JP2003240766A - Method and apparatus for measuring borate ion - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method and an apparatus for measuring borate ions capable of accurately and easily measuring the borate ions in waste water and environmental water without being interfered with coexistent substances. <P>SOLUTION: A reagent containing at least a 1-amino-8- hydroxynaphthalene-3,6-disulfonic-acid-based azo dye, a chelating agent, and sodium ions and/or potassium ions is added to a sample liquid. The borate ions in the sample liquid are reacted with the 1-amino-8-hydroxynaphthalene-3,6- disulfonic-acid-based azo dye at a pH of 4-5.4 to measure absorbance. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a borate ion measuring method and a borate ion measuring apparatus. More specifically, for the purpose of measuring boron, which is a regulated substance in wastewater,
The present invention relates to a borate ion measuring method and a borate ion measuring apparatus that can perform accurate and simple measurement without being interfered by coexisting substances.

[0002]

2. Description of the Related Art Atomic absorption spectrometry, ICP, titration, and colorimetry are known as methods for measuring borate ions.
Among these, the atomic absorption spectrometry and ICP require constant use of high-pressure gas such as hydrogen and argon, which requires a large-scale apparatus and is concerned about safety. Further, the titration method can be used only under a very limited condition that the concentration is high and there is no coexisting component.

Further, in the colorimetric method, since the reactivity of borate ions in an aqueous solution is poor, it is unavoidable to use a strong acid, and complicated operations are often involved. For example, when using a coloring reagent such as carminic acid or quinalizarin, the reaction must be carried out in concentrated sulfuric acid. Further, when curcumin is used as the color-developing reagent, it is necessary to carry out an operation of evaporation to dryness, and when methylene blue is used, it is necessary to carry out an operation of solvent extraction. Further, in the case of the azomethine H absorptiometry, the color developing solution is easily oxidized, and even if it is stored in a cool and dark place with a reducing agent coexisting, the life is only about 1 week and it is interfered by many metal ions. I will end up.

In contrast to these colorimetric methods, the method using H-resorcinol as a color-developing solution allows reaction under a mild condition of pH 5.5. In this case, a chelating agent such as ethylenediaminetetraacetato complex (hereinafter referred to as "EDTA") is added to prevent interference of coexisting substances in the sample solution.

[0005]

However, in the method of using H-resorcinol as a color-developing solution, the influence of coexisting components cannot be sufficiently eliminated even if a chelating agent is used, and the effluent in waste water or environmental water cannot be removed. When attempting to measure acid ions, accurate measurement was difficult. In particular, iron ions are often used in the process of treating waste water, so that their coexisting concentration is often high, but they could not be sufficiently masked by the chelating agent. Further, since alkali metal ions such as sodium and potassium originally do not form a complex, the chelating agent cannot be an effective means for eliminating these interferences. The present invention has been made in view of the above circumstances, and a borate ion measuring method and a borate ion measuring device capable of accurately and easily measuring borate ions in waste water or environmental water without being interfered by coexisting substances. The challenge is to provide.

[0006]

[Means for Solving the Problems] At least 1
-Amino-8-hydroxynaphthalene-3,6-disulfonic acid-based azo dye and a reagent containing a chelating agent are added, and borate ions in the sample solution and 1-amino-8 are added.
-A hydroxynaphthalene-3,6-disulfonic acid azo dye is reacted at a pH of 4 to 5.4, and the absorbance is measured.

If the pH during the reaction is lower than 4, borate ions and 1-amino-8-hydroxynaphthalene-3,6-
Coloring with the disulfonic acid azo dye cannot be sufficiently obtained. The more preferable lower limit of pH is pH 4.5. On the other hand, if the pH is higher than 5.4, the masking of coexisting metal ions by the chelating agent will be insufficient. A more preferable upper limit value is lower than pH 5.3, and a still more preferable upper limit value is pH 5.1 or lower. According to the invention,
Since the metal ion such as iron ion can be sufficiently masked while maintaining the sensitivity of the coloring reagent, the borate ion concentration can be accurately measured.

The present invention also provides a sample solution containing at least 1-
Amino-8-hydroxynaphthalene-3,6-disulfonic acid azo dye and a reagent containing sodium ion and / or potassium ion are added, and borate ion in the sample solution and 1-amino-8-hydroxy are added. Naphthalene
Provided is a method for measuring borate ion in a sample solution, which comprises reacting with a 3,6-disulfonic acid-based azo dye and measuring absorbance.

