Residual chlorine detection test paper and preparation method therefor

Abstract

The present application relates to the field of residual chlorine detection. Disclosed are residual chlorine detection test paper and a preparation method therefor. The residual chlorine detection test paper comprises a substrate and a detection reagent layer arranged on the substrate, wherein the detection reagent layer comprises an anionic organic salt. The present application can prevent a chlorine indicator from contaminating a liquid to be detected; and the color indication is uniform during the detection process, the detection accuracy rate is high, and the application prospect is broad.

Description

Residual chlorine detection test paper and preparation method thereof

[0001] The present application relates to the field of residual chlorine detection, in particular to a residual chlorine detection test paper and a preparation method thereof. BACKGROUND

[0002] Residual chlorine is one of the important indicators for water quality detection, especially for tap water, drinking water and swimming pool water. According to relevant standards, residual chlorine is usually tested by spectrophotometry, colorimetry or electrochemical method, while test paper method is the fastest and most convenient as a semi-quantitative method. After the test paper strip is soaked in the test liquid for a period of time, it is taken out, the surface moisture is shaken or dried, and then compared with the test paper color card to realize semi-quantitative analysis.

[0003] The color developing principle of residual chlorine test paper is that the indicator contained therein has reducing property and can react with the oxidizing residual chlorine in water to obtain an oxidation product with different color from the indicator, and the test paper will show different colors with different concentrations of residual chlorine in water.

[0004] The test paper is usually prepared by soaking the test paper base paper in the indicator solution for a period of time, taking it out, pressing and drying, and then cutting it into the test paper size for testing. Among them, the indicator is evenly distributed on the surface of the test paper fiber through the residual water in the test paper fiber and intermolecular force.

[0005] However, when the test paper strip is soaked in the test water, the indicator molecules will move with the diffusion of water in the test paper fiber, or even dissolve directly in the test water sample, which will cause uneven color distribution on the surface of the test paper, affecting the accuracy of color comparison result; in addition, the dissolution of the indicator will pollute the test liquid, and also cause the concentration of the indicator on the test paper to be too low, so that the actual test color is difficult to match the color card color, and the test result is not accurate.

[0006] Therefore, it is necessary to develop a new test paper to solve the problems of indicator leakage and uneven color display. TECHNICAL PROBLEM

[0007] When the test paper strip is immersed in water, the indicator molecules are prone to migrate with the diffusion of water or even dissolve, causing uneven color distribution on the surface of the test paper and affecting the accuracy of color comparison; at the same time, the dissolution of the indicator will also pollute the test water sample, and cause the concentration of the residual indicator on the test paper to decrease, so that the actual color development is difficult to match the standard color card, and finally affects the reliability of the test result. TECHNICAL SOLUTION

[0008] The purpose of the present application is to provide a residual chlorine detection test paper and a preparation method thereof, which can prevent or limit the movement of chlorine indicator with liquid phase by adding anionic organic salt, avoid the dissolution of chlorine indicator, and improve the test accuracy of residual chlorine detection test paper. Advantages

[0009] According to the specific embodiments provided in the application, the following technical effects are disclosed:

[0010] The residual chlorine test paper provided by the application comprises a substrate and a test reagent layer arranged on the substrate. The test reagent layer contains an anionic organic salt, which can avoid the pollution of the chlorine indicator to the liquid to be tested, and the color indication is uniform during the detection process, the detection accuracy is high, and the application prospect is wide. The addition of the anionic organic salt can prevent or limit the movement of the chlorine indicator with the liquid phase, avoid the dissolution of the chlorine indicator, and improve the testing accuracy of the residual chlorine test paper. BRIEF DESCRIPTION OF DRAWINGS

[0011] In order to more clearly illustrate the technical solutions in the embodiments of the application or the related art, the drawings needed to be used in the embodiments will be briefly introduced. Obviously, the drawings in the following description are only some embodiments of the application, and other drawings can be obtained by those skilled in the art without creative labor.

