods using wet ion-selective electrodes have already been proposed and implemented for this purpose.

All of these methods measure by immersing needle-shaped (or rod-shaped) electrodes into biological fluids.
The electrodes require maintenance, cleaning, and conditioning, have a short lifespan, and are easily damaged, making them difficult to manage. Furthermore, each time a measurement is made, it is necessary to fully immerse the electrode head in the test sample solution contained in a container such as a cup, which requires several hundred micrometers or more of the test sample solution. In view of the drawbacks of such wet ion-selective electrodes, a dry type electrode film was developed in JP-A-52-142584 in which a four-layer laminated electrode is provided on a support and the entire structure is in the form of a film.
Disclosed in the issue. In such a film-shaped electrode, a very small amount (for example, 5 μ to 50 μ) of a sample liquid to be tested is placed on a predetermined position of the electrode for measurement. FIG. 1 shows an example of an electrode film having a conventional four-layer laminated structure. In the figure, on the support 1 are a metal layer 2, an insoluble metal salt layer 3, a reference electrolyte layer 4, and an ion selective layer 5.
An electrode film having a four-layer laminated structure laminated in this order is supported. In one preferred embodiment, the metal layer 2 is silver, the insoluble metal salt layer 3 is silver chloride, and the reference electrolyte layer 4 is a hydrophilic organic polymer binder dispersed layer of potassium chloride.

Next, the above-mentioned electrode film is not limited to the four-layer structure, and electrode films having other structures can also be used. For example, in Japanese Patent Application No. 55-92378 (Japanese Unexamined Patent Publication No. 57-17851), the reference electrolyte layer 4 shown in FIG. 1 is removed, and the insoluble metal salt layer 3 is
An electrode film having a three-layer laminated structure on which an ion selective layer 5 made of an organic material is directly provided is disclosed.

The ion selective layer 5 is essential when the ions to be measured are K, Na, Ca〓, HCO ₃ , but when the ions to be measured are Cl,
When the electrode has a layer structure in which silver is used as the metal layer 2 and silver chloride is used as the insoluble metal salt layer 3, or a layer structure in which a layer of potassium chloride is further provided as the reference electrolyte layer 4 in addition to the above layer structure, an ion selective layer is formed. 5 is unnecessary, and instead serves as a mere protective layer, for example, cellulose acetate, which is defined as a halogen ion permeable coating layer in JP-A-55-89741,
Polymethacrylic acid, polyacrylic acid, poly(2
-hydroxyethyl acrylate).

When measuring ion concentration using the two electrodes described above, connect the pair of electrodes with a bridge (described later), connect them to a potentiometer, and then connect the test sample solution and standard solution. By depositing each on the pair of electrode films and measuring the potential difference with a potentiometer, the concentration of the test ion contained in the deposited test sample liquid is measured. In this case, the pair of electrode films must be electrically isolated.
For this purpose, it is particularly advantageous to house the above-mentioned pair of electrodes in a frame made of non-conductive material such as plastic, as shown in FIG. It was proposed in 142584 of 1972.

As illustrated in FIG. 2, the frame 10 is in the form of a flat member 11, which can be conveniently stacked for processing in automated processing equipment or for storage. Two rectangular cavities are formed in the bottom surface 12 of the flat member 11 to house and support in spaced relation two similarly shaped electrodes 13, 14, shown in dashed lines. Holes 15 and 1 are formed on the upper surface of the flat member 11.
6 is formed and the lead wire 21 of the potentiometer 20
and 22 can be brought into electrical contact with the conductive layers of electrodes 13' and 14, respectively. Also formed in the upper surface of member 11 are circular holes 17 and 18, which lie directly above each electrode and communicate with the ion selective layer.
Droplets of the standard solution and test solution are brought into contact with the electrodes through these holes. To prevent droplet expansion across the upper surface of member 11, holes 17 and 18 are enlarged to create a sloped surface at the border edge.

hole 17, as required in potentiometric measurements.
A "bridge 19" is formed between the holes 17 and 18 to allow movement of ions between the droplets located on the holes 17 and 18. Bridge 1 like this
9 is the shape of a groove formed between holes 17 and 18. Preferably, the grooves are coated with a surfactant capable of promoting ion migration. When the frame plastic is hydrophobic, examples of suitable surfactants are octylphenoxypolyethoxyethanol, nonylphenoxyethanol. The drops then flow together due to capillary action to create a junction. Alternatively, groove 19
can be coated with an ionic porous material. The ionic porous material consists of, for example, a binder, a thickener and a material such as polycarbonate or polyamide, which material is mixed with atomized silica or glass powder.

