JPS58201056A - Instrument for determining ionic activity - Google Patents

Abstract

PURPOSE:To obtain easily an instrument for determining ionic activity, making a shield case composed of a cover sheet and a frame disused, by forming a cover sheet made integral with a bridge for exerting capillary action by covering the surfaces of a twin electrode with a porous member which constitutes a bridge for exerting capillary action. CONSTITUTION:Filmy ion-selective electrodes 7 and 8 are placed at relative positions separted from each other in order to secure electric insulation, and are attached through an adhesive layer 9 to a porous part 11 which is supported by a water-impermeable layer 10, respectively. On the other hand, a capillarily active bridge 1 is allocated on the porous part 11 with the use of a shield 4, which is blocked against liquid diffusion by closing the capillarily active continuous vacancies. Further, the porous part 11 is provided with liquid-receiving holes 2 and 3, which supply a liquid to be tested and the standard liquid to the surfaces of the electrodes and penetrate the porous part 11, and with holes 5 and 6, of electric connecting terminals, where electric connecting terminals of the ionic selective electrodes and a potentiometer for measuring differential electric potential. In addition, when paper made of a blend of polyethylene and pulp is used as the porous part 11, and a polyethylene laminate is used as the water-impermeable supporting layer 10, the shield part 4 can be constructed by being attached easily and separately by heat with capillarily active continuous vacancies.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an instrument useful for analyzing the ionic activity of an ionic analyte in an aqueous solution sample, particularly an aqueous liquid sample of biological origin. The present invention relates to an ion activity measuring device having an integrated cover with a capillary action bridge (porous bridge) effective for IJ-wise measurement of the amount of ion activity.

There are many instruments in the prior art for measuring the activity of ions in a solution. Particularly in recent years, ion adsorption measurement instruments using dry-type film-like ion-selective electrodes that are easy to store, handle, and perform measurement operations have become widely known. This measuring instrument incorporates an ion-selective electrode that is sensitive to a specific ion and generates a potential proportional to the logarithm of the ion's activity, and is generally known to have the shape shown in FIG. Thus, in FIG. 1, two ion-selective electrodes 12 and 14 are provided within an electrically insulating frame 16, and a capillary bridge 18 is provided with two ion-selective electrodes 12 and 14 for receiving the solution deposited on the electrodes. The receiver has holes 20 and 22, and the receiver is provided to allow ion migration of the solution applied to the holes. This capillary action bridge generally consists of a water-impermeable support layer, a porous intermediate layer that allows for ion migration, and a non-porous covering layer that preferably exhibits hydrophobic properties.
Both are made of a trilaminate structure (not shown). When a standard solution of known ionic activity is applied to the hole in one receiver and a droplet of the test sample solution is applied to the hole in the other receiver, the solution diffuses into the porous layer of the capillary action bridge. Finally, they come into contact to form a contact interface, allowing ion movement between the droplets. The potential between the electrodes generated at this time is taken as the differential potential of the ion activity between the standard solution and the test sample solution, and the potentiometer 2
Read with 4. Japanese Patent Application Laid-Open No. 56-6148 describes the above-mentioned problems in assembling the ion-selective electrode and the fact that the liquid applied to the capillary action bridge leaks from the edge of the bridge and reaches the electrode surface. Measuring instruments have been proposed that improve the negative effects on results (hereinafter such effects are referred to as external bridging) and are adaptable to automated measuring devices. That is, in the invention, the porous bridge is embedded in the cover sheet as a part of the cover sheet made of a non-porous material, with at least the liquid receiver extending enough to cause the flow of ions between the holes. The cover sheet is formed as a ribbon-shaped porous material, and the cover sheet and a frame made of electrically non-conductive material constitute a shield case, and the cover sheet and frame are each formed into long strips to form a cover. A manufacturing method is disclosed in which a single ion activity measuring device is obtained by forming and cutting a composite band material in which a film-like electrode is sandwiched between a sheet and a frame. However, compared to the material cost of the ion activity measurement device manufactured in this way,
The manufacturing cost is not cheap, and the manufacturing process is not necessarily easy. The present invention provides a capillary action bridge made of a porous member that eliminates the need for the above-mentioned electrically insulating frame and cover sheet containing the porous bridge, solves the above-mentioned drawbacks, and is adaptable to automated measuring devices. .

