pH MEASUREMENT KIT, pH MEASUREMENT METHOD USING THE SAME AND MEASUREMENT DEVICE

Abstract

To provide a pH measurement kit, a pH measurement method using the same and a measurement device that can measure pH with high sensitivity without the measurement device coming into contact with a sample to be measured.SOLUTION: A pH measurement kit according to the present invention includes: a glass plate which has an uneven shape on one surface; and a pH indication layer which is fixed onto the one surface. The pH indication layer is a reactant between a dye compound and a silane coupling agent. The dye compound has a substituent that reacts with an epoxy group and a pH indication portion. The silane coupling agent has an epoxy group.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a pH measurement kit, a pH measurement method using the same, and a measurement device. [Background technology]

[0002] The evolution of camera functions in smartphones and other devices has led to the development and widespread use of high-performance, low-cost semiconductor image sensors, making it possible to easily measure the color of various objects with simple operations. It is now possible to quantify chemical substances from the color information acquired by the device, and it has reached a level of general-purpose use comparable to precise spectroscopic measurements (e.g., Non-Patent Document 1). Such techniques use a method of processing color information in a color space proposed by the International Commission on Illumination (CIE), and a method of measuring the amount of a substance generated or disappeared by a chemical reaction at a deviation angle D around a reference point on the CIE xy coordinate system (Patent Document 1, Patent Document 2) has been reported. Material inventions related to polymeric dyes that reversibly change color depending on the pH of water have also been reported (for example, Patent Document 3, Patent Document 4). A quantitative analysis method using quantitative analysis on chromaticity coordinates has also been disclosed (for example, Patent Document 5). In particular, Patent Document 5 discloses a quantitative analysis method in which, for an analytical material that changes color due to interaction with a substance, numerical color information is measured using a colorimeter such as a measuring device, and the color is converted into chromaticity points on the three-dimensional color coordinates of the CIE XYZ color system, and the content of a substance (T) in a sample to be measured is calculated using a measurement scale obtained in advance. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 5665187 [Patent Document 2] Patent No. 6224410 [Patent Document 3] Patent No. 6594279 [Patent Document 4] Patent No. 6594280 [Patent Document 5] Patent Publication No. 2022-119081 [Non-patent literature]

[0004] [Non-Patent Document 1] Capitan-Vallvey, LF, et al. (2015). “Recent developments in computer vision-based analytical chemistry: A tutorial review.” Analytica Chimica Acta 899: 23-56. Summary of the Invention [Problem to be solved by the invention]

[0005] On the other hand, it is very difficult to prepare equipment with different specifications depending on the measurement location and environment, etc. There is a strong demand for an environment where general measurement equipment can be used in any situation. In both of the above patented and non-patented methods, the material had to be placed in the test water to measure the pH, and the measuring device to measure the color change had to be immersed in the test water together with the material. This inevitably required waterproofing measures to prevent the electrical circuitry of the device from coming into contact with water.

[0006] In the present invention, a pH measurement kit is devised in which a dye that indicates a pH change by a color change is fixed only on one side of a transparent substrate, and the measurement part of various measurement devices can be directly installed on the other side. As a result, when the sample to be measured is water, there is no need to introduce the measurement water to the measurement part, and the measurement device does not come into contact with the measurement water. Since no waterproofing treatment is required, existing color measurement devices can be used as they are. That is, the present invention aims to provide a pH measurement kit, a pH measurement method using the same, and a measurement device that can measure the sample to be measured without the measurement device touching the sample to be measured by arranging a color change part that comes into contact with the sample to be measured and a measurement part that measures the color with a color measurement device on different sides of a glass plate. In addition, the present invention aims to provide a pH measurement kit, a pH measurement method using the same, and a measurement device that can perform high-sensitivity measurement by arranging the color change part on the side of the glass substrate that has an uneven shape. [Means for solving the problem]

[0007] In order to solve the above problems, the present invention employs the following means.

