Detection reagents and methods for calcium hardness, magnesium hardness and total hardness of water

Abstract

The present invention provides a detection reagent and a detection method for calcium hardness, magnesium hardness and total hardness of water. The detection reagent comprises a liquid color developing component, a liquid buffer component, a first liquid masking agent component and a second liquid masking agent component. The liquid color developing component comprises a color developing agent that can react with both calcium ions and magnesium ions. The liquid buffer component adjusts the pH value of the color developing reaction to be greater than 12. The first liquid masking agent component is used to mask the calcium ions and magnesium ions in the water quality, and the second liquid masking agent component is used to mask the calcium ions in the water quality. The detection reagent can simultaneously measure the calcium hardness, magnesium hardness and total hardness in the water quality. The detection method has high accuracy, good parallelism, convenience and rapidity, and the detection time of the three indicators of calcium hardness, magnesium hardness and total hardness of a single sample is short.

Description

Technical Field

[0001] The present invention relates to the field of analytical chemistry, in particular to the field of water quality detection technology, and more particularly to a detection reagent and a detection method for calcium hardness, magnesium hardness and total hardness of water. Background Art

[0002] With the rapid development of industrialization and urbanization, water quality issues have received increasing attention. Water hardness is one of the important indicators for measuring water quality, of which calcium hardness and magnesium hardness are the two main components of total hardness. Magnesium hardness usually refers to the content of magnesium ions in water, and calcium hardness usually refers to the content of calcium ions in water. The total amount of calcium and magnesium ions represents the total hardness of water.

[0003] At present, the commonly used methods for determining the content of calcium and magnesium ions are mainly EDTA complexometric titration, potentiometric titration, spectrophotometry, atomic absorption spectrometry, etc. Among them, atomic absorption and plasma emission spectrometry are mature and stable, with high test accuracy and good test parallelism. They are instrumental analysis methods commonly used for the determination of calcium and magnesium ions. However, the instruments are expensive, complicated to operate, and require certain experimental environmental conditions, which do not meet the needs of on-site testing and general users. The traditional EDTA complexometric titration method is complicated, time-consuming, and has low sensitivity (the lower limit of determination is only 0.05mmol / L), which cannot meet the determination requirements of industrial boiler water quality (≦0.03mmol / L). The determination of the content of a single ion by ultraviolet spectrophotometry has the advantages of high sensitivity, simple and fast operation. However, the color developer commonly used in ultraviolet spectrophotometry can react with calcium ions and magnesium ions at the same time, and it is impossible to quantitatively test calcium hardness and magnesium hardness separately. In addition, if the color developer is prepared in the form of an aqueous solution, its properties are extremely unstable and it is usually oxidized by air and becomes ineffective within 1 month. If it needs to be prepared as a solid indicator, the amount of reagent added is difficult to control due to the uniformity of the solid reagent, and the test reproducibility is poor.

[0004] Therefore, it is difficult to measure magnesium and calcium separately in the existing common hardness test methods. Therefore, it is necessary to develop a fast, accurate and simple water quality calcium hardness, magnesium hardness and total hardness rapid detection reagent to solve the above problems. Summary of the invention

[0005] Based on the above problems, the purpose of the present invention is to provide a detection reagent and method for calcium hardness, magnesium hardness and total hardness of water. The detection reagent can simultaneously measure calcium hardness, magnesium hardness and total hardness in water quality. The detection method has high accuracy, good parallelism, convenience and rapidity, and the detection time of the three indicators of calcium hardness, magnesium hardness and total hardness of a single sample is short.

[0006] To achieve the above-mentioned purpose, the first aspect of the present invention provides a detection reagent for calcium hardness, magnesium hardness and total hardness of water. The detection reagent for calcium hardness, magnesium hardness and total hardness of water comprises a liquid color component, a liquid buffer component, a first liquid masking agent component and a second liquid masking agent component, wherein the liquid color component comprises a color developer that can react with both calcium ions and magnesium ions, the liquid buffer component adjusts the pH value of the color reaction to be greater than 12, the first liquid masking agent component is used to mask the calcium ions and magnesium ions in the water, and the second liquid masking agent component is used to mask the calcium ions in the water.

