PH test composition, pH test tablet containing pH test composition and application of pH test composition and pH test tablet

Abstract

The invention provides a pH test composition, a pH test tablet containing the pH test composition and application. The pH test composition comprises a pH indicator, a dechlorinating agent and an additive, wherein the dechlorinating agent comprises any one or a combination of at least two of sodium thiosulfate, sodium sulfite or sodium ascorbate. The dechlorinating agent is added into the pH testing composition, so that the original pH detection is not influenced, the detection sensitivity and the detection precision of the pH in the chlorine-containing water phase to be detected can be improved, and the pH testing composition can be applied to pH detection of swimming pool water and tap water and has a wide application prospect.

Description

Technical Field

[0001] The present invention relates to the technical field of pH detection, and in particular to a pH testing composition, a pH testing tablet containing the same, and applications thereof. Background Art

[0002] The pH value of water bodies is one of the core indicators for assessing the safety and applicability of water quality: in a swimming pool environment, a pH that is too high (>7.8) will significantly reduce the bactericidal efficiency of chlorine-containing disinfectants, leading to the risk of microbial growth. At the same time, alkaline water can easily irritate human skin and eyes; a pH that is too low (<7.2) will accelerate the corrosion of metal components in the pool and cause discomfort to swimmers. For tap water, a pH deviation from the neutral range (6.5-8.5) may aggravate the dissolution of heavy metals (such as lead and copper) in the water supply network, threatening the safety of drinking water and affecting the taste and daily use. In addition, water quality standards in various countries have set strict limits on pH. For example, GB5749-2022 "Sanitary Standards for Drinking Water" clearly requires a pH between 6.5 and 8.5. Therefore, rapid and accurate pH testing is a key link in ensuring the functional compliance of water bodies, the durability of facilities and public health.

[0003] Traditional water quality pH detection methods have significant limitations in practical applications: the pH test paper method relies on visual colorimetry, the color boundary is fuzzy and easily interfered by ambient light and subjective judgment, especially in chlorinated swimming pool water, the color reaction specificity is poor, and the test paper is easily affected by moisture and becomes ineffective, making it difficult to ensure long-term stability; although portable pH meters can be quantitatively measured, they require frequent calibration and face the problem of electrodes being easily contaminated by residual chlorine, calcium and magnesium ions. The equipment purchase and maintenance costs are high, making it difficult to meet the needs of home users and outdoor scenarios; the liquid reagent colorimetric method is cumbersome to operate, requires precise control of the reagent addition amount, has the risk of leakage, and some corrosive reagents produce hazardous waste, while indicator methods such as phenolphthalein have a narrow detection range, are easily interfered by water turbidity, and have a high threshold for use by non-professionals.

[0004] Therefore, it is necessary to develop new technologies for pH detection to improve convenience as well as accuracy and sensitivity in portable scenarios. Summary of the Invention

[0005] To solve the above technical problems, the present invention provides a pH testing composition, a pH testing tablet containing the same, and applications thereof. By adopting a specific dechlorinating agent, the composition can minimize interference with the pH of the water body and utilize the limited buffering capacity in a low-alkalinity environment to concentrate the color gradient in the target detection range (pH 6.5-8.5). This achieves high-sensitivity color development in a narrow range without the need to introduce an external buffer, and can be well applied to pH detection of swimming pool water and tap water.

[0006] To achieve this object, the present invention adopts the following technical solutions:

[0007] In a first aspect, the present invention provides a pH test composition, comprising a pH indicator, a dechlorinating agent, and an additive; wherein the dechlorinating agent comprises any one of sodium thiosulfate, sodium sulfite, or sodium ascorbate, or a combination of at least two thereof.

