JP3343161B2 - Moisture measurement method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for measuring the amount of water dissolved or dispersed in a sample whose water concentration is unknown.
More specifically, the present invention relates to a moisture measuring method suitable for measuring a moisture concentration in a cleaning solution or the like of electronic parts or precision parts.

[0002]

2. Description of the Related Art
As a method for measuring the water concentration in a solution, an infrared absorption method, a dielectric constant method, an ultrasonic velocity method, a Karl Fischer method, and the like have been used.However, these measurement methods require expensive measurement equipment. In addition, there is a problem that the measurement operation requires skill, and an inexpensive and simple method for measuring moisture has been required.

On the other hand, in the field of cleaning precision parts and jigs, terpene-based cleaning liquids have been replaced with chlorine-based and chlorofluorocarbon-based cleaning liquids, which have been abolished in recent years in order to prevent ozone layer destruction. Solvent, hydrocarbon solvent,
Alternative cleaning liquids such as a solvent-based cleaning liquid such as an alcohol-based solvent and an aqueous cleaning liquid containing a surfactant or the like have been developed.

In some of the above alternative cleaning solutions, water is added for the purpose of eliminating the flammability of the solvent or the surfactant and making the material non-hazardous. When the water content is lower than a certain concentration, the cleaning liquid becomes a hazardous substance. On the contrary, when the water content is higher than a certain concentration, the cleaning efficiency is reduced, so that water management is essential. For this reason, the above-described method for measuring the moisture content is also used in the field of cleaning. However, as in the case of measuring the concentration of moisture in the solution, an inexpensive and simple method for measuring the moisture content has been required.

In the field of analytical chemistry, there is a method of inexpensively and simply measuring using a test paper obtained by drying a filter paper containing an aqueous solution of cobalt chloride (JP-A-2-91551). Is very unstable because it absorbs moisture in the air, and there is a problem that accurate measurement is difficult.

Also, a method for quantifying water utilizing the fact that when water is added to a solution having an absorption maximum at 671 nm obtained by dissolving cobalt (II) chloride anhydrate in anhydrous ethyl alcohol, the absorbance changes [Japan “Chemical Society of Japan,“ New Experimental Chemistry Lecture 15 Analysis ”p121 (1991)] has been reported, but in this method, when measuring a hydrophobic sample, a uniform liquid could not be obtained in some cases. In addition, since the coloring efficiency is low, a large number of samples are required, and there is a problem that it is difficult to identify colors when measuring a colored sample.

Accordingly, it is an object of the present invention to provide a method for measuring moisture in a sample whose moisture concentration is unknown, which can be simply and inexpensively measured with high accuracy over a wide range of moisture concentrations.

[0008]

The present inventors have SUMMARY OF THE INVENTION As a result of extensive studies by paying attention to the alcoholic solution of cobalt chloride is discolored by water, a halogenated cobalt or copper halide and surfactant hydrophobic The inventors have found that the above object can be achieved by preparing a calibration curve using a water measurement reagent dissolved in a mixed solution with a neutral solvent, and have completed the present invention.

That is, according to the present invention, cobalt halide or copper halide is dissolved in a mixture of a surfactant and a hydrophobic solvent in a plurality of test solutions having different water concentrations and known in water concentration. The water measurement reagents were added and mixed at predetermined ratios to prepare a plurality of samples having different degrees of coloring according to the water concentration, and the cobalt halide in the water measurement reagent was prepared.
Or, the ratio of the copper halide and the surfactant is
With respect to 100 parts by weight of the surfactant,
0.1 to 2.0 parts by weight of copper halide or copper halide, and measures the absorbance at a predetermined absorption wavelength at a predetermined temperature of each obtained sample, and expresses the relationship between the absorbance of each sample and the moisture concentration. A calibration curve was created, while the boundary was
The water measurement reagent is added and mixed at a predetermined ratio to a cleaning solution containing a surfactant and / or a solvent and water to color the sample, and the colored sample is colored at a predetermined temperature at the predetermined temperature. the absorption at the absorption wavelength is measured, and an absorbance and the calibration curve colored the sample, is to provide a moisture measuring how that comprises determining the moisture of the sample.

