Total chlorine detection reagent and preparation method thereof

Abstract

The invention relates to the technical field of water quality analytical chemical detection, and provides a total chlorine detection reagent and a preparation method thereof, the total chlorine detection reagent is composed of the following three agents: a first agent potassium iodide solution, a second agent DPD color developing agent solution, and a third agent composite buffer stabilizer solution; the first medicament potassium iodide solution is prepared from the following raw materials in percentage by weight: 0.15 to 0.25 percent of potassium iodide and the balance of water; the second medicament DPD color developing agent solution is prepared from the following raw materials in percentage by weight: 0.10 percent to 0.20 percent of N, N-diethyl p-phenylenediamine, 0.40 percent to 0.60 percent of sulfuric acid and the balance of water; in terms of 100 wt%, the third medicament composite buffer stabilizer solution comprises the following raw materials: 6.30%-7.70% of a phosphate buffer agent, 0.40%-0.70% of a composite stabilizer and the balance of water. The total chlorine detection reagent provided by the invention has the characteristics of simple manual operation, reagent saving, strong anti-interference capability and good stability.

Description

Technical Field

[0001] The present invention relates to the technical field of water quality analysis and chemical detection, in particular to a total chlorine detection reagent and a preparation method thereof. Background Art

[0002] Chlorine is a chemical substance widely used in water treatment, disinfection, industrial production and other fields. Total chlorine refers to the sum of free chlorine and combined chlorine in water samples. Its detection is of great significance for evaluating water quality, ensuring drinking water safety, monitoring sewage treatment effects and disinfection effects in industrial production processes. For example, in drinking water, accurate determination of the total chlorine content can ensure disinfection effectiveness while avoiding harm to human health and the environment caused by excessive chlorine.

[0003] In the existing technology, the detection methods of total chlorine mainly include chemical method, spectrophotometry, electrochemistry, etc. Among them, the more commonly used is N,N-diethyl-1,4-phenylenediamine (DPD) spectrophotometry. The principle of measuring total chlorine is: under the condition of pH 6.2-6.5, in the presence of excess potassium iodide, elemental chlorine reacts with DPD to form a red compound. The absorbance of the red compound is measured by spectrophotometry at a wavelength of 515nm to determine the total chlorine.

[0004] With stricter environmental regulations and increasing demands for industrial water safety, water quality monitoring is shifting from offline laboratory testing to high-precision, low-latency online monitoring. Traditional N,N-diethyl-1,4-phenylenediamine (DPD) spectrophotometry is limited by complex manual operation, reagent failure, high maintenance costs, insufficient anti-interference capabilities, and insufficient long-term stability.

[0005] Patent CN 109612951 A discloses a detector for detecting residual chlorine / total chlorine content in water, as well as its preparation method and detection method. The total chlorine detector includes reagent A and reagent C. Reagent A is an indicator composed of a mixture containing 1.1g / L anhydrous DPD sulfate and 2g / L disodium EDTA, and reagent C is a total chlorine buffer solution containing 10% potassium iodide. The detector disclosed in this application can solve the problem that the DPD color developer cannot be stored for a long time at room temperature. However, it does not solve the problems of traditional N,N-diethyl-1,4-phenylenediamine (DPD) spectrophotometry, such as complex manual operation, easy reagent failure, high maintenance cost, and insufficient anti-interference ability.

[0006] Therefore, there is an urgent need on the market for a total chlorine detection reagent that can solve the problems of complex manual operation, high reagent consumption, weak anti-interference ability and insufficient long-term stability in the existing technology, and realize the efficiency, low cost and high reliability of online total chlorine detection. Summary of the Invention

[0007] In response to the problems existing in the prior art, the present invention uses three reagents to form a total chlorine detection reagent. The three reagents can be added in a "one-click" manner, reducing manual intervention steps, significantly reducing operation complexity and human errors, and through the coordination of the three reagents, the anti-interference ability and stability of the total chlorine detection reagent are enhanced. Modified polyethylene glycol is designed to be added to the composite stabilizer of the third reagent, the composite buffer stabilizer solution, to further prevent the reagent from crystallizing, thereby improving the stability of the reagent.