[0008] In pH testing of pool and tap water, residual chlorine can oxidize the pH indicator, causing color abnormalities (such as fading, delayed color development, or color shift), seriously affecting the accuracy of test results. A dechlorinator is added to the tablet, which reacts rapidly with free chlorine in the water to form a neutral product. This ensures the structural integrity of the indicator molecule without introducing additional acid or alkaline components, ensuring that the test results reflect only the true pH value of the water.

[0009] In the selection of a specific dechlorinating agent in the pH test composition provided by the present invention, researchers have found that the following requirements are required:

[0010] 1) The dechlorinating agent itself and the product after the dechlorination reaction should not have color. Since the pH test composition is expected to be used to detect the pH of the test liquid by colorimetry, dechlorinating agents with their own color cannot be used.

[0011] 2) Considering that more pH detection can also be carried out by spectral detection, the dechlorination agent cannot have an absorption peak at a wavelength of 300-700 nm before and after the dechlorination reaction.

[0012] 3) The dechlorination agent is not only required to react with the residual chlorine, but also to not affect the pH of the system itself after addition, that is, no OH is generated during the reaction. - and H + .

[0013] 4) The dechlorinating agent and the pH indicator or additive do not chemically react with each other or negatively affect each other, especially do not affect the color development effect of the pH indicator.

[0014] Based on the above requirements, the researchers found that the addition of sodium thiosulfate, sodium sulfite or sodium ascorbate can improve the detection sensitivity and accuracy of pH in chlorine-containing test solutions.

[0015] Specifically, the dechlorination agent includes any one of sodium thiosulfate, sodium sulfite or sodium ascorbate, or a combination of at least two of them, wherein typical but non-limiting combinations are a combination of sodium thiosulfate and sodium sulfite, a combination of sodium ascorbate and sodium sulfite, a combination of sodium thiosulfate and sodium ascorbate, and a combination of sodium ascorbate, sodium thiosulfate and sodium sulfite.

[0016] Preferably, the mass ratio of the dechlorinating agent to the pH indicator is (10-50):1, for example, it can be 10:1, 15:1, 19:1, 24:1, 28:1, 33:1, 37:1, 42:1, 46:1 or 50:1, but is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0017] When the dechlorinating agent reacts with the free chlorine in the test liquid, the buffering properties of the test liquid itself change, affecting the color range of the pH indicator. Therefore, the amount of dechlorinating agent and pH indicator must be matched to minimize the deviation in the pH measurement caused by the free chlorine in the test liquid. Specifically, research has found that when the mass ratio of dechlorinating agent to pH indicator is within the above range, better detection results are achieved in test liquids containing residual chlorine.

[0018] Preferably, the pH indicator comprises any one of phenol red, bromothymol blue or meta-cresol violet or a combination of at least two thereof, wherein typical but non-limiting combinations are a combination of phenol red and bromothymol blue, a combination of meta-cresol violet and bromothymol blue, a combination of phenol red and meta-cresol violet, and a combination of meta-cresol violet, phenol red and bromothymol blue.

[0019] Preferably, the mass percentage of the pH indicator in the pH test composition is 0.03-0.4%, for example, it can be 0.03%, 0.05%, 0.08%, 0.09%, 0.1%, 0.12%, 0.15%, 0.18%, 0.2%, 0.22%, 0.25%, 0.28%, 0.3%, 0.32%, 0.35% or 0.4%, etc., but is not limited to the listed values, and other values ​​not listed within this range are also applicable.

[0020] It is worth noting that the mass content of the pH indicator in the pH test composition of the present invention is optimized and a dechlorinating agent is used in combination, thereby achieving high-sensitivity color development within a narrow range.

[0021] In order to overcome the color development limitations of low-alkalinity water bodies, the amount of pH indicator added needs to be strictly controlled: excessive use will significantly interfere with the pH of the water body to be tested due to the acid-base properties of the pH indicator itself, causing the color development results to deviate from the true value; and insufficient use of pH indicator will fail to form an effective color scale.

[0022] Preferably, the additives include a filler and a binder; the additives may also optionally include a disintegrant and / or a lubricant.

