Ph measuring cell, ph measuring device, ph measuring method, and method for manufacturing ph measuring cell

Abstract

To provide a pH measuring cell with excellent durability and usability.SOLUTION: A pH measuring cell 2 for housing a sample liquid and measuring the pH of the sample liquid is made of a resin containing a pH response copolymer, which changes its color according to the pH.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a pH measuring cell, a pH measuring device, a pH measuring method, and a method for manufacturing a pH measuring cell. [Background technology]

[0002] For example, as shown in Patent Document 1, a pH-responsive copolymer has been considered that is formed by copolymerizing a monomer component that includes an ion-sensitive site and a polymerization reaction site with a monomer component that includes a pH-responsive site and a polymerization reaction site (pH-responsive monomer).

[0003] As an application example of this pH-responsive copolymer, a configuration in which the pH-responsive copolymer is molded into a film and attached to a holder is considered, as shown in Patent Document 2. The measurement target is brought into contact with one side of this film, and a sensor is provided on the opposite side of the film to measure the color development of the film. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2012-163484 A [Patent Document 2] JP 2015-81806 A Summary of the Invention [Problem to be solved by the invention]

[0005] However, films made from pH-responsive copolymers have durability problems and may be damaged over long-term use. In addition, films need to be attached to a holder, which makes them less convenient to use.

[0006] Therefore, the present invention has been made to solve the above problems, and it is an object of the present invention to provide a pH measuring cell which is excellent in durability and ease of use. [Means for solving the problem]

[0007] In other words, the pH measurement cell of the present invention is a pH measurement cell for containing a sample liquid and measuring the pH of the sample liquid, and is characterized in that it is made of a resin containing a pH-responsive copolymer that changes color depending on the pH.

[0008] According to the pH measuring cell configured in this manner, since it is formed from a resin containing a pH responsive copolymer, it is possible to provide a pH measuring cell that is excellent in durability and ease of use.

[0009] If the nonionic monomer (cell-forming resin) does not have light transmission, the color change of the pH-responsive monomer in the liquid-contacting portion inside the cell may not be visible or detectable. For this reason, it is preferable that the pH-responsive copolymer is copolymerized containing a pH-responsive monomer, which is a monomer component having a pH-responsive portion and a polymerization reaction portion, and that the color change of the pH-responsive copolymer is visible or detectable when the sample liquid is contained therein.

[0010] In a specific embodiment, the pH-responsive copolymer is copolymerized with a pH-responsive monomer and a non-ionic monomer that is a monomer component containing the electrically neutral portion or an ion-sensitive portion and a polymerization reaction portion, and the non-ionic monomer is considered to be translucent.

[0011] As a specific embodiment of the pH measuring cell, it is desirable that the pH measuring cell is an in-line type provided in a sample liquid pipe through which the sample liquid flows.

[0012] The pH measuring device according to the present invention is characterized by comprising the above-mentioned pH measuring cell and a color detection mechanism for detecting the color of the pH-responsive copolymer.

[0013] It is desirable that the color detection mechanism includes a light irradiating unit that irradiates the pH measuring cell with light, and a light detecting unit that detects reflected light from the pH measuring cell.

[0014] The user can judge the pH using the color of the pH-responsive copolymer detected by the light detection unit. In order to objectively judge the pH, it is preferable to further include a pH calculation unit that calculates the pH of the sample liquid from the detection signal obtained by the color detection mechanism.

[0015] As a specific embodiment of the pH measurement device of the present invention, it is desirable that the pH of the sample liquid is continuously measured. In this configuration, the pH measurement cell used in the pH measurement device is considered to be an in-line type.

[0016] Furthermore, the pH measurement method of the present invention is characterized in that a sample liquid is placed in a pH measurement cell made of a resin containing a pH response copolymer, and the pH of the sample liquid is measured based on the color of the pH response copolymer.

