A total chlorine detection reagent and a preparation method thereof

Abstract

The application relates to the technical field of water quality analysis and chemical detection, and provides a total chlorine detection reagent and a preparation method thereof. The total chlorine detection reagent is composed of three kinds of reagents: a first reagent potassium iodide solution, a second reagent DPD chromogenic agent solution and a third reagent composite buffer stabilizer solution. The first reagent potassium iodide solution comprises the following raw materials: 0.15%-0.25% of potassium iodide and the balance of water, with 100wt% as a basis. The second reagent DPD chromogenic agent solution comprises the following raw materials: 0.10%-0.20% of N,N-diethyl-p-phenylenediamine, 0.40%-0.60% of sulfuric acid and the balance of water, with 100wt% as a basis. The third reagent composite buffer stabilizer solution comprises the following raw materials: 6.30%-7.70% of a phosphate buffer, 0.40%-0.70% of a composite stabilizer and the balance of water, with 100wt% as a basis. The total chlorine detection reagent has the characteristics of simple manual operation, reagent saving, strong anti-interference ability and good stability.

Description

Technical Field

[0001] This invention relates to the field of water quality analysis and chemical detection technology, and in particular to a total chlorine detection reagent and its preparation method. Background Technology

[0002] Chlorine is a chemical substance widely used in water treatment, disinfection, and industrial production. Total chlorine refers to the sum of free chlorine and bound chlorine in a water sample. Its detection is of great significance for assessing water quality, ensuring drinking water safety, monitoring the effectiveness of wastewater treatment, and the disinfection effect in industrial production processes. For example, in drinking water, accurate determination of total chlorine content can ensure disinfection effectiveness while avoiding the harm of excessive chlorine to human health and the environment.

[0003] In existing technologies, the main methods for detecting total chlorine include chemical methods, spectrophotometry, and electrochemical methods. Among them, the most commonly used method is the N,N-diethyl-1,4-phenylenediamine (DPD) spectrophotometric method. The principle of measuring total chlorine is as follows: under the condition of pH 6.2 to 6.5, in the presence of excess potassium iodide, elemental chlorine reacts with DPD to generate a red compound. The absorbance of this compound is measured at a wavelength of 515 nm using spectrophotometry to determine the total chlorine.

[0004] With increasingly stringent environmental regulations and rising demands for industrial water safety, water quality monitoring requirements are shifting from offline laboratory testing to high-precision, low-latency online monitoring. Traditional N,N-diethyl-1,4-phenylenediamine (DPD) spectrophotometry has limitations, including complex manual operation, susceptibility to reagent deterioration and high maintenance costs, insufficient resistance to interference, and inadequate long-term stability.

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

[0006] Therefore, there is an urgent need in 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 high efficiency, low cost and high reliability of online total chlorine detection. Summary of the Invention

[0007] To address the problems existing in the prior art, this 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 operational complexity and human error. Furthermore, the combination of the three reagents enhances the anti-interference ability and stability of the total chlorine detection reagent. Modified polyethylene glycol is designed to be added to the composite stabilizer of the third reagent composite buffer stabilizer solution to further prevent crystallization of the reagent, thereby improving the stability of the reagent.

[0008] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

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

[0010] Based on 100 wt%, the first reagent potassium iodide solution comprises the following raw materials: 0.15%-0.25% potassium iodide, with the balance being water;

[0011] The second reagent, DPD colorimetric solution, comprises the following raw materials in 100 wt% form: 0.10%-0.20% N,N-diethyl-p-phenylenediamine, 0.40%-0.60% sulfuric acid, with the balance being water;

[0012] The third type of pharmaceutical compound buffer stabilizer solution, calculated at 100 wt%, comprises the following raw materials: 6.30%-7.70% phosphate buffer, 0.40%-0.70% compound stabilizer, and the balance being water.

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

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

[0015] The applicant added an appropriate amount of sulfuric acid to the DPD colorimetric reagent solution in the second reagent to adjust the pH of the reaction system to 6.2-6.5, so as to ensure the optimal conditions for the colorimetric reaction and inhibit the self-oxidation of DPD.

[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, the third pharmaceutical compound buffer stabilizer solution further comprises 0.15%-0.25% sodium pyrophosphate, based on 100 wt%.