[0010] will be described in detail below the onset Akira method of moisture measurement. As the test solution used when preparing a specimen in the present invention, a solution containing water, a solvent and / or a surfactant can be used. Examples of the solvent include, but are not particularly limited to, hydrophilic solvents such as lower alcohols (eg, ethanol and isopropyl alcohol), ketones (eg, acetone), and glycols (eg, polyethylene glycol). The surfactant is not particularly limited, and includes the same substances as the surfactants listed as surfactants used in the samples described below. When a solvent and a surfactant are contained, the above-mentioned hydrophilic solvent may be used as the solvent, and a hydrophobic solvent such as kerosene, benzene, and hexane may be used.

[0011] The water content measuring reagent used in the present invention comprises cobalt halide or copper halide as a surfactant.
And a reagent dissolved in a mixed solution of a solvent and a hydrophobic solvent .

The halogen in the cobalt halide or copper halide used in the water content measuring reagent is not particularly limited, but is preferably chlorine or bromine. Examples of the cobalt halide include cobalt chloride,
Cobalt bromide and the like are mentioned, and the above-mentioned copper halide is, for example, copper chloride and copper bromide. Further, since the absorbance of cobalt is larger than that of copper, cobalt halide is particularly preferable. The cobalt halide or the copper halide in the water measurement reagent , a surfactant and a hydrophobic agent;
Proportion of dissolving the mixture of sexual solvents, interfacial active agent 1
Against 00 parts by weight, the halogenated cobalt or copper halide 0. 1 to 2.0 parts by weight.

The above-mentioned surfactant used in the above-mentioned moisture measuring reagent includes anionic, cationic, zwitterionic,
Nonionic surfactants are used, but in consideration of the accuracy of moisture measurement, nonionic surfactants (nonionic surfactants) having a small amount of water in the surfactant product are preferable, and specific examples include the following. And the like.

Examples of the nonionic surfactant include ether types such as alkyl ether type, alkyl allyl ether type and alkyl thioether type; ester types such as alkyl ester type and sorbitan alkyl ester type;
Condensed type with an amine such as polyoxyalkylene alkylamine; Condensed type with an amide such as polyoxyalkylene alkyl amide; Pluronic or tetronic type obtained by random or block condensation of polyoxyethylene and polyoxypropylene; Polyethyleneimine And the like. Examples of the anionic surfactant include alkyl benzene sulfonate, alkyl or benzene sulfonate, alkyl or alkenyl ether sulfate,
Examples thereof include an alkyl or alkenyl sulfate, an olefin sulfonate, an alkane sulfonate, a higher fatty acid salt, an α-sulfofatty acid salt or ester, and a carboxylate of an alkyl or alkenyl ether. Examples of the cationic surfactant and the amphoteric surfactant include an alkyl or / and alkenyl amine salt, a quaternary ammonium salt, an alkyl betaine, an alkyl amine oxide, an alkyl alanine, a polyamine, a polyamine salt, an imidazoline type amphoteric surfactant, And sulfobetaine-type amphoteric surfactants. Here, any surfactant liquid or solid at normal temperature can also be used.

Further, the moisture measurement reagent Rukoto used on SL halogenated cobalt or the copper halide as a liquid which was dissolved in a mixture of the surfactant and the hydrophobic solvent
More, it is possible to perform good measure moisture and halogenated cobalt or copper halide moisture measurement reagent is accurate the higher the efficiency of efficiently hydration colored in a sample.