[0012] FIG. 1 is a structural schematic diagram of a residual chlorine test paper provided by an embodiment of the application.

[0013] FIG. 2 is a flowchart of a preparation method of a residual chlorine test paper provided by an embodiment of the application.

[0014] Reference signs: substrate-1; test reagent layer-2. Best mode for carrying out the application

[0015] To achieve the above-mentioned purpose, the application provides the following solutions:

[0016] In a first aspect, the application provides a residual chlorine test paper, which comprises a substrate and a test reagent layer arranged on the substrate; the test reagent layer contains an anionic organic salt.

[0017] In a second aspect, the application provides a preparation method of a residual chlorine test paper, which is applied to the residual chlorine test paper described above, and the preparation method comprises: first immersing the substrate in a solution containing a chlorine indicator and drying, then immersing the substrate in a solution containing an anionic organic salt and drying, to obtain the residual chlorine test paper. Embodiments of the application

[0018] With reference to the drawings of the embodiments of the present application, the technical solutions in the embodiments of the present application will be clearly and completely described, obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments of the present application, all other embodiments obtained by those skilled in the art without creative work fall within the scope of protection of the present application.

[0019] In order to make the above-mentioned purposes, features and advantages of the present application more obvious and easy to understand, the present application will be further described in detail below with reference to the drawings and specific embodiments.

[0020] In a first aspect, as shown in FIG. 1, the present application provides a residual chlorine detection test paper, which comprises a substrate 1 and a detection reagent layer 2 arranged on the substrate 1.

[0021] The detection reagent layer 2 contains an anionic organic salt.

[0022] By adding an anionic organic salt, the present application can fix the chlorine indicator on the substrate 1, thereby avoiding the leakage or transfer of the chlorine indicator during the detection process, which can bring the following three advantages.

[0023] 1. Avoiding the problem of uneven color development caused by the transfer of chlorine indicator, which leads to more chlorine indicator in some areas and less chlorine indicator in some areas on the test paper, thereby making the subsequent colorimetric detection more accurate.

[0024] 2. Avoiding the problem of contamination of the to-be-detected liquid caused by the leakage of chlorine indicator into the to-be-detected liquid.

[0025] 3. Avoiding the problem that the color development concentration is relatively low compared to the real data caused by the leakage of chlorine indicator, which leads to the reduction of chlorine indicator concentration on the original test paper, thereby further improving the accuracy of detection.

[0026] In an example, the detection reagent layer 2 further contains a chlorine indicator; the chlorine indicator penetrates into the substrate 1 and adheres to the surface of the substrate 1, and the anionic organic salt forms a surface film layer on the substrate 1.

[0027] In an example, the surface film layer is fixedly connected with the chlorine indicator by electrostatic adsorption; and the surface film layer has a connecting hydrogen bond with the substrate 1.

[0028] It is worth noting that there are two main points for the fixation of the chlorine indicator in the present application. One is that the chlorine indicator is fixed on the surface film layer formed by the anionic organic salt through electrostatic adsorption, so as not to move during the detection process. The other is that the anionic organic salt is fixed on the substrate 1 through hydrogen bond, so as to fix the chlorine indicator on the substrate 1.

[0029] In an example, the anionic organic salt is an anionic high-molecular organic salt.

[0030] In an example, the anionic organic salt comprises any one or a combination of at least two of a carboxymethyl cellulose salt, an alginate salt, a hyaluronate salt, or a sulfonate salt, wherein typical but non-limiting combinations are a combination of a carboxymethyl cellulose salt and an alginate salt, a combination of a hyaluronate salt and an alginate salt, a combination of a carboxymethyl cellulose salt and a hyaluronate salt, a combination of a hyaluronate salt and an alginate salt, a combination of a sulfonate salt and an alginate salt.