In the embodiment shown in FIG.
As a result, a groove is provided between holes 17 and 18,
This bridge 19 is not limited to that shown in FIG. For example, in Japanese Patent Application Laid-Open No. 55-20499, as shown in FIG. Configurations have been proposed that allow the movement of ions. The bridge 19 used here is generally referred to as a capillary action bridge, and its details will be described below.

Capillarity Bridge The capillarity bridge 19, shown in cross-section in FIG. 4, is a means for promoting ion transfer between electrodes 13 and 14. Capillarity bridge 19 can be formed from three-layer trilaminates of various compositions. As shown, the bridge is a flat composite strip with holes 17 and 18 into which droplets of solution 27, 28 are deposited. The capillarity bridge consists of (a) a non-porous bottom support layer 24, which faces the electrode, (b) an intermediate porous layer 25 and
(c) consisting of a top non-porous hydrophobic layer 26, which emanates from the electrodes;

In order to prevent an interlayer short circuit of the electrode due to flow of the test sample solution or standard solution from the bridge to the electrode, the bridge is sealed to the electrode at least around the holes 17 and 18.

Examples of intermediate porous layers 25 are porous paper, membrane filters, threads, textiles, into which the droplets 27 and 28 are absorbed and ion movement and thus contact is achieved. When a drop of solution is placed in holes 17 and 18, the liquid fills the holes and forms a large cap on top layer 26 and is then absorbed into layer 25 within 5 to 30 seconds. Liquid from each droplet spreads through the capillary bridge until contact occurs approximately in the center of the bridge and ionic coupling is achieved. Also, sufficient liquid remains unabsorbed to fill holes 17 and 18.

Other examples of suitable materials for the porous intermediate layer are described in JP-A-52-142584.

Furthermore, other embodiments of the bridge can be found in JP-A-Sho.
It is described in No. 55-59326, No. 55-71942, etc.

When measuring ion concentration using the equipment shown in FIGS. 2 and 3, droplets of the standard solution and test solution are placed in the holes 17 and 11, respectively, as described above.
8, the wire-shaped lead wires 21 and 22 are brought into contact with the electrode films 13 and 14,
The potential difference generated at this time is read by a potentiometer 20 to measure ion concentration. Therefore,
After each measurement of the test liquid, the measuring cell must be disconnected from the potentiometer leads 21 and 22 and discarded. Therefore, the leads 21 and 22 of the potentiometer 20 must be connected to the electrodes of the measurement cell for each measurement of each test liquid, and the contact resistance between the leads and the electrodes occurs for each measurement. Measurement errors caused by changes and variations in the values were a problem. For details,
The measurement accuracy when using a conventional PH meter etc. is 1
On the other hand, when using the above-mentioned equipment, a measurement accuracy of the order of 0.1 mV is required, so the contact resistance mentioned above plays a large role in the measurement error. Conceivable.

Secondly, the measurement cell as mentioned above is a so-called disposable device that must be discarded after each test liquid to be tested, so the production process is complicated;
By minimizing waste, it is desirable to supply uniform measuring instruments in large quantities and at low cost, with no variation among measuring instruments. 1st to 4th
The film-like electrode shown in the figure is manufactured by the following steps.

(1) A metal layer 2 is provided on a support 1 such as a polyethylene terephthalate (PET) film by vapor deposition or chemical plating of a metal such as silver.

(2) After protecting a part of the metal vapor deposited layer with tape or the like, an insoluble metal salt layer 3 is provided.

(3) In the case of an electrode with a four-layer structure, a reference electrolyte layer 4 is provided.

(4) Finally, the ion selective layer 5 is provided by means such as coating.