[0008] [1] A glass plate having an uneven surface on one side; A pH indicator layer fixed on said one surface; A pH measurement kit comprising: the pH indicator layer is a reaction product of a dye compound and a silane coupling agent, the dye compound has a substituent reactive with an epoxy group and a pH indicator moiety; The pH measurement kit, wherein the silane coupling agent has an epoxy group. [2] The pH measurement kit described in [1], wherein the glass plate is frosted glass or ground glass. [3] The pH measurement kit according to [1] or [2], wherein the dye compound is a pH indicator having at least one group selected from the group consisting of an amino group (NH2), a carboxyl group (COOH), and a hydroxyl group (OH). [4] The pH measurement kit according to any one of [1] to [3], wherein the pigment compound is at least one selected from the group consisting of bromocresol purple (BCP), bromothymol blue (BTB), phenol red (phenolsulfonephthalein, PR), and bromochlorophenol blue (BCPB). [5] The pH measurement kit according to any one of [1] to [4], wherein the silane coupling agent is 3-glycidyloxypropyltrimethoxysilane (GPTMS). [6] A step of contacting a sample to be measured with the pH indicator layer of the pH measurement kit according to any one of [1] to [5]; measuring the chromaticity of the pH indicator layer from the opposite side of the pH indicator layer of the pH measurement kit using a color measuring device; A pH measuring method comprising the steps of: [7] A pH measurement kit according to any one of [1] to [5], A pH measurement device having a color measurement device, The pH measurement kit comprises: a color-changing portion on the pH indicator layer that comes into contact with a sample to be measured; A measurement unit on one surface of the glass plate that does not have a concave-convex shape; A pH measuring device comprising: Effect of the Invention

[0009] According to the present invention, it is possible to provide a pH measurement kit, a pH measurement method using the same, and a measurement device that can measure pH with high sensitivity without the measurement device coming into contact with the sample to be measured. [Brief description of the drawings]

[0010] [Figure 1] FIG. 1 is a conceptual diagram showing an example of a pH indicating kit of the present embodiment. [Diagram 2] This is a diagram showing the principle of acid-base equilibrium, in which bromocresol purple (BCP) fixed to a glass plate changes color depending on the hydrogen ion concentration (pH). [Diagram 3]The principle diagram (Scheme 1) shows a method for producing G-GPTMS, in which GPTMS is supported on a frosted glass plate. [Figure 4] FIG. 2 is a diagram (Scheme 2) illustrating the principle of a method for preparing G-GPTMS-BCP in which a dye is supported on G-GPTMS. [Diagram 5] FIG. 1 is a conceptual diagram showing an example of a pH measurement device according to an embodiment of the present invention. [Figure 6] 1 is a plot showing the conversion process to chromaticity points on the CIE xy chromaticity diagram. [Figure 7] In the CIE xy chromaticity diagram, the color change at each pH was calculated as the deviation angle D, and this is a graph created with pH on the horizontal axis and the deviation angle D on the vertical axis. pKa was calculated using logistic approximation. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] Hereinafter, an embodiment for carrying out the pH measurement kit according to the present embodiment, the pH measurement method using the same, and the measurement device will be described.

[0012] (pH indicator kit) 1 is a conceptual diagram showing one embodiment of the pH indicator kit of the present invention. A pH indicator kit 10 of one embodiment of the present invention (sometimes referred to as the pH indicator kit of this embodiment) has a glass plate 4 having an uneven surface 4a, and a pH indicator layer 2 fixed onto the surface. The pH indicator layer 2 is a reaction product of a dye compound (not shown) and a silane coupling agent (not shown). The dye compound has a substituent that reacts with an epoxy group and a pH indicator site. The silane coupling agent has an epoxy group. The pH indicator layer 2 shown in Fig. 1 is a layer having a flat surface shape and a constant thickness, but this is not meant to be limiting. The pH indicator layer 2 may be formed thinly on the uneven surface of the glass substrate 4, and may maintain a constant uneven surface shape. Also, for example, the thickness of the pH indicator layer may be zero on some of the convex portions of the uneven shape of the glass substrate 4 (i.e., there may be some portions where the pH indicator layer 2 is not formed).

[0013] The reaction product of the dye compound (not shown) and the silane coupling agent (not shown) may be an organic / inorganic matrix formed on the glass plate 4 by a bond between the glass plate 4 and the silane coupling agent formed by reacting the silane coupling agent with the dye compound (for example, a bond by a dehydration reaction, hereinafter referred to as a first bond); and a bond formed by reacting the dye compound (not shown) with the silane coupling agent (for example, a bond by a reaction between an epoxy group and a substituent that reacts with an epoxy group, hereinafter referred to as a second bond). The reaction product may also be an organic / inorganic matrix formed by the first bond, the second bond, and a bond formed by reacting the silane coupling agents with each other (for example, a bond by a dehydration reaction, hereinafter referred to as a third bond), or a bond formed by reacting the dye compounds with each other (hereinafter referred to as a third bond).