[0031] For the selection of the anionic organic salt, the following factors need to be mainly considered: the substrate 1 of the test paper is generally cotton fiber material, and the main component is cellulose. There are a large number of -OH in the cellulose molecules, so it has excellent water absorption. The chlorine indicator molecules are attached to the surface of the cellulose molecules. If a thin high-molecular surface film layer is additionally attached to the surface of the cellulose at this time, it needs to be able to reduce the dissolution amount of the indicator while maintaining the wetting speed of the test paper.

[0032] In addition, since the chlorine indicator is usually in the form of a cationic salt, especially with a positive charge in the colored state, if the high-molecular surface film layer has a negative charge (anion), the indicator can be bound to the high-molecular film through electrostatic adsorption (positive and negative ion combination), thereby effectively limiting the movement of the indicator with water, achieving the effect of uniform color development.

[0033] In order to achieve the above effects, the basic requirements for the anionic organic salt are as follows.

[0034] (1) Affinity with cellulose molecules. The anionic organic salt can form a strong intermolecular force with cellulose through a large number of intermolecular hydrogen bonds.

[0035] (2) A large number of anion groups: a large number of groups such as carboxyl and sulfonic acid groups exist in the high-molecular structure of the anionic organic salt. These groups can not only provide anions to bind cationic indicators, but also increase the hydrophilicity of the high-molecule, thereby improving or maintaining the water absorption performance of the test paper itself.

[0036] (3) Film-forming stability: a thin film (protective layer) can be formed on the surface of cellulose, and this thin film (protective layer) can remain stable in water for a short time (at least within 10-20 seconds of the use of the test paper), without dissolving.

[0037] According to the above property requirements, the application preferably uses any one or a combination of at least two of a carboxymethyl cellulose salt, an alginate salt, a hyaluronate salt, or a sulfonate salt as the anionic organic salt, which can better achieve the following points:

[0038] 1. Forming electrostatic adsorption between the chlorine indicator and the anionic organic salt.

[0039] 2. Fixed by a large number of hydrogen bonds between the cellulose substrate 1.

[0040] 3. Excellent hydrophilic performance itself, can improve or maintain water wettability.

[0041] 4. After film formation, it can maintain stability in water within the detection time without dissolving.

[0042] In an example, the anionic organic salt includes any one or a combination of at least two of sodium salt, potassium salt or calcium salt, wherein typical but non-limiting combinations are a combination of sodium salt and potassium salt, a combination of calcium salt and potassium salt, and a combination of sodium salt and calcium salt.

[0043] In an example, the weight average molecular weight of the carboxymethyl cellulose salt is 5000-100000, for example, it can be 5000, 15000, 26000, 36000, 47000, 57000, 68000, 78000, 89000 or 100000, etc., preferably 10000-30000.

[0044] The carboxymethyl cellulose salt of the present application is a linear polymer, which can be dissolved in water to form a hydrogel, and the weight average molecular weight is preferably controlled within the above range, which can ensure that the thickness of the surface film layer is within a reasonable range, thereby better guaranteeing the reaction sensitivity of the test paper, and also taking into account the adhesion to the substrate 1, guaranteeing the fixing effect of the chlorine indicator, and avoiding the shedding of itself in water or the leakage of the chlorine indicator.

[0045] In an example, the degree of substitution of the carboxymethyl cellulose salt is 0.5-1.5, for example, it can be 0.5, 0.7, 0.8, 0.9, 1, 1.1, 1.2, 1.3, 1.4 or 1.5, etc., preferably 0.9-1.2.

[0046] Carboxymethyl cellulose sodium is obtained by carboxymethylation of cellulose molecules, and one glucose unit of the cellulose molecule has three free hydroxyl groups, and the maximum degree of substitution is theoretically 3. The CMC preferably applied in the present application has a degree of substitution of 0.5-1.5, which can better guarantee the hydrophilicity of the surface film layer and the fixing effect of the chlorine indicator.