The hydrophobic solvent used in the moisture measuring reagent is not particularly limited as long as it is a solvent that does not easily hydrate water, but the smaller the hydration amount, the larger the amount of water that hydrates with cobalt. Since the measurement sensitivity increases, the smaller the amount of hydration, the better. For example, kerosene, benzene,
Examples include hydrocarbon solvents such as hexane and xylene. The mixing ratio of the upper <br/> Symbol hydrophobic solvent and the surfactant, a hydrophobic solvent, surfactant, type of sample, which varies with moisture content, but are not limited to, against surfactant 100 parts by weight, it is preferable to be less than 1 0000 parts by weight of hydrophobic solvent, further preferably set to 100 to 3000 parts by weight.

In the case of a combination of the water measurement reagent and the sample that causes the emulsification of the water measurement reagent during the water measurement, the water measurement reagent suppresses emulsification and performs accurate measurement. For this purpose, an emulsifier may be added as necessary. The emulsification inhibitor is not particularly limited as long as it has a function of suppressing emulsification, and examples thereof include higher fatty acids and higher amines.

Further, at the time of preparing the moisture measuring reagent, a lower alcohol such as ethanol may be added to facilitate dissolution of the cobalt halide or the copper halide. In addition, water may be added in advance to adjust the discoloration range of the specimen.

[0019] In the present invention, a sample to be subjected to moisture measurement, interfacial active agent and / or washing solution containing the solvent and water
It is .

The washing liquid containing the surfactant and / or the solvent and water is, specifically, added with water in order to prevent a solvent or a mixture of two or more solvents described below from becoming a hazardous substance. A solvent-based cleaning liquid comprising: a water-based cleaning liquid comprising one or a mixture of two or more surfactants described below and water, if necessary, to which the above-mentioned solvent is added. Preferable examples include a CFC-substitute cleaning solution used for cleaning of a kind.

The solvent contained in the washing solution is not particularly limited, but terpene solvents containing terpenes such as d-limonene obtained from animals and plants as active ingredients, and hydrocarbons such as kerosene, benzene and xylene are effective. Examples thereof include a hydrocarbon solvent as a component, and an alcohol solvent containing a lower alcohol such as isopropyl alcohol, ethyl alcohol, and methyl alcohol as an active ingredient.

As the surfactant contained in the cleaning solution, anionic, cationic, amphoteric, nonionic surfactants and the like are used, but considering the influence on members such as electronic parts, Nonionic surfactants are preferred, for example, alkyl ether type, alkyl allyl ether type, ether type such as alkyl thioether type; alkyl ester type, ester type such as sorbitan alkyl ester type; amine such as polyoxyalkylene alkylamine; Condensed type with an amide such as polyoxyalkylene alkyl amide; pluronic or tetronic type obtained by random or block condensation of polyoxyethylene and polyoxypropylene; and surfactants such as polyethyleneimine. Among them, in particular, hydrocarbons having 4 to 22 carbon atoms Those having a are preferably exemplified.

The washing liquid may contain additives such as a builder, a chelating agent, a rust preventive and an antifoaming agent, if necessary, in addition to the above-mentioned components. May be arbitrarily used in combination of two or more.

In order to carry out the method (one embodiment) of measuring the water content of the cleaning liquid of the present invention, the above-mentioned water measurement reagents are respectively added to a plurality of the above-mentioned test liquids each having a different water concentration and having a known water concentration. The samples were added and mixed in proportions to prepare a plurality of samples having different degrees of coloring according to the water concentration, and the absorbance of each of the obtained samples at a predetermined absorption wavelength at a predetermined temperature was measured. Create a calibration curve representing the relationship with concentration,
On the other hand, to the sample whose water concentration is unknown, the water measurement reagent is added and mixed at the predetermined ratio to color the sample, and the absorbance of the colored sample at the predetermined temperature at the predetermined absorption wavelength is measured. From the measured and colored absorbance of the sample and the calibration curve, the water content of the sample is quantified.

