JPH08178888A - Japanese lacquer matrix sensitive film ion electrode - Google Patents

Abstract

PURPOSE: To precisely measure the concentration of ions in a sample by improving the stability of a contact potential between a sensitive film obtained by hardening Japanese lacquer in which a sensitive substance is mixed and a substrate set at a detecting part and reducing drifts of a measuring potential difference in a Japanese lacquer matrix sensitive film ion electrode which detects the concentration of ions in a sample by bringing the sample into touch with the sensitive film. CONSTITUTION: A silver plate 18 is used as a substrate to place the Japanese lacquer matrix sensitive film 10 thereon. In this case, the potential is more stabilized if a silver chloride 22 is interposed between the silver plate 18 and sensitive film 10, enabling more precise measurements. When copper 20 is inserted between the silver plate 18 and sensitive film 10, the Japanese lacquer is hardened at a low temperatures, thereby, a sensitive film of higher quality can be obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ion electrode using, as a sensitive film, a lacquer matrix sensitive film obtained by curing lacquer mixed with a sensitive substance.

[0002]

2. Description of the Related Art As a sensitive film of a liquid film type ion electrode, a film obtained by dissolving an ion sensitive substance in an organic solvent is mixed with PVC (polyvinyl chloride) which is a matrix agent and gelled to form a film. Matrix-sensitive membranes are mainly used. However, since the PVC matrix sensitive film is soft and easily damaged, when used in applications where particles or powder come into contact with the sensitive film, for example, when measuring ion concentration in soil, the sensitive film is damaged and its characteristics deteriorate. There is. When PVC is used as a matrix agent when producing a liquid film type ion electrode for measuring divalent cations such as calcium ions and magnesium ions, PVC and a divalent cation sensitive substance (for example, di-n-octylphenylphosphorus) are used. Since it is not compatible with calcium acid), only a sensitive film that cannot be measured in a short period of time can be obtained.

On the other hand, there has been proposed an ion electrode using a lacquer matrix sensitive film obtained by curing lacquer mixed with an ion sensitive substance (Japanese Patent Publication No. 54-15518).
issue). Since the lacquer matrix sensitive membrane has high hardness and is not easily damaged, the lacquer matrix sensitive membrane ion electrode using the lacquer matrix sensitive membrane can be suitably used for applications where particles or powder come into contact with the sensitive membrane. Further, in the method of using lacquer as the matrix agent, a good sensitive film can be obtained by using a divalent cation sensitive material having poor compatibility with PVC.

[0004]

In the lacquer matrix sensitive membrane ion electrode, a lacquer matrix sensitive membrane is arranged on the substrate. This lacquer matrix sensitive membrane is prepared by applying lacquer mixed with a sensitive substance to the substrate. A film is formed by curing. In this case, since lacquer is hard to cure if copper is not present, it has been attempted to apply a lacquer mixed with a sensitive substance onto a substrate made of copper and cure the lacquer to obtain a sensitive film. However, in the lacquer matrix sensitive membrane ion electrode using a copper plate as the substrate for the sensitive membrane, there is a problem that the measured potential difference drifts with time and precision measurement cannot be performed. One of the reasons is that the surface of the copper plate is easily deteriorated due to oxidation or the like, and the copper plate does not form an electrically stable battery, so that the stability of the contact potential between the sensitive film and the copper plate deteriorates. It is possible.

The present invention has been made in view of the above circumstances and is excellent in the stability of the contact potential between the sensitive film and the substrate, and the drift of the measured potential difference is small, so that the precision measurement can be performed with the lacquer matrix. It is an object to provide a membrane ion electrode.

[0006]

Means and Actions for Solving the Problems In order to achieve the above object, the present invention provides a substrate with a sensitive film formed by curing lacquer mixed with a sensitive substance, and brings the sample into contact with the sensitive film. In the ion electrode for detecting the ion concentration in the sample, a lacquer matrix sensitive membrane ion electrode is provided in which the substrate on which the sensitive membrane is arranged is a silver plate (claim 1). When a silver plate is used as the substrate, the substrate is less likely to deteriorate due to oxidation etc. than when a copper plate is used, so the stability of the contact potential between the sensitive film and the substrate is improved, and the drift of the measured potential difference is small. It is considered to be.

In the ion electrode of the present invention, silver chloride can be interposed between the silver plate and the sensitive film (claim 2).
As a result, a silver-silver chloride battery, which is a stable battery, is formed by the silver plate and silver chloride, so that the potential becomes more stable,
More precise measurement is possible. Examples of means for interposing silver chloride between the silver plate and the sensitive film include a method of plating silver chloride on the silver plate.

