Detection reagent for fluoride ion online monitoring instrument and preparation method thereof

Abstract

This invention provides a detection reagent for an online fluoride ion monitoring instrument and its preparation method. The detection reagent includes reagent A and reagent B. Reagent A is an aqueous solution containing alizarin aminocarboxylic acid complexing agent and sodium acetate, and reagent B is an aqueous solution containing lanthanum nitrate, glacial acetic acid, and Triton. Reagent A, by adding sodium acetate, makes the aqueous solution weakly alkaline, allowing the powdered alizarin aminocarboxylic acid complexing agent, which is difficult to dissolve directly in neutral distilled water, to dissolve rapidly. In reagent B, Triton is added as an adjuvant to promote the complete dissolution of the alizarin aminocarboxylic acid complexing agent and the chromogenic substance, preventing solution turbidity and increasing solution clarity. Furthermore, the preparation of the detection reagent does not require attention to pH value, and it has the advantages of simple preparation, stable color development, and easy cleaning.

Description

Technical Field

[0001] This invention belongs to the field of detection reagent technology, specifically relating to a detection reagent for an online fluoride ion monitoring instrument and its preparation method. Background Art

[0002] The existing fluoride reagent method for testing fluoride ions requires highly skilled personnel to prepare the reagents, and strict control of the pH value of the reagents and the ratio of the reagents to the water sample is necessary to ensure the consistency of the experimental results.

[0003] When testing fluoride ions using laboratory methods, the pH value of the test reagents can be monitored at any time using a pH meter or test strips. The pH value is then adjusted by adding a refluxing solution based on the results to ensure consistency of the experimental results. Online fluoride ion monitoring instruments ensure the accuracy of water sample test results by repeating pre-set steps. However, when operating online monitoring instruments, because the pre-set steps (e.g., adding 2 mL of water sample, then adding reagent 1, reagent 2, and reagent 3 sequentially, mixing, and waiting for colorimetric detection) are followed, it is impossible to monitor and adjust the pH value in real time. If the test reagents rely on pH control to ensure consistency, there will be a technical problem where the consistency of experimental results is difficult to guarantee. Summary of the Invention

[0004] The purpose of this invention is to improve a detection reagent that does not require pH adjustment and can ensure the accuracy of detection results in online fluoride ion monitoring instruments, thereby solving the technical problem that existing detection reagents rely on strict pH control to ensure accurate detection results.

[0005] To achieve the above objectives, the present invention provides a detection reagent for an online fluoride ion monitoring instrument, comprising reagent A and reagent B, wherein reagent A is an aqueous solution comprising alizarin aminocarboxylic acid complexing agent and sodium acetate, and reagent B is an aqueous solution comprising lanthanum nitrate, glacial acetic acid, and Triton.

[0006] In one specific embodiment, each 1000 ml of reagent A comprises 0.06–0.15 g of alizarin aminocarboxylic acid complexing agent and 5.0–15.0 g of anhydrous sodium acetate; each 1000 ml of reagent B comprises 0.05–0.2 g of lanthanum nitrate, 20–50 mL of glacial acetic acid, and 0.1–0.5 mL of Triton.

[0007] In one specific embodiment, each 1000 ml of reagent A comprises 0.08–0.13 g of alizarin aminocarboxylic acid complexing agent and 6.0–12.0 g of anhydrous sodium acetate; each 1000 ml of reagent B comprises 0.07–0.15 g of lanthanum nitrate, 25–45 mL of glacial acetic acid, and 0.1–0.3 mL of Triton.

[0008] In one specific embodiment, each 1000 ml of reagent A comprises 0.1 g alizarin aminocarboxylic acid complexing agent and 8.2 g anhydrous sodium acetate; each 1000 ml of reagent B comprises 0.1 g lanthanum nitrate, 30 mL glacial acetic acid, and 0.2 mL Triton.

[0009] In one specific embodiment, reagent B further includes anhydrous ethanol, and each 1000 mL of reagent B includes 20 to 100 mL of anhydrous ethanol.

[0010] In one specific embodiment, each 1000 mL of reagent B includes 30 mL of anhydrous ethanol.

[0011] In one specific embodiment, the detection reagent is prepared using the following method:

[0012] (1) Take alizarin aminocarboxylic acid complexing agent and anhydrous sodium acetate respectively, add them to water, mix them evenly, and make up to volume to obtain reagent A;

[0013] (2) Dissolve lanthanum nitrate in water to obtain lanthanum nitrate solution. Then add glacial acetic acid, Triton and anhydrous ethanol to the lanthanum nitrate solution, mix well and make up to volume to obtain reagent B.