[0017] Furthermore, the manufacturing method of a pH measurement cell according to the present invention is a manufacturing method of a pH measurement cell for containing a sample liquid and measuring the pH of the sample liquid, and is characterized in that the pH measurement cell is molded using a resin containing a pH responsive copolymer that changes color depending on the pH. Effect of the Invention

[0018] According to the present invention, a pH measuring cell having excellent durability and ease of use can be provided. [Brief description of the drawings]

[0019] [Figure 1] FIG. 1 is a schematic diagram showing the configuration of an in-line pH measurement device according to one embodiment of the present invention. [Diagram 2] FIG. 13 is a schematic diagram showing the configuration of a batch-type pH measurement device according to a modified embodiment. [Diagram 3]13 is a schematic diagram showing a modified example of the measurement cell and the color detection mechanism. FIG. [Figure 4] FIG. 1 is a schematic diagram showing an example of application to a semiconductor manufacturing device. [Diagram 5] FIG. 13 is a schematic diagram showing an example of application to a chemical liquid supplying device. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0020] An embodiment of a pH measuring device using a pH measuring cell according to the present invention will be described below with reference to the drawings. Note that in all of the drawings shown below, for ease of understanding, some parts are omitted or exaggerated as appropriate and schematic drawings are used. Identical components are given the same reference numerals and descriptions thereof are omitted as appropriate.

[0021] <Device configuration> The pH measurement device 100 according to this embodiment is an in-line type provided in a sample liquid pipe D through which a sample liquid flows, and continuously measures the pH of the sample liquid.

[0022] Examples of sample liquids include liquids used in the semiconductor manufacturing field, such as semiconductor manufacturing equipment, liquids used in the food industry, such as food processing equipment, tap water, drinking water, water from rivers and swamps, industrial wastewater, industrial effluent, laboratory reagents, sewage, water supply and sewage, medical reagents, cooling water for air conditioning, and leachate treated in leachate treatment facilities.

[0023] Specifically, the pH measuring device 100 is a so-called colorimetric pH meter, and as shown in FIG. 1, is equipped with a pH measuring cell 2 that changes color depending on the pH, a color detection mechanism 3 that detects the color of the pH measuring cell 2, a pH calculation unit 4 that calculates the pH from the detection signal obtained by the color detection mechanism, a relationship data storage unit 5 that stores relationship data used by the pH calculation unit 4, and a display unit 6 that displays the calculated pH.

[0024] The pH measurement cell 2 is for storing a sample liquid and measuring the pH of the sample liquid. The pH measurement cell 2 is of a flow type, and has a storage space 2S for storing the sample liquid therein. The pH measurement cell 2 also has an inlet port P1 through which the sample liquid is introduced and an outlet port P2 through which the sample liquid is discharged, and a sample liquid pipe D is connected to each of the ports P1 and P2.

[0025] The pH measurement cell 2 is formed from a resin containing a pH responsive copolymer that changes color depending on the pH. Specifically, the material of at least the surrounding wall forming the storage space 2S of the pH measurement cell 2 is a resin containing a pH responsive copolymer. In this embodiment, the material of the entire pH measurement cell 2 is the pH responsive copolymer.

[0026] Here, the pH-responsive copolymer is described in the above Patent Documents 1 and 2, and is obtained by copolymerizing a pH-responsive monomer, which is a monomer component containing a pH-responsive site and a polymerization reaction site, and a nonionic monomer, which is a monomer component containing an electrically neutral site and a polymerization reaction site.

[0027] Examples of pH-responsive monomers include dimethylaminoazobenzene (meth)acrylate, spiropyran (meth)acrylate, and sodium 5-[(p-nitro-m-vinyl-phenyl)azo]salicylate.

[0028] Furthermore, examples of the pH responsive site of the pH responsive monomer include the following. Examples of pH-responsive sites derived from azo systems include N,N-dimethyl-4-(phenylazo)-benzene, sodium 4'-dimethylaminoazobenzene-4-sulfonate, 2-(N,N-dimethyl-4-aminophenyl)azobenzenecarboxylic acid, N-(4-(bis(4-(dimethylamino)phenyl)methylene)cyclohexa-2,5-dien-1-ylidene)methanaminium chloride), 5-(4-nitrophenylazo)salicylic acid, and sodium 3,3'-(1E,1'E)-biphenyl-4,4'-diylbis(diazene-2,1-diyl)bis(4-aminonaphthalene-1-sulfonate).