[0014] An example of a pH indicator kit 10 of this embodiment shown in FIG. 1 is a flat-plate-shaped pH indicator kit in which a pH indicator layer 2 is disposed on a flat glass plate 4. However, the shape of the pH indicator kit of this embodiment is not limited to a flat plate, and for example, a glass plate having a certain curved surface such as a spherical surface may be used. In this case, the pH indicator layer may be disposed on the inner surface or outer surface of the sphere. For example, as another embodiment of the pH measuring device described later, when a color measuring device is disposed inside a tube, it is preferable to dispose the pH indicator layer on the outside of the bottom of the tubular glass tube. Furthermore, if necessary, for example, from the viewpoint of increasing the sensitivity of the measurement, a convex spherical lens shape with light-collecting properties may be formed on surface 4b of glass plate 4, which does not have an uneven shape, as shown in Fig. 2. In this case, more light can be collected by the sensor of the color measuring device, and measurement sensitivity exceeding the predetermined sensitivity of the color measuring device can be obtained.

[0015] [Glass plate] The glass plate 4 used in the pH indicator kit of this embodiment has a first surface 4a having an uneven shape and a second surface 4b having an uneven shape. The thickness of the glass plate 4 according to the present embodiment is not particularly limited as long as it does not impair the object of the present invention. For example, from the viewpoint of resistance to breakage, the thickness may be 0.1 mm, 0.5 mm, or 1 mm or more. Also, from the viewpoint of measurement sensitivity, the thickness may be, for example, 10 mm or less, or 5 mm or less. The uneven shape of the glass plate 4 according to this embodiment may be a regular uneven shape or an irregular uneven shape. From the viewpoint of a simple formation method, an irregular uneven shape is preferable. The surface roughness of the first surface 4a having the uneven shape of the glass plate 4 according to this embodiment may be, for example, 0.5 μm or more, 1 μm or more, or 5 μm or more in terms of maximum height (Rmax / JIS). From the viewpoint of ease of formation, it may be, for example, 200 μm or less, 100 μm or less, or 50 μm or less. The first surface 4a of the glass plate 4 according to this embodiment, which has an actual surface area (S0) and a reference surface area (St) calculated from the outer dimensions, may have a surface area increase rate (ΔS0) expressed by the following formula (A) of 50% or more, 80% or more, or 500% or less. ΔS0={100*(S0-St) / S0(%) (A) The surface roughness and the surface area increase rate can be evaluated by known methods, such as a non-contact surface profiler and a scanning probe microscope.

[0016] A known method can be used to form the above-mentioned uneven shape on one side of the glass plate. For example, a physical surface treatment method using sandblasting or silica sand to roughen the surface; a chemical surface treatment method using an etching agent such as a roughening agent; a film formation method in which a silicon alkoxide-based coating material is applied and hydrolyzed on a transparent glass substrate; etc. may be mentioned. In addition, after the treatment using a physical method, further treatment using a chemical method may be performed.

[0017] There is no particular limitation within the scope of the present invention, but examples thereof include the shape of the frosted surface of frosted glass formed by a known glass surface treatment method, or the shape of the ground surface of ground glass. Examples of the glass plate 4 having an uneven shape include frosted glass, ground glass, etc. Among these, frosted glass is preferred from the viewpoints of being easily available commercially and being easily observed from the opposite side of the frosted surface.

[0018] The glass plate 4 having an uneven surface 4a according to this embodiment can fix a larger amount of pH reagent per unit area than a glass plate without an uneven surface (for example, a transparent glass plate such as a normal cover glass). For this reason, it is considered that the pH measurement kit of this embodiment using the glass plate 4 having an uneven surface has better color development and a higher pH measurement range and sensitivity.

[0019] [pH indicator layer] The pH indicator layer of the pH measurement kit of this embodiment is obtained by reacting the dye compound with the silane coupling agent on the glass plate 4. A layer of the silane coupling agent may be formed on the glass plate 4 first, and then the layer of the silane coupling agent and the dye compound may be reacted. Alternatively, the silane coupling agent may be reacted with the dye compound first, and then applied onto the glass plate 4. From the viewpoint of sufficient contact between the silane coupling agent and the glass plate 4, it is preferable to first form a layer of the silane coupling agent on the glass plate 4, and then react the layer of the silane coupling agent with the dye compound to form a pH indicator layer.

[0020] For example, in the case of a method in which the silane coupling agent layer is first formed and then the silane coupling agent layer is reacted with the dye compound, the pH indicator layer may have a layer structure of the silane coupling agent-derived layer, the silane coupling agent-derived layer, and the uneven surface of the glass plate 4 (hereinafter, simply referred to as the "uneven surface"). In a specific example described in the examples described later, it is considered that, between the uneven surface of the glass plate 4 and the silane coupling agent-derived layer, the alkoxy group derived from the silane coupling agent is hydrolyzed to generate a silanol group, and then a covalent bond is generated through a dehydration condensation reaction with the hydroxyl group on the uneven surface (one specific example is shown in Scheme 1 in FIG. 4, for example). In addition, it is considered that a covalent bond is formed between the silane coupling agent-derived layer and the dye compound by reacting an epoxy group with a hydroxyl group. As a result, the dye compound is fixed to the uneven surface of the glass plate 4 via the silane coupling agent-derived layer (one specific example is shown in Scheme 2 in FIG. 4, for example).