[0007] In the technical solution adopted by the present invention, the liquid color component can react with calcium ions and magnesium ions, and the liquid buffer component adjusts the pH value of the color reaction to be greater than 12 to provide an alkaline environment required for the color reaction. The first liquid masking agent component is used to mask the calcium ions and magnesium ions in the water quality, thereby providing a test blank of calcium ions and magnesium ions during the test, and the second liquid masking agent component is used to mask the calcium ions in the water quality, thereby providing a test blank of calcium ions during the test. Therefore, the first liquid masking agent component and the second liquid masking agent component are respectively subjected to masking treatment after color development on the water quality to be tested, and the color difference between the two after the masking treatment is the color development effect of magnesium ions. Similarly, the second liquid masking agent component is subjected to masking treatment after color development on the water quality to be tested, and the color difference between the masking treatment and the water quality to be tested is the color development effect of calcium ions. Therefore, the calcium hardness and magnesium hardness in the water quality to be tested can be obtained by combining the test instrument, and the total hardness of the water quality to be tested can be obtained by calculating the sum of the calcium hardness and the magnesium hardness.

[0008] The second aspect of the present invention provides a method for preparing a reagent for detecting calcium hardness, magnesium hardness and total hardness of water, comprising the steps of: (1) Preparation of standard curve Prepare magnesium hardness-absorbance standard curve and calcium hardness-absorbance standard curve; (2) Color rendering Take water and add the liquid color developing component to mix, then add the liquid buffer component to mix, and then pour into three cuvettes respectively as samples to be tested; (3) Magnesium hardness test Add the first liquid masking agent component to the first cuvette, shake well and dissolve, and use it as a blank sample for magnesium ion test; add the second liquid masking agent component to the second cuvette, shake well and dissolve, and use it as a sample for magnesium ion test; take the blank sample for magnesium ion test and put it into a spectrophotometer for background calibration; then take the sample for magnesium ion test and put it into a spectrophotometer analyzer for reading the absorbance value; and use the magnesium hardness-absorbance standard curve to obtain magnesium hardness; (4) Calcium hardness test The second cuvette is used as a blank sample for calcium ion test, and the third cuvette is used as a sample to be tested for calcium ion test. The blank sample for calcium ion test is placed in a spectrophotometer for background calibration, and then the sample to be tested for calcium ion test is placed in a spectrophotometer analyzer for reading the absorbance value, and the calcium hardness is obtained using the calcium hardness-absorbance standard curve; (5) Total hardness test The total hardness value is equal to the calcium hardness value plus the magnesium hardness value.

[0009] The detection method of the present invention is to divide the water into three parts after color development, the first part uses the first liquid masking agent component to mask calcium ions and magnesium ions, the second part uses the second liquid masking agent component to mask calcium ions, and the third part is not masked. The absorbance difference obtained by the absorbance test after the first and second parts are respectively masked (that is, the sample treated with the first liquid masking agent component is used as a blank control) can obtain the absorbance value of magnesium ions, and the magnesium hardness can be obtained through the magnesium hardness-absorbance standard curve. The absorbance difference obtained by the absorbance test after the second part is masked and the third part is tested (that is, the sample treated with the second liquid masking agent component is used as a blank control) can obtain the absorbance value of calcium ions, and the calcium hardness can be obtained through the calcium hardness-absorbance standard curve. This test method can simultaneously obtain the calcium hardness and magnesium hardness in the water quality by overall color development, separate masking, and comparative measurement of absorbance. It is simple and fast to operate, and the corresponding values ​​can be obtained within 10 minutes. The method has high accuracy and good parallelism. DETAILED DESCRIPTION

[0010] The detection reagent for calcium hardness, magnesium hardness and total hardness of water quality of the present invention comprises a liquid color developing component, a liquid buffer component, a first liquid masking agent component and a second liquid masking agent component.