[0008] In order to achieve the above object, the technical solution adopted by the present invention is as follows:

[0009] In one aspect, the present invention provides a total chlorine detection reagent, which is composed of the following three reagents: a first reagent, a potassium iodide solution, a second reagent, a DPD color developer solution, and a third reagent, a composite buffer stabilizer solution;

[0010] The first agent potassium iodide solution comprises the following raw materials based on 100 wt %: 0.15% to 0.25% potassium iodide, and the balance is water;

[0011] The second reagent DPD developer solution comprises the following raw materials based on 100 wt %: 0.10%-0.20% N,N-diethyl-p-phenylenediamine, 0.40%-0.60% sulfuric acid, and the balance water;

[0012] Based on 100 wt%, the third agent composite buffer stabilizer solution includes the following raw materials: 6.30%-7.70% of phosphate buffer, 0.40%-0.70% of composite stabilizer, and the balance is water.

[0013] In some embodiments of the present invention, the volume ratio of the first agent potassium iodide solution, the second agent DPD color developer solution and the third agent composite buffer stabilizer solution is 1: (0.9-1.2): (1.05-1.4).

[0014] Preferably, the volume ratio of the first agent potassium iodide solution, the second agent DPD color developer solution and the third agent composite buffer stabilizer solution is 1:1.067:1.2.

[0015] The applicant added an appropriate amount of sulfuric acid to the second reagent DPD color developer solution and adjusted the pH of the reaction system to 6.2-6.5 to ensure the optimal conditions for the color development reaction and inhibit DPD self-oxidation.

[0016] In some embodiments of the present invention, the phosphate buffer comprises 3.80%-4.50% potassium dihydrogen phosphate and 2.50%-3.20% disodium hydrogen phosphate.

[0017] In some embodiments of the present invention, based on 100 wt %, the third agent composite buffer stabilizer solution further comprises 0.15%-0.25% sodium pyrophosphate.

[0018] The applicant added a phosphate buffer composed of potassium dihydrogen phosphate and disodium hydrogen phosphate in a specific ratio to the third agent composite buffer stabilizer solution to maintain the pH of the reaction system at 6.2-6.5, ensuring that the color development reaction is carried out under the optimal acid-base environment; further, the applicant added a small amount of sodium pyrophosphate to chelate the interfering metal ions (such as Fe 3 +、Cu 2 +), eliminating the interference of manganese oxide and hexavalent chromium, so that the total chlorine detection reagent has good anti-interference ability.

[0019] In some embodiments of the present invention, the composite stabilizer is a mixture of glycerol, propylene glycol and modified polyethylene glycol.

[0020] In some embodiments of the present invention, the mass ratio of glycerol, propylene glycol and modified polyethylene glycol in the composite stabilizer is 1:(0.5-0.8):(0.3-0.6).

[0021] Preferably, the mass ratio of glycerol, propylene glycol and modified polyethylene glycol in the composite stabilizer is 1:0.6:0.5.

[0022] In some embodiments of the present invention, the method for preparing the modified polyethylene glycol comprises the following steps:

[0023] (1) Add polyethylene glycol to deionized water, stir, add p-aminobenzoic acid, stir, filter, and freeze-dry to obtain product 1 for later use;

[0024] (2) adding chitosan to an acetic acid aqueous solution, stirring, ultrasonicating, and standing to obtain a solution for later use;

[0025] (3) adding the product 1 of step (1) to deionized water, stirring, adding the solution of step (2), stirring, adding glutaraldehyde, shaking, standing, filtering and freeze-drying to obtain product 2 for use;

[0026] (4) The product 2 of step (3) is mixed with sodium citrate and ball-milled to obtain modified polyethylene glycol.

[0027] Wherein, the polyethylene glycol is PEG 400 or PEG 600;

[0028] In the step (1), the mass ratio of polyethylene glycol to p-aminobenzoic acid is 1:(1.5-2.2).

[0029] In some embodiments of the present invention, the mass ratio of the product 1 to chitosan is 1:(0.15-0.3).

[0030] Preferably, the mass ratio of the product 1 to chitosan is 1:0.25.

[0031] In some embodiments of the present invention, in step (4), the mass ratio of product 2 to sodium citrate is 1:(0.2-0.4).

[0032] Preferably, in step (4), the mass ratio of product 2 to sodium citrate is 1:0.3.

[0033] Both glycerol and propylene glycol are hygroscopic, which can maintain the humidity of the reagent and provide a relatively stable environment for the reagent, thereby reducing the risk of reagent crystallization. However, the anti-crystallization effect of the two still needs to be improved, and they need to be used in combination with other substances to enhance the overall stability of the reagent. Among them, polyethylene glycol, as a high molecular polymer, has good moisturizing and solubility. When combined with glycerol and propylene glycol, it can further prevent the crystallization of the reagent.

