JPS5855748A - Composite type covered electrode - Google Patents

Abstract

PURPOSE:To measure ion concentration accurately with a small amt. of sample by forming a covered ion selective electrode and a covered reference electrode which are respectively specific to one body with an electrical insulating material therebetween, and covering the surfaces of the respective electrodes other than the surfaces in contact with liquid to be measured with an electrical insulating resin layer. CONSTITUTION:A conductive undercoating layer 7 is applied on one surface of an electrical insulating material C, and a layer 1 wherein ion exchange liquid (a decanol soln. or the like of (C8H7)4NCl or the like in the case of measuring anions) is dispersed in a resin having high water resistance or small water permeability (acrylic resin, etc.) is formed on the surface of the layer 7, whereby an ion selective electrode A is provided. A conductive undercoating layer 7 is formed on the other surface of the material C, and a precipitable silver halide (AgCl, etc.) layer 2, a resin (vinyl chloride, etc.) layer 3 of low water resistance or high water permeability dispersed with fine particles of a halide salt (KCl, etc.), and a protecting layer 4 of an acrylic resin, etc. having higher water resistance and smaller water permeability than the layer 3 are formed thereon, whereby a reference electrode B is constituted. The surfaces of the electrodes A, B other than the surfaces in contact with liquid to be measured are covered with an insulating resin 5. Thus the small sized composite electrode having a long life is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a composite coated electrode, and more particularly to a compact composite electrode that integrates a coated ion selective electrode and a coated 11111 eclipse electrode.

For example, in biochemical research, in order to measure the ion concentration of a biological fluid, it is desirable that the amount of the fluid to be measured be small.

Conventional liquid film type electrodes require an internal solution to be held in a thin glass container, resulting in a large overall volume and a large amount of liquid to be measured in which the electrode is immersed.

Moreover, thin film glass containers are fragile and difficult to handle.

Therefore, in order to overcome the above drawbacks, the present inventors developed an anion-selective electrode consisting of a working layer of epoxy resin in which an ion exchanger with the anion to be detected as a ligand is dispersed, and a precipitated halogenated electrode. He invented a composite coated electrode that combines a reference electrode with a layer of metal salt and a layer of reinforced vinyl resin in which halide salts are dispersed as the active layer, but researched the necessary characteristics of the resin used. As a result, we have arrived at the present invention.

The gist of the present invention is that a coated ion-selective electrode A and a coated reference electrode B are integrated with an electrically insulating IC sandwiched therebetween, and the coated ion-selective electrode A is a highly water-resistant electrode in which ion exchange body fluid is dispersed. Alternatively, the layer 1 of a resin with low water permeability is placed in contact with the liquid to be measured, and the coated reference electrode B is formed on the layer 2 of the precipitable metal halide salt.
o A second resin protective film 4 covering the first resin layer 3 with low water resistance or high water permeability in which fy base salt fine particles are dispersed is placed in contact with the liquid to be measured, and these Electrodes A and B are coated with a layer 5 of electrically insulating resin on the surfaces other than the layers 1 and 4 that come into contact with the liquid to be measured. A composite film characterized in that conductive wires 8 are drawn out from each conductive undercoat layer 7 (excluding those in which layer 1 is made of Nyxy resin, layer 3 is made of vinyl chloride resin, and film 4 is made of epoxy resin). This can be achieved by a lid-covered electrode.

The composite lid-coated electrode of the present invention has various shapes, for example, a vertical flat plate shape (Fig. 1) when immersed in the liquid to be measured, and a flat plate with a horizontal lid when the liquid to be measured is placed on the top surface of the electrode. (FIGS. 2 and 3) or C, F-shape (FIG. 4).The side-covered plate-shaped covered electrode in FIG. In this case, the horizontal cover plate-shaped covered electrode shown in Fig. 3 is coated with a conductive undercoat on the conductive metal base 6'.
This is a case where 7 is not applied. In either case, it is significantly smaller than the conventional liquid film type electrode, and the main surface of the flat electrode can be approximately 4+wg+, and the inner bottom surface of the cup-shaped electrode can be approximately 8m. Therefore, only a small amount of liquid is required for measurement, and particularly in the case of a horizontal flat plate or a pot, an extremely small amount, for example 0.1 rnl, is sufficient.