The present invention has the following features: (1) An ion-selective electrode consisting of a pair structure in an electrically insulated positional relationship, and a liquid receiver that allows the application of a test liquid and a standard solution to each electrode of the pair structure, which has a hole in the water. It has a porous member having continuous voids having capillary action with an impermeable layer as a support layer, and the porous member is provided on the electrode so as to connect the electrodes of the paired structure, and at least The liquid receiver is bonded to the electrode through the water-impermeable layer except for the bottom of the hole, and the liquid receiver is configured to allow both liquids to diffuse within the porous member after each liquid is applied to the hole. In an ion activity measurement device that generates an ion flow, the porous member covers substantially the entire surface of the pair of electrodes, and the liquid receiver includes holes in one area to collect the liquid. An ion activity measurement device characterized in that the porous member is provided with a porous bridge consisting of a region partitioned by a shield that blocks the diffusion of The ion activity measurement device according to (1), which is provided by filling continuous voids having In the ion activity measuring instrument according to (1), the shield is provided by fusing and filling continuous voids having capillary action in the porous member by heating. be.

Further, one embodiment of the present invention will be described.

In FIG. 2, 11 is a porous member bonded on the ion selective electrode of the paired structure, and 2 and 6 are for applying the test solution and standard solution to the electrode surface provided through the porous member. The liquid receiver is a hole, 4 is a shield that closes the continuous gap having capillary action in the porous member 11 provided to surround the holes 2 and 3, and blocks the diffusion of the liquid.1 is a shield. Capillary action bridge (also referred to as porous bridge) formed by 4, 5 and 6
is an iltl loss terminal hole provided in the porous member 11,
A potentiometer (not shown) for measuring differential potential is connected to the electrical connection terminal portion of the ion selection electrode. Figure 6 is the second
In the cross-sectional view taken along line I-1 in the figure, 7 and 8 are film-like ion-selective electrodes placed at a distance from each other to ensure electrical insulation. A porous member layer 11 having the same structure as above is attached via an adhesive layer 9.

In a preferred embodiment of the present invention configured as described above, the shield is heated with a heating member such as a iron having a mold corresponding to the shield shown in 4 in FIG. 2 cut out from the porous member before the electrode i is attached. In this way, the continuous voids having capillary action in the porous member are closed by fusion to form a capillary action bridge.

A porous member capable of achieving this purpose is a conventional filter paper (e.g. Whatman Chroma 42) coated with a layer (water-impermeable) of a thermoplastic polymer (e.g. polyethylene, polypropylene, ethylene-propylene copolymer, hynyritene chloride-vinyl chloride copolymer) on both sides. In addition to being able to use a trilaminate structure with a support layer),
A dilaminate comprising a paper containing organic polymer (e.g., polyethylene) fibers and having a hydrophobic surface and provided with a water-impermeable support layer on one side, which was previously disclosed by the present inventors in Japanese Patent Application No. 34/1970. Structures are particularly preferred. Examples of paper containing organic polymer fibers include paper made from 100% polyethylene pulp and mixed paper made from 50% polyethylene pulp and 60% natural pulp (LBKP).