[0034] Although polyethylene glycol has a good ability to prevent reagent crystallization, it still has certain limitations in terms of stability. Moreover, due to its high moisture retention properties, it may also provide a more suitable growth environment for microorganisms. These problems will affect the overall stability of the reagent and cause the reagent to crystallize. The applicant first selected polyethylene glycol (PEG 400 or PEG 600) of a specific molecular weight, which can maintain a good balance in terms of moisture retention and viscosity, so that the reagent has better anti-crystallization properties; further, the applicant modified the hydroxyl group at the end of the polyethylene glycol to an amino group, and then introduced chitosan to modify it. The introduction of the cross-linked structure effectively improved the stability of the polyethylene glycol, and chitosan has natural antibacterial properties, which can inhibit the growth of microorganisms in the reagent, making the reagent more stable; further, the applicant introduced sodium citrate to compound with the above product to obtain modified polyethylene glycol. The introduction of sodium citrate can increase the hydrophilicity of the modified polyethylene glycol and improve the stability of the composite stabilizer in the reagent. Sodium citrate can chelate metal ions in the reagent to prevent metal ions from catalyzing solute crystallization. In addition, there is a certain physical adsorption and electrostatic interaction between sodium citrate and the above product, which further enhances the stability of the composite stabilizer.

[0035] Another aspect of the present invention further provides a method for preparing the total chlorine detection reagent described in the above technical solution, comprising the following steps:

[0036] S1. Preparation of a first agent potassium iodide solution: Mix potassium iodide and water and stir to obtain a first agent potassium iodide solution;

[0037] S2. Preparation of a second reagent DPD color developer solution: N,N-diethyl-p-phenylenediamine, sulfuric acid, and water are mixed and stirred to obtain a second reagent DPD color developer solution;

[0038] S3. Preparation of a third compound buffer stabilizer: mixing a phosphate buffer, sodium pyrophosphate, a compound stabilizer, and water, and stirring to obtain a third compound buffer stabilizer;

[0039] The first agent, potassium iodide solution, the second agent, DPD color developer solution, and the third agent, composite buffer stabilizer, are packaged separately. When in use, the three agents are added to the colorimetric chamber respectively for testing.

[0040] Compared with the prior art, the present invention has the following beneficial effects:

[0041] (1) The present invention comprises three reagents to form a total chlorine detection reagent, which can be added in a "one-button" manner, thereby reducing manual intervention steps, significantly reducing operation complexity and human errors, and enhancing the anti-interference ability and stability of the total chlorine detection reagent through the coordination of the three reagents. Modified polyethylene glycol is designed to be added to the composite stabilizer of the composite buffer stabilizer solution of the third reagent, which can further prevent the crystallization of the reagent, thereby improving the stability of the reagent.

[0042] (2) The present invention adds a composite stabilizer to the third agent composite buffer stabilizer solution, which is composed of glycerol, propylene glycol and modified polyethylene glycol in a certain proportion, wherein the modified polyethylene glycol is modified by amino and chitosan and composited with sodium citrate, which can make the composite stabilizer have better stability, moisture retention and dispersibility, thereby effectively preventing the crystallization of the reagent and prolonging the stability of the total chlorine detection reagent.

[0043] (3) The total chlorine detection reagent prepared by the present invention has the characteristics of simple manual operation, reagent saving, strong anti-interference ability and good stability, can be widely used in the field of water quality analysis and chemical detection technology, and has good commercial application value. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] In order to make the content of the present invention more clearly understood, the present invention is further described in detail below based on specific embodiments of the present invention in conjunction with the accompanying drawings, wherein:

[0045] Figure 1 This is a schematic diagram of the colorimetric chamber for total chlorine determination;

[0046] Figure numerals: 1, water sample inlet; 2, first dosing port; 3, second dosing port; 4, third dosing port; 5, 515nm detection light source; 6, light intensity sensor. DETAILED DESCRIPTION

[0047] The present invention will be described below in conjunction with specific embodiments. It should be noted that the following examples are illustrative of the present invention and are intended only to illustrate the present invention and are not intended to limit the present invention. Other combinations and various modifications within the scope of the present invention may be made without departing from the spirit or scope of the present invention.

