Dilution multiple method chromaticity standard substance as well as preparation method and application thereof

Abstract

The embodiment of the invention discloses a dilution multiple method chromaticity standard substance as well as a preparation method and application thereof, and belongs to the technical field of analytical chemistry. The method comprises the following steps: weighing 0.105 g to 10.5 g of anhydrous sodium carbonate, and dissolving the anhydrous sodium carbonate in 1000mL of ultrapure water; adding a phenolphthalein indicator into the solution, and testing the pH value of the system; according to the equivalent relationship between the pH value of the system and the dilution ratio, the dilution ratio method chromaticity standard substance is valued. The standard substance provided by the invention has a determined chemical composition, the fixed value result of the standard substance can be traced to the pH measurement standard, the traceable fixed value can be realized by establishing the quantitative relation between the pH value and the dilution multiple, the accuracy of water quality chromaticity detection data and the reliability of the measurement result are remarkably improved, and the method is suitable for popularization and application. The technical defects of subjective judgment deviation, poor result reproducibility and the like existing in chromaticity detection of a traditional dilution multiple method are effectively overcome.

Description

Technical Field

[0001] Embodiments of the present invention relate to the technical field of analytical chemistry, and particularly to a dilution multiple method chromaticity reference material, a preparation method thereof, and an application thereof. Background Art

[0002] In the field of water quality monitoring, chromaticity is an important physical index, which reflects the degree of absorption and scattering of light by dissolved substances or suspended substances in water bodies. The traditional method for detecting water quality chromaticity usually adopts the dilution multiple method, that is, the operator visually compares the color difference between the dilution solution and the original sample to determine the dilution multiple at which the color judgment end point is reached. However, this method has significant deficiencies.

[0003] First of all, visual judgment has a large subjective error. Different operators may have differences in color sensitivity and judgment criteria, resulting in inconsistent dilution multiple results for the same water sample under the operation of different personnel, which affects the accuracy of the detection. Secondly, the traditional dilution multiple method lacks traceability. Due to the subjectivity of visual judgment, it is impossible to establish a stable mathematical model or standard curve to trace and verify the detection results, making the reliability of the detection results questioned. In addition, the traditional method also has stability defects. In actual operation, due to the influence of environmental factors (such as light, temperature, etc.) and operation processes (such as dilution, stirring, etc.), the change of the color judgment end point may occur, further increasing the uncertainty of the detection results.

[0004] At present, there are few types of dilution multiple method chromaticity reference materials, and most of them use platinum-cobalt chromaticity standard solution or potassium dichromate solution as raw materials. However, the platinum-cobalt method is applicable to low-chromaticity water samples, and the potassium dichromate method has toxicity problems (hexavalent chromium pollution), and the color is quite different from that of natural water bodies. Therefore, it is very necessary to develop a dilution multiple method chromaticity reference material with a wide application range, traceability, and environmental friendliness. Summary of the Invention

[0005] For this reason, embodiments of the present invention provide a dilution multiple method chromaticity reference material, a preparation method thereof, and an application thereof.

[0006] In order to achieve the above object, embodiments of the present invention provide the following technical solutions:

[0007] According to the first aspect of the embodiments of the present invention, the present invention provides a preparation method of a dilution multiple method chromaticity reference material, and the method includes:

[0008] Weigh 0.105 g to 10.5 g of anhydrous sodium carbonate and dissolve it in 1000 mL of ultrapure water; add phenolphthalein indicator to the solution, measure the pH value of the system; and determine the value of the dilution multiple method chromaticity reference material according to the equivalent relationship between the pH value of the system and the dilution multiple.

[0009] Further, the concentration of the phenolphthalein indicator is 1% - 1.5%, and the addition amount is 150 μL - 200 μL.

[0010] Further, the equivalent relationship is: N = 10 (pH-8.3) , where N represents the dilution multiple of the chromaticity standard substance, and pH represents the acidity and alkalinity of the system.

[0011] Further, the purity of the anhydrous sodium carbonate is 99.9% - 100%.

[0012] According to the second aspect of the embodiments of the present invention, the present invention provides a dilution multiple method chromaticity standard substance, which is prepared by the preparation method described in any one of the above.

[0013] According to the third aspect of the embodiments of the present invention, the present invention provides the application of the dilution multiple method chromaticity standard substance described above in the detection of water quality chromaticity.

[0014] The embodiments of the present invention have the following advantages:

[0015] (1) The quantity value can be traced back to the pH value, and the traceability chain is complete: Through the pH-chromaticity correlation mechanism, the present invention realizes the traceable calibration of the chromaticity standard substance. The integrity of this traceability chain ensures the accuracy and reliability of the measurement results, and helps to improve the overall level of water quality chromaticity detection.