The water concentration in each of the plurality of test solutions varies depending on the water concentration required for the sample to be measured, and is not particularly limited. When the measurement is performed in the range of 20% by weight, it is preferable that the difference is made every 0.1 to 4% by weight, and the number thereof is also preferably 3 to 40.

The above-mentioned predetermined ratio when the above-mentioned water measurement reagent is added to the above-mentioned test solution and the sample may be appropriately set depending on the water contained in the test solution. It is preferable that the above-mentioned water measurement reagent is set in the range of 0.5 to 100 with respect to the liquid 1. If the predetermined ratio is less than 0.5, it may not be possible to determine the change in the absorbance of the moisture measurement reagent due to the coloring components contained in the sample. It is not preferable because it becomes small and the error becomes large.

The colored assay solution and the colored sample are filled in a measuring container (the colored assay solution filled in the measuring container is used as the specimen).
The measurement container is not particularly limited as long as it is transparent and can measure the absorbance, but is made of glass, quartz,
A cell made of plastic or the like may be used.

The predetermined absorption wavelength in the present invention is:
Depending on the reagent used, for example, when cobalt chloride is used, absorption appears at 550 to 700 nm.

In the present invention, the predetermined temperature when measuring the absorbance of the sample is preferably in the range of 0 to 70 ° C. If the temperature is lower than 0 ° C., the test solution may freeze, and if the temperature is higher than 70 ° C., the water in the test solution evaporates during the measurement, and the correct water concentration cannot be measured. .

In order to measure the absorbance of each of the above-mentioned specimens at the predetermined temperature, the absorbance can be measured by using an absorption measuring device or the like. The absorption measurement device is not particularly limited as long as the absorbance at the predetermined absorption wavelength can be quantified, and examples thereof include an absorptiometer, and when the absorptiometer is used, The absorbance is determined as absorbance.

In order to create the above calibration curve, the absorbance and the water concentration are set on the vertical and horizontal axes of the graph, respectively, and the obtained data is plotted on the graph. It can be created by tying it into a function graph.

The above-mentioned predetermined ratio when adding the above-mentioned water measurement reagent to the above-mentioned sample is the same as the above-mentioned predetermined ratio when adding the above-mentioned water measurement reagent to the above-mentioned test solution. The temperature and the absorption wavelength when measuring the absorbance of the colored sample are the same as the predetermined temperature and the predetermined absorption wavelength when the sample is prepared, and the measurement of the absorbance is also performed on the sample. The measurement can be performed in the same manner as the measurement of the absorbance.

When a moisture measuring reagent whose absorption range shifts at different temperatures is used as the moisture measuring reagent, the sample and the sample are heated to different temperatures, for example, 0 ° C. and 25 ° C. Alternatively, by adjusting the temperature at the time of measurement after cooling, the region of absorbance can be adjusted to the upper and lower limits of the measurement. That is, in the present invention, by changing the temperature of the sample, the water concentration at which the absorbance of the sample significantly changes can be shifted to the range of the optimum water concentration according to the sample to be measured. By changing the above-mentioned predetermined temperature at the time of measuring even with a moisture measuring reagent, the moisture concentration of a sample whose colorimetry is difficult can be easily measured.

To determine the water content of the sample from the absorbance of the sample and the calibration curve, the absorbance of the sample is compared with the calibration curve, and the absorbance of the sample on the calibration curve is obtained. It can be quantified by confirming the water concentration at the time.

Next, another embodiment of the method for measuring the water content of a sample which can be carried out according to the present invention will be described in detail. In addition, about the point which is not specifically described, that is, about a specific measuring method,
All the items described in one embodiment of the above-described moisture measurement method are applicable.