[0011] Wherein, the liquid color developing component is an aqueous solution comprising a color developer, a sensitizer and a first stabilizer. The color developer can react with calcium ions and magnesium ions. The concentration of the color developer is 0.5~5.0g / L. As an example, the concentration can be but not limited to 0.5g / L, 1.0g / L, 1.5g / L, 2.0g / L, 2.5g / L, 3.0g / L, 3.5g / L, 4.0g / L, 4.5g / L, 5.0g / L. The color developer includes one or more of calcium magnesium reagent, chrome black T, acid chrome blue K and azo chlorophosphine III, preferably calcium magnesium reagent (1-(1-hydroxy-4-methyl-2-phenylazo)-2-naphthol-4-sulfonic acid). The concentration of sensitizer is 20~60g / L, as an example, the concentration can be but not limited to 20g / L, 25g / L, 30g / L, 35g / L, 40g / L, 45g / L, 50g / L, 55g / L, 60g / L, the concentration of sensitizer is too low, can not play the role of sensitization, and the concentration is too high, then the solution viscosity increases, affecting the accuracy of reagent pipetting.Sensitizer is a nonionic surfactant, such as fatty alcohol polyoxyethylene ether, alkylphenol polyoxyethylene ether, polyol polyoxyethylene ether fatty acid ester, alkylolamide, polyol mono-fatty acid ester and glycerol fatty acid ester, preferably fatty alcohol polyoxyethylene ether, alkylphenol polyoxyethylene ether, polyol polyoxyethylene ether fatty acid ester of polyoxyethylene series.More preferably Triton X-100, OP-10, OP-7, Sintanol DT-7, Sintanol DS-10, Span 20. The addition of a sensitizer can not only improve the sensitivity of color development, but also form intermolecular hydrogen bonds with the first stabilizer to form a huge mesh structure covering the surface of the solution, preventing the solution from contacting the air, and further protecting the color developer. The concentration of the first stabilizer is 10~50g / L. As an example, the concentration can be but not limited to 10g / L, 15g / L, 20g / L, 25g / L, 30g / L, 35g / L, 40g / L, 45g / L, 50g / L. The first stabilizer contains one or more of benzoic acid, p-nitrobenzoic acid and benzenesulfonic acid. Calcium magnesium reagent, chrome black T, acid chrome blue K and azochlorophosphine III are all azo compounds. When made into aqueous solution, they are extremely unstable and easily oxidized by air. The addition of benzoic acid, p-nitrobenzoic acid and benzenesulfonic acid containing -COOH, -SO 3 Organic compounds with electron-withdrawing groups such as H can not only provide an acidic environment that makes the developer more stable, but also protect the developer from oxidation and deterioration.

[0012] The liquid buffer component adjusts the pH value of the color development reaction to be greater than 12, and is an aqueous solution containing an alkaline compound, the concentration of the alkaline compound is 300-600 g / L, as an example, the concentration can be but not limited to 300 g / L, 350 g / L, 400 g / L, 450 g / L, 500 g / L, 550 g / L, 600 g / L. The alkaline compound is sodium hydroxide and / or triethanolamine, preferably a mixed solution of 300 g / L sodium hydroxide and 200 g / L triethanolamine, wherein triethanolamine can not only provide the alkaline environment required for the reaction, but also mask other interfering metal ions.

[0013] The first liquid masking agent component is used to mask calcium ions and magnesium ions in water. The first liquid masking agent component is an aqueous solution containing disodium ethylenediaminetetraacetate and a second stabilizer. Disodium ethylenediaminetetraacetate is a masking agent with a concentration of 0.5 to 2.0 mol / L. As an example, the concentration of disodium ethylenediaminetetraacetate can be, but not limited to, 0.5 mol / L, 0.8 mol / L, 1.0 mol / L, 1.3 mol / L, 1.5 mol / L, 1.8 mol / L, and 2.0 mol / L. The concentration of the second stabilizer is 0.05 to 0.50 mol / L. As an example, the concentration of the second stabilizer can be, but not limited to, 0.05 mol / L, 0.10 mol / L, 0.15 mol / L, 0.20 mol / L, 0.25 mol / L, 0.30 mol / L, 0.35 mol / L, 0.40 mol / L, 0.45 mol / L, and 0.50 mol / L. The second stabilizer contains formaldehyde and / or methanol, and the second stabilizer can protect disodium ethylenediaminetetraacetate from being oxidized and deteriorated. The first liquid masking agent component can mask calcium, magnesium and other interfering metal ions in water quality, and provide a test blank when testing magnesium hardness.

[0014] The second liquid masking agent component is used to mask calcium ions in water. The second liquid masking agent component is an aqueous solution containing ethylene glycol bis (2-aminoethyl ether) tetraacetic acid and sodium hydroxide, and the concentration of ethylene glycol bis (2-aminoethyl ether) tetraacetic acid is 0.05-0.50 mol / L. As an example, the concentration of disodium ethylenediaminetetraacetate can be, but not limited to, 0.05 mol / L, 0.10 mol / L, 0.15 mol / L, 0.20 mol / L, 0.25 mol / L, 0.30 mol / L, 0.35 mol / L, 0.40 mol / L, 0.45 mol / L, 0.50 mol / L. The concentration of sodium hydroxide is 20-100 g / L. As an example, the concentration can be, but not limited to, 20 g / L, 30 g / L, 40 g / L, 50 g / L, 60 g / L, 70 g / L, 80 g / L, 90 g / L, 100 g / L. Since ethylene glycol bis(2-aminoethyl ether) tetraacetic acid has a low solubility in water, sodium hydroxide is added to promote the solubility of ethylene glycol bis(2-aminoethyl ether) tetraacetic acid. The second liquid masking agent component can mask calcium and other interfering metal ions in water quality, providing a test blank when testing calcium hardness.