[0023] The present invention further preferably adds a disintegrant as an excipient for rapidly releasing the active ingredient from the pH test tablet formed by the pH test composition, thereby improving the disintegration speed and detection timeliness of the tablet formed by the pH test composition.

[0024] Preferably, the filler comprises any one or a combination of at least two of soluble starch, sucrose, mannitol, lactose or inorganic salts, wherein typical but non-limiting combinations are a combination of soluble starch and sucrose, a combination of mannitol and sucrose, a combination of soluble starch and mannitol, a combination of lactose and sucrose, and a combination of inorganic salt and sucrose.

[0025] First, the filler needs to be chemically inert to the pH indicator to avoid interfering with the detection accuracy; second, it needs to have rapid dissolution properties to ensure that the pH test tablets formed by the pH test composition can quickly release the active ingredients when exposed to water, among which soluble starch and inorganic salts have a high water solubility rate; at the same time, it needs to have good compressibility to ensure the molding hardness of the tablets. Mannitol and lactose can reduce the sticking phenomenon during the production process due to their excellent compression properties; in addition, hygroscopic ingredients such as sucrose need to be compounded to improve the stability of the tablets. As the excipient with the highest mass proportion, the filler directly determines the mechanical strength, dissolution rate and detection reliability of the pH test tablets formed by the pH test composition. The above-mentioned fillers can be used alone or in combination according to different needs.

[0026] Preferably, the inorganic salt comprises any one or a combination of at least two of NaCl, KCl, Na2SO4 or K2SO4, wherein typical but non-limiting combinations are a combination of NaCl and KCl, a combination of Na2SO4 and KCl, a combination of NaCl and Na2SO4, a combination of K2SO4 and KCl, and a combination of NaCl and K2SO4.

[0027] Preferably, the filler preferably comprises a combination of sucrose and an inorganic salt.

[0028] The preferred filler of the present invention is a combination of the above two, which has a better detection effect.

[0029] Preferably, the mass ratio of sucrose to inorganic salt is (3-5):1, for example, it can be 3:1, 3.3:1, 3.5:1, 3.7:1, 3.9:1, 4.2:1, 4.4:1, 4.6:1, 4.8:1 or 5:1, etc., but is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0030] Preferably, the content of the filler in the pH test composition is 92 to 99 wt%, for example, it can be 92 wt%, 92.8 wt%, 93.6 wt%, 94.4 wt%, 95.2 wt%, 95.9 wt%, 96.7 wt%, 97.5 wt%, 98.3 wt% or 99 wt%, etc., but is not limited to the listed values, and other values ​​not listed within this range are also applicable.

[0031] Preferably, the binder comprises any one or a combination of at least two of methylcellulose, hydroxypropyl cellulose, hydroxypropyl methylcellulose or polyethylene glycol, wherein typical but non-limiting combinations are a combination of methylcellulose and hydroxypropyl cellulose, a combination of hydroxypropyl methylcellulose and hydroxypropyl cellulose, a combination of methylcellulose and hydroxypropyl methylcellulose, a combination of polyethylene glycol and hydroxypropyl cellulose, and a combination of methylcellulose and polyethylene glycol.

[0032] First, the binder needs to have appropriate bonding ability to ensure that the pH test tablets formed by the pH test composition are tightly formed during the tableting process to avoid looseness or cracking. For example, methylcellulose and hydroxypropyl methylcellulose can provide stable binding force due to the entanglement of the polymer chains; secondly, the binder needs to be rapidly water-soluble to avoid residual effects on the disintegration of the pH test tablets formed by the pH test composition and the timeliness of pH detection. Hydroxypropyl cellulose and polyethylene glycol can accelerate the dissolution of the pH test tablets formed by the pH test composition due to their high hydrophilicity; at the same time, it is necessary to ensure that there is no chemical interference between the binder and the pH indicator and other excipients to avoid moisture absorption or agglomeration and ensure storage stability.

