JP2004053613A - Oxidation-reduction potential measuring device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an oxidation-reduction potential measuring device which can make accurate measurements using a minor amount of a sample, is safe even if inserted into a living body, comprises a reference electrode containing an easy-to-handle inner solution, and can obtain the same measurement value whoever makes measurements. <P>SOLUTION: A porous material film (filter paper) impregnated, for example, with 1N-KCl is disposed on a reference electrode side silver chloride electrode 5, and a filter paper impregnated with a sample solution is superposed thereon. An upper lid 1 of an electrode portion is calmly closed to make up a battery of platinum-sample-KCl salt electrode-silver chloride. When the upper cap 1 of the electrode portion is closed, a measurement delay switch 14 works, thereby digitally indicating a stable potential in mV unit relative to NHE on an ORP counting indicator 10 after the lapse of a few seconds (5 to 120 seconds). <P>COPYRIGHT: (C)2004,JPO

Description

(4) The present invention relates to an oxidation-reduction potential measuring device for measuring the concentration (hereinafter referred to as concentration / activity) of an electrolyte contained in a sample solution and a concentration ratio. ADVANTAGE OF THE INVENTION According to this invention, the density | concentration of the ion in biological fluids, such as blood, urine, and saliva, the substance density | concentration of an oxidant / reductant, or those ratios can be measured.

酸化 A redox potential measurement device is widely known as a device for measuring the concentration of an electrolyte contained in a sample liquid and the ion concentration ratio of an oxidant / reductant. The basic principle of this device is as follows. One electrode is inserted into the electrolyte solution (one combination of the electrode and the solution in direct contact is called a single electrode). Electrons are transferred at the interface between the electrode and the solution, and the electrode is connected to the electrode. An electric potential is generated. A battery in which two single electrodes are combined is called a battery. If both single electrode potentials are different, a potential difference appears between the two electrodes. The unipolar potential cannot be measured alone, and is generally converted into a set of batteries in combination with another reference electrode, after actually measuring the potential difference between the two electrodes. The reference electrode is called a reference electrode, and a standard hydrogen electrode (NHE) is used based on the definition in electrochemistry. The standard hydrogen electrode is a gas electrode obtained by plating a platinum electrode with platinum black and saturating hydrogen gas at 1 atm. The potential of this electrode is defined as zero at all temperatures.

Although the standard hydrogen electrode is used as a standard for monopolar potential measurement, using a gas electrode for actual measurement involves a number of difficulties and inconveniences. An electrode having a constant and stable potential with respect to the hydrogen electrode is used as a secondary reference. A representative reference electrode, ie, a reference electrode, is a calomel electrode. Calomel electrode is represented by Pt│Hg│Hg ₂ Cl ₂ │KCl. For the calomel electrode, a set of batteries can be easily made by inserting the tip of the salt bridge of KCl into the monopolar solution to be measured.
In addition, the silver-silver chloride electrode is used as a secondary standard similarly to the calomel electrode.
The indicator electrode paired with the reference electrode is generally a metal electrode. For example, copper can be inserted into a copper sulfate solution as an electrode to determine the concentration of copper ions in the solution. As another example, by using an inert electrode such as platinum and measuring the potential difference between the two electrodes, the concentration ratio between the oxidized form and the reduced form of the soluble component can be known. .

For example, when measuring a biological fluid such as saliva in a conventional oxidation-reduction potential measuring device, the volume of the collected sample should be as small as possible. There is a risk that the body will be violated by the toxicity of silver chloride. This is particularly undesirable for infants and pets.
In addition, in the conventional reference electrode, whether the calomel electrode or the silver-silver chloride electrode is used, the KCl solution reservoir of the salt bridge is required, and if the handling is not handled carefully, the potential becomes unstable or bubbles are generated in the salt bridge portion. Accumulation makes measurement impossible, or during storage, the KCl solution oozes out of the liquid junction by capillary action without limit and white crystals spread around and contaminate the surroundings.
Further, in the conventional apparatus, the temperature of the sample solution is separately measured, and the potentials of the various reference electrodes used are measured with reference to NHE. After measuring the potential difference, it is necessary to add or subtract to correct the NHE standard. In the measurement of the oxidation-reduction potential, the indication response speed may be slow or unstable depending on the viscosity, temperature, reactivity with air, or other physical or chemical properties of the sample solution. These difficult problems are that even when the desired chemical properties of the sample solution are the same, that is, when the same potential is to be measured, different redox potentials vary depending on the operator or the measurement site. As a result.