[0018] The applicant added a phosphate buffer composed of potassium dihydrogen phosphate and disodium hydrogen phosphate in a specific ratio to the third reagent compound buffer stabilizer solution to maintain the pH of the reaction system at 6.2-6.5, ensuring that the colorimetric reaction proceeds under optimal acid-base conditions. Furthermore, the applicant added a small amount of sodium pyrophosphate to chelate interfering metal ions (such as Fe) in the water sample. 3 +、Cu 2 +) eliminates the interference of manganese oxide and hexavalent chromium, giving the total chlorine detection reagent 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 includes the following steps:

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

[0024] (2) Add chitosan to an aqueous acetic acid solution, stir, sonicate, and let stand to obtain a solution for later use;

[0025] (3) Add product 1 from step (1) to deionized water, stir, add the solution from step (2), stir, add glutaraldehyde, shake, let stand, filter and freeze dry to obtain product 2 for later use.

[0026] (4) Mix product 2 from step (3) with sodium citrate and ball mill to obtain modified polyethylene glycol.

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

[0028] In 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 product 1 to chitosan is 1:(0.15-0.3).

[0030] Preferably, the mass ratio of 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, thereby reducing the risk of reagent crystallization. However, the anti-crystallization effect of both still needs to be improved and they need to be used in combination with other substances to enhance the overall stability of the reagent. Polyethylene glycol, as a high molecular polymer, has good moisturizing and solubility properties. When combined with glycerol and propylene glycol, it can further prevent the reagent from crystallizing.

[0034] Although polyethylene glycol has a good ability to prevent reagent crystallization, it still has certain limitations in terms of stability. Furthermore, its high moisture retention may provide a suitable growth environment for microorganisms. These issues can affect the overall stability of the reagent and lead to crystallization. The applicant first selects polyethylene glycol (PEG 400 or PEG 600) with a specific molecular weight, which maintains a good balance between moisture retention and viscosity, giving the reagent excellent anti-crystallization properties. Further, the applicant modifies the terminal hydroxyl groups of the polyethylene glycol to amino groups, and then introduces chitosan for modification. The introduction of the cross-linking structure effectively improves the stability of the polyethylene glycol, and chitosan has natural antibacterial properties, which can inhibit the growth of microorganisms in the reagent, allowing the reagent to exist more stably. Further still, the applicant introduces sodium citrate to combine with the above products to obtain modified polyethylene glycol. The introduction of sodium citrate increases the hydrophilicity of the modified polyethylene glycol, improves the stability of the composite stabilizer in the reagent, and sodium citrate can chelate metal ions in the reagent, preventing metal ions from catalyzing solute crystallization. In addition, there are certain physical adsorption and electrostatic interactions between sodium citrate and the above products, further enhancing the stability of the composite stabilizer.

[0035] In another aspect, the present invention provides a method for preparing the total chlorine detection reagent described above, comprising the following steps:

[0036] S1. Preparation of the first reagent, potassium iodide solution: Mix potassium iodide and water, stir, and the first reagent, potassium iodide solution, is obtained.

[0037] S2. Preparation of the second reagent DPD colorimetric solution: Mix N,N-diethyl-p-phenylenediamine, sulfuric acid and water, and stir to obtain the second reagent DPD colorimetric solution;

[0038] S3. Preparation of the third type of pharmaceutical compound buffer stabilizer: Mix phosphate buffer, sodium pyrophosphate, compound stabilizer and water, stir, and the third type of pharmaceutical compound buffer stabilizer is obtained.

[0039] The first reagent, potassium iodide solution, the second reagent, DPD colorimetric reagent solution, and the third reagent, composite buffer stabilizer, are packaged separately. When using, the three reagents are added separately to the colorimetric chamber for testing.

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

[0041] (1) 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 error. Furthermore, the combination of the three reagents enhances the anti-interference ability and stability of the total chlorine detection reagent. Modified polyethylene glycol is designed to be added to the composite stabilizer of the third reagent composite buffer stabilizer solution, which can further prevent the reagent from crystallizing, thereby improving the stability of the reagent.

[0042] (2) In this invention, a composite stabilizer is added to the third reagent composite buffer stabilizer solution. The composite stabilizer is composed of glycerol, propylene glycol and modified polyethylene glycol in a certain proportion. The modified polyethylene glycol is obtained by modifying with amino and chitosan and then compounding with sodium citrate. This can make the composite stabilizer have better stability, moisturizing properties and dispersibility, thereby effectively preventing the crystallization of the reagent and extending 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. It can be widely used in the field of water quality analysis chemical detection technology and has good commercial application value. Attached Figure Description

[0044] To make the content of this invention easier to understand, the invention will be further described in detail below with reference to specific embodiments and accompanying drawings, wherein...