[0021] The pH indicator layer of this embodiment is formed on the uneven surface of the glass plate 4, and is formed via a layer derived from a silane coupling agent. As a result, in the application of the pH measuring device described below, the above-mentioned dye compound that can come into contact with the sample to be measured can be fixed at a high density in the measuring section (FIG. 3, 2s). Therefore, excellent pH responsiveness can be obtained.

[0022] Since the pH indicator layer of this embodiment is formed on the uneven surface of the glass plate 4, it is difficult to evaluate the layer thickness by a normal method, but it can be evaluated by the mass formed per unit area of ​​the glass plate 4. For example, it can be calculated from the area of ​​the glass plate from the mass conversion of the glass plate before and after treatment with the silane coupling agent. The thickness of the pH indicator layer in this embodiment is not particularly limited, although it depends on the uneven shape of the glass plate 4. For example, 2 or more, 0.5 kg / m 2 May be more than 1kg / m 2 It may be 10 kg / m or more. 2It may be less than 5 kg / m 2 It may be the following.

[0023] The surface shape of the pH indicator layer in this embodiment is formed on the uneven surface of the glass plate 4, so it may be flat or uneven, depending on the surface roughness of the uneven shape and the film thickness of the pH indicator layer (simply the amount of area formed). For example, when used in a pH measuring device described later, an uneven shape is preferable from the viewpoint of a large contact surface with the sample to be measured.

[0024] The surface of the pH indicator layer of the present embodiment is not particularly limited, but for example, when used in a pH measuring device described later, it is preferable that the surface has a high affinity with the medium of the sample to be measured. For example, when the medium of the sample to be measured is an aqueous solvent, it is preferable that the surface is hydrophilic from the viewpoint of a large contact surface with the sample to be measured.

[0025] The surface state of the pH indicator layer of this embodiment is not particularly limited, but for example, when used in a pH measuring device described later, it is preferable that the sample to be measured can penetrate below the surface layer in view of the wide contact surface with the sample to be measured. For example, the penetration depth may be 0.1 μm or more, 0.5 μm or more, or 1 μm or more. Also, for example, it may be the entire layer of the pH indicator layer, or 100 μm or less, or 10 μm or less.

[0026] <Dye compounds> The dye compound (sometimes referred to as the dye compound according to the present embodiment) used as one of the raw materials of the pH indicator layer of the present embodiment is a dye compound having a substituent that reacts with an epoxy group and a pH indicator site. The substituent that reacts with the epoxy group is preferably at least one selected from the group consisting of an amino group (NH2), a carboxyl group (COOH), and a hydroxyl group (OH), and is more preferably a hydroxyl group (OH). The pH indicator site refers to a portion of the dye compound other than the substituent that reacts with the epoxy group. And, even after the dye compound is reacted with an epoxy group contained in the silane coupling agent according to the present embodiment described later and the dye compound is fixed as one structure of the pH indicator layer, the pH indicator site exists and can contribute to color change. That is, the pH indicator site is a site that can contribute to changing the color of the dye compound when the pH changes in the range of pH 1 to 14. The pH indicator site exists and can function even when the dye compound according to the present embodiment is fixed to the pH indicator layer, and can change the color of the pH indicator layer. Examples of the dye compound include bromocresol purple (BCP), bromothymol blue (BTB), phenol red (PR, phenolsulfonephthalein), bromochlorophenol blue (BCPB), etc. In the examples described later, bromocresol purple (BCP) was used as the dye compound according to this embodiment.