As a result of experiments, the present inventors have found that the degree of influence of the alkali metal ion on the sensitivity hardly changes at a certain concentration or higher. Therefore, it has been found that, by adding a sufficient amount of alkali metal ions in advance, interference can be eliminated by keeping the influence of the alkali metal ions in the sample solution on the sensitivity constant. That is, according to the present invention, the borate ion concentration can be accurately measured by eliminating the interference of sodium ion and / or potassium ion.

The present invention also provides a sample solution containing at least 1-
Amino-8-hydroxynaphthalene-3,6-disulfonic acid azo dye, a chelating agent, and a reagent containing sodium ion and / or potassium ion are added, and borate ion in the sample solution and 1-amino acid are added. -8-hydroxynaphthalene-3,6-disulfonic acid azo dye
Provided is a method for measuring borate ion in a sample solution, which comprises reacting with H4 to 5.4 and measuring absorbance.
According to the present invention, as described above, while maintaining the sensitivity of the color-forming reagent, the metal ions such as iron ions are sufficiently masked, and the interference of sodium ions and / or potassium ions is eliminated to accurately The borate ion concentration can be measured. A more preferable pH range is 4.5 or more and less than 5.3, and a further preferable pH range is 4.5 or more and 5.1 or less.

In the present invention, borate ions in the sample solution and the 1-amino-8-hydroxynaphthalene-
It is preferable to stop the reaction with the 3,6-disulfonic acid-based azo dye halfway and measure the absorbance. This allows
The absorbance with good linearity can be obtained, accurate measurement can be performed over a wide measurement range, and the measurement time can be shortened.

In this case, borate ions in the sample solution and the 1-amino-8-hydroxynaphthalene-3,6-
By allowing the reaction with the disulfonic acid-based azo dye to proceed by heating the mixed liquid of the sample liquid and the reagent at 40 to 100 ° C., and then cooling to a temperature of 0 ° C. or higher and lower than 40 ° C. It is preferable to stop.
The reaction proceeds by heating at 40 to 100 ° C,
Sufficient color development is obtained. In addition, it is 40 degrees Celsius above 0 degrees
By cooling to a lower temperature, the reaction can be stopped with certainty, which enables measurement with good reproducibility. Considering the heat resistance of the reaction container and the like, a more preferable heating temperature is 80 ° C or lower. Further, a more preferable heating temperature is 60 ° C. or higher in order to enhance the masking effect of the interfering component and to promote the reaction promptly. Further, in order to more surely stop the reaction, a more preferable cooling temperature is 30 ° C. or lower, further preferably 25 ° C. or lower. Further, considering the fear of freezing and the dew condensation inside the apparatus, the more preferable cooling temperature is 10 ° C. or higher.

When cooling the sample solution, it is preferable to add pure water to the mixed solution to accelerate the cooling when cooling the mixed solution. As a result, the temperature of the mixed solution can be drastically lowered, and more reproducible and quick measurement can be performed.

The present invention also comprises a reaction space, means for introducing the sample liquid and the reagent into the reaction space, and means for measuring the absorbance of the mixed liquid of the sample liquid and the reagent in the reaction space,
The reagent contains at least 1-amino-8-hydroxynaphthalene-3,6-disulfonic acid azo dye and a chelating agent, and the pH of the mixed solution is adjusted to 4 to 5.4 by the reagent. An apparatus for measuring borate ions in a sample liquid, which is characterized by being adjusted. According to the present invention, as described above, while sufficiently maintaining the sensitivity of the color-forming reagent, metal ions such as iron ions are sufficiently masked,
The borate ion concentration can be measured accurately. A more preferable pH range is 4.5 or more and less than 5.3,
A more preferable pH range is 4.5 or more and 5.1 or less.

The present invention also comprises a reaction space, means for introducing the sample solution and the reagent into the reaction space, and means for measuring the absorbance of the mixed solution of the sample solution and the reagent in the reaction space,
The reagent contains at least 1-amino-8-hydroxynaphthalene-3,6-disulfonic acid azo dye and sodium ion and / or potassium ion. I will provide a. According to the present invention, as explained above, the interference of sodium ions and / or potassium ions is eliminated,
The borate ion concentration can be measured accurately.