[0015] The preparation method of the detection reagent of calcium hardness, magnesium hardness and total hardness of water quality of the present invention comprises the steps of: mixing the respective materials of the liquid color developing component, the liquid buffer component, the first liquid masking agent component and the second liquid masking agent component at room temperature and then packaging them separately.

[0016] The method for detecting calcium hardness, magnesium hardness and total hardness of water quality of the present invention comprises the following steps.

[0017] (1) Preparation of standard curve Prepare magnesium hardness-absorbance standard curve and calcium hardness-absorbance standard curve.

[0018] (2) Color rendering Take water and add the liquid color developing component to mix well, then add the liquid buffer component to mix well, and then pour into three cuvettes respectively as samples to be tested.

[0019] (3) Magnesium hardness test Add the first liquid masking agent component to the first cuvette, shake well and dissolve it, and use it as a blank sample for magnesium ion test. Add the second liquid masking agent component to the second cuvette, shake well and dissolve it, and use it as a sample for magnesium ion test. Take the blank sample of magnesium ion test and put it into the spectrophotometer for background calibration, then take the sample to be tested and put it into the spectrophotometer analyzer for reading the absorbance value, and use the magnesium hardness-absorbance standard curve to obtain the magnesium hardness.

[0020] (4) Calcium hardness test The second cuvette is used as a blank sample for calcium ion testing, and the third cuvette is used as a sample to be tested for calcium ion testing. The blank sample for calcium ion testing is placed in a spectrophotometer for background calibration, and then the sample to be tested for calcium ion testing is placed in a spectrophotometer for reading the absorbance value, and the calcium hardness is obtained using a calcium hardness-absorbance standard curve. (5) Total hardness test The total hardness value is equal to the calcium hardness value plus the magnesium hardness value.

[0021] The preparation of the magnesium hardness-absorbance standard curve may include the following steps.

[0022] ① Prepare a series of magnesium standard solutions of different concentrations.

[0023] ② Add the liquid colorimetric component to each magnesium standard solution and mix well, then add the liquid buffer component and mix well, then pour into two cuvettes respectively as samples to be tested.

[0024] ③ Add the first liquid masking agent component to the first cuvette, shake well and dissolve it as a blank sample for magnesium ion test. Add the second liquid masking agent component to the second cuvette, shake well and dissolve it as a sample for magnesium ion test. Take the blank sample for magnesium ion test and put it into the spectrophotometer for background calibration, then take the sample for magnesium ion test and put it into the spectrophotometer analyzer for reading to obtain the absorbance value corresponding to the magnesium standard solution at this concentration. ④ Make a standard curve with the absorbance value as the X-axis and the concentration of the magnesium standard solution as the Y-axis.

[0025] The preparation of calcium hardness-absorbance standard curve may include the following steps.

[0026] ㈠Prepare a series of calcium standard solutions of different concentrations.

[0027] ㈡ Add the liquid colorimetric component to each calcium standard solution and mix well, then add the liquid buffer component and mix well, and then pour into two cuvettes respectively as samples to be tested.

[0028] (iii) Add the second liquid masking agent component to the first cuvette, shake well and dissolve it as a blank sample for calcium ion test, and take the second cuvette as the sample to be tested for calcium ion test. Put the blank sample of calcium ion test into the spectrophotometer for background calibration, and then take the sample to be tested into the spectrophotometer analyzer to read the absorbance value corresponding to the calcium standard solution at this concentration. ㈣ Make a standard curve with the absorbance value as the X-axis and the concentration of the calcium standard solution as the Y-axis.

[0029] Regardless of whether it is the preparation of magnesium hardness-absorbance standard curve, the preparation of calcium hardness-absorbance standard curve or the detection of water quality, the cuvette can use a 10mL standard cuvette, and a 100mL measuring cylinder or volumetric flask can be used for quantification before adding the sample to the cuvette. In each sample, the amount of the liquid color component and the liquid buffer component can be selected according to the actual situation. Preferably, 1mL of each is added to the measuring cylinder or volumetric flask and sealed with a lid and then inverted several times to mix. After the sample is added to the cuvette, the amount of the first liquid masking agent component and the second liquid masking agent component can be selected according to the actual situation. Preferably, 1 drop of each is taken and shaken. The sample in the cuvette is preferably flush with the 10mL scale line. The order of step (3) magnesium hardness test and step (4) (4) calcium hardness test can be interchanged. In actual operation, it can be selected to obtain magnesium hardness or calcium hardness first according to needs.