In the ion electrode of the present invention, copper can be interposed between the silver plate and the sensitive film (claim 3). This makes it easier for lacquer to harden due to the presence of copper when applying lacquer mixed with a sensitive substance to the substrate and hardening it, so that it is possible to cure the lacquer at a low temperature and obtain a sensitive film of better quality. It will be possible. That is, when copper is not present during lacquer hardening, it is necessary to harden the lacquer by heating and drying at about 120 ° C., so there is a possibility that the lacquer, which is a polymer compound, may deteriorate due to high temperature and the quality of the sensitive film may deteriorate. When copper is interposed between the silver plate and the sensitive film, the lacquer can be cured at a low temperature of about 50 to 80 ° C., so that the alteration of the lacquer due to the high temperature can be prevented. Examples of means for interposing copper between the silver plate and the sensitive film include a method of plating copper on the silver plate.

Further, in the ion electrode of the present invention, silver chloride and copper can be interposed between the silver plate and the sensitive film (claim 4). As a result, an electrode having the effects of the electrodes according to claims 1 to 3, that is, the potential is extremely stable,
Moreover, it is possible to obtain an electrode having a lacquer matrix-sensitive film of better quality that is cured at a low temperature. in this case,
It is particularly preferable that silver chloride and copper are interposed between the silver plate and the sensitive film such that both the substrate and the sensitive film are in contact with both silver chloride and copper, respectively. Examples of means for interposing silver chloride and copper between the silver plate and the sensitive film include a method of plating silver chloride and copper on the silver plate. In this case, the order of silver chloride plating and copper plating does not matter. Since the plating only covers the surface to be plated thinly, whichever is plated first, the surface of the silver plate is in a state of being mixed with silver chloride and copper.

In the electrodes of claims 1 and 2, copper is mixed with the sensitive substance in the lacquer, whereby
It is also conceivable to enable curing at a low temperature as in the case of the electrodes of 4 and 4. However, in this case, when the mixed copper is exposed on the surface of the sensitive film, there is a problem that it is directly electrically connected to the test liquid.

In the present invention, any kind of lacquer can be used. Further, the ion electrode of the present invention can be used as a sodium ion electrode, a potassium ion electrode, an ammonium ion electrode, a nitrate ion electrode, or a divalent cation electrode such as a calcium ion electrode or a magnesium ion electrode by appropriately selecting a sensitive substance. It can be configured to any type of ion electrode. In this case, the ion electrode of the present invention can have the same structure as a known liquid film type ion electrode.

[0012]

EXAMPLES The present invention will be specifically described below with reference to apparatus examples, production examples, and measurement examples, but the present invention is not limited to the following examples.

[Apparatus Example] FIG. 1 shows a lacquer matrix sensitive membrane ion electrode according to an embodiment of the present invention. In the electrode of FIG. 1, 2 is an electrode body and 4 is an electrode body 2.
Of the porous liquid junction formed on the tip side peripheral wall of the electrode body, 6 is a lead wire attached to the electrode body 2, 8 is an electrode chip detachably formed in the tip part of the electrode body 2, and 10 is an electrode chip 8 Lacquer matrix sensitive film provided at the tip of
Reference numeral 12 denotes a connector provided on the electrode tip 8, and 14 denotes a cap for fixing the electrode tip 8 to the electrode body 2.

The electrode tip 8 has the structure shown in FIG. FIG. 2 is an enlarged cross-sectional view in which the intermediate portion is omitted when the cap 14 is not attached to the electrode tip 8. That is, the silver plate 18 is fixed to the front end of the cylindrical support 16 whose base end is closed, and the copper plating layer 20 and the silver chloride plating layer 2 are formed on the silver plate 18.
2 is formed, and the lacquer matrix sensitive film 10 is fixed to the silver chloride plating layer 22. Further, the connector 12 is attached by penetrating the base end closed portion of the cylindrical support 16, and the connector 12 and the silver plate 18 are connected by a silver wire 24. In the figure, 26 indicates solder. Although the copper plating layer 20 and the silver chloride plating layer 22 are schematically shown in FIG. 2, the surface of the silver plate 18 is actually covered with silver chloride and copper in a mixed state.