When measuring anion activity, the composite coated electrode of the present invention can measure each ion of chlorine, iodine, nitric acid, nitrous acid, or perchloric acid, and the ion-selective electrode AK is ion-selective. As exchangers, trioctylmethyl heptammonium salt, benzyldimethyltetradecylammonium salt, and ceyltrimethylammonium salt are associated with ions of chlorine, iodine, nitric acid, nitrous acid, or perchloric acid, respectively.

Alkylammonium salts such as dodecyltrimethylammonium salts are used. Among these ammonium salts, trioctylmethylammonium salt is soluble in the liquid to be measured.
＜There is an optimum amount from the viewpoint of electrode life.

The ion exchanger is dissolved or dispersed in an organic solvent such as l-decanol, nitrobenzene, chloroform tritil, or 2-dichloroethane to form an ion exchange body fluid.

The concentration of the ion exchanger in these solvents can be changed depending on the degree of ionic activity of the liquid to be measured, but is generally 0.1 to 80% by weight.

This ion exchange body fluid is dispersed in a resin and coated on a base material to form an electrode.In order to retain the ion exchange body fluid within the resin, a resin with strong water resistance or low water permeability is used as the resin. 9.Resins with strong water resistance or low water permeability are generally tough resins with few microscopic voids and do not show changes in properties such as swelling in water. For example, acrylic resin or urethane resin can be used.

Dispersion of ion-exchange body fluids into these resins is possible in the case of two-component resins by mixing the two-component with the ion-exchange body fluid and solidifying it, and in the case of one-component resins such as acrylic resins or urethane resins. can be mixed with ion-exchanged body fluids and solidified. That is, the resin is mixed with the ion exchange fluid in the form of a circulating fluid, applied onto a conductive metal substrate or a conductive undercoat applied to the substrate, and then the resin is cured to disperse the ion exchange fluid into the resin. It is then solidified to form an electrode.

Reference electrode B of the composite coated electrode of the present invention comprises a precipitable metal halide salt, such as silver chloride, silver bromide or a mixture thereof, on a conductive metal substrate or a conductive undercoat 7 applied to a substrate 6. A layer 3 in which fine particles of a halide salt such as potassium chloride, potassium bromide, or a mixture thereof are dispersed in a resin is formed on the layer 3, and this layer is further covered with a resin impulsion film 4. The resin that becomes this protective film is
Is it possible to use a resin that disperses the fine particles of rognized salt, such as a resin with strong water resistance or low water permeability? Oxygen resins, acrylic resins or urethane resins are suitable. As the resin for dispersing the fine particles of the halide salt, a resin having relatively high water permeability when viewed microscopically is suitable; for example, vinyl chloride resin can be used. Each resin layer in this reference electrode is also formed by the same method as in the case of the ion-selective electrode.

That is, the resin is dispersed in the form of a circulating fluid, and then applied onto the layer of the precipitable metal halodanide salt and cured to form layer 3, and on top of this, a layer 3 is formed that has strong water resistance or water resistance. A water-permeable /J1 resin may be applied in the form of a circulating fluid and cured.

In addition, in the ion-selective electrode A, the appropriate weight ratio of ion exchange body fluid to resin is 1:3 to 2:1. If the size is too small, the ion-exchanged body fluid will often leak out of the membrane, which is not appropriate.Also, in the reference electrode, the weight ratio of the fine particles of halide salt to the resin for dispersing them is 2: A ratio of 1 to 5:l is suitable; if the proportion of resin is too large, the membrane resistance becomes large, and also in case of 9, the amount of halide salt in the membrane decreases, so that a stable potential is not exhibited. If it is too small, large halide salt crystals will precipitate when hardening the film, making it difficult to form a uniformly dispersed film.

The base material of the composite coated electrode of the present invention is a conductive metal or a conductive base coated thereon, or a non-conductive base material such as resin or paper coated with a conductive base coat. In addition, if the material is not water-resistant, the parts that will come into direct contact with the test aqueous solution may be treated with a water-resistant coating such as a polymer coating.

In the case of conductive metals, a conductive undercoat of 1 m is not required, but it is still desirable to apply a conductive undercoat to improve adhesion with the next layer, especially if the base material on the side of the reference electrode is a precipitating layer. When forming the layer 2 of the metal halide salt, an oxide film is likely to be formed, and in this case, the adhesiveness is poor. This problem can be solved by using noble metals such as silver and platinum, which do not easily oxidize, but they are expensive. In the case of conductive metals, the shape is vertical and flat (Fig. 1).
Then, there is a problem that it cannot be used in common with electrical insulating material C. Therefore, it is convenient to use a synthetic resin such as an epoxy resin as a base material and apply a conductive undercoat.