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

[0046] Figure labels: 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 Implementation

[0047] The present invention will be described below with reference to specific embodiments. It should be noted that the following embodiments are examples of the present invention and are used only to illustrate the invention, not to limit it. Other combinations and various modifications within the scope of the present invention can be made without departing from its spirit or scope.

[0048] In the following examples and comparative examples, except for the modified polyethylene glycol, all other compounds, monomers and related reagents used were commercially available. The polyethylene glycol was PEG 400 or PEG 600; the chitosan was purchased from Donghao Chemical (Shandong) Co., Ltd.; and the sulfuric acid was analytical grade.

[0049] Preparation Example 1

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

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

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

[0053] (3) Add 10g of product 1 from step (1) to 50ml of deionized water, stir for 30min, add the solution from step (2), stir, add 0.8g of 50wt% glutaraldehyde aqueous solution, shake for 30min, let stand for 6h, filter and freeze dry to obtain product 2 for later use.

[0054] (4) Mix 10g of product 2 from step (3) with 3g of sodium citrate and ball mill for 30min to obtain modified polyethylene glycol A.

[0055] Preparation Example 2

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

[0057] Preparation Example 3

[0058] Modified polyethylene glycol C is implemented in the same way as modified polyethylene glycol A, except that the mass of sodium citrate in step (4) is replaced with 1.5g.

[0059] Preparation Example 4

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

[0061] Example 1

[0062] A total chlorine detection reagent, comprising the following three reagents: potassium iodide solution, DPD colorimetric reagent solution, and a composite buffer stabilizer solution.

[0063] The first reagent, potassium iodide solution, comprises the following raw materials in 100 wt% form: 0.19% potassium iodide, with the balance being water;

[0064] The second reagent, DPD colorimetric solution, comprises the following raw materials at 100 wt%: 0.14% N,N-diethyl-p-phenylenediamine, 0.45% sulfuric acid, and the balance being water;

[0065] The third pharmaceutical compound buffer stabilizer solution, calculated at 100 wt%, comprises the following raw materials: 4.10% potassium dihydrogen phosphate, 2.80% disodium hydrogen phosphate, 0.20% sodium pyrophosphate, 0.50% compound stabilizer, and the balance being water.

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

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

[0068] S1. Preparation of the first reagent, potassium iodide solution: Mix potassium iodide and water, stir evenly, and the first reagent, potassium iodide solution, is obtained.

[0069] S2. Preparation of the second reagent DPD colorimetric solution: Mix N,N-diethyl-p-phenylenediamine, sulfuric acid and water, and stir evenly to obtain the second reagent DPD colorimetric solution;

[0070] S3. Preparation of the third type of pharmaceutical compound buffer stabilizer: Mix phosphate buffer, sodium pyrophosphate, compound stabilizer and water, stir evenly to obtain the third type of pharmaceutical compound buffer stabilizer.

[0071] The first reagent, potassium iodide solution, the second reagent, DPD colorimetric reagent solution, and the third reagent, composite buffer stabilizer, are packaged separately. When using, the three reagents are added separately to the colorimetric chamber 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 using the automatic detection system's sample injection control device. A 13ml sample is added from the water inlet 1. Simultaneously, the dosing system controls the addition of 75µL of potassium iodide solution (first reagent) from the first dosing port 2, 80µL of DPD colorimetric reagent solution (second reagent) from the second dosing port 3, and 90µL of composite buffer stabilizer solution (third reagent) from the third dosing port 4. After dosing, the mixture is stirred for 1 minute to ensure complete dissolution and reaction. Illumination is emitted from the 515nm 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 side. The result according to the national standard method (HJ 586-2010 replacing GB 11898-89) is 0.2mg / L. (A schematic diagram of the total chlorine determination colorimetric chamber is shown below.) Figure 1 (As shown)

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

[0075] Example 2

[0076] A total chlorine detection reagent, comprising the following three reagents: potassium iodide solution, DPD colorimetric reagent solution, and a composite buffer stabilizer solution.

[0077] The first reagent, potassium iodide solution, comprises the following raw materials in 100 wt% form: 0.15% potassium iodide, with the remainder being water;

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

[0079] The third pharmaceutical compound buffer stabilizer solution, calculated at 100 wt%, comprises the following raw materials: 3.80% potassium dihydrogen phosphate, 2.50% disodium hydrogen phosphate, 0.15% sodium pyrophosphate, 0.40% compound stabilizer, and the balance being water.