Generally, when an ion selective layer is provided by means such as coating, there is a high risk of coating unevenness in the vicinity of the exposed part of the metal layer, as shown by A in FIG. 5, that is, in the peripheral area. When the electrode is actually used, it is necessary to create an electrode of such a length that it has a predetermined dead portion A relative to the exposed metal portion, as shown in FIG. In this case, since silver and ion selective layers are expensive, even if a uniform electrode can be obtained, production costs will inevitably increase.

The present invention was made in view of the shortcomings of conventional measuring instruments, and its purpose is to provide uniform quality, inexpensive measuring instruments that do not require complicated operations such as masking and striping in the production process. An object of the present invention is to provide a solid electrode integrated plate for measuring ion concentration or ion activity with high measurement accuracy, which has a film electrode for measuring ion concentration or ion activity.

The solid electrode stack plate for measuring ion concentration or ion activity of the present invention comprises two or more elongated solid electrodes each having one common electrical connection terminal at one end or in the vicinity thereof in the longitudinal direction, and the above-mentioned electrodes. The device is characterized by having a plurality of dry bridges including a porous member that allows ion transfer between the electrodes after the liquid is deposited on the electrode.

Furthermore, in the method of using the solid electrode integrated plate for measuring ion concentration or ion activity of the present invention, when measuring the ion concentration or ion activity of a specific ion in a test sample solution, one longitudinal end of each or two or more elongated solid electrodes having one common electrical connection terminal near the electrodes, and a plurality of porous members that allow ions to move between the electrodes after a liquid is deposited on the electrodes. A potentiometric measuring device for measuring ion concentration or ion activity as a potential change is connected to the common electrical connection terminal of the solid electrode integrated plate for measuring ion concentration or ion activity having a dry bridge. Alternatively, during ion activity measurement, the electrical connection is fixed, and the standard solution and the analyte are placed on the part of the bridge facing the electrode located at the farthest point from the common terminal part along the long solid electrode. A test sample solution is spotted, both solutions diffuse through the bridge, and the tip interfaces of both solutions are brought into contact in the middle of the bridge, and the potential difference in the test sample solution is determined from the potential difference measured by the potentiometer. A step of measuring the ion concentration or ion activity of a specific ion, and then cutting off the spent bridge located at the farthest point by cutting the electrode between the used bridge and the unused bridge. It is characterized by consisting of.

The background to the realization of the solid electrode integrated plate with the above structure is that by using a dry capillary action bridge as the bridge, the test sample solution and standard solution are spotted on the bridge, and both solutions are absorbed into the bridge. It is only when the tip interfaces of both liquids come into contact in the middle of the bridge that ions can move within the bridge. Therefore, when measuring ion concentration or ion activity using the bridge located farthest from the common electrical connection terminal of the long solid electrode, unless the other bridges are contaminated with an aqueous solution, etc. Even if there are many dry bridges on the long solid electrode that are closer to the common terminal than the bridge in use, these can be ignored from an electrical point of view, and the test sample liquid It does not interfere with the measurement of ion concentration or ion activity in the sample.

Hereinafter, the present invention will be explained in detail with reference to the drawings.

FIG. 6-1 is a plan view showing an embodiment of the solid electrode stack plate for measuring ion concentration or ion activity of the present invention, in which a long solid electrode 30 for standard solution and a long solid electrode for test sample solution are shown. 31 form a pair, the metal layer 2 is exposed at one end of each electrode, forming a common electrical connection terminal part 34, and the common terminal part 34 is connected to the lead wire of the potentiometer 20 through the probe 32. 2
1 and 22. As is clear from the figure, the long solid electrodes 30 and 31 are as follows:
This is a conventionally known film electrode or a film electrode disclosed in Japanese Patent Application No. 55-92378 shown in FIG. 5, which is extended in the longitudinal direction (in the direction of the horizontal arrow in FIG. 5). In this case, the length is
The electrical resistance of the film electrode can be set arbitrarily within a range that does not affect the measured value. A plurality of ladder-like bridges 19 are provided on the pair of elongated solid electrodes 30 and 31 as shown. In these plurality of bridges 19, in order to prevent contamination between adjacent bridges due to seepage of the test sample solution or standard solution, sufficient distance between the bridges should be maintained, or each bridge should be connected to the test sample solution or the standard solution. It is desirable to seal it so that the liquid or standard solution does not seep out. As for the bridge, any conventionally used capillary action bridge can be used.