The electrode tip 8 is a lacquer in which a silver plate 18 is fixed to the tip of a cylindrical support 16, copper plating and silver chloride plating are sequentially performed on the silver plate 18, and a sensitive material is mixed on the silver plating. Is applied, and then the lacquer is cured at a low temperature to form the lacquer matrix sensitive film 10.

[Production Example] (A)-
The ion electrode of (D) was manufactured. (A) Lacquer Matrix Sensitive Membrane Ion Electrode for Nitrate Ion Measurement Using a Silver Plate as a Substrate for Disposing a Sensitive Membrane (Example 1 of the Present Invention) After adhering the silver plate to the tip of the support of the electrode chip, Polish the surface with a sandpaper to make it smooth. Place the tip in a CuSO ₄ solution placed in a beaker as the cathode and the copper rod as the anode, and put the tip 1 under stirring.
Copper plating is performed by passing a current of 0.2 mA per 0 piece for 1 hour. Silver chloride plating is performed by placing a chip in a KCl solution placed in a beaker as an anode and a silver rod as a cathode, and applying a current of 0.1 mA per 10 chips under stirring for 1 hour. NPOE (ortho-nitrophenyl octyl ether)
0.1 g of lacquer is added to a solution of 0.05 g of trioctylammonium nitrate as a sensitive substance in 0.05 g and the mixture is stirred, and this is applied onto the silver chloride plating layer of the chip obtained in the above. The chips are heated and dried at 80 ° C. to harden the lacquer to form a sensitive film. An ion electrode is manufactured using the obtained chip.

(B) Lacquer Matrix Sensitive Membrane Ion Electrode for Divalent Cation Measurement Using Silver Plate as Substrate for Disposing Sensitive Membrane (Invention Example 2) A silver plate was adhered to the tip of the support of the electrode chip. After that, the surface of the silver plate is smoothed by sanding with a paper file. Place the tip in a CuSO ₄ solution placed in a beaker as the cathode and the copper rod as the anode, and put the tip 1 under stirring.
Copper plating is performed by passing a current of 0.2 mA per 0 piece for 1 hour. Silver chloride plating is performed by placing a chip in a KCl solution placed in a beaker as an anode and a silver rod as a cathode, and applying a current of 0.1 mA per 10 chips under stirring for 1 hour. t-HD as a sensitive substance in 0.05 g of n-decanol
0.1 g of lacquer is added to a solution of 0.05 g of OPP Ca (di-n-octylphenyl calcium phosphate) and stirred, and this is applied onto the silver chloride plating layer of the chip obtained in the above. The chips are heated and dried at 80 ° C. to harden the lacquer to form a sensitive film. An ion electrode is manufactured using the obtained chip.

(C) Lacquer Matrix Sensitive Membrane Ion Electrode for Nitrate Ion Measurement Using Copper Plate as Substrate for Sensitive Membrane (Comparative Example 1) After adhering the copper plate to the tip of the support of the electrode chip, the surface of the copper plate Polish with a file to make it smooth. 0.1 g of lacquer in 0.05 g of NPOE and 0.05 g of trioctylammonium nitrate dissolved as a sensitive substance
Is added and stirred, and this is coated on the copper plate of the chip obtained in. The chips are heated and dried at 80 ° C. to harden the lacquer to form a sensitive film. An ion electrode is manufactured using the obtained chip.

(D) PVC Matrix Sensitive Membrane Ion Electrode for Divalent Cation Measurement (Comparative Example 2) 0.5 g of n-decanol and 0.01 g of t-HDOPP Ca as a sensitive substance were put in a glass container, and 8 ml of tetrahydrofuran was added, Stir with a stirrer. Further, 0.2 g of PVC powder is added while stirring with a stirrer. A membrane filter impregnated with tetrahydrofuran is placed at the tip of the support of the electrode tip. Add 10 to 20 μl of the solution prepared in this at 20 minute intervals.
After dropping once, it is left to stand for 24 hours to completely vaporize tetrahydrofuran to form a sensitive film. An ion electrode is manufactured using the obtained chip.

[Measurement Example 1] Nitrate ion concentration 100 ppm
Using the standard solution of No. 2 as the test solution, the nitrate ion concentration was measured using the lacquer matrix sensitive membrane ion electrode of (A) (Example 1 of the present invention) and the lacquer matrix sensitive membrane ion electrode of (C) (Comparative Example 1). The change over time in the measured potential difference when the test was performed was examined. The results are shown in Fig. 3. From FIG. 3, it was found that the electrode of the present invention using a silver plate as the substrate has a small drift of the measured potential difference over time. On the other hand, in the electrode of the comparative example using the copper plate as the substrate, the measured potential difference largely drifted with time.