[0029] Examples of pH-responsive sites derived from triphenylmethane or having a lactone group include 3-(3'-methyl-4'-hydroxyphenyl)-phthalidyl-4-hydroxyphenyl, 3,3-bis(4-hydroxyphenyl)-1,3-dihydroisobenzofuran-1-one, 2-[bis(4-hydroxyphenyl)methyliumyl]benzenesulfonate, 3,3-bis(2-methyl-4-hydroxy-5-isopropylphenyl)isobenzofuran-1(3H)-one, 3,3',5,5'-tetrabromophenolsulfonephthalein, 2,6-dibromo-4-[3-(3,5-dibromo-4-hydroxyphenyl)-1,1-dioxo-3-benzo[c]oxathiolyl]phenol, 4,4'-(1,1-dioxide-3H-2,1-benzoxathiol-3,3-diyl)bis(2-bromo-6-isopropylphenyl) 3-methylphenol), [4-{bis(4-dimethylaminophenyl)methylene}-2,5-cyclohexadiene-1-ylidene]dimethylammonium chloride, 3,3-bis(3-methyl-4-hydroxyphenyl)-3H-2,1-benzoxathiol 1,1-dioxide, 4-[9-(4-hydroxy-2-methyl-5-propan-2-yl-phenyl)-7,7-dioxo-8-oxa-7λ Examples include 6-thiabicyclo[4.3.0]nona-1,3,5-trien-9-yl]-5-methyl-2-propan-2-yl-phenol, 4,4'-(1,1-dioxide-3H-2,1-benzoxathiol-3,3-diyl)bis(2-bromo-6-isopropyl-3-methylphenol), 4-[(4-dimethylaminophenyl)-phenyl-methyl]-N,N-dimethyl-aniline, and the like.

[0030] Other examples of pH responsive sites that are naturally occurring substances include anthocyanin, litmus, etc. In addition, pigments such as xanthene, anthraquinone, alizarin, thiazine, coumarin, and porphyrin can also be used as pH responsive sites.

[0031] Examples of nonionic monomers include (meth)acrylamide, ethers of vinyl alcohol, and esters of (meth)acrylic acid such as methyl acrylate. Hydroxyalkyl (meth)acrylates and the like can make the copolymer insoluble or poorly soluble in water. As the nonionic monomer, one that has light-transmitting properties after cell formation (after copolymerization) is preferable. Since the nonionic monomer has light-transmitting properties after cell formation (after copolymerization), the color change of the pH-responsive copolymer becomes visible or detectable in a state where a sample liquid is contained. As the nonionic monomer, one that becomes transparent after cell formation (after copolymerization) is preferable.

[0032] In addition, examples of the polymerization reaction sites of pH-responsive monomers and nonionic monomers include polymers made of chloroethene or chloroethylene (which become polyvinyl chloride resin (PVC) when polymerized), polymers made of vinyl acetate monomers (which become vinyl acetate resin (PVAC) when polymerized), polymers made of vinyl alcohol (which become polyvinyl alcohol (PVAL) when polymerized), polymers made of aldehydes (polyvinyl butyral (PVB) when reacted with aldehydes), polymers made of bisphenol A and phosgene (which become polycarbonate (PC) when polymerized), polymers made of polymethyl methacrylate (which become methacrylic resin (PMMA) when polymerized), polymers made of polyphenylene oxide (which become polyphenylene resin (PPO) when polymerized), polymers made of ethylene (which become polyethylene (PE) when polymerized), polymers made of polypropylene (which become polypropylene (PP) when polymerized), polymers made of amide bonds (which become polyamide (nylon) (PA) when polymerized), and polymers made of formaldehyde and 1,3,Polymers made of 5-trioxane (when polymerized, they become polyacetal (polyoxymethylene) (POM)), polymers made of benzene rings and sulfur atoms (when polymerized, they become polyphenylene sulfide (PPS)), polymers made of vinyl chloride (PVC) and acrylonitrile (when polymerized, they become polyvinylidene chloride resin (PVDC)), polymers made of ethylene glycol and terephthalic acid or ethylene glycol and dimethyl terephthalate (when polymerized, they become polyethylene terephthalate (PETP)), polymers made of tetrafluoroethylene (when polymerized, they become polytetrafluoroethylene (tetrafluoroethylene (PTFE)), polymers made of chlorotrifluoroethylene (when polymerized, they become polychlorotrifluoroethylene (trifluoroethylene (PCTFE, CTFE)), ), a monomer made of vinylidene fluoride (when polymerized it becomes polyvinylidene fluoride (PVDF)), a polymer made of vinyl fluoride (when polymerized it becomes polyvinyl fluoride (PVF)), a polymer made of tetrafluoroethylene and perfluoroether (when polymerized it becomes perfluoroalkoxy fluororesin (PFA)), a polymer made of hexafluoropropylene and tetrafluoroethylene (when polymerized it becomes tetrafluoroethylene-hexafluoropropylene copolymer (FEP)), a polymer made of ethylene and tetrafluoroethylene (when polymerized it becomes ethylene-tetrafluoroethylene copolymer (ETFE)), a polymer made of ethylene and chlorotrifluoroethylene (when polymerized it becomes ethylene-chlorotrifluoroethylene copolymer (ECTFE)), etc. can be mentioned.