The present invention also comprises a reaction space, means for introducing the sample solution and the reagent into the reaction space, and means for measuring the absorbance of the mixed solution of the sample solution and the reagent in the reaction space,
The reagent contains at least 1-amino-8-hydroxynaphthalene-3,6-disulfonic acid azo dye, a chelating agent, and sodium ion and / or potassium ion, and the reagent mixes the mixed solution. The pH of the sample is adjusted to 4.5 to 5.4, and an apparatus for measuring borate ion in a sample solution is provided. According to the invention,
As explained above, while maintaining the sensitivity of the coloring reagent,
It is possible to accurately measure the borate ion concentration while sufficiently masking metal ions such as iron ions and eliminating the interference of sodium ions and / or potassium ions. A more preferable pH range is 4.5 or more and less than 5.3, and a still more preferable pH range is 4.5 or more and 5.
It is 1 or less.

In the present invention, the borate ion in the sample liquid and the 1-amino-8-hydroxynaphthalene-
It is preferable to stop the reaction with the 3,6-disulfonic acid-based azo dye halfway and measure the absorbance. This allows
The absorbance with good linearity can be obtained, accurate measurement can be performed over a wide measurement range, and the measurement time can be shortened.

Specifically, the mixed solution is mixed with 40 to 100
It is preferable to include means for heating to 0 ° C and means for cooling to a temperature of 0 ° C or higher and lower than 40 ° C. 40-10
By heating at 0 ° C., the reaction proceeds and sufficient color development is obtained. Further, by cooling to a temperature of 0 ° C. or higher and lower than 40 ° C., the reaction can be surely stopped, so that measurement with good reproducibility becomes possible. In addition,
Considering the heat resistance of the reaction container and the like, a more preferable heating temperature is 80 ° C or lower. Further, a more preferable heating temperature is 60 ° C. or higher in order to enhance the masking effect of the interfering component and to promote the reaction promptly. Further, in order to more surely stop the reaction, the more preferable cooling temperature is 3
It is 0 ° C. or lower, and more preferably 25 ° C. or lower. Also,
Considering the risk of freezing and the dew condensation inside the apparatus, the more preferable cooling temperature is 10 ° C or higher.

Further, it is preferable to have a means for adding pure water to the mixed solution, and when cooling the mixed solution, it is preferable to add pure water to the mixed solution to promote cooling. This allows
The temperature of the mixed solution can be drastically lowered, and reproducibility is improved, and rapid measurement is possible.

[0020]

Embodiments of the present invention will be described below with reference to the drawings, but the present invention is not limited to the following embodiments. FIG. 1 is a schematic configuration diagram of a borate ion measuring device according to the present embodiment. As shown in FIG. 1, the borate ion measuring apparatus according to the present embodiment includes a reaction cell 10 that constitutes a reaction space, and a sample liquid introducing pipe S1 for introducing a sample liquid into the reaction cell 10 and a reagent. The reagent introducing tubes R1, R2, R3 for performing the operation and the outlet tube S2 for leading out the mixed solution of the sample solution and the reagent in the reaction cell 10 are inserted.

The reaction cell 10 is arranged in a constant temperature bath 20 having a heater (not shown) and is heated to a predetermined temperature. Further, the constant temperature bath 20 is provided with an inlet 20a and an outlet 20b for supplying cooling water to the inlet 20a.
The mixed solution in the reaction cell 10 can be cooled by flowing the mixed solution in the reaction cell 10 to the outlet 20b. Further, a stirring means (not shown) for stirring the mixed liquid in the reaction cell 10, such as a stirrer or a magnetic stirrer, is appropriately provided.

The sample liquid introducing pipe S1 is provided with a sample liquid measuring device M1.
And the dilution water meter M2 are interposed, and the sample solution measured by the sample solution meter M1 is swept over the pure water measured by the dilution water meter M2 and introduced into the reaction cell 10. It is like this. In addition, reagent injection pumps RP1, RP2, and RP3 are provided in the reagent introduction tubes R1, R2, and R3, respectively, so that reagents 1 to 3 described later are introduced into the reaction cell 10. Further, a colorimeter 30 is provided at the destination where the mixed liquid is led out by the lead-out pipe S2.

Reagent 1 is a color forming liquid and is a 1-amino-8-hydroxynaphthalene-3,6-disulfonic acid azo dye (hereinafter referred to as "H acid azo dye") having the structure shown in [Chemical Formula 1]. .

[Chemical 1]

In [Chemical formula 1], Ar is an aryl group, and examples of the aryl group include the following [Chemical formula 2] to
[Chemical formula 3] is mentioned.