[0030] The magnesium standard solution can be in the concentrations of 0.10mg / L, 0.50mg / L, 1.00mg / L, 2.00mg / L, 4.00mg / L (in terms of CaCO 3 The calcium standard solution can be 0.10mg / L, 0.50mg / L, 1.00mg / L, 2.00mg / L, 4.00mg / L, 8.00mg / L (in terms of CaCO 3 Therefore, the total water hardness value in mg / L is equal to the total water hardness value in mg / L (CaCO 3 ) plus the calcium hardness value in mg / L (CaCO 3 ) is the magnesium hardness value in units.

[0031] In order to better illustrate the purpose, technical scheme and beneficial effects of the present invention, the present invention will be further described below in conjunction with specific embodiments. It should be noted that the following implementation method is a further explanation of the present invention and should not be used as a limitation of the present invention.

[0032] Part 1: Obtaining water calcium hardness, magnesium hardness, and total hardness test reagents Example 1 This embodiment is a detection reagent for calcium hardness, magnesium hardness, and total hardness of water, including a liquid color component, a liquid buffer component, a first liquid masking agent component, and a second liquid masking agent component. The liquid color component is an aqueous solution containing calcium magnesium reagent (concentration of 1g / L), Triton X-100 (concentration of 20g / L), and benzoic acid (concentration of 10g / L). The liquid buffer component is an aqueous solution of sodium hydroxide with a concentration of 300g / L and triethanolamine with a concentration of 200g / L. The first liquid masking agent component is an aqueous solution of disodium ethylenediaminetetraacetate with a concentration of 1.0mol / L, formaldehyde with a concentration of 0.05mol / L, and methanol with a concentration of 0.05mol / L. The second liquid masking agent component is an aqueous solution of ethylene glycol bis(2-aminoethyl ether)tetraacetic acid with a concentration of 0.2mol / L and sodium hydroxide with a concentration of 70g / L. Example 2 This embodiment is a detection reagent for calcium hardness, magnesium hardness, and total hardness of water, including a liquid color component, a liquid buffer component, a first liquid masking agent component, and a second liquid masking agent component. The liquid color component is an aqueous solution containing chlorophosphine azo III (concentration of 3g / L), Triton X-100 (concentration of 40g / L), and benzoic acid (concentration of 30g / L). The liquid buffer component is an aqueous solution of triethanolamine with a concentration of 600g / L. The first liquid masking agent component is an aqueous solution of disodium ethylenediaminetetraacetate with a concentration of 1.0mol / L, formaldehyde with a concentration of 0.05mol / L, and methanol with a concentration of 0.05mol / L. The second liquid masking agent component is an aqueous solution of ethylene glycol bis(2-aminoethyl ether)tetraacetic acid with a concentration of 0.2mol / L and sodium hydroxide with a concentration of 45g / L. Example 3 This embodiment is a detection reagent for calcium hardness, magnesium hardness, and total hardness of water, including a liquid color component, a liquid buffer component, a first liquid masking agent component, and a second liquid masking agent component. The liquid color component is an aqueous solution containing calcium magnesium reagent (concentration of 5g / L), OP-10 (concentration of 60g / L), and benzenesulfonic acid (concentration of 50g / L). The liquid buffer component is an aqueous solution of sodium hydroxide with a concentration of 300g / L and triethanolamine with a concentration of 200g / L. The first liquid masking agent component is an aqueous solution of disodium ethylenediaminetetraacetate with a concentration of 1.0mol / L and formaldehyde with a concentration of 0.25mol / L. The second liquid masking agent component is an aqueous solution of ethylene glycol bis(2-aminoethyl ether)tetraacetic acid with a concentration of 0.4mol / L and 70g / L of sodium hydroxide. Comparative Example 1 This comparative example is a detection reagent for calcium hardness, magnesium hardness, and total hardness of water, including a liquid color component, a liquid buffer component, a first liquid masking agent component, and a second liquid masking agent component. The liquid color component is an aqueous solution containing a calcium magnesium reagent (concentration of 1g / L) and Triton X-100 (concentration of 20g / L). The liquid buffer component is an aqueous solution of sodium hydroxide with a concentration of 300g / L and triethanolamine with a concentration of 200g / L. The first liquid masking agent component is an aqueous solution of disodium ethylenediaminetetraacetate with a concentration of 1.0mol / L, formaldehyde with a concentration of 0.05mol / L, and methanol with a concentration of 0.05mol / L. The second liquid masking agent component is an aqueous solution of ethylene glycol bis(2-aminoethyl ether)tetraacetic acid with a concentration of 0.2mol / L and sodium hydroxide with a concentration of 70g / L. Comparative Example 2 This comparative example is a detection reagent for calcium hardness, magnesium hardness, and total hardness of water, including a liquid color component, a liquid buffer component, a first liquid masking agent component, and a second liquid masking agent component. The liquid color component is an aqueous solution containing a calcium magnesium reagent (concentration of 1g / L) and benzoic acid (concentration of 10g / L). The liquid buffer component is an aqueous solution of sodium hydroxide with a concentration of 300g / L and triethanolamine with a concentration of 200g / L. The first liquid masking agent component is an aqueous solution of disodium ethylenediaminetetraacetate with a concentration of 1.0mol / L, formaldehyde with a concentration of 0.05mol / L, and methanol with a concentration of 0.05mol / L. The second liquid masking agent component is an aqueous solution of ethylene glycol bis(2-aminoethyl ether)tetraacetic acid with a concentration of 0.2mol / L and sodium hydroxide with a concentration of 70g / L. Comparative Example 3 This comparative example is a detection reagent for calcium hardness, magnesium hardness and total hardness of water, including a liquid color component, a liquid buffer component, a first liquid masking agent component and a second liquid masking agent component. The liquid color component is a calcium-magnesium reagent aqueous solution with a concentration of 1g / L. The liquid buffer component is an aqueous solution of sodium hydroxide with a concentration of 300g / L and triethanolamine with a concentration of 200g / L. The first liquid masking agent component is an aqueous solution of disodium ethylenediaminetetraacetate with a concentration of 1.0mol / L, formaldehyde with a concentration of 0.05mol / L, and methanol with a concentration of 0.05mol / L. The second liquid masking agent component is an aqueous solution of ethylene glycol bis(2-aminoethyl ether)tetraacetic acid with a concentration of 0.2mol / L and sodium hydroxide with a concentration of 70g / L. The shelf life test was conducted using the detection reagents of Examples 1 to 3 and Comparative Examples 1 to 3. The test process is as follows: at room temperature, 100 mL of the liquid color components in Examples 1 to 3 and Comparative Examples 1 to 3 were prepared respectively, and when placed in a reagent bottle for 0d, 5d, 15d, 30d, 90d, 180d, 360d, and 720d, 0.1 mL of the liquid color component was accurately transferred to a 10 mL colorimetric tube and fixed to the scale line, and then 1 mL of the liquid buffer component was added respectively, mixed and pure water was used as a reference, and the absorbance was tested at 525 nm. The results are shown in Table 1 below.