[0033] Preferably, the content of the binder in the pH test composition is 0.2 to 0.5 wt%, for example, it can be 0.2 wt%, 0.24 wt%, 0.27 wt%, 0.3 wt%, 0.34 wt%, 0.37 wt%, 0.4 wt%, 0.44 wt%, 0.47 wt% or 0.5 wt%, etc., but is not limited to the listed values, and other values ​​not listed within this range are also applicable.

[0034] Preferably, the disintegrant comprises low-substituted hydroxypropyl cellulose and / or sodium carboxymethyl starch.

[0035] Low-substituted hydroxypropyl cellulose forms a network structure through swelling, accelerating the disintegration of the pH test tablet formed from the pH test composition. Its moderate degree of substitution balances hydrophilicity and mechanical strength, preventing premature breakage of the pH test tablet formed from the pH test composition due to excessive swelling. Sodium carboxymethyl starch rapidly absorbs water and swells due to its high water absorption, generating disintegration dynamics. The disintegrant must be chemically inert with the pH indicator and filler to avoid interfering with the test reaction or absorbing moisture and agglomerating.

[0036] Preferably, the proportion of hydroxypropyl in the low-substituted hydroxypropyl cellulose is 5-16%, for example, 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15% or 16%.

[0037] Preferably, the mass ratio of low-substituted hydroxypropyl cellulose and sodium carboxymethyl starch in the disintegrant is (0.7-0.9):1, for example, it can be 0.7:1, 0.73:1, 0.75:1, 0.77:1, 0.79:1, 0.82:1, 0.84:1, 0.86:1, 0.88:1 or 0.9:1, etc., but is not limited to the listed values, and other values ​​not listed within this range are also applicable.

[0038] Preferably, the content of the disintegrant in the pH test composition is 0.5-2wt%, for example, it can be 0.5wt%, 0.67wt%, 0.84wt%, 1wt%, 1.17wt%, 1.34wt%, 1.5wt%, 1.67wt%, 1.84wt% or 2wt%, etc., but is not limited to the listed values, and other values ​​not listed within this range are also applicable.

[0039] Preferably, the lubricant comprises polyethylene glycol.

[0040] First, the lubricant needs to effectively reduce the friction between the particles and the mold during the tableting process. Polyethylene glycol forms a lubricating film through the ductility of its molecular chain to avoid sticking or tablet surface defects, thereby ensuring production continuity and tablet appearance integrity. Second, it is necessary to ensure that there is no chemical interference with the pH indicator, filler and disintegrant. Polyethylene glycol materials can avoid affecting the accuracy of the detection reaction due to their chemical inertness.

[0041] Preferably, the weight average molecular weight of the polyethylene glycol in the lubricant is 4000-6000, for example, 4000, 4220, 4440, 4660, 4880, 5110, 5330, 5500, 5700 or 6000, but is not limited to the listed values, and other values ​​not listed within this range are also applicable.

[0042] Preferably, the content of lubricant in the pH test composition is 0.2 to 4 wt%, for example, it can be 0.2 wt%, 0.7 wt%, 1.1 wt%, 1.5 wt%, 1.9 wt%, 2.4 wt%, 2.8 wt%, 3.2 wt%, 3.6 wt% or 4 wt%, etc., but is not limited to the listed values, and other values ​​not listed within this range are also applicable.

[0043] In a second aspect, the present invention provides a pH test tablet, comprising the pH test composition according to the first aspect.

[0044] In the present invention, the pH test composition described in the first aspect is preferably made into a pH test tablet, which is convenient for use, carrying and testing.

[0045] Generally speaking, the amount of pH indicator used in 15 mL of the test solution is 0.04-0.5 mg. However, this is not limited to the absolute amount of pH indicator used in a single pH test tablet. The present invention can be used to prepare pH test tablets with a relative mass percentage content within the range of 0.03-0.4%, and the number of pH test tablets used can be adjusted.