[Chemical 2]

[Chemical 3]

The H-acid type azo dye reacts with boric acid to give 1:
1 complex is formed. In particular, the aryl group is [Chemical Formula 2] 1
-(2,4-Dihydroxy-1-phenylazo) -8-
Hydroxynaphthalene-3,6-disulfonic acid (hereinafter referred to as "H-resorcinol") is the most sensitive and preferred. H-resorcinol and boric acid are represented by [Chemical formula 4]
And reacts as shown in (1) to form a 1: 1 complex having an absorption maximum wavelength of 510 nm.

[0026]

[Chemical 4]

The reagent 2 is a chelating agent, which masks the metal ions in the sample solution, inhibits the reaction with the coloring reagent and eliminates the interference by the metal ions. As the chelating agent, EDTA disodium salt (dihydrate), EDTA tetrasodium salt (tetrahydrate), CyDTA (trans-1,2-cyclohexanediamine tetraacetate), GEDTA (glycol ether diamine tetrahydrate) (Acetic acid salt) and the like, and mixtures thereof. Particularly, EDTA / disodium salt (dihydrate), ED
TA / tetrasodium salt (tetrahydrate) and a mixture thereof are preferable because they can mask a high concentration of metal ions. Examples of metal ions that can be masked with a chelating agent include iron ions, copper ions, and aluminum ions.

The reagent 3 is a pH buffer solution, so that the pH during the reaction is 4-5.4, preferably 4.5 or more and less than 5.3, more preferably 4.5 or more and 5.1 or less, for example p.
A buffer solution that can be adjusted to H5.0 is selected. As such a buffer solution, an acetic acid-based buffer solution can be preferably used. By reacting under such a pH condition, complex formation between a metal ion such as iron ion and a chelating agent can be promoted and the masking effect can be enhanced. On the other hand, even under such pH conditions, sufficient color development by the reagent 3 can be obtained. Therefore, metal ions such as iron ions can be sufficiently masked while maintaining the sensitivity of the color forming reagent, so that the borate ion concentration can be accurately measured.

Further, the buffer solution contains sodium ions and / or potassium ions. As the buffer solution capable of adjusting the pH range as described above and containing both sodium ion and potassium ion, for example, acetic acid-sodium acetate buffer solution to which potassium nitrate is added is preferably used. You can
The concentration of sodium ion in the buffer solution at the time of reaction is preferably 2000 to 6000 mg / L, more preferably 3000 to 5000 mg / L, for example 4000.
It can be mg / L. The preferable concentration of potassium ion in the buffer solution at the time of reaction is 2000
~ 7000 mg / L, more preferably 2500-550
It is 0 mg / L, and can be set to 4600 mg / L, for example. In this way, if a sufficient amount of alkali metal ions is added in advance, interference can be eliminated by keeping the influence of the alkali metal ions in the sample solution on the sensitivity constant, and the borate ion concentration can be accurately measured. .

When measuring the borate ion in the sample liquid with the borate ion measuring apparatus of this embodiment, the sample liquid meter M1
The sample solution weighed in 1 is introduced into the reaction cell 10 together with the pure water weighed in the diluting water meter M2 using the sample solution introducing pipe S1. Further, the reagent injection pumps RP1, RP2, RP3 are operated to introduce the reagents 1 to 3 using the reagent introduction pipes R1, R2, R3.

Then, the water in the constant temperature bath 20 is heated to heat the mixed solution in the reaction cell 10 to react the borate ion in the sample solution with the reagent 1 (color developing solution). The preferable heating temperature at this time is 40 to 100 ° C., more preferably 60 to 80 ° C., and may be 70 ° C., for example. Further, the preferable reaction time (heating time) is 20 to 4
0 minutes, more preferably 25 to 35 minutes, for example 30
It can be minutes. By selecting such temperature and reaction time, it is possible to obtain the absorbance with sufficient sensitivity and good linearity.

After that, cooling water is poured into the constant temperature bath 20. At the same time, pure water measured by the diluting water meter M2 is injected into the reaction cell 10. Thereby, the reaction cell 10
The mixed solution inside is cooled both from the outside and from the inside to stop the reaction between borate ion in the sample solution and reagent 1 (coloring solution). The preferred cooling temperature at this time is 0 ° C or higher and lower than 40 ° C, more preferably 10 to 30 ° C.
℃, more preferably 10 to 25 ℃, for example 20
It can be ° C. Further, the cooling time may be, for example, 5 to 10 minutes, although it depends on the temperature and the flow velocity of the cooling water. By cooling to such a temperature, the reaction is surely stopped and a highly reproducible absorbance is obtained. In particular, by injecting pure water into the inside of the reaction cell 10, the temperature of the mixed solution can be drastically lowered, and more reproducible and quick measurement becomes possible.