[0027] For example, when an example of the dye compound according to the embodiment is bromocresol purple (BCP), bromocresol purple (BCP) can be fixed to frosted glass by the procedure of Example 1 described later, for example, as shown in the principle diagrams of Figures 4 and 5. That is, as a raw material for forming the pH indicator layer of this embodiment, BCP has two hydroxyl groups (OH). One OH is a substituent that reacts with the epoxy group, and the other BCP structure containing the other OH is the pH indicator site of BCP. As shown in Figure 2, the pH indicator site of BCP fixed in the pH indicator layer changes from yellow to purple depending on the pH of the in-house environment. A glass plate having a G-GPTMS-BCP layer (referred to as G-GPTMS-BCP), which is a pH measurement kit prepared in Example 1 described later, showed the following color change in a buffer solution. Yellow at pH 4.0 to 7.0; green at pH 7.5 to 9.0; Blue at pH 9.5 - 11.5

[0028] <Silane coupling agent> The silane coupling agent (sometimes referred to as the silane coupling agent according to the present embodiment) used as one of the raw materials of the pH indicator layer of the present embodiment is preferably an epoxy group-containing trialkoxysilane and / or its hydrolysis condensate. The epoxy group-containing trialkoxysilane is not particularly limited in structure as long as it is a trialkoxysilane containing an epoxy group in addition to the functional group portion that is lost by hydrolysis, etc., and may be, for example, a compound represented by the following formula (I).

[0029] R-Si(OR 1 )3(I)

[0030] (In the formula, R represents a hydrocarbon group having an epoxy group or a glycidoxy group, R 1 represents an unsubstituted or substituted alkyl group having 1 to 10 carbon atoms.

[0031] R may contain one or more epoxy groups or glycidoxy groups, preferably 1 to 3, and may contain both epoxy groups and glycidoxy groups. Specific examples of the "hydrocarbon group" in the "hydrocarbon group having an epoxy group or a glycidoxy group" of R include an alkyl group, a cycloalkyl group, and a cycloalkylalkyl group. The number of carbon atoms is preferably in the range of 1 to 30, and more preferably in the range of 1 to 10.

[0032] Specific examples of the "alkyl group" include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a t-butyl group, an n-pentyl group, an isopentyl group, a neopentyl group, an n-hexyl group, an isohexyl group, an n-heptyl group, an n-octyl group, an n-nonyl group, an isononyl group, an n-decyl group, a lauryl group, a tridecyl group, a myristyl group, a pentadecyl group, a palmityl group, a heptadecyl group, and a stearyl group. Specific examples of the "cycloalkyl group" include a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, and a cyclooctyl group. Specific examples of the "cycloalkylalkyl group" include a cyclopropylmethyl group, a cyclopropylethyl group, a cyclopropylpropyl group, a cyclobutylmethyl group, a cyclopentylmethyl group, a cyclohexylmethyl group, a cycloheptylmethyl group, and a cyclooctylmethyl group. A cycloalkyl group having 3 to 10 carbon atoms and an alkyl group having 1 to 10 carbon atoms are preferably bonded to each other. The above-mentioned "hydrocarbon group" may have a substituent other than an epoxy group or a glycidoxy group. Specific examples of such a substituent include a halogen atom, an alkyl group, an alkenyl group, an alkoxy group, and a (meth)acryloxy group. Specific examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom. Specific examples of the alkoxy group include a methoxy group, an ethoxy group, an n-propoxy group, an isopropoxy group, an n-butoxy group, an isobutoxy group, and a t-butoxy group. Examples of the alkyl group and alkenyl group include the same alkyl group and alkenyl group as those for R above.

[0033] R 1 Examples of the "alkyl group having 1 to 10 carbon atoms" in the "unsubstituted or substituted alkyl group having 1 to 10 carbon atoms" include the same alkyl groups as those in R above. Specific examples of the substituent in "having a substituent" include a halogen atom, an alkoxy group, a (meth)acryloxy group, etc. Specific examples of the halogen atom and the alkoxy group include the same specific examples as the halogen atom and the alkoxy group exemplified as the substituent other than the epoxy group and the glycidoxy group in R above. Specific examples of the epoxy group-containing trialkoxysilane or its hydrolysis condensate as the raw material include, but are not limited to, the following compounds. These may be used alone or in combination of two or more. R 1 Examples of the "alkyl group having 1 to 10 carbon atoms" in the "unsubstituted or substituted alkyl group having 1 to 10 carbon atoms" include the same alkyl groups as those in R above. Specific examples of the substituent in "having a substituent" include a halogen atom, an alkoxy group, a (meth)acryloxy group, etc. Specific examples of the halogen atom and the alkoxy group include the same specific examples as the halogen atom and the alkoxy group exemplified as the substituent other than the epoxy group and the glycidoxy group in R above. Specific examples of the epoxy group-containing trialkoxysilane or its hydrolysis condensate as the raw material include, but are not limited to, the following compounds. These may be used alone or in combination of two or more. Among them, glycidoxy alkyl trialkoxy silane or glycidoxy alkenyl alkoxy silane is preferable, and glycidoxy alkyl trialkoxy silane is more preferable. Specifically, the compound shown in the following formula can be exemplified. These can be used alone or in combination of two or more kinds. 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane 3-Glycidoxypropyltrimethoxysilane (GPTMS) 3-Glycidoxypropyltriethoxysilane (GPTES)

[0034] The silane coupling agent according to this embodiment may further contain a compound represented by the following formula (II).