[0046] In a third aspect, the present invention provides a use of the pH test composition of the first aspect and / or the pH test tablet of the second aspect, wherein the pH test composition and / or the pH test tablet are used for pH detection in an aqueous phase.

[0047] Preferably, the aqueous phase contains chlorine.

[0048] Preferably, the aqueous phase comprises tap water and / or swimming pool water.

[0049] Preferably, the application method comprises: mixing the pH test tablet and the aqueous phase to be tested, and measuring the pH value of the aqueous phase to be tested according to a colorimetric method or a pH electrode.

[0050] Compared with the prior art, the present invention has at least the following beneficial effects:

[0051] (1) The pH test composition provided by the present invention can offset the effect of at least 10 ppm of residual chlorine in water by adding a dechlorinating agent and adjusting the amount of pH indicator and the ratio of the dechlorinating agent, thereby achieving accurate detection of swimming pool water with a pH of 6.5 to 8.5, with a test accuracy of ±0.1.

[0052] (2) The present invention develops a fast-response pH test tablet for detecting the pH of swimming pool water or tap water. The tablet is easy to use and has broad application prospects. DETAILED DESCRIPTION

[0053] For the convenience of understanding the present invention, the present invention is given below with examples. It should be understood by those skilled in the art that the examples are only for the purpose of helping to understand the present invention and should not be regarded as specific limitations of the present invention.

[0054] For the convenience of experimental comparison, the following examples and comparative examples were prepared into tablets using the following method, which includes:

[0055] (1) Grinding and crushing a pH indicator, a dechlorinating agent, a filler, a disintegrant, and a lubricant in corresponding mass proportions, mixing them thoroughly, and sieving them to obtain a mixed powder;

[0056] (2) dissolving the binder in a solvent at a target concentration to obtain a binder solution, and adding a predetermined amount of the binder solution to the mixed powder in step (1) to form a soft material, so that the soft material exhibits a state of "forming a mass when lightly pressed and disintegrating upon being touched";

[0057] (3) sieving the soft material described in step (2), and then placing it in a drying oven for drying to obtain a dried powder;

[0058] (4) The powder after drying in step (3) is sieved and granulated to prevent the powder from agglomerating into large particles that reduce the fluidity of the tableting process, and then tablets are pressed according to the quality of the tablets to obtain corresponding pH test tablets.

[0059] In step (2) of the above preparation method, the solvent is water.

[0060] The present invention has no special requirements for the target concentration of the binder in the binder solution, and the concentration of the binder solution that can be used for preparing tablets and is well known to those skilled in the art can be used.

[0061] Example 1 to Example 4

[0062] Examples 1 to 4 provide a pH test composition, the composition of which is shown in Table 1.

[0063] Table 1

[0064]

[0065] Example 5

[0066] This embodiment provides a pH test composition. The pH test composition is the same as that in Example 1 except that the absolute mass of the dechlorinating agent is 0.5 mg, that is, the ratio of the dechlorinating agent to the pH indicator is adjusted to 4.17:1. Detailed description thereof will not be given here.

[0067] Example 6

[0068] This embodiment provides a pH test composition. The pH test composition is the same as that in Example 1 except that the absolute mass of the dechlorinating agent is 3.0 mg, that is, the ratio of the dechlorinating agent to the pH indicator is adjusted to 25:1. Detailed description thereof will not be given here.

[0069] Example 7

[0070] This embodiment provides a pH test composition. The pH test composition is the same as that in Example 1, except that the absolute mass of phenol red is 0.05 mg, i.e., the mass percentage of phenol red is 0.04%, and the absolute mass of the dechlorinating agent is adaptively adjusted to 0.3335 mg to maintain the mass ratio of the dechlorinating agent to phenol red unchanged. Details thereof will not be repeated here.