When measuring ion concentration or ion activity using the solid electrode stack configured as described above, the potentiometer 20 is connected to the common terminal section 34 via the probe 32, as described above. After that, the standard solution and the test sample solution are respectively placed in the holes 17 and 18 of the bridge 19 located at the farthest point with respect to the common terminal part 34, and both solutions spread into the bridge, and both solutions are mixed in the middle of the bridge. The ion concentration or ion activity is measured based on the potential difference indicated by the potentiometer 20 after the tip interfaces of the two contacts. After completing the measurement of the ion concentration or ion activity of the test sample liquid, the used bridge 19 is discarded as shown in FIG. 6-2. The next measurement of ion concentration or ion activity is performed using a new bridge 19 that was adjacent to the truncated bridge 19 and by the same operation. Such operations are performed in sequence, and the pair of long solid electrodes 30 and 31 are used as common electrodes for the number of measurements corresponding to the number of bridges provided therein. In the measurement of ion concentration or ion activity using the solid electrode integrated plate configured as described above, the potentiometer 20 is always connected to the probe 32 while the measurement is being carried out a number of times corresponding to the number of bridges 19. Since the electrical contact resistance between the potentiometer 20 and the long solid electrodes 30 and 31 is always constant, it is different from the conventional connection for each test cell. It is relatively reliable and stable. Furthermore,
The dead space near the boundary between the coating layer, for example, the ion selective layer 5 and the metal layer 2, is only needed at one location compared to multiple bridges 19, so manufacturing waste can be minimized and production costs can be reduced. be able to.

In the embodiment described above, the potentiometer 20 is connected to the probe 3.
2 to the common terminal section 34, however, the connection method is not limited to this. Specifically, without providing the common terminal portion 34, the entire long solid electrodes 30, 31 have a substantially uniform half-cell structure, while the lead wires 21, 22 of the potentiometer 20
It is also possible to use a configuration in which the tips of the electrodes are used as needle-like connection terminals, and these are inserted from above or below the long solid electrodes 30 and 31, so that the tips are electrically connected to the metal layer 2. Furthermore, if an inexpensive metal such as nickel is used instead of an expensive metal such as silver as the metal layer 2, the thickness of this metal layer should be increased to a certain extent to provide rigidity, and the support 1 may be omitted. is also possible. In this case, the electrical connection between the potentiometer 20 and the metal layer 2 can be made directly between the metal layer 2 and the lead wires 21, 22 below the long solid electrodes 30, 31.

Further, as for the support 1 of the long solid electrode, it is possible to use a material with some degree of rigidity and to form a pallet-shaped solid electrode stack. may be housed in a housing, for example, a cartridge-like housing 35 for photographic film, as shown in FIG. 7, and electrically connected to a potentiometer at its rotation axis. In this case, the support 1 may be a common support for the long solid electrodes 30 and 31 as shown in the figure, and may also be used to provide electrical insulation between the long solid electrodes, etc., for measuring the ion concentration or ion activity described above. Needless to say, consideration must be given to the design to avoid any problems. Furthermore, if a cutter for cutting the bridge is integrally provided in the cartridge-shaped housing 35, it will be more effective.

Another embodiment according to the present invention will be described with reference to FIG.