 Thus, the present invention provides an accurate measurement with a small amount of sample, a method that is safe even if it is inserted into a living body, a reference electrode that allows easy handling of an internal solution, or a method that can obtain the same measurement value regardless of who measures it. It is an object to provide a simple measuring device and the like.

The present invention provides an oxidation-reduction potential measuring apparatus for detecting a chemical property of a sample solution by measuring a potential of a single electrode in which an electrode such as a metal is inserted into the sample solution. Measurement of the oxidation-reduction potential of a liquid by impregnating a porous substance which is chemically or electrochemically inactive, so that only the solution impregnated with the porous substance comes into direct contact with the surface of the electrode such as the metal. An indicator electrode for a device is provided.
According to the present invention, for example, it is sufficient to wet the porous substance to the mouth with saliva, so that the measurement can be performed quickly and safely. Moreover, a small amount of the sample solution is sufficient, and there is no need to insert a dangerous electrode into the body.
Here, examples of the porous substance include, but are not limited to, filter paper, filter paper, blotting paper, sponge, cotton, and the like. The material used is electrochemically or chemically inert. Examples of such a material include cellulose ester and polyethylene phthalate.
The porous substance is preferably in the form of a thin film depending on the application.
When a sufficient amount of the sample solution can be used, a polymer block (diameter 20 mm, thickness 10 mm) can be used as the porous substance.
Note that the porous substance is brought into contact with the indicator electrode, and examples of the indicator electrode include metal electrodes such as platinum, silver, palladium, gold, nickel, copper, aluminum, and indium, glass electrodes, and polymer film electrodes. It can be used, but is not limited thereto.
Therefore, the term “metal or the like” used in claim 1 and the like includes metals, metal salts, polymer films, glass, and plastics.

Further, the present invention relates to an oxidation-reduction potential measuring device for measuring a chemical property of a sample solution by measuring a potential of a single electrode in which an electrode of a metal or the like is inserted into the sample solution. A single electrode serving as an indicator electrode in which an active porous material is impregnated with a certain concentration of an electrolyte solution, and only the certain concentration of the electrolyte solution impregnated in the porous material is brought into direct contact with the surface of a specific metal or metal salt. Provided is a reference electrode for an oxidation-reduction potential measuring device which assists in measuring a potential of a pole.
That is, the present invention makes it possible to provide a measuring device that cleans an electrode by using a solid-state reference electrode, thereby preventing the electrolyte solution used as an internal solution of a normal reference electrode from oozing out, and thus cleans the electrode. it can.
Here, the same porous material as described above can be used. As the metal electrode, for example, a silver electrode, calomel which is a hardly soluble salt, silver chloride, silver sulfide electrode, or the like can be used. Further, as the electrolyte solution, a solution used as a normal internal solution of the reference electrode can be used. For example, KCl, NH ₄ Cl, NaHCO ₃ , NaHSO _{3 and the} like can be used, but not limited thereto. The concentration of the electrolyte solution is preferably 0.1 N to room temperature saturation.

Furthermore, the present invention is an oxidation-reduction potential measuring device that inserts an indicator electrode and a reference electrode into a sample solution, measures the monopolar potential of the indicator electrode with the aid of the reference electrode, and detects the chemical properties of the sample solution. A battery in which a porous material impregnated with a sample solution, a porous material impregnated with a certain concentration of an electrolyte solution, a metal or a metal salt of a reference electrode, and the like are sequentially arranged. To provide an electrode system for an oxidation-reduction potential measuring apparatus.
Further, between the porous material impregnated with the sample solution and the porous material impregnated with the electrolyte solution of a certain concentration, a partition membrane that conducts electrons but does not easily pass material molecules such as liquid may be inserted. . This makes it difficult for the sample solution and the electrolyte solution of the reference electrode to mix, and extends the life of the reference electrode.
As the partition membrane, for example, a porous glass having a small pore diameter, a porous nylon membrane, or the like can be used. Further, it is preferable that the porous substance is formed in a thin film shape and / or the electrode is formed in a plate shape. Thereby, the electrode and the porous material can be easily overlapped with each other, so that the contact and the separation can be easily performed.