In order to carry out another embodiment of the present invention, the above-mentioned water measuring reagents are added and mixed at predetermined ratios to a plurality of test solutions having known water concentrations, each having a different water concentration. A plurality of samples having different degrees of coloring are prepared, the obtained samples are measured for absorbance at a predetermined absorption wavelength at various temperatures, and the relationship between the absorbance, temperature, and moisture concentration of each sample is stored in a storage device. In the meantime, a database is created, and on the other hand, the moisture measurement reagent is added and mixed at the above-mentioned predetermined ratio to the above-mentioned sample whose water concentration is unknown, and the sample is colored. The absorbance of the wavelength is measured, and the absorbance of the colored sample and the above-mentioned arbitrary temperature are compared with the data of the database to determine the water content of the sample.

The range of the various temperatures at the time of measuring the absorbance of the sample is preferably in the range of 0 to 70 ° C. in the same manner as the predetermined temperature in one embodiment of the above-mentioned moisture measurement method. Further, it is preferable that the above-mentioned arbitrary temperature at the time of measuring the sample is also in the range of 0 to 70 ° C. Then, as the various temperatures when measuring the absorbance of the sample, so that the arbitrary temperature at the time of measuring the sample can be selected without being particularly limited within the above range,
Preferably, a number of temperature conditions are employed, for example, 1
It is preferable to measure every 10 to 10 ° C.

As a storage device, a hard disk or a floppy disk of a computer can be preferably used.

In order to determine the water content of the sample by comparing the absorbance of the colored sample and the arbitrary temperature with the data of the database, the following methods 1) and 2) can be mentioned. 1) Calibration curve method: A method of creating a function that captures the relationship between the absorbance of a sample and the amount of moisture, and converting moisture from the absorbance of the sample based on the function. 2) Table method: A method in which the relationship between the absorbance of a sample and the amount of moisture is tabulated, and the moisture is converted from the absorbance of the sample based on the table. In the above-mentioned calibration curve method, by inputting a function for obtaining the above-mentioned calibration curve in the above-mentioned database, a system capable of instantaneously quantifying moisture simply by inputting the absorbance of the sample and various measurement conditions. Can also be built.

[0040]

The present invention utilizes the change in the absorbance of cobalt halide due to water of crystallization. For example, taking cobalt chloride as an example, when water is added to a solution of anhydrous cobalt chloride, it hydrates, and the absorbance changes according to the amount of water added. Therefore, by adding a solution of anhydrous cobalt chloride to a test solution having a different water concentration, samples having various absorbances can be obtained, and a calibration curve created from the absorbance and the water concentration of each sample, and a measured curve. The water content of the sample can be quantified by comparing the absorbance of a colored sample obtained by performing the same operation on the liquid sample.

[0041]

EXAMPLES The present invention will be described in more detail with reference to the following Examples, but it should not be construed that the present invention is limited thereto.

Reference Example 1 Cobalt (II) chloride anhydrate was dissolved in polyoxyethylene (ethylene oxide added mole = 10 mol) octyl phenyl ether, and the concentration of cobalt (II) chloride anhydrate was 1 g. Per liter of water was obtained. Also,
Water is added to isopropyl alcohol so that the water concentration becomes zero.
4% by weight (0%, 4%,
(8 wt%, 12 wt%, 16 wt%, 20 wt%) were obtained. 2 ml of each test solution and 2 ml of a water measurement reagent were mixed in a 10 ml test tube and allowed to stand to obtain 6 kinds of specimens. The absorbance (absorbance) at 660 nm and 600 nm at 20 ° C. of the obtained specimen was measured with an absorptiometer,
A calibration curve was prepared by plotting the relationship between the absorbance (absorbance) of each sample and the water concentration on a graph. The obtained calibration curve is shown in FIG.

Next, 2 ml of a sample of unknown water content (composition of isopropyl alcohol and water) and 2 ml of a water measurement reagent were mixed in a 10 ml test tube and allowed to stand to color the sample. The absorbance at 660 nm (absorbance) of the colored sample at 20 ° C. was measured with an absorptiometer, and the absorbance was 0.27. The water concentration of the sample was determined from the measured values obtained and the calibration curve shown in FIG.
%Met.