[0071] Example 8

[0072] This embodiment provides a pH test composition. The pH test composition is the same as that in Example 1, except that the absolute mass of phenol red is 0.7 mg, i.e., the mass percentage of phenol red is 0.55%, and the absolute mass of the dechlorinating agent is adaptively adjusted to 4.669 g to maintain the mass ratio of the dechlorinating agent to phenol red unchanged. Details thereof will not be repeated here.

[0073] Comparative Example 1

[0074] This comparative example provides a pH test composition. The pH test composition is the same as Example 1 except that no dechlorinating agent is added, and details thereof will not be repeated here.

[0075] Comparative Example 2

[0076] This comparative example provides a pH test composition. The pH test composition is the same as that in Example 1 except that sodium thiosulfate is replaced by sodium bisulfite, and details thereof will not be repeated here.

[0077] Comparative Example 3

[0078] This comparative example provides a pH test composition. The pH test composition is the same as that in Example 1 except that sodium thiosulfate is replaced by sodium metabisulfite, and details thereof will not be repeated here.

[0079] Comparative Example 4

[0080] This comparative example provides a pH test composition, which is the same as Example 1 except that sodium thiosulfate is replaced by ferrous sulfate. Due to the color of ferrous sulfate itself, pH detection cannot be performed.

[0081] Comparative Example 5

[0082] This comparative example provides a pH test composition. The pH test composition is the same as that in Example 1 except that sodium thiosulfate is replaced by sodium oxalate, and details thereof will not be repeated here.

[0083] Comparative Example 6

[0084] This comparative example provides a pH test substance, which is a commercially available pH tablet A, which can be used to test swimming pool water and tap water, with a nominal test range of pH 6.5 to 8.4.

[0085] Test method: Dissolve one pH test tablet in 15 mL of the test solution. After the tablet is stirred and dissolved, the pH is determined by colorimetry. A pH electrode is used to detect the pH of the original test solution and the test solution after the pH test tablet is added.

[0086] The pH test results in the chlorine-free aqueous phase (0 ppm) are shown in Table 1 for the test results of the above embodiments and comparative examples.

[0087] Table 1

[0088]

[0089] The pH test results in the first group of chlorine-free water phase (0 ppm residual chlorine, pH = 8.2), the second group of chlorine-containing water phase (10 ppm residual chlorine, pH = 8.2) and the third group of chlorine-containing water phase (20 ppm residual chlorine, pH = 8.2) are shown in Table 2.

[0090] Table 2

[0091]

[0092] From Tables 1 and 2, we can see the following points:

[0093] (1) Based on Examples 1 to 4, it can be seen that the pH test composition provided by the present invention can be formed into tablets to better detect the pH in water. When the pH test composition is tested in a chlorine-free aqueous phase, the error between the pH test result and the pH electrode test result is only within 0.05; when the pH test is performed in a chlorine-containing aqueous phase, the error between the pH test result and the pH electrode test result is also only within 0.1. This shows that the tablet formed by the pH test composition provided by the present invention is suitable for pH detection in chlorine-containing or chlorine-free aqueous phases, and can be preferably used for pH detection of swimming pool water or tap water.

[0094] (2) From Example 1 and Examples 5-6, it can be seen that the mass ratio of the dechlorinating agent to the pH indicator in Example 1 is 6.67:1, compared with 4.17:1 and 25:1 in Examples 5-6 respectively. The difference between the pH obtained by the colorimetric method in Example 1 and the pH value of the test solution detected by the electrode is only within 0.05, while the solution pH obtained by the colorimetric method in Example 5 is 0.5 higher than the electrode detection result in the first group of tests, 0.05 higher than the electrode detection result in the second group of tests, and 0.3 lower than the electrode detection result in the third group of tests, indicating that the test stability is poor and the detection accuracy is relatively low; the solution pH obtained by the colorimetric method in Example 6 is 0.5 higher than the electrode detection result in the first group of tests, 0.6 lower than the electrode detection result in the second group of tests, and 1.5 lower than the electrode detection result in the third group of tests, indicating that the test stability is poor and the detection accuracy is relatively low; thus, it is shown that the present invention preferably controls the mass ratio of the dechlorinating agent to the pH indicator within a reasonable range, which can better improve the detection accuracy.