Further, in the present invention, a temperature sensor may be installed near the porous material impregnated with the sample solution. This makes it possible to know the oxidation-reduction potential obtained by converting the temperature correction using the read number itself on the display unit. A storage unit for storing a potential value of the reference electrode with respect to the standard hydrogen electrode (NHE); a calculation unit for calculating a measured value into a potential value for the standard hydrogen electrode based on the potential value stored in the storage unit; A display unit for displaying a value calculated by the unit. Thus, a constant mV value is added or subtracted by the calculation unit depending on the reference electrode used, and the true oxidation-reduction potential converted into NHE can be directly displayed. In this case, the type of the reference electrode is not limited, and even if a single electrode obtained by combining an electrolyte solution having an appropriate constant concentration and a metal electrode is used, if a stable NHE potential is known in advance, the true oxidation-reduction potential in terms of NHE can be calculated. Can be displayed directly.

Further, a time measuring unit may be provided to display the indicator electrode potential after a lapse of a predetermined time from the moment when the indicator electrode comes into contact with the impregnated sample solution. As a result, instability of indication due to a transient phenomenon after the indicator electrode is brought into contact with the sample solution can be eliminated. The time depends on the viscosity of the sample solution and the complexity of the chemical reaction, but it is appropriate after about 5 to 120 seconds have elapsed. If the time is too long, the electrolyte solution and the sample solution are mixed by diffusion, and the concentration of the sample in contact with the surface of the indicator electrode may be diluted with the electrolyte solution to hinder the measurement. Furthermore, conventionally, the measured value of the oxidation-reduction potential has been evaluated to be largely variable and poor in universality depending on the person or the place of measurement, but according to claims 6 (temperature) and 7 (NHE) of the present invention. Criteria) and claim 8 (transient response characteristics) remarkably improve the objectivity of the measured values, re-recognize the usefulness of the oxidation-reduction potential measurement method, and are extremely effective in spreading this method.

 According to the present invention, since the measurement can be performed by the degree that the porous substance is added to the mouth and moistened with saliva, infants and the like can quickly and safely measure without violating toxicity. In addition, a small amount of the sample solution is sufficient. Also, since the electrode system can be made semi-solid state and the porous substance is disposable, cleaning is easy, the electrode system can be kept clean, and accurate measurement can be performed. Further, according to the present invention, the measured value of the oxidation-reduction potential, which is evaluated as having large fluctuations and poor universality depending on the measurer or the measurement place, is significantly improved in the objectivity of the measured value, and the oxidation-reduction potential measurement method is improved. Will be re-recognized as useful, and will be extremely effective in promoting this method.

FIG. 1 shows an overall schematic view of the apparatus according to the present invention.
The device of the present invention roughly includes an electrode portion E and an electronic circuit portion C. The electrode portion E is connected to the electrode portion upper lid 1 and the electrode portion support 2 so as to be openable and closable by an opening / closing hinge 3. The electrode unit upper lid 1 and the electrode unit support 2 are formed of an insulating material such as polyacrylamide resin or nylon resin, and have a circular hole of the same size in the center. In addition, the thickness of the electrode portion top cover 1 and the electrode portion support 2 is not particularly limited, but is preferably 10 to 50 mm, and the vertical and horizontal sizes are preferably 20 to 100 mm × 40 to 180 mm. The indicator electrode side platinum electrode 4 and the reference electrode side silver chloride electrode 5 are inserted into the holes at the center. The electrodes 4 and 5 are connected to lead wires, respectively, and the lead wires penetrate through the electrode portion top cover 1 and the electrode portion support body 2, and the indication electrode side connection connectors 6 and 6 ′ and the reference electrode side connection connector 7, 7 'electrically connects to the electronic circuit section C. In addition, a measurement delay switch 14 is provided on the electrode unit support 2, and the switch operates when the electrode unit upper lid 1 is closed.

 Although not shown, the electronic circuit section C houses an operational amplifier, an NHE potential storage element, an arithmetic element, and the like. Further, the electronic circuit section C has an ORP counting display 10, a power switch 11, a scale calibration switch 12, and an input switch 13. The scale calibration switch 12 is for calibrating the scale using a standard sample solution of known concentration, and the input switch 13 is a switch for inputting the potential difference between the indicator electrode and the reference electrode to an operational amplifier.