[0047] In an example, the weight average molecular weight of the hyaluronic acid salt is 400-2000, for example, it can be 400, 500, 700, 900, 1100, 1200, 1400, 1600, 1800 or 2000, etc., preferably 800-1200.

[0048] The weight average molecular weight of the hyaluronate is preferably controlled in the above range, which can ensure that the thickness of the surface film layer is within a reasonable range, thereby better ensuring the reaction sensitivity of the test paper, and taking into account the adhesion to the substrate 1, ensuring the fixing effect of the chlorine indicator, avoiding the shedding of itself in water or the leakage of the chlorine indicator.

[0049] In an example, the sulfonate includes polystyrene sulfonate.

[0050] The polystyrene sulfonate is preferably used, in which the side chain of the linear high polymer with phenyl can increase the viscosity of the high polymer aqueous solution, and compared with other sulfonates, the polystyrene sulfonate has the advantages of good water solubility, small toxicity, simple synthesis and low cost.

[0051] In an example, the weight average molecular weight of the sulfonate is 50,000-100,000, for example, can be 50,000, 56,000, 62,000, 67,000, 73,000, 78,000, 84,000, 89,000, 95,000 or 100,000, etc.

[0052] The weight average molecular weight of the sulfonate is preferably controlled in the above range, which can ensure that the thickness of the surface film layer is within a reasonable range, thereby better ensuring the reaction sensitivity of the test paper, and taking into account the adhesion to the substrate 1, ensuring the fixing effect of the chlorine indicator, avoiding the shedding of itself in water or the leakage of the chlorine indicator.

[0053] In an example, the thickness of the surface film layer is 0.01-5 μm, for example, can be 0.01 μm, 0.02 μm, 0.03 μm, 0.04 μm, 0.05 μm, 0.1 μm, 0.2 μm, 0.5 μm, 1 μm, 1.5 μm, 2.0 μm, 2.5 μm, 3.0 μm, 3.5 μm, 4 μm, 4.5 μm or 5.0 μm, etc.

[0054] In an example, the chlorine indicator includes a cationic indicator, preferably an amine cationic indicator.

[0055] In an example, the chlorine indicator includes any one or a combination of at least two of N,N-diethyl-p-phenylenediamine, 3,3',5'5'-tetramethylbenzidine, 4,4'-bis(dimethylamino)thiobenzophenone or 3,3'-dimethylbenzidine, wherein a typical but non-limiting combination is a combination of N,N-diethyl-p-phenylenediamine and 3,3',5'5'-tetramethylbenzidine, a combination of 4,4'-bis(dimethylamino)thiobenzophenone and 3,3',5'5'-tetramethylbenzidine, a combination of N,N-diethyl-p-phenylenediamine and 3,3'-dimethylbenzidine, a combination of 3,3'-dimethylbenzidine and 3,3',5'5'-tetramethylbenzidine.

[0056] In an example, the residual chlorine test paper has a loading density of the chlorine indicator of 0.2-4.0 mg / cm 3 , for example, 0.2 mg / cm 3 , 0.3 mg / cm 3 , 0.5 mg / cm 3 , 0.8 mg / cm 3 , 1.0 mg / cm 3 , 1.2 mg / cm 3 , 1.3 mg / cm 3 , 1.5 mg / cm 3 , 1.8 mg / cm 3 , 2.0 mg / cm 3 , 2.5 mg / cm 3 , 3.0 mg / cm 3 , 3.5 mg / cm 3 , or 4.0 mg / cm 3 , etc.

[0057] In an example, the residual chlorine test paper has a loading density of the anionic organic salt of 0.01-1 mg / cm 3 , for example, 0.01 mg / cm 3 , 0.02 mg / cm 3 , 0.03 mg / cm 3 , 0.05 mg / cm 3 , 0.1 mg / cm 3 , 0.12 mg / cm 3 , 0.15 mg / cm 3 , 0.2 mg / cm 3 , 0.22 mg / cm 3 , 0.25 mg / cm 3 , 0.3 mg / cm 3 , 0.4 mg / cm 3 , 0.5 mg / cm 3 , 0.7 mg / cm 3 , 0.9 mg / cm 3 , or 1.0 mg / cm 3 , etc.