[0014] This invention provides a method for preparing detection reagents for an online fluoride ion monitoring instrument, comprising the following steps:

[0015] (1) Take 0.06-0.15g of alizarin aminocarboxylic acid complexing agent and 5.0-15.0g of anhydrous sodium acetate respectively, add them to distilled water, mix them evenly, and make up to 1000ml of reagent A;

[0016] (2) Dissolve 0.05-0.2g of lanthanum nitrate in distilled water to obtain a lanthanum nitrate solution. Then add 20-50mL of glacial acetic acid and 0.1-0.5mL of Triton to the lanthanum nitrate solution and mix well. Make up to 1000mL of reagent B.

[0017] In one specific embodiment, step (2) further includes adding 20 to 100 mL of anhydrous ethanol to the lanthanum nitrate solution.

[0018] The present invention also provides a detection reagent for an online fluoride ion monitoring instrument, which is prepared by the detection reagent preparation method described above.

[0019] The beneficial effects of the present invention include at least the following:

[0020] The detection reagents for an online fluoride ion monitoring instrument provided in this invention include reagent A and reagent B. Reagent A is an aqueous solution containing alizarin aminocarboxylic acid complexing agent and sodium acetate, and reagent B is an aqueous solution containing lanthanum nitrate, glacial acetic acid, and Triton. The addition of sodium acetate makes the aqueous solution of reagent A weakly alkaline, allowing the powdered alizarin aminocarboxylic acid complexing agent, which is difficult to dissolve directly in neutral distilled water, to dissolve rapidly. In reagent B, the addition of Triton as an adjuvant promotes the complete dissolution of the alizarin aminocarboxylic acid complexing agent and the colorimetric substance (the reaction product of fluoride ions with the alizarin aminocarboxylic acid complexing agent and lanthanum nitrate), preventing turbidity and adhesion to the test tube, and increasing the clarity of the solution.

[0021] 2. Reagent B also includes anhydrous ethanol. The addition of a small amount of anhydrous ethanol is used to suppress the bubbles generated after adding Triton.

[0022] Third, since lanthanum nitrate can affect the color development, the amount of lanthanum nitrate used needs to be controlled within the range specified in this application. If the amount of lanthanum nitrate is too low, the reaction will be incomplete, while if the amount of lanthanum nitrate is too high, it will affect the color development and thus affect the accuracy of the results.

[0023] Fourth, the test standard solution and water sample using the detection reagent for the online fluoride ion monitoring instrument provided by this invention have an error of less than 10%, which meets the 10% requirement of the online monitoring instrument. Moreover, the preparation of the detection reagent does not require attention to the pH value. It has the advantages of simple preparation, stable color development, and easy cleaning (the colorimetric substance is completely soluble in water and will not deposit on the test tube). Detailed Implementation

[0024] The present invention will be described in detail below with reference to embodiments, but the present invention may be implemented in many different ways as limited and covered by the claims.

[0025] It should be noted that: Triton X-100 in this invention is composed of polyoxyethylene-8-octylphenyl ether, also known as polyethylene glycol p-isooctylphenyl ether; alizarin aminocarboxylic acid complexing agent, molecular formula C 19 H 19 NO 10 Alternative Chinese names: Alizarin complexation indicator, CAS No. 3952-78-1; Fluoride ion standard solution 100mg / L, CAS No. 109-63-7.

[0026] Alizarin aminocarboxylic acid complexing agent is referred to as fluorine reagent in the examples.

[0027] A light intensity signal can be understood as a voltage signal or voltage value, and the logarithm of the light intensity signal corresponds to the light intensity value / absorbance.

[0028] Example 1: Preparation of test reagents

[0029] Reagent A: Accurately weigh 0.1g of fluorine reagent (alizarin aminocarboxyl complexing agent) and 8.2g of anhydrous sodium acetate into a beaker, add distilled water, and bring the volume to 1000mL;

[0030] Reagent B: Accurately weigh 0.1g of lanthanum nitrate into a 500mL beaker, add distilled water to dissolve it to obtain a lanthanum nitrate solution. Then, use pipettes with different graduations to transfer 30mL of glacial acetic acid, 0.2mL of Triton, and 30mL of anhydrous ethanol into the beaker respectively, mix the glacial acetic acid, Triton, anhydrous ethanol and lanthanum nitrate solution, and then add distilled water to make up to 1000mL.

[0031] Prepare reagents A and B separately.