 In the above configuration, at the time of measurement, a film (filter paper) of, for example, a porous substance impregnated with 1N-KCl is placed on the silver chloride electrode 5 on the reference electrode side, and the filter paper impregnated with the sample solution is placed thereon. Layer. The upper cover 1 of the electrode is gently closed to form a platinum-sample-KCl salt-silver chloride battery. When the electrode unit top cover 1 is closed, the measurement delay switch 14 is operated, and after waiting for several seconds (5 to 120 seconds), a stable potential is digitally displayed on the ORP counting display 10 in mV of NHE.

 FIG. 2 shows an embodiment of the electrode section of the present invention. This embodiment is a schematic diagram when the electrode unit upper lid 1 and the electrode unit support 2 are closed (measurement state) in FIG. A metal (silver) reference electrode 22 whose surface is coated with silver chloride is placed on the electrode part lower frame 21, and a porous film 23 impregnated with an electrolyte solution is stacked thereon. The thickness of the reference electrode 22 is about 0.5 to 5 mm, preferably 0.5 to 2.0 mm. As the porous membrane, for example, filter paper for analytical chemistry is used, and the thickness is about 0.2 to 10 mm, preferably 0.5 to 1.0 mm. As the electrolyte solution, for example, a 1N-KCl solution is used.

 Further, a porous film 24 impregnated with a sample solution, an indicator electrode (for example, platinum) 25, and an electrode part upper frame 26 are laminated on the porous film 23. For the porous membrane 24, the same filter paper as described above can be used, and the thickness is about 0.1 to 10 mm, preferably 2 to 5 mm. The thickness of the indicator electrode 25 is about 0.2 to 1 mm, preferably 0.3 to 0.5 mm. The signal between the reference electrode 22 and the indicator electrode 25 is sent to the operational amplifier 29 via the lead wires 27 and 28, and after a certain calculation processing, is displayed on the display unit 30 as a potential based on NHE.

 Further, the present invention is not limited to the above configuration, and may have the configuration of FIG. The configuration of FIG. 3 is an example in which the porous membrane in the configuration of FIG. 2 is replaced with a thick film such as a porous polymer block instead of a thin film such as filter paper. 3, the same components as those in FIG. 2 are denoted by the same reference numerals. In this embodiment, a porous polymer block 31 impregnated with an electrolyte solution and a block (polymer block) 32 of a porous material impregnated with a sample solution are laminated on a reference electrode 22. The indicator electrode 33 is inserted into the block 32. For the blocks (polymer blocks) 31 and 32 of the porous substance, for example, an electrically and chemically inert polymer substance such as polyethylene, polystyrene, cellulose ester, or glass fiber is used. The thickness of the polymer block 31 is about 1 to 10 mm, preferably 2 to 5 mm, and the thickness of the polymer block 32 is about 5 to 30 mm, preferably 10 to 15 mm.

 Further, the present invention may have the configuration of FIG. This embodiment is an example in which only a so-called indicator electrode employs an embodiment of the present invention, and a reference electrode is the same as a conventional electrode. In FIG. 4, reference numeral 41 denotes a support, on which a porous material 42 impregnated with a sample solution is placed. The electrode portion contacts the porous material 42. The electrode portion has a glass tube 47 inserted into a hollow cylinder 43, and a platinum plate 45 connected to a lead wire 46 is adhered inside the glass tube 47. The platinum plate 45 serves as an indicator electrode, and the platinum plate 45 contacts the porous substance 42 impregnated with the sample solution. An electrolyte solution (KCl solution) 50 is accommodated in the outer periphery of the glass tube 47, and a reference electrode (silver-silver chloride electrode) 44 is inserted into the electrolyte solution (KCl solution) 50. A liquid junction 48 is provided in the cylinder 43, and a cylindrical glass tube 49 whose inner surface is made of ground glass is fitted therein. That is, the KCl solution 50 is conducted to the porous substance containing the sample solution from the gap of the ground glass on the inner surface of the glass tube 49 via the liquid junction 48. When the measurement is performed, the porous substance 42 is held down by the electrode section, and the battery circuit is closed. Therefore, it is preferable that the porous material 42 has elasticity such as sponge.