[0048] In the following examples and comparative examples, except for modified polyethylene glycol, the other compound monomers and related reagents used can be purchased from the market, wherein polyethylene glycol is PEG 400 or PEG 600; chitosan is purchased from Donghao Chemical (Shandong) Co., Ltd.; and sulfuric acid is analytical grade.

[0049] Preparation Example 1

[0050] The preparation method of modified polyethylene glycol A comprises the following steps:

[0051] (1) Add 12 g of PEG 600 to 100 ml of deionized water, stir for 30 min, add 22 g of p-aminobenzoic acid, stir for 1 h, filter, and freeze-dry to obtain product 1 for later use;

[0052] (2) Add 2.5 g of chitosan to 50 ml of 0.5% (v / v) acetic acid aqueous solution, stir for 2 h, sonicate for 30 min, and let stand for 1 h to obtain a solution for use;

[0053] (3) 10 g of the product 1 of step (1) was added to 50 ml of deionized water, stirred for 30 min, the solution of step (2) was added, stirred, 0.8 g of a 50 wt% glutaraldehyde aqueous solution was added, shaken for 30 min, allowed to stand for 6 h, filtered, and freeze-dried to obtain product 2 for later use;

[0054] (4) 10 g of the product 2 from step (3) and 3 g of sodium citrate were mixed and ball-milled for 30 min to obtain modified polyethylene glycol A.

[0055] Preparation Example 2

[0056] The specific implementation method of modified polyethylene glycol B is the same as that of modified polyethylene glycol A, except that the mass of chitosan in step (2) is replaced with 1.2 g.

[0057] Preparation Example 3

[0058] The specific implementation method of modified polyethylene glycol C is the same as that of modified polyethylene glycol A, except that the mass of sodium citrate in step (4) is replaced by 1.5 g.

[0059] Preparation Example 4

[0060] The specific implementation method of modified polyethylene glycol D is the same as that of modified polyethylene glycol A, except that the mass of sodium citrate in step (4) is replaced with 4.5 g.

[0061] Example 1

[0062] A total chlorine detection reagent, the total chlorine detection reagent is composed of the following three reagents: a first reagent is a potassium iodide solution, a second reagent is a DPD color developer solution, and a third reagent is a composite buffer stabilizer solution;

[0063] The first agent potassium iodide solution comprises the following raw materials based on 100 wt %: 0.19% potassium iodide and the balance water;

[0064] The second reagent DPD developer solution includes the following raw materials based on 100 wt %: 0.14% N,N-diethyl-p-phenylenediamine, 0.45% sulfuric acid, and the balance water;

[0065] Based on 100 wt %, the third agent composite buffer stabilizer solution includes the following raw materials: 4.10% potassium dihydrogen phosphate, 2.80% disodium hydrogen phosphate, 0.20% sodium pyrophosphate, 0.50% composite stabilizer, and the balance is water.

[0066] The composite stabilizer is a mixture of glycerol, propylene glycol and modified polyethylene glycol A, with a mass ratio of 1:0.6:0.5.

[0067] The preparation method of the total chlorine detection reagent in this embodiment comprises the following steps:

[0068] S1. Preparation of a first agent potassium iodide solution: Mix potassium iodide and water and stir evenly to obtain a first agent potassium iodide solution;

[0069] S2. Preparation of a second reagent DPD color developer solution: N,N-diethyl-p-phenylenediamine, sulfuric acid, and water are mixed and stirred to obtain a second reagent DPD color developer solution;

[0070] S3. Preparation of the third compound buffer stabilizer: mixing the phosphate buffer, sodium pyrophosphate, compound stabilizer and water, and stirring evenly to obtain the third compound buffer stabilizer;

[0071] The first agent, potassium iodide solution, the second agent, DPD color developer solution, and the third agent, composite buffer stabilizer, are packaged separately. When in use, the three agents are added to the colorimetric chamber respectively for testing.