[0080] The composite stabilizer is a mixture of glycerol, propylene glycol and modified polyethylene glycol A in 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 in Example 1, except that the volumes of the first reagent potassium iodide solution, the second reagent DPD colorimetric reagent solution, and the third reagent composite buffer stabilizer solution are 75uL, 68uL, and 79uL, respectively.

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

[0084] Example 3

[0085] A total chlorine detection reagent, comprising the following three reagents: potassium iodide solution, DPD colorimetric reagent solution, and a composite buffer stabilizer solution.

[0086] The first reagent, potassium iodide solution, comprises the following raw materials in 100 wt% form: 0.25% potassium iodide, with the remainder being water;

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

[0088] The third pharmaceutical compound buffer stabilizer solution, calculated at 100 wt%, comprises the following raw materials: 4.50% potassium dihydrogen phosphate, 3.20% disodium hydrogen phosphate, 0.25% sodium pyrophosphate, 0.70% compound stabilizer, and the balance being water.

[0089] The composite stabilizer is a mixture of glycerol, propylene glycol and modified polyethylene glycol A in 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 in Example 1, except that the volumes of the first reagent potassium iodide solution, the second reagent DPD colorimetric reagent solution, and the third reagent composite buffer stabilizer solution are 75uL, 90uL, and 105uL, respectively.

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

[0093] Example 4

[0094] A total chlorine detection reagent, comprising the following three reagents: potassium iodide solution, DPD colorimetric reagent solution, and a composite buffer stabilizer solution.

[0095] The first reagent, potassium iodide solution, comprises the following raw materials in 100 wt% form: 0.19% potassium iodide, with the balance being water;

[0096] The second reagent, DPD colorimetric solution, comprises the following raw materials at 100 wt%: 0.14% N,N-diethyl-p-phenylenediamine, 0.45% sulfuric acid, and the balance being water;

[0097] The third pharmaceutical compound buffer stabilizer solution, calculated at 100 wt%, comprises the following raw materials: 4.10% potassium dihydrogen phosphate, 2.80% disodium hydrogen phosphate, 0.50% compound stabilizer, and the balance being water.

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

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

[0100] S1. Preparation of the first reagent, potassium iodide solution: Mix potassium iodide and water, stir evenly, and the first reagent, potassium iodide solution, is obtained.

[0101] S2. Preparation of the second reagent DPD colorimetric solution: Mix N,N-diethyl-p-phenylenediamine, sulfuric acid and water, and stir evenly to obtain the second reagent DPD colorimetric solution;

[0102] S3. Preparation of the third type of pharmaceutical compound buffer stabilizer: Mix the phosphate buffer, the compound stabilizer and water, and stir evenly to obtain the third type of pharmaceutical compound buffer stabilizer.

[0103] The first reagent, potassium iodide solution, the second reagent, DPD colorimetric reagent solution, and the third reagent, composite buffer stabilizer, are packaged separately. When using, the three reagents are added separately to the colorimetric chamber for testing.

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

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

[0106] Example 5

[0107] This embodiment provides a total chlorine detection reagent and its preparation method. The specific implementation method is the same as that in Embodiment 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: The total chlorine concentration was calculated to be 0.18 mg / L by comparing the absorbance with the calibration curve.

[0109] Example 6

[0110] This embodiment provides a total chlorine detection reagent and its preparation method. The specific implementation method is the same as that in Embodiment 1, except that modified polyethylene glycol A is replaced by an equal amount of modified polyethylene glycol B.

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

[0112] Example 7

[0113] This embodiment provides a total chlorine detection reagent and its preparation method. The specific implementation method is the same as that in Embodiment 1, except that modified polyethylene glycol A is replaced by an equal amount of modified polyethylene glycol C.

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

[0115] Example 8

[0116] This embodiment provides a total chlorine detection reagent and its preparation method. The specific implementation method is the same as that in Embodiment 1, except that modified polyethylene glycol A is replaced by modified polyethylene glycol D in an equal amount.

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

[0118] The data above show that the total chlorine detection reagents in Examples 1-3 of this invention have detection results that are almost identical to the national standard method (HJ586-2010 replacing GB 11898-89) result of 0.2 mg / L, indicating that the water quality total chlorine detection reagent is accurate and reliable. In Example 4, sodium pyrophosphate was not added to the third reagent composite buffer stabilizer solution, resulting in a decrease in the reagent's anti-interference ability and consequently a decrease in the accuracy of the test results. Example 5 changed the amount of modified polyethylene glycol A added to the composite stabilizer, and Examples 6-8 changed the ratio between the main components in the modified polyethylene glycol A synthesis process. Although these changes affected the stability of the total chlorine detection reagent, they had little impact on its accuracy.