Using the conventional method of inserting electrodes into a sample solution and the present invention (the configuration of FIG. 2) in which a sample solution and an electrolyte solution are impregnated in a filter paper for analytical chemistry, the potential difference given by each electrode pair is precisely measured by a potentiometer. Was measured and compared.
(Experiment conditions)
Temperature: 28 ° C
Electrode: Pt vs. sat.Ag/AgCl
Porous substance: Filter paper for analytical chemistry (Advantech, size 110mm, thickness 0.5mm)
Electrolyte solution: 1N KCl aqueous solution Potentiometer: ORP meter (manufactured)

本発明は、従来法とほぼ同一の電位を示し、本発明の方法が有効であることを示している。 (Experimental result)
Table 1 shows the experimental results.

The present invention shows almost the same potential as the conventional method, indicating that the method of the present invention is effective.

　上記結果は、本発明によれば、ろ紙を口にくわえて唾液で湿らす程度で測定できるから、被験者は電極の毒性などに犯されることなく、迅速で安全に測定できることを示している。 In addition, an experiment was performed by impregnating human saliva into a filter paper for analytical chemistry (wet the filter paper to the mouth and wet with saliva) under the same conditions as above, except that Pt vs. 1NAg / AgCl was used as the electrode.

The above results show that, according to the present invention, the measurement can be carried out only by holding the filter paper in the mouth and moistened with saliva, so that the subject can measure quickly and safely without violating the toxicity of the electrode.

ADVANTAGE OF THE INVENTION According to this invention, the density | concentration of the ion in biological fluids, such as blood, urine, and saliva, the substance density | concentration of an oxidant / reductant, or those ratios can be measured.

Overall schematic diagram of the present invention One embodiment of the laminated electrode of the present invention Illustration of porous polymer block impregnated with liquid Diagram in which the configuration of the present invention is adopted only for the indicator electrode

Explanation of reference numerals

4: indicator electrode side platinum electrode 5: reference electrode side silver chloride electrode 22: reference electrode 23: porous membrane 24 impregnated with electrolyte solution 24: porous membrane 25 impregnated with sample solution: indicator electrodes 31, 32: porous Material Block 42: Porous Material

Claims (8)

In an oxidation-reduction potential measurement device that detects the chemical properties of a sample solution by measuring the potential of a single electrode in which an electrode such as a metal is inserted into the sample solution, the sample solution is treated with a chemically or / chemically inert material. An indicator electrode for a liquid oxidation-reduction potential measuring device, wherein a porous material is impregnated so that only a solution impregnated in the porous material directly contacts the surface of an electrode such as the metal. An oxidation-reduction potential measurement device that detects the chemical properties of a sample solution by measuring the potential of a single electrode in which a metal or other electrode is inserted into the sample solution. Impregnated with a certain concentration of electrolyte solution and assisted in measuring the potential of a single electrode as an indicator electrode, in which only a certain concentration of the electrolyte solution impregnated in the porous substance is brought into direct contact with the surface of a specific metal or metal salt. Reference electrode for the oxidation-reduction potential measurement device. An indicator electrode and a reference electrode are inserted into a sample solution, and a monopolar potential of the indicator electrode is measured with the aid of the reference electrode to detect a chemical property of the sample solution. An oxidation-reduction potential measuring device characterized by comprising a battery in which a porous material impregnated with a sample solution | a porous material impregnated with a constant concentration of an electrolyte solution | a metal or a metal salt of a reference electrode | Electrode system. 4. An electrode system for an oxidation-reduction potential measuring apparatus according to claim 3, wherein electrons are conducted between the porous material impregnated with the sample solution and the porous material impregnated with the electrolyte solution of a certain concentration, but a substance such as a liquid. An oxidation-reduction potential measurement device that inserts a partition membrane through which molecules do not easily pass. 5. The oxidation-reduction potential measuring apparatus according to claim 1, wherein the porous substance is formed in a thin film shape and / or the electrode is formed in a plate shape. 6. The oxidation-reduction potential measuring device according to claim 3, wherein a temperature sensor is installed near the porous material impregnated with the sample solution. 7. The oxidation-reduction potential measuring device according to claim 1, wherein a storage unit for storing a potential value of the reference electrode with respect to the standard hydrogen electrode, and a measured value based on the potential value stored in the storage unit with respect to the standard hydrogen electrode. An oxidation-reduction potential measuring apparatus, comprising: a calculation unit for calculating a value calculated by the calculation unit; 8. The oxidation-reduction potential measuring device according to claim 7, further comprising a time measuring unit, wherein the indicator electrode potential is displayed after a lapse of a predetermined time from the moment when the indicator electrode comes into contact with the impregnated sample solution. .

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