After the reaction is completed, the mixed solution in the reaction cell 10 is
It is led out by the lead-out pipe S2 and led to the colorimeter 30. And
Absorbance is measured by this colorimeter 30. The absorbance is preferably measured at 510 nm which is the maximum absorption wavelength of the complex formed by borate ion and the reagent 1 (coloring liquid).
Measurement is possible within the range of 490 to 530 nm.

In the borate ion measuring device of this embodiment,
The blank value can be measured by the following procedure.
In the measurement of the blank value, the same amount of the sample liquid and pure water as in the case of heating to proceed the reaction is measured from the sample liquid introducing pipe S1 by the sample liquid measuring device M1 and the diluting water measuring device M2, and the reaction cell 1
Introduce to 0. Similarly, the same amount of reagents 1 to 3 is introduced from the reagent introduction pipes R1, R2, and R3 by operating the reagent injection pumps RP1, RP2, and RP3.

Then, the reaction step of heating the water in the constant temperature bath 20 is omitted, and the same amount of pure water as that added when the reaction is stopped is measured by the dilution water meter M2 and injected into the reaction cell 10. . Immediately thereafter, the mixed liquid in the reaction cell 10 is led out to the colorimeter 30 by the lead-out pipe S2. Then, with this colorimeter 30, the absorbance is measured at the same wavelength as in the case of heating to allow the reaction to proceed.

The blank value thus measured is subtracted from the measured value when the reaction is advanced by heating, so that the absorption amount of the color originally possessed by the reagent or the sample solution is removed to obtain an accurate value. Various measurements are possible. In this embodiment, since the reagent 1 (color-developing liquid) itself has a considerably large absorption in the wavelength range of absorbance measurement, measurement of this blank value is very important. Further, the absorption of the reagent 1 (color-developing liquid) itself largely changes in a short period of time as the reagent 1 deteriorates. Therefore, it is desirable to measure the blank value as often as possible, preferably each time. Thereby, the replacement frequency of the reagent 1 can be set to about 30 days.

In the present embodiment, the reagents are divided into reagents 1 to 3 and separate reagent injection pumps RP1 and RP are provided.
2. Introduced into the reaction cell 10 using RP3, but if there is no problem in consideration of the storage stability and stability of the reagent, they may be put together or separately. For example, the reagent 2 and the reagent 3 may be combined in advance and supplied by one reagent injection pump. Further, the addition of pure water in the blank measurement may be performed once instead of two times if there is no particular problem due to circumstances such as a measuring device. Further, in the present embodiment, the absorbance was measured by deriving the mixed solution into a colorimeter arranged outside the reaction cell, but the reaction cell itself was used as a colorimetric cell, or a light guide probe was inserted into the reaction cell. Therefore, the mixed solution may be measured without being led out of the reaction cell.

Further, in the above embodiment, the so-called batch measurement, in which the sample solution or the like is retained in the reaction cell to cause the reaction, is a so-called batch injection analysis (FIA) in which the sample solution is reacted while flowing in the tube. It may be a simple flow measurement. In this case, the inside of the tube becomes the reaction space.

[0039]

[Experimental Example 1] As a sample solution, boric acid standard solutions having boron concentrations of 0, 1, 2, 3, 4, 5 mg / L were prepared. Further, 0.4 g of H-resorcinol was dissolved in pure water to obtain 1000 mL, which was used as a color developing solution (reagent 1). In addition, 215 g of EDTA disodium salt (dihydrate),
And EDTA tetrasodium salt (tetrahydrate) 150g
Was dissolved in pure water to make 5000 mL, which was used as a chelating agent (reagent 2). Also, acetic acid (JIS standard product) 185 m
L, 1000 g of sodium acetate, 500 g of potassium nitrate
Was adjusted to 5000 mL with pure water to obtain a pH buffer solution (reagent 3).