[Measurement Example 2] Ion concentrations of 1, 10, 10
When Ca solution and Mg solution of 0 and 1000 ppm were used as test liquids, and calcium ion concentration and magnesium ion concentration were measured using the lacquer matrix sensitive membrane ion electrode (Example 2 of the present invention) of (B), respectively. The measured potential difference is shown in FIG. As a result, it was found that the electrode of the present invention using a silver plate as the substrate had a good correlation between the divalent cation concentration and the measured potential difference.

[Measurement Example 3] A Ca solution having an ion concentration of 10, 100 and 1000 ppm was used as a test solution, and (B)
Of the lacquer matrix-sensitive membrane ion electrode of the present invention (Example 2 of the present invention) and the PVC matrix-sensitive membrane ion electrode of (D) (Comparative Example 2) were used to measure the calcium ion concentration. . The results are shown in FIGS. FIG. 5 shows the result of the electrode (B), and FIG. 6 shows the result of the electrode (D). From FIGS. 5 and 6, the measurement potential difference drifts in the PVC matrix sensitive membrane ion electrode for divalent cation measurement in a short period of time, whereas the measurement potential difference drifts with time in the lacquer matrix sensitive membrane ion electrode of the present invention. I found it small.

The lacquer matrix sensitive membrane ion electrode of the present invention is not limited to the above embodiment. For example, in the above-mentioned embodiment, the electrode is of the tip exchange type, but the electrode body and the electrode tip may be integrally formed. Also,
Other configurations may be variously modified without departing from the scope of the present invention.

[0024]

EFFECTS OF THE INVENTION Since the lacquer matrix sensitive membrane ion electrode of the present invention uses a silver plate as the substrate for disposing the sensitive membrane, the stability of the contact potential between the sensitive membrane and the substrate is excellent, and the drift of the measured potential difference. It is possible to carry out precise measurement with less.
In this case, when silver chloride is interposed between the silver plate and the sensitive film, the potential becomes more stable and more precise measurement becomes possible. Further, when copper is interposed between the silver plate and the sensitive film, it becomes possible to cure the lacquer at a low temperature to obtain a sensitive film with better quality. Furthermore, when silver chloride and copper are interposed between the silver plate and the sensitive film, the potential becomes more stable,
A more precise measurement can be performed, and lacquer can be cured at a low temperature to obtain a sensitive film of better quality.

[Brief description of drawings]

FIG. 1 is an exploded view showing an embodiment of a lacquer matrix sensitive membrane ion electrode of the present invention.

FIG. 2 is a sectional view showing an electrode tip of the electrode of FIG.

FIG. 3 shows changes with time of the measured potential difference when the nitrate ion concentration was measured using the lacquer matrix sensitive membrane ion electrode of the present invention using a silver plate as the substrate and the lacquer matrix sensitive membrane ion electrode using the copper plate as the substrate. It is a graph shown.

FIG. 4 is a graph showing the relationship between the ion concentration and the measured potential difference when the divalent cation concentration is measured using the lacquer matrix sensitive membrane ion electrode of the present invention using a silver plate as the substrate.

FIG. 5 is a graph showing a time-dependent change in measured potential difference when a divalent cation concentration is measured using the lacquer matrix-sensitive membrane ion electrode of the present invention using a silver plate as a substrate.

FIG. 6 is a graph showing a time-dependent change in measured potential difference when a divalent cation concentration is measured using a PVC matrix sensitive membrane ion electrode.

[Explanation of symbols]

 2 electrode body 8 electrode chip 10 lacquer matrix sensitive film 16 support 18 silver plate 20 copper plating layer 22 silver chloride plating layer

Claims (4)

[Claims] 1. An ion electrode in which a sensitive film formed by curing lacquer mixed with a sensitive substance is provided on a substrate, and a sample is brought into contact with the sensitive film to detect an ion concentration in the sample. Lacquer matrix sensitive membrane ion electrode, characterized in that the substrate to be placed is a silver plate. 2. The ion electrode according to claim 1, wherein silver chloride is interposed between the silver plate and the sensitive film. 3. The ion electrode according to claim 1, wherein copper is interposed between the silver plate and the sensitive film. 4. The ion electrode according to claim 1, wherein silver chloride and copper are interposed between the silver plate and the sensitive film.