In addition, silver paste or Karn (
- If the coating is suitable, the active layer of electrodes A and B is formed thereon, in which case the conductor wires are drawn out from the base coat layer. Of course, if a conductive metal is used as the base material, the conductive wire may be directly drawn out from this metal.

The conductive undercoat layer 7 and the precipitable metal halide layer 2 may be mixed and integrated. For example, a suitable mixing ratio of silver paste and silver chloride is about 15:85 by weight.

In addition, in the case of a vertical electrode, since it is immersed in the test aqueous solution, the test aqueous solution other than layers 1 and 4 of electrodes A and B, respectively! The exposed surface is coated with electrically insulating resin or epoxy resin.

For the thickness of each layer or membrane, the thickness of the ion-selective electrode is 0, 1-0.5.
■ is appropriate. If it is thicker than this, the membrane resistance will increase.
If it is too thin, the film will lack strength and will have poor durability. On the reference electrode side B, the thickness of the haq/r' metal layer 2 and the first resin layer 3 in which halide salt is dispersed is 0.1 to 1.0.
-, but a range of 0.2 to 0.5 is sufficient. Second resin layer 10! ! I4 is for layering the first resin layer 3, and if it is too thick, the film resistance will be too large, so a range of 0.05 to 0.3 is preferable.

The composite coated electrode of the embodiment has two types: a vertical flat plate shape and a horizontal cup shape.
As a seed, two types of ion-selective electrodes were prepared, one for iodine ions and one for nitrate ions. The vertical plate-like and horizontal cup-like shapes have structures shown in FIGS. 1 and 4.

In the ion electrode, a silver epoxy paste layer was formed as a conductive undercoat layer 7 having a thickness of about 0.2 square centimeters on an epoxy resin as a base material 6. When selectively measuring iodine ions and nitrate ions, 1 containing 0.3% by weight of trioctylmethylammonium salt associated with each ion is used.
- A decanol solution acrylic resin face was mixed and cured at room temperature to form a working layer 1 with a thickness of about 0.3 mm. The ratio of ion exchange body fluid to resin is about 1:2 by weight.

Incidentally, trioctylmethylammonium salt associated with iodine ions, 1-decanol was added to trioctylmethylammonium chloride in an amount of over 40% by weight,
Approximately the same volume of an aqueous potassium iodide solution of mol/mole/torr was added, stirred and centrifuged to remove the aqueous layer, and this process was repeated three times to obtain the mixture.

When nitrate ions are to be associated, a similar method can be used using potassium nitrate as an ion source, but the ion exchange reaction requires 7 to 8 repetitions. The exchange reaction of trioctylmethylammonium chloride for chlorine ions into desired ions can be completed by checking the presence or absence of chloride ions in the aqueous layer to be removed by dropping silver nitrate.

A silver paste layer with a thickness of about 0.2 cm as a conductive undercoat multilayer 7 should be formed on the resin as a reference voltage 11 BFi yellow sulfur, and a layer 2 of a precipitable metal halide salt should be formed. Masking the surface of the layer, the silver chloride is deposited on the layer 7 by dipping it several times alternately in a 0.5 molar hydrochloric acid aqueous solution and a 0.5 molar silver nitrate aqueous solution. Potassium chloride mold powder as chloride salt in a weight ratio of 3:1
A vinyl chloride layer 3 dispersed in
A rubber layer film 4 was formed.

In the case of a horizontal chip-shaped composite electrode, electrodes A and B were prepared separately and then bonded together using an epoxy oligomer and a curing agent to form an electrical insulating material C, which was then combined into a chip-like composite electrode.

For these 4'ldJ composite electrodes with different shapes and ion selectivities, the ion activity range U of the liquid to be measured is 4
FIG. 5 shows the results of measuring the potential difference between the electrodes as a total of 10-' to 5 x 10-'M. Curve ti, 12
tiIt is a vertical plate shape and shows the measurement results of an ion-selective electrode for iodine and nitric acid, respectively, and track 921.22 is a horizontal cup-like shape and shows the measurement results for an ion-selective electrode for iodine and nitric acid, respectively. The results show that the time required for response stabilization to reach 95% was several tens of seconds. Regarding ion selectivity, the selection constant KP OL, = &X/C&
j ) 1/n (in the formula 1, J az is the relationship between the logarithm log ai of the activity of the ion to be measured l and the potential difference, and the horizontal straight line where the potential difference is constant by taking the influence of the interfering ion j) The intercept activity is the logarithmic value of the ion activity to be measured, which is indicated by the intersection of the extension and the extension of the unaffected slope straight line, aj is the activity of the interfering ion, and 0 is the charge number of the interfering ion. ) is Cl
was less than 1 for most anions, except for 2-3 for O4- and I-.