8 mL of each sample solution obtained as described above, 4 mL of color developing solution, 5 mL of chelating agent, 5 mL of pH buffer, and 20 mL of pure water as dilution water were put into a reaction cell and mixed.
This mixed solution had a pH of 5.0. This mixed solution was heated to 70 ° C. using a constant temperature bath. After 30 minutes, 28 mL of pure water was added into the reaction cell while cooling water of about 15 ° C. was injected into the constant temperature bath. This was measured for absorbance at 510 nm and designated as absorbance A. Next, as a blank measurement,
8 mL of each sample solution obtained as described above, 4 mL of color developing solution,
5 mL of chelating agent, 5 mL of pH buffer, and 20 mL of pure water as dilution water were put into a reaction cell and mixed, and further, pure water 2
8 mL was added. Absorbance measurement of this at 510nm,
The absorbance was set to B.

FIG. 2 shows the measurement results for each sample solution. The difference in absorbance in FIG. 2 is a value obtained by subtracting the absorbance B from the absorbance A. Under the conditions of the reaction temperature and the reaction time of this experimental example, the reaction between boric acid in the sample solution and the color developing solution seems not to be completed, but as shown in FIG. 2, the boron concentration is 0 to 5 mg / L. Good linearity was obtained over a wide range. Also, sufficient sensitivity was obtained even under the condition of pH 5.

[Experimental Example 2] Absorbance A and absorbance B were measured under the same conditions as in Experimental Example 1 except that the reaction temperature was 100 ° C. FIG. 3 shows the measurement results for each sample solution. The absorbance difference in FIG. 3 is a value obtained by subtracting the absorbance B from the absorbance A. Under the reaction temperature and reaction time conditions of this experimental example, the reaction between boric acid in the sample solution and the color developing solution was
Although it seems to be almost completed, as shown in FIG. 3, good linearity was obtained only when the boron concentration was in the range of 0 to 3 mg / L.

[Experimental Examples 3 to 12] In order to investigate the influence of coexisting ions, boric acid standard solutions containing different coexisting ions for each experimental example and having a boron concentration of 1 mg / L were prepared as sample solutions. Specifically, in Experimental Example 3, in order to investigate the effect of iron ions, ammonium sulfate iron (III) dodecahydrate was added. In Experimental Example 4, copper sulfate pentahydrate was added to examine the effect of copper ions. In Experimental Example 5, potassium aluminum sulfate dodecahydrate was added to investigate the effect of aluminum ions. In Experimental Example 6, manganese (II) chloride tetrahydrate was added in order to investigate the effect of manganese ion. In Experimental Example 7, nickel ammonium sulfate hexahydrate was added to investigate the effect of nickel ions.
In Experimental Example 8, in order to investigate the influence of magnesium ions,
Magnesium sulfate heptahydrate was added. In Experimental Example 9, calcium carbonate was added to examine the effect of calcium ions. In Experimental Example 10, zinc sulfate heptahydrate was added to examine the effect of zinc ions. In Experimental Example 11, ammonium chloride was added to investigate the effect of ammonium ions. In Experimental Example 12, ammonium thiocyanate was added to examine the effect of thiocyanate. Further, the same color developing solution (reagent 1), chelating agent (reagent 2), and pH buffer solution (reagent 3) as in Experimental Example 1 were prepared.

8 mL of each sample solution obtained as described above, 4 mL of color-developing solution, 5 mL of chelating agent, 5 mL of pH buffer, and 20 mL of pure water as dilution water were put into a reaction cell and mixed.
This mixed solution had a pH of 5.0. This mixed solution was heated to 100 ° C. using a constant temperature bath. And after 30 minutes,
Cooling water of about 15 ° C. was injected into the constant temperature bath, and 28 mL of pure water was added into the reaction cell. This was measured for absorbance at 510 nm and designated as absorbance A. Next, as a blank measurement, 8 mL of each sample solution obtained as described above and 4 m of color developing solution
L, chelating agent 5 mL, pH buffer solution 5 mL, and pure water 20 mL as dilution water were put into the reaction cell and mixed, and further pure water 28 mL was added. This was measured for absorbance at 510 nm and designated as absorbance B.

Tables 1 to 10 show the composition of each sample liquid and the measurement results. The boric acid concentration conversion values in each table are
The value obtained by subtracting the absorbance B from the absorbance A was divided by the same value as that of a 1 mg / L (boron concentration) standard solution having zero coexisting ions. From the above experimental example, it was found that iron ions, copper ions, and aluminum ions can coexist up to about 100 mg / L, and masking with a chelating agent is sufficiently performed under the condition of pH 5. Also, the interference with other coexisting ions was substantially negligible.