[0072] The specific method for determining total chlorine is as follows:

[0073] The water sample to be tested in the colorimetric chamber is updated through the automatic detection system sampling control device. A volume of 13 ml of the water sample to be tested is added from the water sample inlet 1. The dosing system controls the simultaneous addition of 75 μL of the first reagent potassium iodide solution from the first dosing port 2, 80 μL of the second reagent DPD colorimetric solution from the second dosing port 3, and 90 μL of the third reagent composite buffer stabilizer solution from the third dosing port 4. After adding the reagents, stir for 1 minute to allow the reagents to fully dissolve and react. Light is emitted from the 515 nm detection light source 5 on the left side of the colorimetric chamber, and the absorbance is measured by the light intensity sensor 6 on the right. The national standard method (HJ 586-2010 replaces GB 11898-89) test result is 0.2 mg / L. (Schematic diagram of the colorimetric chamber for total chlorine determination is shown in the figure below.) Figure 1 shown)

[0074] Measurement results: By comparing the absorbance with the calibration curve, the total chlorine concentration was calculated to be 0.21 mg / L.

[0075] Example 2

[0076] A total chlorine detection reagent, the total chlorine detection reagent is composed of the following three reagents: a first reagent is a potassium iodide solution, a second reagent is a DPD color developer solution, and a third reagent is a composite buffer stabilizer solution;

[0077] The first agent potassium iodide solution comprises the following raw materials based on 100 wt %: 0.15% potassium iodide and the balance water;

[0078] The second reagent DPD developer solution comprises the following raw materials based on 100 wt %: 0.10% N,N-diethyl-p-phenylenediamine, 0.40% sulfuric acid, and the balance water;

[0079] Based on 100 wt%, the third agent composite buffer stabilizer solution includes the following raw materials: 3.80% potassium dihydrogen phosphate, 2.50% disodium hydrogen phosphate, 0.15% sodium pyrophosphate, 0.40% composite stabilizer, and the balance is water.

[0080] The composite stabilizer is a mixture of glycerol, propylene glycol and modified polyethylene glycol A, with a mass ratio of 1:0.5:0.3.

[0081] The preparation method of the total chlorine detection reagent in this embodiment is the same as that in Example 1.

[0082] The specific method for determining total chlorine in this embodiment is the same as that in Example 1, except that the volumes of the first reagent, potassium iodide solution, the second reagent, DPD color developer solution, and the third reagent, composite buffer stabilizer solution, are 75uL, 68uL, and 79uL, respectively.

[0083] Measurement results: By comparing the absorbance with the calibration curve, the total chlorine concentration was calculated to be 0.19 mg / L.

[0084] Example 3

[0085] A total chlorine detection reagent, the total chlorine detection reagent is composed of the following three reagents: a first reagent is a potassium iodide solution, a second reagent is a DPD color developer solution, and a third reagent is a composite buffer stabilizer solution;

[0086] The first agent potassium iodide solution comprises the following raw materials based on 100 wt %: 0.25% potassium iodide and the balance water;

[0087] The second reagent DPD developer solution comprises the following raw materials based on 100 wt %: 0.20% N,N-diethyl-p-phenylenediamine, 0.60% sulfuric acid, and the balance water;

[0088] Based on 100 wt %, the third agent composite buffer stabilizer solution includes the following raw materials: 4.50% potassium dihydrogen phosphate, 3.20% disodium hydrogen phosphate, 0.25% sodium pyrophosphate, 0.70% composite stabilizer, and the balance is water.

[0089] The composite stabilizer is a mixture of glycerol, propylene glycol and modified polyethylene glycol A, with a mass ratio of 1: (0.5-0.8): (0.3-0.6).

[0090] The preparation method of the total chlorine detection reagent in this embodiment is the same as that in Example 1.

[0091] The specific method for determining total chlorine in this embodiment is the same as that in Example 1, except that the volumes of the first reagent, potassium iodide solution, the second reagent, DPD color developer solution, and the third reagent, composite buffer stabilizer solution, are 75uL, 90uL, and 105uL, respectively.

[0092] Measurement results: By comparing the absorbance with the calibration curve, the total chlorine concentration was calculated to be 0.22 mg / L.

[0093] Example 4

[0094] A total chlorine detection reagent, the total chlorine detection reagent is composed of the following three reagents: a first reagent is a potassium iodide solution, a second reagent is a DPD color developer solution, and a third reagent is a composite buffer stabilizer solution;

[0095] The first agent potassium iodide solution comprises the following raw materials based on 100 wt %: 0.19% potassium iodide and the balance water;

[0096] The second reagent DPD developer solution includes the following raw materials based on 100 wt %: 0.14% N,N-diethyl-p-phenylenediamine, 0.45% sulfuric acid, and the balance water;

[0097] Based on 100 wt %, the third agent composite buffer stabilizer solution includes the following raw materials: 4.10% potassium dihydrogen phosphate, 2.80% disodium hydrogen phosphate, 0.50% composite stabilizer, and the balance is water.