[0032] Example 2: Online monitoring instrument testing standard solution

[0033] Preparation of standard substances: 100 mg / L of commercially purchased fluoride ion standard solution was diluted with distilled water to obtain five standard solutions with fluoride ion concentrations of 0.2 mg / L, 0.4 mg / L, 0.6 mg / L, 1 mg / L, and 2 mg / L, respectively. The volume of each of the five standard solutions was 1 L.

[0034] A. Blank calibration:

[0035] (1) Clean the test tank with distilled water;

[0036] (2) Add 2 mL of distilled water to the detection cell;

[0037] (3) Add 0.5 mL of reagent A to the detection cell;

[0038] (4) Add 0.5 mL of reagent B to the detection cell, mix well and wait for 300 seconds;

[0039] (5) Turn on the 620nm light source and record the light intensity signal A0 of the detection cell at this time.

[0040] B. Standard solution calibration

[0041] (1) Clean the test tank with distilled water;

[0042] (2) Add 2 mL of fluoride ion standard solution with a concentration of 2 mg / L to the detection cell;

[0043] (3) Add 0.5 mL of reagent A to the detection cell;

[0044] (4) Add 0.5 mL of reagent B to the detection cell, mix well and wait for 300 seconds;

[0045] (5) Turn on the 620nm light source and record the light intensity signal A1 of the detection cell at this time.

[0046] C. Standard solution test

[0047] (1) Clean the test tank with distilled water;

[0048] (2) Add 2 mL of water sample to the detection cell;

[0049] (3) Add 0.5 mL of reagent 1 to the detection cell;

[0050] (4) Add 0.5 mL of reagent 2 to the detection cell, mix well and wait for 300 seconds;

[0051] (5) Turn on the 620nm light source and record the light intensity signal A-bxx in the detection cell at this time.

[0052] In step (2), the 2 mL water samples added were fluoride ion standard solutions with concentrations of 0.2 mg / L, 0.4 mg / L, 0.6 mg / L, and 1 mg / L, respectively.

[0053] It should be noted that the standard solutions of different concentrations were tested separately, and each standard was tested 6 times. The light intensity signal corresponding to the 0.2 mg / L standard solution is A-b1x, the light intensity signal corresponding to the 0.4 mg / L standard solution is A-b2x, the light intensity signal corresponding to the 0.6 mg / L standard solution is A-b3x, and the light intensity signal corresponding to the 1.0 mg / L standard solution is A-b4x.

[0054] D. Calculation

[0055] The instrument calculations utilize the Lambert-Beer law. Two points are obtained from blank calibration and standard solution calibration: (0, lg(A0)) and (2, lg(A1)). From these two points, a straight line y = kx + b can be derived. The values ​​of k and b can be calculated by substituting these two points. When testing the water sample, the light intensity A - bxx is converted to absorbance lg(A - bxx), thus yielding the fluoride ion concentration x in the water sample. The calculation results are shown in Table 1.

[0056] Table 1. Results of online instrument testing for different standard solutions

[0057]

[0058] The data in the table above shows that the error of the online equipment in testing standard solutions of different concentrations is within 5%, which meets the 10% accuracy requirement of online monitoring instruments.

[0059] Example 3: Online monitoring instruments test water quality at different times in a chemical plant.

[0060] Example 3 is basically the same as Example 2, except that the online monitoring instrument in Example 3 tests the water quality of the chemical plant at different times, with 6 samples taken and 1 test per sample; while the online monitoring instrument in Example 2 tests the standard solution and performs 6 tests.

[0061] Table 2 shows the water quality test results of the chemical plant at different time periods. The test numbers in Table 2 are the sample numbers collected at different time periods.

[0062] Table 2 Comparison of online monitoring test results with laboratory test results

[0063] Test serial number 1 2 3 4 5 6 Online monitoring data 0.182 0.133 0.172 0.093 0.142 0.166 Laboratory test data 0.18 0.136 0.17 0.1 0.144 0.161

[0064] The data in the table above shows that the error of the online monitoring instrument in testing water samples at different time periods is within 7%, which meets the 10% accuracy requirement of the online monitoring instrument.

[0065] Comparative Example 1

[0066] Preparation of test reagents:

[0067] Reagent A: Accurately weigh 0.1g of fluorine reagent (alizarin aminocarboxyl complexing agent) and 8.2g of anhydrous sodium acetate into a beaker, add distilled water, and bring the volume to 1000mL;

[0068] Reagent Bd: Accurately weigh 0.1g of lanthanum nitrate into a 500mL beaker, add distilled water to dissolve it to obtain a lanthanum nitrate solution, then use pipettes with different graduations to transfer 30mL of glacial acetic acid and 30mL of anhydrous ethanol into the beaker respectively, mix the glacial acetic acid, anhydrous ethanol and lanthanum nitrate solution, then add distilled water to make up to 1000mL.