[0033] The polymerization reaction site is a polymer having a conjugated structure in the main chain or side chain, and the conjugated structure may be a naphthalene, benzene ring, biphenyl, or other polycyclic structure.

[0034] Alternatively, the pH-responsive copolymer may be copolymerized with an ionic monomer, which is a monomer component containing an ion-sensitive site and a polymerization reaction site, together with a pH-responsive monomer and a nonionic monomer, as described in the above Patent Documents 1 and 2. Examples of the ion-sensitive site include a sulfonium group, a phosphate group, a carboxy group, a nitro group, an amide bond, an ester bond, a carbonyl group, a thioketone group, a thioester, a thiol (thiocarbonyl), a thioimide, and a thioamide.

[0035] The pH measurement cell 2 is manufactured by mixing and melting a predetermined amount of a pH responsive monomer and a predetermined amount of a nonionic monomer to copolymerize them, and then molding the mixture into a cell shape using a molding die. In this way, the pH measurement cell 2 is manufactured. As a molding method, injection molding, blow molding, extrusion molding, vacuum molding, pressure molding, or the like can be appropriately adopted.

[0036] The color detection mechanism 3 is of a light reflection type, and includes a light irradiating unit 31 that irradiates the pH measurement cell 2 with light, and a light detecting unit 32 that detects reflected light from the pH measurement cell 2. The light irradiating unit 31 and the light detecting unit 32 are provided on the same side of the pH measurement cell 2 (the lower side in FIG. 1).

[0037] The light irradiating unit 31 can be configured using, for example, an LED that emits white light. The wavelength of the light irradiated by the light irradiating unit 31 can be appropriately selected according to the color tone of the pH responsive copolymer used in the pH measurement cell 2. In addition, the light irradiating unit 31 may have a lens that collects light.

[0038] The light detection unit 32 can be configured using, for example, a photomultiplier tube, a photodiode, an image sensor, etc. The wavelength of light detected by the light detection unit 32 can be appropriately selected according to the color tone of the pH responsive copolymer used in the pH measurement cell 2. In addition, the light detection unit 32 may have a lens that collects light, etc.

[0039] The pH calculation unit 4 calculates the pH of the sample liquid from the detection signal obtained by the light detection unit 32. Specifically, the pH calculation unit 4 calculates the pH of the sample liquid from the detection signal obtained by the light detection unit 32, using relationship data indicating the relationship between the detection signal and pH. The pH obtained by the pH calculation unit 4 can be displayed on the display unit 6.

[0040] Here, the relational data is obtained in advance by experiments, etc. Specifically, a reference liquid with a known pH is introduced into the pH measurement cell 2, and the detection signal obtained by the light detection unit 32 at that time is associated with the pH of the reference liquid to create the relational data. This relational data is stored in the relational data storage unit 5.

[0041] <Effects of this embodiment> According to the pH measuring device 100 configured in this manner, the pH measuring cell 2 is formed from a cell-forming resin composition containing a pH responsive copolymer, so that the pH measuring cell 2 can be made to have excellent durability and ease of use.

[0042] In addition, since the cell-forming resin composition is translucent, the discoloration of the pH-responsive copolymer can be detected with high accuracy when a sample liquid is contained therein, thereby improving the accuracy of pH measurement.

[0043] <Other embodiments> The present invention is not limited to the above-described embodiment.

[0044] For example, the pH measuring device 100 may be of a batch type. Specifically, as shown in FIG. 2, the pH measuring cell 2 may be attached to the device body 10. The device body 10 is provided with a cell attachment section 11 for attaching the pH measuring cell 2, a color detection mechanism 3, a pH calculation section 4, a related data storage section 5, and a display section 6. The pH measuring device 100 may be of a handy type that can be operated by holding it in one's hand. Although the color detection mechanism 3 in FIG. 2 is of a light reflection type, the device may be of a light transmission type in which the light irradiation section 31 and the light detection section 32 are provided on both sides of the pH measuring cell 2.