[0098] The composite stabilizer is a mixture of glycerol, propylene glycol and modified polyethylene glycol A, with a mass ratio of 1:0.6:0.5.

[0099] The preparation method of the total chlorine detection reagent in this embodiment comprises the following steps:

[0100] S1. Preparation of a first agent potassium iodide solution: Mix potassium iodide and water and stir evenly to obtain a first agent potassium iodide solution;

[0101] S2. Preparation of a second reagent DPD color developer solution: N,N-diethyl-p-phenylenediamine, sulfuric acid, and water are mixed and stirred to obtain a second reagent DPD color developer solution;

[0102] S3. Preparation of the third compound buffer stabilizer: mixing the phosphate buffer, the compound stabilizer and water, and stirring evenly to obtain the third compound buffer stabilizer;

[0103] The first agent, potassium iodide solution, the second agent, DPD color developer solution, and the third agent, composite buffer stabilizer, are packaged separately. When in use, the three agents are added to the colorimetric chamber respectively for testing.

[0104] The specific method for determining total chlorine in this embodiment is the same as that in Example 1.

[0105] Measurement results: By comparing the absorbance with the calibration curve, the total chlorine concentration was calculated to be 0.17 mg / L.

[0106] Example 5

[0107] This embodiment provides a total chlorine detection reagent and a preparation method thereof. The specific implementation method is the same as that of Example 1, except that the mass ratio of glycerol, propylene glycol and modified polyethylene glycol A in the composite stabilizer is 1:0.6:0.15.

[0108] Measurement results: By comparing the absorbance with the calibration curve, the total chlorine concentration was calculated to be 0.18 mg / L.

[0109] Example 6

[0110] This embodiment provides a total chlorine detection reagent and a preparation method thereof. The specific implementation method is the same as that of Example 1, except that modified polyethylene glycol B is used to replace modified polyethylene glycol A in equal amounts.

[0111] Measurement results: By comparing the absorbance with the calibration curve, the total chlorine concentration was calculated to be 0.22 mg / L.

[0112] Example 7

[0113] This embodiment provides a total chlorine detection reagent and a preparation method thereof. The specific implementation method is the same as that of Example 1, except that modified polyethylene glycol C is used to replace modified polyethylene glycol A in equal amounts.

[0114] Measurement results: By comparing the absorbance with the calibration curve, the total chlorine concentration was calculated to be 0.19 mg / L.

[0115] Example 8

[0116] This embodiment provides a total chlorine detection reagent and a preparation method thereof. The specific implementation method is the same as that of Example 1, except that modified polyethylene glycol D is used to replace modified polyethylene glycol A in equal amounts.

[0117] Measurement results: By comparing the absorbance with the calibration curve, the total chlorine concentration was calculated to be 0.22 mg / L.

[0118] As can be seen from the above data, the test results of the total chlorine detection reagent in Examples 1-3 of the present invention are almost consistent with the national standard method (HJ586-2010 replaces GB 11898-89) test result of 0.2 mg / L, indicating that the water quality total chlorine detection agent is accurate and reliable. Among them, Example 4 is the third agent composite buffer stabilizer solution without adding sodium pyrophosphate, resulting in the deterioration of the anti-interference ability of the detection reagent, which in turn leads to a decrease in the accuracy of the test results; Example 5 changes the addition amount of modified polyethylene glycol A in the composite stabilizer, and Examples 6-8 change the ratio between the main components in the synthesis process of modified polyethylene glycol A. Although it affects the stability of the total chlorine detection reagent, it has little effect on accuracy.

[0119] The stability of the total chlorine detection reagents of Examples 1-8 above was tested, and the test results are shown in Table 1.

[0120] The stability of the total chlorine detection reagent was characterized by testing the stability of the third agent, the composite buffer stabilizer solution, in the total chlorine detection reagent, and observing whether crystallization occurred after storing it at room temperature for 30 days.