[0058] In a second aspect, as shown in FIG. 2, the application provides a preparation method of a residual chlorine test paper, which is applied to the residual chlorine test paper described above, and comprises the following steps.

[0059] S1. The substrate 1 is first soaked in a solution containing a chlorine indicator and dried, and then soaked in a solution containing an anionic organic salt and dried, to obtain the residual chlorine test paper.

[0060] The preparation method of the residual chlorine detection test paper of the present application can produce the residual chlorine detection test paper with excellent performance, simple preparation process and wide application prospect. The present application needs to first soak the chlorine indicator and then soak the solution containing anionic organic salt, and the surface film layer is used to fix the chlorine indicator inside.

[0061] In an example, the concentration of the chlorine indicator in the solution containing the chlorine indicator is 0.05-2wt%, for example, it can be 0.05wt%, 0.27wt%, 0.49wt%, 0.7wt%, 0.92wt%, 1.14wt%, 1.35wt%, 1.57wt%, 1.79wt% or 2wt%, etc., preferably 0.2-1wt%.

[0062] In an example, the solvent of the solution containing the chlorine indicator includes ethanol or a mixed solvent of ethanol and water.

[0063] In an example, the solution containing the chlorine indicator also contains a pH buffer.

[0064] The present application does not have special requirements for the pH buffer. According to different chlorine indicators, different pH needs to be controlled, for example, the pH buffer includes a phosphate buffer.

[0065] In an example, the concentration of the anionic organic salt in the solution containing the anionic organic salt is 0.1-5wt%, for example, it can be 0.1wt%, 0.7wt%, 1.2wt%, 1.8wt%, 2.3wt%, 2.9wt%, 3.4wt%, 4wt%, 4.5wt% or 5wt%, etc., preferably 0.5-2wt%.

[0066] The present application preferably controls the concentration of the anionic organic salt in the above range, which can better control the viscosity of the solution containing the anionic organic salt in the range of 100-1000mPa·s (for example, it can be 100mPa·s, 200mPa·s, 300mPa·s, 500mPa·s, 700mPa·s, 800mPa·s, 900mPa·s or 1000mPa·s), thereby ensuring the adhesion of the surface film layer on the substrate 1 and the reaction sensitivity of the test paper, while improving the detection accuracy and avoiding the leakage of the chlorine indicator.

[0067] In an example, the solvent of the solution containing the anionic organic salt includes water.

[0068] As an example of the technical scheme of the present application, the preparation method includes the following steps.

[0069] The substrate 1 is first soaked in an ethanol and / or water solution containing a pH buffer and the concentration of the chlorine indicator is 0.05-2wt%, and then the excess water is squeezed out and dried.

[0070] Re-infiltrated in the aqueous solution containing 0.1-5wt% anionic organic salt, extruded to remove excess water and dried to obtain the residual chlorine test paper.

[0071] The base 1 of the present application is not particularly limited, and the base 1 for test paper known to those skilled in the art can be used, and can be adjusted according to the actual situation, for example, cellulose paper, filter paper or water-absorbing cotton paper can be used.

[0072] The drying in the above process is also not particularly limited, and any device and method known to those skilled in the art can be used, and can be adjusted according to the actual process, for example, air drying, vacuum drying or drying can be used, and different ways can be combined.

[0073] The present application has at least the following beneficial effects:

[0074] (1) The residual chlorine test paper provided by the present application forms a surface film layer by adding an anionic organic salt, and the chlorine indicator is fixed on the surface of the test paper fiber.