[0119] The stability of the total chlorine detection reagents in 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 reagent compound buffer stabilizer solution in the total chlorine detection reagent. After storing it at room temperature for 30 days, it was observed whether crystallization occurred.

[0121] Table 1

[0122] Group Whether it crystallizes Example 1 no Example 2 no Example 3 no Example 4 no Example 5 A small amount of crystals were produced. Example 6 A small amount of crystals were produced. Example 7 A small amount of crystals were produced. Example 8 A small amount of crystals were produced.

[0123] As shown in Table 1, none of the third-type pharmaceutical composite buffer stabilizer solutions in Examples 1-4 of this invention crystallized, indicating good overall stability. However, Example 5 changed the amount of modified polyethylene glycol A added to 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 the formation of a small amount of crystals after long-term storage.

[0124] The above embodiments are only for illustrating the technical concept and features of the present invention, and are intended to enable those skilled in the art to understand the content of the present invention and implement it. They should not be used to limit the scope of protection of the present invention. All equivalent changes or modifications made in accordance with the spirit and essence of the present invention should be covered within the scope of protection of the present invention.

Claims

1. A total chlorine detection reagent, characterized by, The total chlorine detection reagent is composed of three reagents: a first reagent potassium iodide solution, a second reagent DPD chromogenic agent solution, and a third reagent composite buffer stabilizer solution; The first reagent potassium iodide solution comprises, based on 100wt%, the following raw materials: potassium iodide 0.15%-0.25%, and the balance being water; The second reagent DPD chromogenic agent solution comprises, based on 100wt%, the following raw materials: N,N-diethyl-p-phenylenediamine 0.10%-0.20%, sulfuric acid 0.40%-0.60%, and the balance being water; The third reagent composite buffer stabilizer solution comprises, based on 100wt%, the following raw materials: phosphate buffer 6.30%-7.70%, composite stabilizer 0.40%-0.70%, and the balance being water; The composite stabilizer is a mixture of glycerol, propylene glycol and modified polyethylene glycol; The preparation method of the modified polyethylene glycol comprises the following steps: (1) polyethylene glycol is added to deionized water, stirred, p-aminobenzoic acid is added, stirred, filtered, freeze-dried to obtain product 1 for standby; (2) chitosan is added to an aqueous acetic acid solution, stirred, ultrasonicated, and left to stand to obtain a solution for standby; (3) product 1 of step (1) is added to deionized water, stirred, the solution of step (2) is added, stirred, glutaraldehyde is added, shaken, left to stand, filtered, and freeze-dried to obtain product 2 for standby; (4) product 2 of step (3) and sodium citrate are mixed and ball-milled to obtain the modified polyethylene glycol; The polyethylene glycol is PEG 400 or PEG 600.

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

3. The total chlorine test reagent according to claim 1, characterized in that, The phosphate buffer comprises potassium dihydrogen phosphate 3.80%-4.50% and disodium hydrogen phosphate 2.50%-3.20%.

4. The total chlorine test reagent according to claim 1, wherein The third reagent composite buffer stabilizer solution further comprises, based on 100wt%, sodium pyrophosphate 0.15%-0.25%.

5. The total chlorine test reagent according to claim 1, wherein 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).

6. The total chlorine test reagent according to claim 1, wherein The mass ratio of product 1 and chitosan is 1:(0.15-0.3).

7. The total chlorine test reagent according to claim 1, wherein In step (4), the mass ratio of product 2 and sodium citrate is 1:(0.2-0.4).

8. A method of preparing the total chlorine test reagent according to any one of claims 4 to 7, characterized in that, The method comprises the following steps: S1, preparation of the first reagent potassium iodide solution: potassium iodide and water are mixed and stirred to obtain the first reagent potassium iodide solution; S2, preparation of the second reagent DPD chromogenic agent solution: N,N-diethyl-p-phenylenediamine, sulfuric acid and water are mixed and stirred to obtain the second reagent DPD chromogenic agent solution; S3, preparation of the third reagent composite buffer stabilizer: phosphate buffer, sodium pyrophosphate, composite stabilizer and water are mixed and stirred to obtain the third reagent composite buffer stabilizer; The first medicament is potassium iodide solution, the second medicament is DPD color developing agent solution, and the third medicament is a composite buffer stabilizer, which are separately packaged and added into a colorimetric chamber for testing when used.

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