Example 1 Cobalt (II) chloride anhydride was dissolved in a mixture of 90% by weight of hexane and 10% by weight of polyoxyethylene (the number of moles of ethylene oxide added: 10 moles) of octylphenyl ether. (II) A moisture measurement reagent having an anhydrate of 1 g / liter was obtained. In addition, water is added to isopropyl alcohol, and the water concentration is reduced to 0 to 5% by weight in increments of 1% by weight (0%, 1%, 2%, 3%, 4%, 5%). Six adjusted test solutions were obtained. 2 ml of each assay solution and 2 ml of a water measurement reagent were mixed in a 10 ml test tube and allowed to stand, thereby obtaining six kinds of specimens. The absorbance (absorbance) at 660 nm of the obtained sample at 20 ° C. was measured with an absorptiometer, and the absorbance (absorbance) of each obtained sample was measured.
A calibration curve was created by plotting the relationship between the water content and the water concentration on a graph. The obtained calibration curve is shown in FIG.

Next, 2 ml of a sample of unknown water content (composition of isopropyl alcohol and water) and 2 ml of a water measurement reagent were mixed in a 10 ml test tube and allowed to stand, and the sample was colored. The absorbance at 660 nm (absorbance) of the colored sample at 20 ° C. was measured with an absorptiometer, and the absorbance was 0.81. The water concentration of the sample was determined from the measured values obtained and the calibration curve shown in FIG.
% By weight.

Example 2 Cobalt (II) chloride anhydrous was dissolved in a mixture of 90% by weight of hexane and 10% by weight of octylphenyl ether of polyoxyethylene (the number of moles of ethylene oxide added: 10 mol), and cobalt chloride was dissolved in the mixture. (II) A moisture measurement reagent having an anhydrate of 1 g / liter was obtained. Further, water was added to polyoxyethylene (ethylene oxide added mole number = 2 mole) butyl ether, and the water concentration was 2% by weight, 4% by weight,
Four kinds of test solutions adjusted to 6% by weight and 7% by weight were obtained.
2 ml of each test solution and 2 ml of a water measurement reagent were mixed in a 10 ml test tube and allowed to stand to obtain four types of specimens. 2 of the obtained specimen
The absorbance at 660 nm (absorbance) at 0 ° C. was measured with an absorptiometer, and the relationship between the absorbance (absorbance) of each obtained sample and the water concentration was plotted on a graph to prepare a calibration curve.
The obtained calibration curve is shown in FIG.

Next, 2 ml of a washing solution whose water content is unknown (composition of polyoxyethylene (addition of mole number of ethylene oxide = 2 mol) butyl ether and water) and 2 ml of a water measurement reagent were added to 1 ml
The above sample was colored by mixing and standing in a 0 ml test tube.
The absorbance at 660 nm (absorbance) of the colored sample at 20 ° C. was measured with an absorptiometer, and the absorbance was 0.11. The water content of the sample was determined from the obtained measured values and the calibration curve shown in FIG. 3, and was found to be 4.0% by weight.

REFERENCE EXAMPLE 2 Cobalt (II) chloride anhydrate was dissolved in octyl alcohol to obtain a water measurement reagent having a cobalt (II) chloride anhydrate concentration of 5 g / l. In addition, water was added to isopropyl alcohol to obtain four kinds of test solutions whose water concentrations were adjusted to 5% by weight, 8% by weight, 12% by weight, and 15% by weight. 10 ml of 2 ml of each test solution and 2 ml of water measurement reagent
The mixture was mixed in a test tube and allowed to stand to obtain four types of specimens. The absorbance (absorbance) at 660 nm of the obtained sample at 20 ° C. was measured with an absorptiometer, and the relationship between the absorbance (absorbance) of each obtained sample and the water concentration was plotted on a graph to prepare a calibration curve. did. The obtained calibration curve is shown in FIG.