[0045] The shape of the pH measurement cell 2 may be a shape having an inlet port and an outlet port, a bottomed cylindrical shape having an opening at the upper end, or any other shape that can contain and store the sample liquid.

[0046] Although the color detection mechanism 3 in the above embodiment has the light irradiating unit 31, it may have a configuration without the light irradiating unit 31.

[0047] The color detection mechanism 3 may be configured as a light-transmitting type for the flow-type pH measurement cell 2, as shown in Fig. 3(a). The color detection mechanism 3 may be configured as a light-reflecting type for the storage-type pH measurement cell 2, as shown in Fig. 3(b). The color detection mechanism 3 may be configured as a light-transmitting type for the storage-type pH measurement cell 2, as shown in Fig. 3(c). The storage-type pH measurement cell 2 is a pH measurement cell 2 in which an inlet port and an outlet port (which may be common) are formed at the top, and a storage space is formed below them.

[0048] Furthermore, the pH responsive copolymer that changes color depending on pH can be applied to a semiconductor manufacturing apparatus as shown in FIG. 4. The semiconductor manufacturing apparatus in FIG. 4 is a cleaning apparatus for cleaning a wafer. A film F made of the pH responsive copolymer is placed on a rotating stage 201 in a processing chamber 200, and a cleaning liquid is supplied to inspect the behavior of the cleaning liquid (cleaning condition, etc.) on the rotating stage 201. Specifically, the color change of the film F to which the cleaning liquid is supplied is detected by the color detection mechanism 3 (light irradiation unit 31, light detection unit 32) through an optical window W1 formed in the processing chamber 200. The optical window W1 may be common to the light irradiation unit 31 and the light detection unit 32, or may be provided separately for each of the light irradiation unit 31 and the light detection unit 32.

[0049] Moreover, the pH responsive copolymer that changes color depending on pH can be applied to a technique for detecting leakage of a chemical liquid (e.g., a cleaning liquid) in a chemical liquid supplying device, as shown in FIG. 5. For example, as shown in FIG. 5(a), a pH responsive copolymer 7 can be provided on the outer peripheral surface of a pipe H (e.g., a pipe made of a fluororesin) through which a chemical liquid flows. In this case, a sheet-like pH responsive copolymer 7 can be provided on the outer peripheral surface of the pipe H. In this way, when a chemical liquid leaks from the pipe, the leakage can be detected by the color change of the pH responsive copolymer. Also, as shown in FIG. 5(b), a sheet-like pH responsive copolymer 7 can be laid on the lower side of the pipe system of the chemical liquid supplying device 300. With this configuration, it can be used as a substitute for a leak sensor, and it becomes easier to check the safety of work in a factory. In FIG. 5(b), the pH measuring device 100 of the above embodiment is provided on the pipe H.

[0050] Furthermore, the measurement target substance in other embodiments is not limited to the above-mentioned pH, and may be, for example, other ions (sodium, potassium, nitrate, nitrite, fluoride, etc.) or residual chlorine, etc. Furthermore, the pH measuring device 100 in other embodiments may be used for various sample liquids such as those in the food industry, tap water, drinking water, water from rivers and swamps, industrial wastewater, industrial waste liquid, experimental reagents, sewage, water supply and sewage, medical reagents, cooling water for air conditioning, and leachate treatment.

[0051] In the above embodiment, the pH measurement cell that contains a sample liquid and changes color depending on the pH has been described, but the present invention is not limited to a pH measurement cell that contains a sample liquid. For example, the pH measurement cell may be a pH measurement device that comes into contact with a sample liquid to measure the pH of the sample liquid, and is made of a resin containing a pH responsive copolymer that changes color depending on the pH.

[0052] This pH meter is for testing for the presence or absence of cavities, tartar, or periodontal disease by measuring the pH of saliva. Specifically, the pH meter is placed in the oral cavity of a subject and brought into contact with saliva in the oral cavity to measure the pH of the saliva. The pH meter can be in the form of a salivary gland such as the parotid gland, submandibular gland, or sublingual gland, or a part of the oral cavity adjacent thereto. The pH meter can be in the form of a chip (e.g., 1 mm square), a rod shape (stick shape), or various other shapes.