[0035] R 2 -Si(OR 1 )3(II)

[0036] (In the formula, R 2 represents a hydrocarbon group having no epoxy group or glycidoxy group, R 2 The hydrocarbon group in the formula (I) has the same meaning as the hydrocarbon group in the formula (I), 1 is R in formula (I) 1 is the same as Examples of the compound represented by the above formula (II) include silane coupling agents such as trimethoxymethylsilane (MeSi). The silane coupling agent according to this embodiment may be, for example, a mixture of 3-glycidoxypropyltrimethoxysilane (GPTMS) and trimethoxymethylsilane (MeSi).

[0037] (pH measurement method) A pH measurement method of one embodiment of the present invention (the pH measurement method of this embodiment) comprises the steps of contacting a sample to be measured with the pH indicator layer of the pH measurement kit of this embodiment, and measuring the chromaticity of the pH indicator layer from the opposite side of the pH indicator layer of the pH measurement kit using a color measuring device such as a colorimeter.

[0038] The pH measurement method of the present embodiment may include a step of pretreating the pH indicator layer before the contact step, if necessary. For example, the pretreatment may involve washing the surface of the pH indicator layer with ion-exchanged water or a buffer solution having a certain pH value. The pH measurement method of the present embodiment may include a calculation step of obtaining the pH of the sample to be measured from the numerical color result obtained by the color measurement device, simultaneously with or after the measurement step, if necessary.

[0039] For the calculation step, for example, a quantitative analysis method such as that disclosed in Patent Document 5 can be used. Color is generated by interaction between the sample to be measured and the structure derived from the pigment compound of the pH measurement layer, and the color of the pH measurement layer is measured using a colorimeter such as a color measuring device, and the color is converted into chromaticity points on the three-dimensional color coordinates of the CIE XYZ color system. Then, the pH of the sample to be measured is calculated using a measurement scale. The measurement scale can be created in advance by the method disclosed in Patent Document 5.

[0040] In the pH measurement method of this embodiment, the pH indicator layer of the pH measurement kit (hereinafter, sometimes referred to as the surface of the pH measurement kit) may be measured with a colorimeter such as a color measuring device, or the color change of the pH indicator layer may be measured from the opposite side of the pH indicator layer of the pH measurement kit (hereinafter, sometimes referred to as the back side of the pH measurement kit), i.e., through a glass plate. In the pH measurement method of this embodiment, the color change of the pH indicator layer is preferably measured from the opposite side of the pH indicator layer (the back side of the pH measurement kit) through a glass plate from the viewpoint of adaptability to changes in the measurement location and environment, and of general measurement equipment being able to handle any situation.

[0041] The pH measurement method of this embodiment can measure pH in a wide range by using the pH measurement kit of this embodiment. The measurement range is not particularly limited. For example, it may be measured in the range of pH 1.5 to pH 12.5, or in the range of pH 2.5 to pH 11.5, or in the range of pH 3.0 to pH 11.0. For example, it can be measured in the range of pH 3.0 to 6.0 (yellow), pH 6.5 to 8.0 (green), and pH 8.5 to 11.0 (blue).

[0042] (pH measuring device) As shown in Fig. 3, a pH measurement device 20 according to one embodiment of the present invention (pH measurement device of this embodiment) is characterized by having the pH measurement kit 10 of this embodiment and a color measurement device 14. The pH measurement kit 20 has a color development section 2s that contacts a measurement target sample 12 on the pH indicator layer 2, and a measurement section 4s on the non-irregular surface 4b of the glass plate 4. The pH measurement device of this embodiment may have a calculation section that calculates pH from chromaticity information, if necessary.

[0043] The calculation unit is not particularly limited as long as it can output a pH value from the input chromaticity information. For example, it can be created with reference to a quantitative analysis method such as that disclosed in Patent Document 5. For example, it may include a sub-calculation unit that converts numerical information of a color measured using a colorimeter such as a color measuring device into a chromaticity point on a three-dimensional color coordinate of the CIE XYZ color system as necessary, and a pH calculation unit that calculates the pH of a sample to be measured by the quantitative analysis method disclosed in Patent Document 5 using a measurement scale. The calculation unit may include a measurement scale calculation unit that creates a measurement scale in advance from the chromaticity information of a standard sample using the method disclosed in Patent Document 5.