[0033] From the results in Table 1, it can be seen that when the sensitizer and the first stabilizer are added to the liquid color development component at the same time, the shelf life of the detection reagent is the longest and can be stored at room temperature for 720 days.

[0034] Table 1 Absorbance test and shelf life effect of Examples 1 to 3 and Comparative Examples 1 to 3

[0035] Part II: Water Quality Testing The detection of calcium hardness, magnesium hardness and total hardness of water quality is carried out using the detection reagents of calcium hardness, magnesium hardness and total hardness of water quality in Example 1, which includes the following steps.

[0036] (1) Preparation of standard curve (I) A magnesium hardness-absorbance standard curve was prepared. The preparation steps are as follows.

[0037] ① Prepare magnesium sulfate standard solutions with concentrations of 0.10mg / L, 0.50mg / L, 1.00mg / L, 2.00mg / L, and 4.00mg / L respectively (in terms of CaCO 3 count).

[0038] ②Put each magnesium sulfate standard solution into a 100mL measuring cylinder and add water to the scale line. Add 1mL of liquid color component to each measuring cylinder, cover the measuring cylinder lid and invert several times to mix evenly. Add 1mL of liquid buffer component, cover the measuring cylinder lid and invert several times to mix evenly. Pour the liquid in each measuring cylinder into two 10mL cuvettes respectively, and the liquid level is flush with the 10mL scale line.

[0039] ③ Add 1 drop of the first liquid masking agent component to the first cuvette, shake well and dissolve it as a blank sample for magnesium ion test, and add 1 drop of the second liquid masking agent component to the second cuvette, shake well and dissolve it as a sample for magnesium ion test. Take the blank sample for magnesium ion test and put it into the spectrophotometer for background calibration, then take the sample for magnesium ion test and put it into the spectrophotometer analyzer to read the absorbance value corresponding to the magnesium sulfate standard solution at this concentration. The absorbance values ​​of each magnesium sulfate standard solution are shown in Table 2.