As shown in Figure 5, the difference in characteristics between the vertical plate-like electrode and the horizontal plate-like electrode due to their structural differences is that the lower response limit of the former is lower; this is because the electrode is immersed in the liquid to be measured. This is thought to be because the liquid was stirred. Note that the fluctuation of the measured potential difference at a constant ion concentration was about ±2 mV for the former, and slightly better for the latter at ±1 mV @ f even at 10''M.

The amount of liquid to be measured required is approximately 0.54 m in the case of a vertical type for immersion, but 0.1 m7 is sufficient when it is placed in the horizontal type electrodes. It has the advantage of requiring only a small amount.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a vertical flat plate electrode which is one embodiment of the composite coated electrode of the present invention, and FIG. 2 is a sectional view of a horizontal plate electrode which is another embodiment of the composite coated electrode of the present invention. FIG. 3 is a sectional view of a flat plate electrode, and FIG. 3 shows a horizontal flat plate electrode which is another embodiment of the composite coated electrode of the present invention, in which a conductive metal is used as the base material of the electrode and a conductive undercoat is used. Fig.4 is a cross-sectional view of a horizontal U-shaped electrode, which is another embodiment of the composite coated electrode of the present invention, and Fig.5 is a cross-sectional view of the case where no 2 is a graph showing the relationship between the logarithm of anion activity and the potential difference of a composite coated electrode. A... Ion selective electrode, B... Reference electrode, C...
・Electrical insulating material, 1...Resin layer in which ion-exchanged body fluid of electrode A is dispersed, 2...Precipitable metal halide salt layer of electrode B, 3... Halodanide salt of electrode B is dispersed. The first
Resin layer, 4... Second resin protective film of electrode B, 5...
・Side surface coating layer, 6... Base material, 6'... Conductive metal base material, 7... Multi-layer conductive undercoat, 8... Conductive wire, 11...
・Vertical electrode (I″″), 12... Vertical electrode (NO, -
), 21... Force, cup-shaped electrode (I'''), 22... Cup-shaped electrode (NO3-). 1F!2 Tsukasa!F3y1

Claims (1)

[Claims] 1. Covered ion selective electrode A and covered reference electrode B
The coated ion-selective electrode A is made of a coated ion-selective electrode A, in which a layer l of resin with strong water resistance or low water permeability in which an ion-exchange body fluid is dispersed is brought into contact with the liquid to be measured. The other coating m*combining electrode B is a fourth resin layer with low water resistance or high water permeability formed on the layer 2 of the precipitable metal halide salt and in which fine particles of the halide salt are dispersed. A second resin protective film 4 covering electrodes A and B is placed in contact with the liquid to be measured, and these electrodes A and B are
The surface in contact with the liquid to be measured other than the layers 1 and 4 is coated with a layer 5 of electrically insulating resin, and the conductive metal base material 6' of these electrodes A and B or a conductive undercoat applied to the base material 6 is coated with a layer 5 of an electrically insulating resin. layer 7
It is characterized by having conductive wires 8 drawn out from each, and the layer 1 is made of Nyxy resin,! ) Composite coated electrodes, except those in which II3 is vinyl chloride resin and membrane 4 is epoxy resin. 2. The ion-selective electrode A and the reference electrode B are arranged so that the main surfaces of the layers 1 and 4 in contact with the liquid to be measured are parallel to the main surface of the electrically insulating film C. Composite coated electrode. 3. The ion-selective electrode and the reference electrode B are arranged so that the upper surfaces of the layers 1 and 4, which respectively carry the liquid to be measured, are on the same plane as the upper surface of the electroinsulating SaC, as set forth in claim 1. composite w1 coated electrode. 4. Claim j113 in which the overall shape is a flat plate.
Composite coated electrode as described in . 5. The composite coated electrode according to claim 3, wherein the overall shape is U-shaped.