[0016] (2) The process controllability is strong, and the chromaticity attenuation rate is significantly reduced: In the preparation process, the present invention adopts precise chemical composition and preparation process to ensure the stability and consistency of the standard substance. This strong controllability process helps to reduce the chromaticity attenuation rate and improve the durability and practicability of the standard substance.

[0017] (3) The dilution multiple method chromaticity standard substance provided by the present invention has a validity period of up to 2 years, providing a more stable and reliable standard substance for the detection of water quality chromaticity. Description of the Drawings

[0018] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are only exemplary, and for those of ordinary skill in the art, without creative efforts, other implementation drawings can also be obtained according to the provided drawings.

[0019] Figure 1 It is the flowchart of the preparation method of the dilution multiple method chromaticity standard substance based on the pH traceability mechanism provided by the present invention;

[0020] Figure 2 It is the stability monitoring diagram of the standard substances prepared in Examples 1 - 3 provided by the present invention. Detailed implementation manners

[0021] The following specific embodiments illustrate the implementation manners of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention.

[0022] Establishment of the mathematical model relationship between dilution factor and solution pH value

[0023] Use ultrapure water to prepare 1000 mL of sodium carbonate solutions with different concentrations. Add 150 μL of a 1% phenolphthalein indicator (prepared with ethanol as the solvent) to each solution for color development, test the pH value, use the dilution factor method to dilute the solution until it becomes colorless, record the dilution factor, and simultaneously test the pH value of the solution at this time. The concentrations, pH values, and dilution factors of the sodium carbonate solutions are shown in Table 1.

[0024]

[0025] From the data in Table 1, through induction and summary, it is found that there is a certain relationship between the dilution factor and the difference in pH value of the sodium carbonate aqueous solution before and after dilution, and the pH value of the solution diluted until it becomes colorless is stable between 8.29 - 8.30, that is, the dilution factor (N) = 10 pH差值 . Since the pH of the colorless solution is basically fixed, the mathematical relationship model between the dilution factor N and the pH value of the original sodium carbonate aqueous solution is expressed as N = 10 （pH-8.30） . The following embodiments also verify this mathematical relationship model.

[0026] As Figure 1 shown, a preparation method of a dilution factor method reference material provided by the present invention includes:

[0027] S110, Preparation. Weigh 0.105 g - 10.5 g of anhydrous sodium carbonate, dissolve it with ultrapure water and make the volume up to 1 L, and add 150 μL - 200 μL of a 1% - 1.5% phenolphthalein indicator.

[0028] S120, pH test. Test the pH value of the above solution and record it.

[0029] S130, Dilution factor method test. Dilute the reference material to colorless according to the dilution factor method and record the dilution factor.

[0030] S140, Endpoint pH determination. Test the pH value of the colorless solution diluted in S120 to determine whether the endpoint is reached.

[0031] S150. Verification. Substitute the experimental data into the established mathematical model relationship between the dilution factor and the pH value of the solution, and verify it with the results obtained by the dilution factor method.

[0032] Example 1: Preparation of the reference material for the 100-fold dilution factor method

[0033] This example provides a method for preparing a reference material with a standard value of the 100-fold dilution factor method, including the following steps:

[0034] (1) Weigh 1 g of phenolphthalein and dissolve it in 100 mL of ethanol to prepare a 1% phenolphthalein solution.

[0035] (2) Weigh 0.10512 g of anhydrous sodium carbonate into a 1000 mL volumetric flask, dissolve it with ultrapure water and make up the volume to 1 L, add 150 μL of the phenolphthalein solution prepared in step (1), and shake well.

[0036] (3) Measure the pH value of the above solution and record that the pH value of this solution is 10.29.

[0037] (4) Dilute the above solution successively by 10 times and 100 times until the solution becomes colorless, and record the dilution factor at this time as 100 times.

[0038] (5) Measure the pH value of the solution diluted to colorless and record that the pH value of this solution is 8.29.

[0039] (6) Substitute the experimental data into the established mathematical model relationship between the dilution factor and the pH value of the solution N = 10 (pH-8.3) , and calculate to obtain N = 100, which is consistent with the result of 100 times obtained by the dilution factor method.

[0040] Use the dilution factor method to conduct a stability test on the prepared reference material for the 100-fold dilution factor method, and the results are shown in Table 2. The characteristic quantity value of the prepared reference material for the 100-fold dilution factor method has no unidirectional trend change within 2 years, and the stability is good.