FIG. 8 is a plan view showing another embodiment of the present invention. In the figure, members common to those in FIGS. 6-1 and 6-2 are designated by the same reference numerals. The embodiment shown in FIG. 8 has a new elongated solid electrode 3 on the right side when facing the drawing of the solid electrode integrated plate shown in FIG. 6-1.
Long solid electrode 33 having the same configuration as 0, 31
It has been established. In this case, the hole 1 of the bridge 19 corresponding to the long solid electrode 30 located at the center
A standard solution is spotted at 7, and a test sample solution is spotted at holes 18 of bridge 19 corresponding to long film electrodes 31 and 33 located on both sides thereof. By arranging the bridges 19 as indicated by "B" in FIG. 8, the risk of cross-contamination between test sample liquids spotted in the holes 18 of adjacent bridges is reduced, and the distance between adjacent bridges is reduced. As a result, long solid electrodes can be used effectively. Also, in the diagram, "C"
A bridge as shown in can also be used. In this case, it is possible to measure the ion concentration or ion activity of different types of test sample liquids with a single bridge, and it is also possible to measure the ion concentration or ion activity of the same test sample liquid multiple times at the same time. Become. It goes without saying that by changing the shape of the bridge, etc., the number of long solid electrodes corresponding to the sample liquid to be tested can be increased to a plurality. As for the embodiment shown in FIG. 8, it is also possible to make the electrical connection between the linear metal layer 2 and the potentiometer 20 via the needle-like connection terminal as described above, or by storing it in the housing. Needless to say, you can use it.

As described above, according to the present invention, it is possible to eliminate complexity in the production process and realize a solid electrode integrated plate for measuring ion concentration or ion activity that is inexpensive and has high accuracy. In the explanation up to this point, the present invention has been explained along with the illustrated embodiments, but the present invention is not limited to these embodiments. It should be understood that evolutionary modifications may be readily made by those skilled in the art without departing from the invention.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view showing a cross section of an ion-selective electrode. FIGS. 2 and 3 are schematic perspective views showing a conventional ion selective electrode integrated plate for measuring ion concentration. FIG. 4 is a sectional view taken along the line - in FIG. 3. FIG. 5 is a schematic perspective view showing an ion-selective electrode. 6-1 and 6-2 are plan views showing a first embodiment of a solid electrode integrated plate for measuring ion concentration or ion activity according to the present invention. FIG. 7 is a schematic diagram showing an embodiment of the solid electrode integrated plate of the present invention housed in a housing. FIG. 8 is a plan view showing a second embodiment of the present invention. In the figure, 1...Support, 2...Metal layer, 3...Insoluble metal layer, 4...Reference electrolyte layer, 5...Ion selection layer, 10...Frame, 11...Flat member, 12... ...Bottom surface of flat member 11, 13,1
4... Electrode film, 15, 16, 17, 18...
...hole, 19... bridge, 20... potentiometer, 2
1, 22... Lead wire, 23... Hole, 24... Bottom support layer, 25... Middle porous layer, 26... Top non-porous hydrophobic layer, 27, 28... Droplet, 30, 3
1, 33... Long solid electrode, 32... Probe,
34...Common electrical connection terminal portion, A...Dead portion, 35...Patrone-shaped housing.

Claims (1)

[Scope of Claims] 1. Two or more elongated solid electrodes each having one common electrical connection terminal at or near one end in the longitudinal direction, and a liquid disposed between the electrodes after a liquid is spotted on the electrodes. A solid electrode integrated plate for measuring ion concentration or ion activity, characterized by having a plurality of dry bridges containing porous members capable of ion movement. 2. When measuring the ion concentration or ion activity of a specific ion in a test sample solution, two or more long pieces each having one common electrical connection terminal at or near one end in the longitudinal direction. Common to the solid electrode stack plate for measuring ion concentration or ion activity, which has a plurality of dry bridges including a solid electrode and a porous member that allows ion movement between the electrodes after a liquid is spotted on the electrodes. A potential difference measurement device that measures ion concentration or ion activity as potential changes is electrically connected and fixed to the electrical connection terminal section during multiple ion concentration or ion activity measurements, and the above length is connected from the common terminal section. A standard solution and a test sample solution are each spotted on the part of the bridge located at the farthest point along the solid electrode, facing the electrode, and both solutions diffuse through the bridge. The tip interface of both liquids is brought into contact at a distance, and the ion concentration or ion activity of a specific ion in the test sample liquid is measured from the potential difference measured by the potentiometric measuring device. Use of a solid electrode integrated plate for measuring ion concentration or ion activity, comprising the step of cutting off a used bridge by cutting the electrode between the used bridge and an unused bridge. Method.