[0121] Table 1

[0122] Group Whether it is crystallized Example 1 no Example 2 no Example 3 no Example 4 no Example 5 A small amount of crystallization occurs Example 6 A small amount of crystallization occurs Example 7 A small amount of crystallization occurs Example 8 A small amount of crystallization occurs

[0123] As can be seen from the data in Table 1, the third agent composite buffer stabilizer solutions in Examples 1-4 of the present invention did not crystallize, that is, they had good stability as a whole. Among them, Example 5 changed the amount of modified polyethylene glycol A added in the composite stabilizer, and Examples 6-8 changed the modification ratio of chitosan and sodium citrate to polyethylene glycol during the synthesis of modified polyethylene glycol A, resulting in a decrease in the stability of polyethylene glycol, and a small amount of crystallization was produced after long-term storage.

[0124] The above embodiments are only for illustrating the technical concept and features of the present invention. Its purpose is to enable people familiar with this technology to understand the content of the present invention and implement it. It cannot be used to limit the scope of protection of the present invention. Any equivalent changes or modifications made according to the spirit of the present invention should be included in the scope of protection of the present invention.

Claims

1. A total chlorine detection reagent, characterized in that, The total chlorine detection reagent is composed of the following three reagents: a first reagent, a potassium iodide solution, a second reagent, a DPD color developer solution, and a third reagent, a composite buffer stabilizer solution; The first agent potassium iodide solution comprises the following raw materials based on 100 wt %: 0.15% to 0.25% potassium iodide, and the balance is water; The second reagent DPD developer solution comprises the following raw materials based on 100 wt %: 0.10%-0.20% N,N-diethyl-p-phenylenediamine, 0.40%-0.60% sulfuric acid, and the balance water; Based on 100 wt%, the third agent composite buffer stabilizer solution includes the following raw materials: 6.30%-7.70% of phosphate buffer, 0.40%-0.70% of composite stabilizer, and the balance is water.

2. The total chlorine detection reagent according to claim 1, wherein The volume ratio of the first agent potassium iodide solution, the second agent DPD color developer solution and the third agent composite buffer stabilizer solution is 1: (0.9-1.2): (1.05-1.4).

3. The total chlorine detection reagent according to claim 1, wherein The phosphate buffer comprises 3.80%-4.50% of potassium dihydrogen phosphate and 2.50%-3.20% of disodium hydrogen phosphate.

4. The total chlorine detection reagent according to claim 1, wherein Based on 100 wt%, the third agent composite buffer stabilizer solution further includes 0.15%-0.25% sodium pyrophosphate.

5. The total chlorine detection reagent according to claim 1, wherein The composite stabilizer is a mixture of glycerol, propylene glycol and modified polyethylene glycol.

6. The total chlorine detection reagent according to claim 5, characterized in that The mass ratio of glycerol, propylene glycol and modified polyethylene glycol in the composite stabilizer is 1:(0.5-0.8):(0.3-0.6).

7. The total chlorine detection reagent according to claim 5, characterized in that The preparation method of the modified polyethylene glycol comprises the following steps: (1) Add polyethylene glycol to deionized water, stir, add p-aminobenzoic acid, stir, filter, and freeze-dry to obtain product 1 for later use; (2) adding chitosan to an acetic acid aqueous solution, stirring, ultrasonicating, and standing to obtain a solution for later use; (3) adding the product 1 of step (1) to deionized water, stirring, adding the solution of step (2), stirring, adding glutaraldehyde, shaking, standing, filtering and freeze-drying to obtain product 2 for use; (4) The product 2 of step (3) is mixed with sodium citrate and ball-milled to obtain modified polyethylene glycol.

8. The total chlorine detection reagent according to claim 7, characterized in that, The mass ratio of the product 1 to chitosan is 1:(0.15-0.3).

9. The total chlorine detection reagent according to claim 7, characterized in that In the step (4), the mass ratio of product 2 to sodium citrate is 1:(0.2-0.4).

10. A method for preparing a total chlorine detection reagent according to any one of claims 4 to 9, characterized in that: The following steps are involved: S1. Preparation of a first agent potassium iodide solution: Mix potassium iodide and water and stir to obtain a first agent potassium iodide solution; S2. Preparation of a second reagent DPD color developer solution: N,N-diethyl-p-phenylenediamine, sulfuric acid, and water are mixed and stirred to obtain a second reagent DPD color developer solution; S3. Preparation of a third compound buffer stabilizer: mixing a phosphate buffer, sodium pyrophosphate, a compound stabilizer, and water, and stirring to obtain a third compound buffer stabilizer; The first agent, potassium iodide solution, the second agent, DPD color developer solution, and the third agent, composite buffer stabilizer, are packaged separately. When in use, the three agents are added to the colorimetric chamber respectively for testing.

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