In another preferred embodiment of the present invention, the shield is formed by stamping or printing using a stamp surface of the type shown in the figure on the porous member before or after bonding the electrodes, or by extruding the shield from a tapered tube. Curable hydrophobic ink, adhesives, silicone resins, hot melt adhesives, etc. are applied to a heated stand bar using methods such as drawing shapes.
The method is to infiltrate a hot melt adhesive to fill the voids with capillary action to form a capillary action bridge. The porous member of the capillary action bridge that can achieve this purpose was previously proposed by the present inventors in Japanese Patent Application No.
A material made of the material proposed in Japanese Patent No. 112030 can be used. It consists of a di-laminate integrated structure of a porous member with a hydrophobic surface and a water-impermeable support layer, and the porous member is: ■ Paper made from a mixture of pulp made of synthetic polymer fibers and pulp made of vegetable natural fibers. ■ Paper made from pulp made of synthetic polymer fibers ◎ Blended fabrics made of synthetic polymer fibers and vegetable natural fibers ◎ Plain fabrics made of vegetable natural fibers ■ Membrane filters with an average pore size of 2 μm or less made of cellulose ester or regenerated cellulose - ■ Membrane filter containing nitrocellulose and having a semiuniform pore diameter of 10 μm or less - ■ Made of paper made from pulp made of vegetable natural fibers and compressed. Specific examples thereof include the following.

Among these members, in cases where the surface is weakly hydrophobic, the porous member may be coated with a known water repellent such as silicone-based or fluorine-based water repellent on the surface.

■ Paper made from a mixture of pulp made from synthetic polymer fibers and pulp made from vegetable natural fibers.

Examples of pulps made of synthetic polymer fibers: polyethylene,
Polyethylene terephthalate is a pulp made from cellulose ester (cellulose diacetate, cellulose triacetate, cellulose acetate butyrate, cellulose acetate propionate, cellulose acetate phthalate, etc.) fibers.

Examples of pulps made of vegetable natural fibers: cotton pulp, linter pulp, flax (L part n) pulp, hemp (Hemp) pulp,
Oki 5ieb, ) Pulp, Mitsumata (Edgew
orjhiapapyrif8ra5ieb,
'et Zucc,)/(Lupu, Ganbi (Wiks)
troemia 5ikOk1ana Franch,
etSav, ) Pulp, Manila Hemp
xtj-1io), Nispar) (ESpartOkari ass) pulp, bamboo valve, hardwood bleached semi-chemical pulp ωardWOOclbleached semi
-chemical pulp), coniferous sulfite pulp (Conifer 5ulfite pulp).

Pulp composed of vegetable natural fibers based on the total pulp weight (
Hereinafter referred to as natural pulp. ) is 20% or less, preferably 60% or less.

As for the type of paper, like filter paper or absorbent paper, the paper is substantially free of excipients, pastes, and sizing agents, and preferably has a surface that is free of fluff (fibers do not stand up).

◎ Paper made from pulp made of synthetic polymer fibers.

This paper is the same as the mixed paper in item ① above, except that the pulp is entirely made of synthetic polymer fibers.

◎ A blended fabric consisting of synthetic polymer fibers and plant-based natural fibers.

Examples of synthetic polymer fibers: polyethylene terephthalate,
Fibers of cellulose esters (cellulose acetate, cellulose triacetate), polyamides (polycapramide, polyhexamethylene sebaamide, polyundecaneamide, etc.), or regenerated cellulose.

Examples of vegetable natural fibers: cotton fibers, linter fibers, flax fibers, hemp fibers.

Plain woven fabrics such as silk cloth, kimono, broadcloth, and boblin are woven with threads of 20 to 120 count, which are a blend of synthetic polymer fibers and plant-based natural fibers (hereinafter referred to as natural fibers). or fabrics of other weaves.

It is also possible to blend two or more types of both synthetic polymer fibers and natural fibers.

■ Plain woven fabric made of plant-based natural fibers.

In addition to the natural fibers listed in ◎ above, plain woven fabrics such as kimonos, broadcloths, and boblins are woven with threads of 20 to 120 counts made of regenerated cellulose fibers.

A yarn made by blending two or more natural fibers can be used, and the warp and weft can also be made of different types of yarn.

■ Membrane filter made of cellulose ester or regenerated cellulose with an average pore size of 2 μm or less, preferably an average pore size of 1.2 μm or less, most preferably an average pore size of 0
．． Membrane filter of 8μm or less.