[0046]

[Table 1]

[0047]

[Table 2]

[0048]

[Table 3]

[0049]

[Table 4]

[0050]

[Table 5]

[0051]

[Table 6]

[0052]

[Table 7]

[0053]

[Table 8]

[0054]

[Table 9]

[0055]

[Table 10]

[Experimental Example 13] In order to investigate the influence of pH,
A boric acid standard solution containing iron ions and having a boron concentration of 1 mg / L was prepared. Further, as the pH buffer solution (reagent 3), 50 g of ammonium acetate was dissolved in pure water and adjusted to pH 5.5 with acetic acid to make 1000 mL. The other conditions were the same as in Experimental Example 3, and the absorbance A and the absorbance B were measured.

Table 11 shows the composition of Experimental Example 13 and the measurement results. In addition, the boric acid concentration conversion value in Table 11 is a value obtained by subtracting the absorbance B from the absorbance A, which is 1 when the coexisting ions are zero.
It is divided by the same value of mg / L (boron concentration) standard solution. From the above experimental example, it was found that iron ion was 5 mg / L and significant interference was already observed, and that masking with the chelating agent was not sufficiently performed under the condition of pH 5.5.

[0058]

[Table 11]

[Experimental Examples 14 to 17] In order to investigate the influence of coexisting ions, the sample liquid contains different coexisting ions for each experimental example, and the boron concentration is 0 mg / L or 1 mg / L, respectively.
L boric acid standard solution was prepared. Specifically, Experimental Example 14
Then, in order to examine the effect of sodium ions, disodium hydrogen phosphate was added. In Experimental Example 15, potassium nitrate was added to examine the effect of potassium ions. In Experimental Example 16, potassium nitrate was added to examine the effect of nitrate ions. In Experimental Example 17, disodium hydrogen phosphate was added to examine the effect of phosphate ions. Regarding each of the above samples, the absorbance A and the absorbance B were measured under the same conditions as in Experimental Examples 3 to 12 except that the reaction temperature was 70 ° C.

Tables 12 to 15 show the composition of each sample liquid and the measurement results. The boric acid concentration conversion values in each table are obtained by dividing the value obtained by subtracting the absorbance B from the absorbance A by the same value of the 1 mg / L (boron concentration) standard solution with zero coexisting ions. From the above experimental example, sodium ion,
It was found that both potassium ions can coexist up to 1000 mg / L or more, and interference can be eliminated by adding these alkali ions in advance. Also,
The interference with other coexisting ions was also negligible.

[0061]

[Table 12]

[0062]

[Table 13]

[0063]

[Table 14]

[0064]

[Table 15]

[Experimental Example 18] In order to investigate the effect of no addition of alkali ions, boric acid standard solutions containing sodium ions and having boron concentrations of 1 mg / L each were prepared. Also, p
As the H buffer solution (reagent 3), 50 g of ammonium acetate was dissolved in pure water and adjusted to pH 5.5 with acetic acid to 1000
What was made into mL was used. The pH during the reaction is 5.
It was 0. The other conditions were the same as in Experimental Example 14, and the absorbance A and the absorbance B were measured.

Table 16 shows the composition of Experimental Example 18 and the measurement results. The boric acid concentration conversion value in Table 16 is the value obtained by subtracting the absorbance B from the absorbance A as 1 when the coexisting ions are zero.
It is divided by the same value of mg / L (boron concentration) standard solution. From the above experimental example, the sodium ion is 1000
At mg / L, 5% interference was already observed.

[0067]

[Table 16]

[0068]

According to the borate ion measuring method and borate ion measuring apparatus of the present invention, borate ions can be measured accurately and easily without being interfered by coexisting substances.
Therefore, it is highly practical in monitoring the boron concentration in water in the wastewater treatment process and environmental water, and is useful from the viewpoint of environmental protection.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of a borate ion measuring device according to the present embodiment.

FIG. 2 is a graph showing the results of Experimental Example 1.

FIG. 3 is a graph showing the results of Experimental Example 2.