[0040] Table 2 Absorbance values ​​of various magnesium sulfate standard solutions

[0041] ④ The standard curve is made with the absorbance value as the coordinate X axis and the concentration of the magnesium sulfate standard solution as the coordinate Y axis. The regression equation of the standard curve is y=2.2276x, R 2 =0.9998.

[0042] (II) Prepare a calcium hardness-absorbance standard curve. The preparation steps are as follows.

[0043] 1. Prepare calcium chloride standard solutions with concentrations of 0.10 mg / L, 0.50 mg / L, 1.00 mg / L, 2.00 mg / L, 4.00 mg / L, and 8.00 mg / L respectively (calcium chloride standard solutions with concentrations of CaCO 3 count).

[0044] 2. Pour each calcium chloride standard solution into a 100mL measuring cylinder and add water to the scale. Add 1mL of liquid color component to each measuring cylinder, cover the measuring cylinder lid and invert several times to mix evenly. Add 1mL of liquid buffer component, cover the measuring cylinder lid and invert several times to mix evenly. Pour the liquid in each measuring cylinder into two 10mL cuvettes respectively, and the liquid level is flush with the 10mL scale line.

[0045] ㈢ Add 1 drop of the second liquid masking agent component to the first cuvette, shake well and dissolve it as a blank sample for calcium ion test. Take the second cuvette as the sample to be tested for calcium ion test, put the blank sample of calcium ion test into the spectrophotometer for background calibration, and then take the sample to be tested and put it into the spectrophotometer analyzer to read the absorbance value corresponding to the calcium chloride standard solution at this concentration. The absorbance values ​​of each calcium chloride standard solution are shown in Table 3.

[0046] Table 3 Absorbance values ​​of various calcium chloride standard solutions

[0047] ㈣ The standard curve is made with the absorbance value as the coordinate X axis and the concentration of the calcium chloride standard solution as the coordinate Y axis. The regression equation of the standard curve is y=4.7846x, R 2 =0.9993.

[0048] (2) Color rendering Prepare two water qualities to be tested: an industrial boiler feed water and an industrial circulating cooling water. Take 100 mL of each and place them in three 100 mL measuring cylinders. Add 1 mL of liquid color component to each measuring cylinder, cover the measuring cylinder lid, and invert several times to mix. Add 1 mL of liquid buffer component, cover the measuring cylinder lid, and invert several times to mix. Pour the liquid in each measuring cylinder into three 10 mL cuvettes, and the liquid level is flush with the 10 mL scale line.

[0049] (3) Magnesium hardness test Add 1 drop of the first liquid masking agent component to the first cuvette, shake well and dissolve it as a blank sample for magnesium ion test. Add 1 drop of the second liquid masking agent component to the second cuvette, shake well and dissolve it as a sample for magnesium ion test. Take the blank sample of magnesium ion test and put it into the spectrophotometer for background calibration, then take the sample to be tested of magnesium ion test and put it into the spectrophotometer analyzer to read the absorbance value. The measured absorbance value is calculated using the regression equation of the magnesium hardness-absorbance standard curve to obtain the magnesium hardness of the water quality to be tested, and the results are shown in Table 4.

[0050] (4) Calcium hardness test The second cuvette in the magnesium hardness test of step (3) is used as the blank sample for the calcium ion test, and the third cuvette is used as the sample to be tested for the calcium ion test. The blank sample for the calcium ion test is placed in the spectrophotometer for background calibration, and then the sample to be tested for the calcium ion test is placed in the spectrophotometer analyzer for reading the absorbance value. The measured absorbance value is calculated using the regression equation of the calcium hardness-absorbance standard curve to obtain the calcium hardness of the water quality to be tested, and the results are shown in Table 4. (5) Total hardness test The total hardness value of water quality is equal to the calcium hardness value plus the magnesium hardness value, and the results are shown in Table 4.

[0051] Table 4 Test results of calcium hardness, magnesium hardness and total hardness in the tested water

[0052] Among them, the last column of data in Table 4 is the data of a certain industrial boiler using the conventional EDTA titration method. The results are obtained by testing the calcium hardness, magnesium hardness and total hardness of water and an industrial circulating cooling water.

[0053] It can be seen from the results in Table 4 that the detection reagent and detection method of the present invention can obtain calcium hardness, magnesium hardness and total hardness at one time using only a spectrophotometer. The detection reagent has good test parallelism, the relative standard deviation of 5 test results is less than 5%, the test accuracy is high, the recovery rate is between 95% and 101%, and compared with the traditional EDTA titration method, the test is more sensitive and reliable.