Next, 2 ml of a washing liquid of unknown water (composition of isoproalcohol and water) and 2 ml of a water measuring reagent were mixed in a 10 ml test tube and allowed to stand to color the washing liquid. 660 nm of the colored cleaning solution at 20 ° C.
Was measured with an absorptiometer to find that the absorbance was 0.7. The water concentration of the washing solution was determined from the measured values obtained and the calibration curve shown in FIG.
It was 0% by weight.

Reference Example 3 Anhydrous cobalt (II) chloride was dissolved in acetone to obtain a water content measuring reagent having a concentration of anhydrous cobalt (II) chloride of 1 g / liter. In addition, water was added to polyoxyethylene (ethylene oxide added mole number = 2 mole) butyl ether to adjust the water concentration to 5% by weight, 8% by weight, 12% by weight, and 15% by weight. I got 2 ml of each test solution and 2 ml of a water measurement reagent were mixed in a 10 ml test tube and allowed to stand to obtain four types of specimens. The absorbance (absorbance) at 600 nm of the obtained sample at 20 ° C. was measured with an absorptiometer, and the relationship between the absorbance (absorbance) of each obtained sample and the water concentration was plotted on a graph to prepare a calibration curve. did. The obtained calibration curve is shown in FIG.

Next, 2 ml of a washing solution whose water content is unknown [composition of polyoxyethylene (polyethylene oxide added mole number = 2 moles) butyl ether and water] and 2 ml of a water content measuring reagent were added.
The above washing liquid was colored by mixing and standing in a 0 ml test tube. Then, 600 nm of the colored cleaning solution at 20 ° C.
Was measured with an absorptiometer to find that the absorbance was 0.19. When the water concentration of the cleaning solution was determined from the obtained measured values and the calibration curve shown in FIG. 5,
12.0% by weight.

[0052]

According to the method for measuring the water content of a cleaning solution of the present invention, the water content of a sample whose water content is unknown can be easily and inexpensively determined.
It can be measured accurately over a wide range of moisture concentrations. Therefore, the method for measuring the water content of the cleaning liquid of the present invention is particularly preferably used in a cleaning liquid used for cleaning electronic parts and precision parts, for example, when performing water management of a cleaning liquid that is added as water and is made non-hazardous. be able to.

[Brief description of the drawings]

FIG. 1 is a graph showing a calibration curve obtained in Reference Example 1.

FIG. 2 is a graph showing a calibration curve obtained in Example 1 .

FIG. 3 is a graph showing a calibration curve obtained in Example 2 .

FIG. 4 is a graph showing a calibration curve obtained in Reference Example 2 .

FIG. 5 is a graph showing a calibration curve obtained in Reference Example 3 .

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) G01N 31/00-31/22 G01N 21/75-21/83

Claims (1)

(57) [Claims] 1. A water measurement reagent obtained by dissolving a cobalt halide or copper halide in a mixture of a surfactant and a hydrophobic solvent is added to a plurality of test solutions each having a different water concentration and a known water concentration. It was added at a ratio, to create a plurality of samples having different coloring degree according to water concentration, the water content measurement
The above-mentioned cobalt halide or copper halide in the reagent
And the ratio of the surfactant is 100 weight of the surfactant.
Parts by weight of the above-mentioned cobalt halide or halogenated
0.1 to 2.0 parts by weight of copper. Measure the absorbance of each sample obtained at a predetermined temperature at a predetermined absorption wavelength, and create a calibration curve representing the relationship between the absorbance of each sample and the moisture concentration. On the other hand, a surfactant and / or a sample whose water concentration is unknown
Alternatively , the water measurement reagent is added to and mixed with the cleaning liquid containing the solvent and water at the predetermined ratio to color the sample, and the absorbance of the colored sample at the predetermined temperature at the predetermined absorption wavelength is measured. And measuring the water content of the sample from the absorbance of the colored sample and the calibration curve.