[0075] (2) The residual chlorine test paper provided by the present application has uniform color distribution on the surface when detecting actual water samples, and the color changes more obviously with the change of the index to be measured (residual chlorine concentration), which can significantly improve the resolution and identification accuracy of the color card, and the test accuracy is more than 81%.

[0076] (3) The residual chlorine test paper provided by the present application can improve the contact time of the test paper with the test liquid when detecting low concentration residual chlorine, so as to enrich the residual chlorine in the water on the test paper, enhance the color response of the test paper, and reduce the detection lower limit of the test paper for residual chlorine in water. Under the preferred condition, the minimum detection limit can reach 0.05ppm.

[0077] In the actual application process, for the residual chlorine test paper and its preparation, the present application designs the following examples.

[0078] In a third aspect, the present application also provides a use of the residual chlorine test paper in liquid phase residual chlorine detection. The residual chlorine test paper provided by the present application can be better applied in liquid phase residual chlorine detection. Industrial applicability

[0079] The residual chlorine test paper provided by the present application forms a surface film layer by adding an anionic organic salt, effectively fixes the indicator, makes the color development uniform, the color difference obvious, and the detection accuracy more than 81%. The test paper can also enrich low concentration residual chlorine by prolonging the contact time, reduce the detection lower limit to 0.05ppm, and significantly improve the resolution and detection sensitivity.

Claims

1. A residual chlorine test strip, characterized in that, The residual chlorine test strip includes a substrate and a detection reagent layer disposed on the substrate; The detection reagent layer contains anionic organic salts.

2. The residual chlorine test strip according to claim 1, characterized in that, The detection reagent layer also contains a chlorine indicator; the chlorine indicator penetrates into the substrate and adheres to the substrate surface, and the anionic organic salt forms a film layer on the substrate.

3. The residual chlorine detection test strip according to claim 2, characterized in that, The surface film layer is fixedly connected to the chlorine indicator by electrostatic adsorption; and there are connecting hydrogen bonds between the surface film layer and the substrate.

4. The residual chlorine detection test strip according to claim 1, characterized in that, The anionic organic salt is an anionic high-molecular-weight organic salt; The anionic organic salt includes any one or a combination of at least two of carboxymethyl cellulose salt, alginate, hyaluronic acid salt, or sulfonate; and / or, the anionic organic salt includes any one or a combination of at least two of sodium salt, potassium salt, or calcium salt.

5. The residual chlorine test strip according to claim 4, characterized in that, The carboxymethyl cellulose salt has a weight-average molecular weight of 5,000 to 100,000; and / or the degree of substitution of the carboxymethyl cellulose salt is 0.5 to 1.

5. And / or, the weight-average molecular weight of the hyaluronic acid salt is 400,000 to 2,000,000; And / or, the sulfonate includes polystyrene sulfonate; and / or the weight-average molecular weight of the sulfonate is 50,000 to 100,000.

6. The residual chlorine test strip according to claim 2, characterized in that, The thickness of the surface film layer is 0.01~5μm.

7. The residual chlorine test strip according to claim 2, characterized in that, The chlorine indicator includes a cationic indicator; the cationic indicator is an amine cationic indicator.

8. The residual chlorine detection test strip according to claim 2, characterized in that, The loading density of chlorine indicator on the residual chlorine test strip is 0.2~4.0 mg / cm³. 3 ; And / or, the loading density of anionic organic salts on the residual chlorine test strip is 0.01~1 mg / cm³. 3 .

9. A method for preparing a residual chlorine test strip, characterized in that, The preparation method is applied to the residual chlorine detection test strip according to any one of claims 1-8, and the preparation method includes: The substrate is first immersed in a solution containing a chlorine indicator and dried, then immersed in a solution containing anionic organic salt and dried to obtain the residual chlorine test paper.

10. The preparation method according to claim 9, characterized in that, The concentration of chlorine indicator in the chlorine-containing indicator solution is 0.05~2wt%; And / or the concentration of the anionic organic salt in the solution containing the anionic organic salt is 0.1~5wt%.