[0044] The calculation unit may output a pH value from the input chromaticity information using a known method other than the method of Patent Document 5. For example, examples of color spaces that handle color information include RGB, CMYK, HSV, CIE 1931, and the like, in addition to L*a*b*. In these color spaces, a calibration curve can be drawn and the pH can be estimated from the correlation, as described above.

[0045] The pH measuring device 20 of this embodiment does not need to introduce a measurement medium such as test water to the measurement surface (measurement section 4s), and the pH measuring device 20 does not come into contact with the measurement medium. For example, when the measurement medium is an acidic aqueous solution, there is no need to apply acid-proofing or waterproofing measures, so that an existing color measuring device can be used as is.

[0046] [Other embodiments of the pH measuring device] In other embodiments (not shown) of the pH measuring device of this embodiment, for example, the pH indicator layer of this embodiment can be formed on the outside of the bottom tip of the glass tube by utilizing the feature that no acid-proofing or waterproofing treatment is required. That is, the pH measuring kit of this embodiment can be placed at the bottom of the glass tube, with its color-changing part placed outside the tube and its measuring part placed inside the tube. In this case, the color measuring device can be placed inside the glass tube. And, for example, when the measurement target sample is a fluid liquid, a liquid that changes over time, or a liquid inside a part, the pH measuring device using the above-mentioned tubular pH measuring kit can be suitably used when measuring (monitoring) its pH. Further, as another embodiment (not shown), there is a pH measuring device in which a pH indicator layer is formed on the outside of a hollow glass container, a coloring part is arranged, and a measuring part is arranged inside the coloring part. The color measuring device of the pH measuring device is, for example, a power-saving and compact device, and further has a data storage part that stores the output result or a transmission part that can transmit data to the outside. The pH measuring device of this embodiment is, for example, installed deep in the liquid to be measured, and can measure the time-dependent change and position dependency of the pH of the liquid to be measured. EXAMPLES

[0047] The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples.

[0048] (Evaluation method) "Colorimetric measurement" The color information of the polymer dyes was measured with a Color Munki Photo colorimeter (X-Rite GmbH).

[0049] (raw materials) Acetic acid: TCI (Tokyo Chemical Industry Co., Ltd.), purity, etc. 3-Glycidyloxypropyltrimethoxysilane: TCI, GPTMS Frosted glass plate: Matsunami Glass Industry Co., Ltd., MICRO SLIDE GLASS, water green polished full frost t1.3, size: 76×26mm, thickness: 1.2~1.5mm, Frosted: 76×26mm, Pre-Cleaned: 100Pcs.

[0050] (Preparation Example 1) "Preparation of hydrolyzed GPTMS" An aqueous solution of acetic acid (1.0 mL, 0.0349 mol / L) and 3-glycidyloxypropyltrimethoxysilane (GPTMS, 1.0 mL) were placed in a sample bottle and stirred at room temperature for 1 hour to carry out hydrolysis. An aqueous solution of hydrolyzed GPTMS was prepared.

[0051] (Preparation Example 1) "Preparing the frosted glass plate" A commercially available frosted glass plate was cut in half to produce two frosted glass plates measuring 38 x 26 mm. The frosted surfaces of two frosted glass plates were cleaned with ozone for 10 minutes using a tabletop UV ozone cleaning and modification device ASM401N manufactured by Asumi Giken Co., Ltd. The frosted glass plates that had been cleaned with ozone were then immersed in boiling 2-propanol for 1 minute to prepare frosted glass plates from which impurities had been removed.

[0052] Example 1 "Preparation of pH measurement kit" The pH indicator kit of this example was prepared according to the following procedure. (I) Formation of a GPTMS layer on a frosted glass plate The frosted glass plate prepared in Preparation Example 1 was placed with the frosted surface facing up and placed in an electric furnace set at 120°C, after which 1 mL of hydrolyzed GPTMS prepared in Preparation Example 1 was dropped onto the frosted glass plate and heated for 6 hours. It was then cooled. A GPTMS layer was formed on the frosted surface of the frosted glass plate as the pH indicator layer of this embodiment. A glass plate having a GPTMS layer (referred to as G-GPTMS) was produced. A part of the above reaction (I) is considered to be, in principle, shown in FIG.