[0054] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit the scope of protection of the present invention. Although the present invention is described in detail with reference to the preferred embodiments, it is not limited to those listed in the embodiments. Those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the essence and scope of the technical solution of the present invention.

Claims

1. A water quality calcium hardness, magnesium hardness, and total hardness detection reagent, characterized in that: The invention comprises a liquid color-developing component, a liquid buffer component, a first liquid masking agent component and a second liquid masking agent component, wherein the liquid color-developing component comprises a color-developing agent capable of undergoing a color-developing reaction with both calcium ions and magnesium ions, the liquid buffer component adjusts the pH value of the color-developing reaction to be greater than 12, the first liquid masking agent component is used for masking calcium ions and magnesium ions in water, and the second liquid masking agent component is used for masking calcium ions in water.

2. The water quality calcium hardness, magnesium hardness, and total hardness detection reagent according to claim 1, characterized in that: The liquid color developing component is an aqueous solution comprising a color developer, a sensitizer and a first stabilizer.

3. The water quality calcium hardness, magnesium hardness, and total hardness detection reagent according to claim 2, characterized in that: The concentration of the developer is 0.5-5.0 g / L, and the developer comprises one or more of calcium magnesium reagent, chrome black T, acid chrome blue K and chlorophosphonazo III.

4. The water quality calcium hardness, magnesium hardness, and total hardness detection reagent according to claim 2, characterized in that: The concentration of the sensitizer is 20-60 g / L, and the sensitizer is a nonionic surfactant.

5. The water quality calcium hardness, magnesium hardness, and total hardness detection reagent according to claim 2, characterized in that: The concentration of the first stabilizer is 10-50 g / L, and the first stabilizer comprises one or more of benzoic acid, p-nitrobenzoic acid and benzenesulfonic acid.

6. The water quality calcium hardness, magnesium hardness, and total hardness detection reagent according to claim 1, characterized in that: The liquid buffer component is an aqueous solution containing an alkaline compound, the alkaline compound is sodium hydroxide and / or triethanolamine, and the concentration of the alkaline compound is 300-600 g / L.

7. The water quality calcium hardness, magnesium hardness, and total hardness detection reagent according to claim 1, characterized in that: The first liquid masking agent component is an aqueous solution containing disodium ethylenediaminetetraacetate and a second stabilizer, the concentration of the disodium ethylenediaminetetraacetate is 0.5-2.0 mol / L, and the concentration of the second stabilizer is 0.05-0.50 mol / L.

8. The water quality calcium hardness, magnesium hardness, and total hardness detection reagent according to claim 7, characterized in that: The second stabilizer comprises formaldehyde and / or methanol.

9. The water quality calcium hardness, magnesium hardness, and total hardness detection reagent according to claim 1, characterized in that: The second liquid masking agent component is an aqueous solution comprising ethylene glycol bis(2-aminoethyl ether)tetraacetic acid and sodium hydroxide, the concentration of the ethylene glycol bis(2-aminoethyl ether)tetraacetic acid is 0.05-0.50 mol / L, and the concentration of the sodium hydroxide is 20-100 g / L.

10. A method for detecting water hardness using the water calcium hardness, magnesium hardness, and total hardness detection reagents according to any one of claims 1 to 9, characterized in that: Contains steps: (1) Preparation of standard curve Prepare magnesium hardness-absorbance standard curve and calcium hardness-absorbance standard curve; (2) Color rendering Take water and add the liquid color developing component to mix, then add the liquid buffer component to mix, and then pour into three cuvettes respectively as samples to be tested; (3) Magnesium hardness test Add the first liquid masking agent component to the first cuvette, shake well and dissolve, and use it as a blank sample for magnesium ion test; add the second liquid masking agent component to the second cuvette, shake well and dissolve, and use it as a sample for magnesium ion test; take the blank sample for magnesium ion test and put it into a spectrophotometer for background calibration; then take the sample for magnesium ion test and put it into a spectrophotometer analyzer for reading the absorbance value; and use the magnesium hardness-absorbance standard curve to obtain magnesium hardness; (4) Calcium hardness test The second cuvette is used as a blank sample for calcium ion test, and the third cuvette is used as a sample to be tested for calcium ion test. The blank sample for calcium ion test is placed in a spectrophotometer for background calibration, and then the sample to be tested for calcium ion test is placed in a spectrophotometer analyzer for reading the absorbance value, and the calcium hardness is obtained using the calcium hardness-absorbance standard curve; (5) Total hardness test The total hardness value is equal to the calcium hardness value plus the magnesium hardness value.

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