[0041]

[0042] Example 2: Preparation of the reference material for the 500-fold dilution factor method

[0043] This example provides a method for preparing a reference material with a standard value of the 500-fold dilution factor method, including the following steps:

[0044] (1) Weigh 1 g of phenolphthalein and dissolve it in 100 mL of ethanol to prepare a 1% phenolphthalein solution.

[0045] (2) Weigh 1.05131 g of anhydrous sodium carbonate into a 1000 mL volumetric flask, dissolve it with ultrapure water and make up the volume to 1 L. Add 150 μL of the phenolphthalein solution prepared in step (1), and shake well.

[0046] (3) Measure the pH value of the above solution and record the pH value of this solution as 11.00.

[0047] (4) Dilute the above solution successively by 10 times, 100 times, and 500 times until the solution becomes colorless, and record the final dilution factor as 500 times.

[0048] (5) Measure the pH value of the diluted colorless solution and record the pH value of this solution as 8.30.

[0049] (6) Substitute the experimental data into the mathematical model relationship between the dilution factor and the solution pH value N = 10 (pH-8.3) , and calculate to obtain N = 500, which is consistent with the result of 500 times obtained by the dilution factor method.

[0050] The stability of the prepared standard substance with a dilution factor of 500 times was tested by the dilution factor method, and the results are shown in Table 3. The characteristic quantity values of the prepared standard substance with a dilution factor of 500 times did not show a one-way trend change within 2 years, and the stability was good.

[0051]

[0052] Example 3: Preparation of a standard substance with a dilution factor of 1000 times

[0053] This example provides a preparation method for a standard substance with a standard value of a dilution factor of 1000 times, including the following steps:

[0054] (1) Weigh 1 g of phenolphthalein and dissolve it in 100 mL of ethanol to prepare a 1% phenolphthalein solution.

[0055] (2) Weigh 10.51211 g of anhydrous sodium carbonate into a 1000 mL volumetric flask, dissolve it with ultrapure water and make up the volume to 1 L. Add 150 μL of the phenolphthalein solution and shake well.

[0056] (3) Measure the pH value of the above solution and record the pH value of this solution as 11.29.

[0057] (4) Dilute the above solution successively by 10 times, 100 times, and 1000 times until the solution becomes colorless, and record the final dilution factor as 1000 times.

[0058] (5) Measure the pH value of the diluted colorless solution and record the pH value of this solution as 8.29.

[0059] (6) Substitute the experimental data into the established mathematical model relationship between the dilution multiple and the pH value of the solution N = 10 (pH-8.3) , and calculate to obtain N = 1000, which is consistent with the result of 1000 times obtained by the dilution multiple method.

[0060] The stability of the reference material prepared by the dilution multiple method with a dilution multiple of 1000 times in Example 3 was tested. The results are shown in Table 4. The characteristic quantity value of the prepared reference material with a dilution multiple of 1000 times did not show a one-way trend change within 2 years, indicating good stability.

[0061]

[0062] Although the present invention has been described in detail with general descriptions and specific embodiments above, based on the present invention, some modifications or improvements can be made, which are obvious to those skilled in the art. Therefore, these modifications or improvements made without departing from the spirit of the present invention all fall within the scope of protection required by the present invention.

Claims

1. A preparation method of a chromaticity reference material by dilution multiple method, characterized in that, The method includes: Weigh 0.105 g to 10.5 g of anhydrous sodium carbonate and dissolve it in 1000 mL of ultrapure water; add phenolphthalein indicator to the solution and measure the pH value of the system; determine the dilution factor colorimetric standard substance according to the equivalent relationship between the pH value of the system and the dilution factor.

2. The preparation method of the dilution multiple method chromaticity reference material according to claim 1, wherein The concentration of the phenolphthalein indicator is 1% to 1.5%, and the addition amount is 150 μL to 200 μL.

3. The preparation method of the dilution multiple method chromaticity reference material according to claim 1, characterized in that, The equivalent relationship is: N = 10 (pH-8.3) , where N represents the dilution factor of the chromaticity standard substance, and pH represents the acidity and alkalinity of the system.

4. The preparation method of the chromaticity reference material by the dilution multiple method according to claim 1, characterized in that, The purity of the anhydrous sodium carbonate is 99.9% to 100%.

5. A dilution multiple method chromaticity reference material, characterized in that, It is prepared by the preparation method described in any one of claims 1-4.

6. Application of the dilution factor colorimetric standard substance described in claim 5 in the detection of water quality colority.

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