Cellulose ester mata is a membrane filter with a similar average pore size made of regenerated cellulose containing a known plasticizer.
You can also use

■ Average pore size 10 containing nitrocellulose as the main component
Membrane filter below μm.

Nitrocellulose content ranges from 50% to 100% of the total weight
% (in the case of 100%, other components are not included), preferably in the range of 70% to 95%, and the average pore size is preferably 8 μm or less. Other secondary components include diacetyl cellulose, triacetyl cellulose. Contains organic acid esters of cellulose.

■ Paper made and compressed from pulp made from vegetable natural fibers.

As the natural pulp, the pulp mentioned in (■) above is used,
Filter paper and absorbent paper are examples of paper made from paper, and these papers are compressed by known means to preferably have a smooth surface and substantially eliminate the fluff of the fibers.

The reason why the surfaces of these porous members need to be hydrophobic is as follows. If the surface of the porous member is non-hydrophobic or hydrophilic, the liquid receiver will flow at a faster rate on the surface than the liquid applied to the pores will diffuse through the porous member by capillary action; This is because it is not possible to perform good measurements because the diffusion flow rate is very different from the diffusion flow rate within the member. Further, the liquid flowing on the surface flows down onto the electrode surface, causing the external bridging described above. In order for the surface of a porous member to have hydrophobicity, there is a method of using a member that has hydrophobicity in the porous member itself. In other words, as described above, the flow rate of the liquid flowing on the surface is higher than that of the inside of the porous member due to capillary action. This can be achieved by selecting a material that diffuses and flows at a high speed. Alternatively, this can also be achieved by applying a known water repellent such as silicon-based or fluorine-based water repellent to the surface of the porous member. Next, as a water-impermeable support layer, polyethylene terephthalate (PET) film, bisphenol A polycarbonate film, polyethylene (PE) film, etc.
films, water-impermeable polymer films typified by vinylidene chloride-vinyl chloride copolymer films, metal plates typified by glass plates, aluminum plates, copper plates, copper-zinc alloy plates, and stainless steel plates that are flat and smooth (or have a mirror surface). (having) a plate-like object.

Such a water-impermeable support layer and the above-mentioned porous member are made of an adhesive made of a pressure-sensitive adhesive composition, or both sides of a double-sided adhesive tape such as a polyethylene terephthalate film, a polyvinyl chloride film, a cellulose acetate film, and a cellophane tape. It is integrated with a pressure-sensitive adhesive composition layer.

As a detailed explanation of the present invention, an example will be described in which a porous member made of a mixed paper of polyethylene and pulp is laminated with polyethylene as a water-impermeable support layer. As mentioned earlier, these porous members have hydrophobic surfaces,
Moreover, it is easily melted by heat, and its continuous voids having capillary action can be easily fused to seal the diffusion of liquid.

In addition, since the surface is hydrophobic, it can be used without providing a coating layer, which simplifies manufacturing.Furthermore, by simply providing the above-mentioned shield, external bridging of the liquid does not occur, and the material on the electrode is substantially Since the porous material is layered over the entire surface, there is no need for a conventional shield case, and droplets can be automatically formed and deposited without having to be housed in a folded frame like the one described above. It can also be used in automatic measuring equipment. In this embodiment, a case has been described in which shielding is achieved by heating the porous member, but in other embodiments, for example, hydrophobic ink, adhesive, silicone resin, etc. that can be cured by a stamping method or a printing method may be used. It is also possible to achieve filling of the continuous voids by infiltrating the hot melt adhesive with a heated stan core.

Furthermore, the shape of the shield is not limited to the rectangular shape shown in FIG. 2, but it goes without saying that the liquid receiver can take on various shapes as necessary, such as a tapered shape between the holes 2 and 6.

