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Reagent composition for ph measurement

A technology of compositions and reagents, applied in the direction of testing pH value, using chemical indicators for analysis, and material analysis by observing the effect on chemical indicators, which can solve problems such as stenosis

Inactive Publication Date: 2020-11-24
MIURA COMPANY LIMITED
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, since the color-changing region of the pH indicator is limited to a certain range, the range of pH that can be measured by the above-mentioned alternative method is at most about 1 to 2, which is relatively narrow.

Method used

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  • Reagent composition for ph measurement
  • Reagent composition for ph measurement
  • Reagent composition for ph measurement

Examples

Experimental program
Comparison scheme
Effect test

no. 1 Embodiment approach example

[0037] This embodiment example assumes that the pH of the test water is measured in the range of approximately 4 to 9 (this range includes the entire buffer pH range of carbonic acid), and contains the following color reagents.

[0038] ◎The first chromogenic reagent

[0039] Selected from chromogenic reagents with a pKa in the range of 4.1 to 6.0. For example, it may be selected from methyl red (pKa: 5.1), bromophenol blue (pKa: 4.2) and bromocresol green (pKa: 4.7).

[0040] ◎The second chromogenic reagent

[0041] Selected from chromogenic reagents with a pKa in the range of 6.5 to 8.5. For example, it may be selected from phenol red (pKa: 1.2 and 7.7), neutral red (pKa: 6.7 and 7.4) and cresyl red (pKa: 1.0 and 8.0).

[0042] ◎The third chromogenic reagent

[0043]Selected from chromogenic reagents with a pKa in the range of 5.5 to 7.5. For example, it may be selected from bromocresol purple (pKa: 6.3) and bromothymol blue (pKa: 7.1).

[0044] Specific examples of th...

no. 2 Embodiment approach example

[0060] This embodiment example assumes that the pH of the test water is measured in the range of approximately 4 to 12 (this range also includes the entire buffer pH range of carbonic acid), and contains the following color reagents.

[0061] ◎The first chromogenic reagent

[0062] Selected from chromogenic reagents with a pKa in the range of 4.1 to 6.0. For example, it may be selected from methyl red (pKa: 5.1), bromophenol blue (pKa: 4.2) and bromocresol green (pKa: 4.7).

[0063] ◎The second chromogenic reagent

[0064] Selected from chromogenic reagents with a pKa in the range of 8.5 to 11.5. For example, it may be selected from Alizarin Yellow (pKa: 11.06) and Thymol Blue (pKa: 1.7 and 8.9).

[0065] ◎The third chromogenic reagent

[0066] Two kinds of color-developing reagent A selected from the color-developing reagents whose pKa is in the range of 5.5 to 7.5, and color-developing reagent B selected from the color-developing reagents whose pKa is in the range of 7.0...

Embodiment

[0135] 500 g of reagent compositions having the compositions shown in Table 5 were prepared. This reagent composition corresponds to the reagent composition listed as a specific example of the reagent composition of the first embodiment.

[0136] [table 5]

[0137] table 5

[0138]

[0139] Assuming that 100mL test water added with 0.75g of reagent composition is irradiated with visible light with wavelengths of 420nm, 525nm and 590nm, according to the above formula (1), formula (2) and formula (3) and Henderson-Hassell Balcher's formula calculates the absorbance of visible light at each wavelength predicted in this case. Here, the absorbance of the above-mentioned visible light of each wavelength is calculated for the test water whose pH is different in the range of 1 to 10 at intervals of 0.1.

[0140] According to the calculated absorbance of each wavelength, the relationship between the pH value of the test water and the absorbance ratio (525nm / 420nm) and the relatio...

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Abstract

The reagent composition for measuring the pH of a sample water has each of the following dissolved in prescribed proportions in a diol, e.g., ethylene glycol: methyl red, which has an acid dissociation constant (pKa) of 5.1; phenol red, which has a pKa of 7.7, which is larger than that of methyl red; and bromocresol purple, which has a pKa of 6.3, which is between those of methyl red and phenol red. The absorbance of a sample water to which this reagent composition has been added is measured at three wavelengths, i.e., a wavelength selected from the range from 410-430 nm, a wavelength selectedfrom the range from 515-535 nm, and a wavelength selected from the range from 580-600 nm, and the pH of the sample water is determined on the basis of these absorbances. The pH of the sample water inthe range from 4-9 can thereby be measured.

Description

technical field [0001] The present invention relates to a reagent composition for pH measurement, in particular to a reagent composition for measuring the pH of test water within a predetermined range. This application claims priority based on Japanese Patent Application No. 2018-126905 filed in Japan on July 3, 2018, the contents of which are incorporated herein. Background technique [0002] Various types of water, such as boiler feed water and circulating cooling water for cooling towers, may have pH (hydrogen ion index) adjusted by adding chemicals. In this case, it is necessary to measure the pH of the water after adding the chemical, and to confirm that the pH of the water is adjusted to the target range. [0003] As general methods for measuring the pH of water or a solution, Patent Document 1 proposes a titration method and a measurement method using a glass electrode. However, in the titration method as described in Patent Document 1, when the sample, that is, the...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G01N21/80G01N31/22
CPCG01N21/80G01N31/221G01N21/78G01N31/22G01N21/77
Inventor 浜田裕介石原由贵
Owner MIURA COMPANY LIMITED
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