[Explanation of symbols]

10 ... Reaction cell, 20 ... Constant temperature bath, 30 ... Colorimeter,
S1 ... Sample introduction tube, S2 ... Outflow tube, R1 ... Reagent introduction tube, R2 ... Reagent introduction tube, R3 ... Reagent introduction tube, M1
…… Sample liquid meter, M2 …… Diluent meter, RP1 ……
Reagent injection pump, RP2 ... Reagent injection pump, RP3 ...
… Reagent injection pump,

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Takei Ishii             1-9-10 Takadanobaba, Shinjuku-ku, Tokyo East             Inside ADK Corporation F term (reference) 2G042 AA01 BB15 CA02 CB03 DA06                       DA08 EA13 FA03 FA06 FA11                       FB02 GA01 GA05 HA07                 2G054 AA02 AB07 BA01 CA10 GA03                       GB01                 2G059 AA01 BB04 CC01 DD02 DD03                       DD05 DD12 DD16 DD20 EE01                       FF08 FF12 HH02 HH06 NN01                       PP10

Claims (11)

[Claims] 1. A sample solution containing at least 1-amino-8
-Hydroxynaphthalene-3,6-disulfonic acid-based azo dye and a reagent containing a chelating agent are added, and borate ions in the sample solution and 1-amino-8-hydroxynaphthalene-3,6-disulfonic acid are added. PH of 4 with azo dye
A method for measuring borate ion in a sample solution, which comprises reacting at ˜5.4 and measuring absorbance. 2. A sample solution containing at least 1-amino-8
-Hydroxynaphthalene-3,6-disulfonic acid azo dye and a reagent containing sodium ion and / or potassium ion are added, and borate ion in the sample solution and 1-amino-8-hydroxynaphthalene-3 are added. A method for measuring borate ion in a sample liquid, which comprises reacting with a 6,6-disulfonic acid azo dye and measuring absorbance. 3. A sample solution containing at least 1-amino-8
-Hydroxynaphthalene-3,6-disulfonic acid azo dye, a chelating agent, and a reagent containing sodium ion and / or potassium ion are added, and borate ion in the sample solution and 1-amino-8- Hydroxynaphthalene-3,6-disulfonic acid-based azo dye was added at a pH of 4-5.
4. A method for measuring borate ion in a sample liquid, which comprises reacting in 4 and measuring the absorbance. 4. The borate ion in the sample solution and the 1
The phosphine according to any one of claims 1 to 3, wherein the reaction with the -amino-8-hydroxynaphthalene-3,6-disulfonic acid-based azo dye is stopped halfway and the absorbance is measured. Method for measuring acid ions. 5. The borate ion in the sample solution and the 1
-Amino-8-hydroxynaphthalene-3,6-disulfonic acid-based azo dye is allowed to proceed by heating the mixed solution of the sample solution and the reagent at 40 to 100 ° C, and then at 0 ° C or higher. The borate ion measuring method according to claim 4, wherein the method is stopped by cooling to a temperature lower than 40 ° C. 6. The borate ion measuring method according to claim 5, wherein when the mixed solution is cooled, pure water is added to the mixed solution to accelerate the cooling. 7. The reagent comprises a reaction space, means for introducing a sample solution and a reagent into the reaction space, and means for measuring the absorbance of a mixed solution of the sample solution and the reagent in the reaction space. Contains at least 1-amino-8-hydroxynaphthalene-3,6-disulfonic acid azo dye and a chelating agent, and the pH of the mixed solution is 4 to 4 depending on the reagent.
5. A borate ion measuring device in a sample solution, which is adjusted to 5.4. 8. The reagent is provided with a reaction space, means for introducing a sample solution and a reagent into the reaction space, and means for measuring the absorbance of a mixed solution of the sample solution and the reagent in the reaction space. Is a 1-amino-8-hydroxynaphthalene-3,6-disulfonic acid-based azo dye, and sodium ion and / or potassium ion. 9. The reagent is provided with a reaction space, a means for introducing a sample solution and a reagent into the reaction space, and a means for measuring the absorbance of a mixed solution of the sample solution and the reagent in the reaction space. Is at least 1-amino-8-hydroxynaphthalene-3,6-disulfonic acid azo dye, a chelating agent,
Containing sodium ions and / or potassium ions,
Moreover, the pH of the mixed solution is 4 to 5.4 depending on the reagent.
An apparatus for measuring borate ion in a sample liquid, which is characterized in that 10. The method according to claim 7, further comprising means for heating the mixed liquid to 40 to 100 ° C. and means for cooling the mixed liquid to a temperature of 0 ° C. or higher and lower than 40 ° C. The borate ion measuring device described in 1. 11. A means for adding pure water to the mixed solution, wherein when the mixed solution is cooled, pure water is added to the mixed solution to accelerate the cooling. The borate ion measuring device described in 1.