The ion selective electrode used in the present invention generally has four functions 1@
It is constructed in the form of a laminated layer, a trifunctional layer laminated layer, or a trifunctional layer laminated film. The insoluble salt layer can be omitted) 22, and the electrolyte-containing layer (the electrolyte-containing layer can be omitted) 2
6 and an ion selective layer 24, but a detailed explanation of their structure and operation is not considered necessary for the present invention.

However, details of the embodiment of the electrode and its method of use are described in JP-A-47-82897 and JP-A-52-14258.
No. 4, U.S. Patent No. 4,053,581 and JP-A No. 5
It is disclosed in JP 7-17851 and the like. Furthermore, in differential measurement as in the present invention, which measures the potential difference based on the ionic activity of a test solution containing an unknown ionic activity component and a standard solution of known ionic activity, the electrochemical characteristics of the counter electrode are the same. It is desirable that there be. Based on this viewpoint, the present inventors have proposed an invention in which a counter electrode with the same physical properties can be easily constructed and does not require any special electrical insulation means.
No. 7-40398. That is, in each electrode constituent layer laminated on the electrically insulating support, preferably, before forming the outermost ion selective layer, a scratching process is performed to separate the metal layer from above the electrode constituent layer to form a counter electrode. It composes. This scratching operation can be easily performed with a sharp knife, and moreover, complete vapor insulation between the divided metal layers can be achieved and a counter electrode can be obtained.

Individual capillary action bridges such as one embodiment of the present invention are placed on the long strip-shaped counter electrode constructed in this manner, and then cut after adhesion, or alternatively, as described above, The constructed capillary action bridge may also be constructed as a long strip, and after adhering to the counter electrode, the capillary action bridge and the electrode may be cut together to obtain a single ion activity measuring instrument. In the embodiments described above, the narrower the portion corresponding to the shielded capillary action bridge, the shorter the time required for the contact interface to be formed and the IF trough of ion movement, and the more the deposited liquid This is preferable because the amount can be small.

As described above, the present invention eliminates the need for a conventional type of shield case that uses a cover sheet and frame by covering the counter electrode surface with a porous member constituting a capillary action bridge to form a capillary action bridge integrated cover sheet. Moreover, it is possible to easily obtain an ion activity measuring instrument having the same functions as conventional ones.

[Brief explanation of drawings]

FIG. 1 is a schematic perspective view illustrating the configuration of a conventional type of ion activity measuring instrument. FIG. 6 is a sectional view taken along line 1-1 in FIG. 1... Capillary action bridge, 2, 6... Liquid receiver is hole,
4... Shield, 5, 6... Electrical connection terminal hole, 7,
8... Ion selective electrode, 9... Adhesive layer, 10...
Water impermeability Figure 1 η Figure 2

Claims (1)

[Claims] (1) An ion-selective electrode consisting of a pair structure in an electrically insulated positional relationship, and a liquid receiver that enables application of a test liquid and a standard solution to each electrode of the pair structure has a hole. has a porous member having continuous voids having a water-impermeable layer as a support layer and a capillary M41J tube action, and the porous member is provided on the electrode so as to connect the electrodes of the paired structure. , and at least the liquid receiver is bonded to the electrode through the water-impermeable layer except for the metal at the bottom of the hole, and the liquid receiver is configured such that after applying the liquid to each hole, the liquid is inside the porous member. In an ion activity measurement device that generates an ion flow by diffusing a material, the porous member covers substantially the entire surface of the paired electrode, and the liquid receiver is surrounded so as to be included in one area of the key money. An ion activity measuring instrument characterized in that the porous member is provided with a porous bridge consisting of a region partitioned by a shield that blocks diffusion of liquid. (2) The ion activity measuring instrument according to claim 1, wherein the shield is provided by filling continuous voids having capillary action in the porous member. (5) The porous member has a hydrophobic surface and is heat-sealable, and the shield seals the continuous voids of the porous member that have a capillary action by welding them by heating. An ion activity measuring instrument according to claim 1, which is provided by.