[0069] Prepare reagents A and Bd for later use.

[0070] The difference from Example 1 is that Triton was not added to reagent B.

[0071] The standard solution was tested using an online monitoring instrument following the steps in Example 2. The test results are shown in Table 3.

[0072] Table 3 Results of different standard solutions for the Triton test without the addition of Triton test reagents

[0073]

[0074]

[0075] Without adding Triton, the reaction solution contained a small amount of suspended matter, which may be due to the partial leaching of fluorine reagent under acidic conditions.

[0076] The reason why the instrument test results gradually increase with the number of tests is that the precipitated suspended matter adheres to the detection cell and cannot be cleaned by distilled water, which leads to a gradual decrease in absorbance and an increasingly larger test result.

[0077] The above description, in conjunction with specific preferred embodiments, provides a further detailed explanation of the present invention. It should not be construed that the specific implementation of the present invention is limited to these descriptions. For those skilled in the art, various simple deductions and substitutions can be made without departing from the concept of the present invention, and all such modifications and substitutions should be considered within the scope of protection of the present invention.

Claims

1. A detection reagent for use in an online fluoride ion monitoring instrument, characterized in that, The reagent comprises reagent A and reagent B, wherein reagent A is an aqueous solution containing alizarin aminocarboxylic acid complexing agent and sodium acetate, and reagent B is an aqueous solution containing lanthanum nitrate, glacial acetic acid, and Triton. Each 1000 mL of reagent A contains 0.06–0.15 g of alizarin aminocarboxylic acid complexing agent and 5.0–15.0 g of anhydrous sodium acetate; each 1000 mL of reagent B contains 0.05–0.2 g of lanthanum nitrate, 20–50 mL of glacial acetic acid, 0.1–0.5 mL of Triton, and 20–100 mL of anhydrous ethanol.

2. The detection reagent for an online fluoride ion monitoring instrument according to claim 1, characterized in that, Each 1000 ml of reagent A comprises 0.08–0.13 g of alizarin aminocarboxylic acid complexing agent and 6.0–12.0 g of anhydrous sodium acetate; each 1000 ml of reagent B comprises 0.07–0.15 g of lanthanum nitrate, 25–45 mL of glacial acetic acid, and 0.1–0.3 mL of Triton.

3. The detection reagent for an online fluoride ion monitoring instrument according to claim 2, characterized in that, Each 1000 ml of reagent A comprises 0.1 g alizarin aminocarboxylic acid complexing agent and 8.2 g anhydrous sodium acetate; each 1000 ml of reagent B comprises 0.1 g lanthanum nitrate, 30 mL glacial acetic acid, and 0.2 mL Triton.

4. The detection reagent for an online fluoride ion monitoring instrument according to claim 3, characterized in that, Each 1000 mL of reagent B contains 30 mL of anhydrous ethanol.

5. The detection reagent for an online fluoride ion monitoring instrument according to claim 4, characterized in that, The detection reagent is prepared using the following method: (1) Take alizarin aminocarboxylic acid complexing agent and anhydrous sodium acetate respectively, add them to water, mix them evenly, and make up to volume to obtain reagent A; (2) Dissolve lanthanum nitrate in water to obtain lanthanum nitrate solution. Then add glacial acetic acid, Triton and anhydrous ethanol to the lanthanum nitrate solution, mix well and make up to volume to obtain reagent B.

6. A method for preparing a detection reagent for an online fluoride ion monitoring instrument, characterized in that: The following steps are involved: (1) Take 0.06-0.15g of alizarin aminocarboxylic acid complexing agent and 5.0-15.0g of anhydrous sodium acetate respectively, add them to distilled water, mix them evenly, and make up to 1000ml of reagent A; (2) Dissolve 0.05-0.2g of lanthanum nitrate in distilled water to obtain a lanthanum nitrate solution. Then add 20-50mL of glacial acetic acid, 0.1-0.5mL of Triton and 20-100mL of anhydrous ethanol to the lanthanum nitrate solution, mix well, and make up to 1000mL of reagent B.

7. A detection reagent for an online fluoride ion monitoring instrument, characterized in that, It is prepared using the test reagent preparation method described in claim 6.

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