[0053] (II) Fixation of pH indicator An aqueous solution of acetic acid (100 mL, 0.0349 mol / L) was placed in a beaker, and 20 mg of bromocresol purple (BCP) was dissolved in it. The G-GPTMS was immersed in this aqueous solution for 12 hours. The soaked material was placed GPTMS side up and heated in an electric furnace set at 120 °C for 2 h, then allowed to cool to room temperature overnight. After the cooled material was washed with methanol and pure water, BCP was fixed to the frosted glass plate to prepare a glass plate having a G-GPTMS-BCP layer (referred to as G-GPTMS-BCP) as a pH indicator kit of this embodiment. A part of the above reaction (II) is considered to be, in principle, shown in FIG. It was found that G-GPTMS-BCP obtained in the Example as a pH indicator kit exhibited the following color changes in a buffer solution. Yellow at pH 4.0 to 7.0; green at pH 7.5 to 9.0; Blue at pH 9.5 - 11.5

[0054] "Evaluation of pH indicator kits" (1) Preparation of evaluation equipment G-GPTMS-BCP was thoroughly immersed in buffer solutions prepared at each pH level, and after the color change at that pH level had completed, it was sandwiched between two glass slides. The G-GPTMS-BCP sandwiched between the glass slides was then placed on a white backing material, and the color change was measured using a colorimeter (ColorMunki, manufactured by X-rite Corporation).

[0055] The evaluation procedure is as follows. (I) Buffer solutions with pH values ​​of 3.0 to 12.5 were prepared using ultrapure water, HCl, NaOH, NaH2PO4, and Na2HPO4, and stored under a nitrogen atmosphere. (II) The pH indicator kit prepared in the Example was immersed in the buffer solution of each pH prepared in (I) for about 1 hour. After sufficient equilibrium was reached, the color change of the material was measured by a colorimeter, and the color measurement value was obtained in L*a*b* format. The obtained value was converted to XYZ format and plotted on the CIExy chromaticity diagram to observe the color change behavior. The results are shown in Figure 5. (III) An equilateral triangle was drawn connecting both ends of the measurement points in the entire color change area on the chromaticity diagram created in (II), and the apex of the triangle was set as the reference point. The line connecting the starting point on the chromaticity diagram and the reference point was set as the base line, and the color change at each pH was calculated as the deflection angle D. Next, a graph was created with pH on the horizontal axis and deflection angle D on the vertical axis, and pKa (acid-base dissociation constant - logKa) was calculated by logistic approximation. The results are shown in Figure 6. In addition, the pH range that can be measured using the pH kit was 4 to 11. [Explanation of symbols]

[0056] 2:pH indicator layer 4: Glass plate with uneven surface on one side 4a: Surface having uneven shape 4b: Surface without unevenness 10: pH indicator kit 2s: Contact part 4s: Measuring part 12: Sample to be measured 14: Color measuring device, colorimeter 20:pH measuring device

Claims

1. a glass plate having an uneven shape on one side; a pH indicator layer fixed on said one surface; A pH measurement kit comprising: the pH indicator layer is a reaction product of a dye compound and a silane coupling agent, the dye compound has a substituent reactive with an epoxy group and a pH indicating moiety; A pH measurement kit, wherein the silane coupling agent has an epoxy group.

2. The pH measurement kit according to claim 1 , wherein the glass plate is frosted glass or ground glass.

3. The dye compound has an amino group (NH ２ 3. The pH measurement kit according to claim 1, wherein the pH indicator has at least one selected from the group consisting of a carboxyl group (COOH) and a hydroxyl group (OH).

4. 3. The pH measurement kit according to claim 1, wherein the dye compound is at least one selected from the group consisting of bromocresol purple (BCP), bromothymol blue (BTB), phenol red (PR), and bromochlorophenol blue (BCPB).

5. 3. The pH measurement kit according to claim 1, wherein the silane coupling agent is 3-glycidyloxypropyltrimethoxysilane (GPTMS).

6. A step of contacting a sample to be measured with the pH indicator layer of the pH measurement kit according to claim 1 or 2; measuring the color of the pH indicator layer from the opposite side of the pH indicator layer of the pH measurement kit using a color measurement device; A pH measurement method comprising the steps of:

7. The pH measurement kit according to claim 1; a color measurement device; and a pH measurement device having the color measurement device, The pH measurement kit comprises: a coloring portion on the pH indicator layer that comes into contact with a sample to be measured; a measurement unit on one surface of the glass plate that does not have an uneven surface; A pH measuring device comprising:

8. The pH measurement kit is placed at the bottom of a glass tube, The pH measuring device according to claim 7 , wherein the coloring unit is disposed outside the glass tube, and the measuring unit is disposed inside the glass tube.

9. The color-changing portion is disposed outside a hollow glass container, The pH measuring device according to claim 7 , wherein the measuring unit is disposed inside the glass container.

10. A pH measuring device as described in claim 8 or 9, further having at least one type selected from the group consisting of a data storage unit that stores the output results of the measuring unit and a data transmission unit that transmits the output results to the outside.

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