[0053] This pH measuring device is formed from a resin containing a pH-responsive copolymer that changes color depending on the pH. The pH-responsive copolymer is a copolymer containing a pH-responsive monomer, which is a monomer component containing a pH-responsive portion and a polymerization reaction portion, and a nonionic monomer, which is a monomer component containing an electrically neutral portion and a polymerization reaction portion. The pH-responsive monomer can be one listed in the above embodiment. The nonionic monomer can also be one listed in the above embodiment, but since it is placed in the mouth, it is desirable to use one that is biocompatible. Here, examples of biocompatible nonionic monomers include polyester, polyamide, polyethylene, polypropylene, polytetrafluoroethylene, polyether, polylactide, polyglycolide, polyacrylonitrile, polysulfone, polyvinyl alcohol, chitin, silicone, polymethine methacrylate, polyvinyl chloride, polyethylene terephthalate, chitin, collagen, etc.

[0054] The pH meter that has changed color in this way due to contact with saliva in the oral cavity can be used to measure the pH visually, or the pH can be calculated by measuring the color change of the pH meter using an analytical device such as an absorptiometer. The pH meter can also be used to measure the pH of urine in addition to measuring the pH of saliva.

[0055] With such a pH measuring device, the pH of saliva can be measured even if the amount is small, making pH measurement easier and reducing the burden on the subject compared to a configuration in which saliva is collected and the pH of the collected saliva is measured.

[0056] In addition, when it comes to measuring the pH of saliva, a measuring device having a working electrode and a reference electrode using, for example, an ISFET can be used. In this case, the sensor body having the working electrode and the reference electrode is made of a biocompatible resin. Also, it is considered to use a sodium chloride (NaCl) solution as the internal liquid of the reference electrode. The concentration of this NaCl solution is considered to be about the same as that of physiological saline (for example, 0.7 to 1%).

[0057] The above-mentioned pH measuring device is not limited to use for measuring the pH of saliva, but can also measure other fluids secreted from the human body or other animals, such as vaginal secretions, semen, gastric juices, saliva, and sweat.

[0058] Furthermore, the present invention is not limited to the above-described embodiment, and it goes without saying that various modifications are possible without departing from the spirit and scope of the present invention. [Explanation of symbols]

[0059] 100...pH measuring device 2. pH measuring cell 3. Color detection mechanism 31 Light irradiation unit 32 Light detection section 4...pH calculation section 5. Relational data storage section 6...Display section

Claims

1. A pH measurement cell for storing a sample liquid and measuring the pH of the sample liquid, A pH measurement cell made of a resin containing a pH-responsive copolymer that changes color depending on the pH.

2. The pH-responsive copolymer is copolymerized with a pH-responsive monomer, which is a monomer component having a pH-responsive site and a polymerization reaction site, 2. The pH measuring cell according to claim 1, wherein a color change of the pH responsive copolymer is visible or detectable when the sample liquid is contained therein.

3. The pH-responsive copolymer is copolymerized with a pH-responsive monomer and a nonionic monomer, which is a monomer component having an electrically neutral moiety or an ion-sensitive moiety and a polymerization reaction moiety; 3. The pH measuring cell according to claim 2, wherein the nonionic monomer is light-transmitting.

4. 4. The pH measuring cell according to claim 1, which is an in-line type provided in a sample liquid pipe through which the sample liquid flows.

5. A pH measuring cell according to any one of claims 1 to 3; a color detection mechanism for detecting the color of the pH-responsive copolymer.

6. The color detection mechanism includes: a light irradiating unit that irradiates the pH measuring cell with light; The pH measuring device according to claim 5 , further comprising a light detecting unit that detects reflected light from the pH measuring cell.

7. The pH measuring device according to claim 5 , further comprising a pH calculation unit that calculates the pH of the sample liquid from the detection signal obtained by the color detection mechanism.

8. 6. The pH measuring device according to claim 5, which continuously measures the pH of the sample liquid.

9. A pH measurement method comprising: placing a sample liquid in a pH measurement cell made of a resin containing a pH-responsive copolymer; and measuring the pH of the sample liquid based on the color of the pH-responsive copolymer.

10. A method for manufacturing a pH measurement cell for storing a sample liquid and measuring the pH of the sample liquid, comprising: A method for manufacturing a pH measuring cell, in which a pH measuring cell is molded using a resin containing a pH-responsive copolymer that changes color depending on the pH.

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