[0095] (3) It can be seen from Example 1 and Examples 7 to 8 that the mass percentage of the pH indicator in the pH test composition provided by the present invention has a significant impact on the test results. The present invention preferably controls the mass percentage of the pH indicator within a reasonable range, which has the advantage of accurate test results.

[0096] (4) From the comprehensive analysis of Example 1 and Comparative Examples 1 to 5, it can be seen that no dechlorinating agent was added in Comparative Example 1, resulting in a significant decrease in the accuracy of pH detection in the chlorine-containing aqueous phase; in Comparative Example 2, sodium thiosulfate was replaced by sodium bisulfite, and the reaction of sodium bisulfite with residual chlorine was faster and more thorough under acidic conditions. For the pH range of the test solution (6.5 to 8.5) that is neutral or alkaline, the dechlorination reaction is slow, which easily causes the residual chlorine to oxidize the indicator and thus shift the color, and the accuracy of the final test result is reduced; in Comparative Example 3, sodium thiosulfate was replaced by sodium metabisulfite, and the reaction rate of sodium metabisulfite with residual chlorine was slower, because it was soluble in water and needed to be hydrolyzed before further reacting with residual chlorine, and the reaction process consumed OH in the solution. - (or generate H + ), which will affect the accuracy of the solution pH measurement. In Comparative Example 4, sodium thiosulfate is replaced by ferrous sulfate. Ferrous sulfate itself is light green, and after reacting with residual chlorine, the solution will appear yellow-brown. The color brought by itself will affect the color of the pH indicator. In Comparative Example 5, sodium thiosulfate is replaced by sodium oxalate. After reacting with residual chlorine, sodium oxalate will produce additional OH - , resulting in the original solution pH being affected and the detection deviation. In Comparative Example 6, commercially available pH tablets were used, and the results showed that the detection error was large and the accuracy was low.

[0097] Dissolution rate comparison

[0098] Example 9

[0099] This embodiment provides a pH test composition. The pH test composition is the same as that of Example 1 except that no disintegrant is added, and details thereof will not be repeated here.

[0100] Example 10

[0101] This embodiment provides a pH test composition. The pH test composition is the same as that of Example 1 except that the absolute mass of the disintegrant is 3 mg, that is, the content of the disintegrant in the pH test composition is 2.39 wt %. Detailed description is omitted here.

[0102] Example 11

[0103] This embodiment provides a pH test composition. The pH test composition is the same as that of Example 3 except that all sucrose in the filler is replaced by sodium chloride. The details are not described again.

[0104] Taking Example 1, Example 3, and Examples 9 to 11 as examples, the time required for the pH tablet to dissolve in water was calculated. The results are shown in Table 3.

[0105] Table 3

[0106]

[0107]

[0108] As can be seen from Table 3, the pH tablets provided by the present invention have excellent dissolution effects and can be dissolved within 50 seconds. Comparing Example 1 with Examples 9 and 10, it can be seen that the present invention preferably uses a disintegrant, and excessive addition cannot continuously reduce the dissolution time. Controlling the content of the disintegrant within a reasonable range can better shorten the dissolution time. At the same time, comparing Example 3 with Example 11, it can be seen that using sodium chloride as a filler has a shorter dissolution time.

[0109] The present invention uses the above-described embodiments to illustrate the detailed features of the present invention. However, the present invention is not limited to the above-described detailed features, which does not mean that the present invention must rely on the above-described detailed features to be implemented. Those skilled in the art should understand that any improvements to the present invention, equivalent replacements for the selected technical features of the present invention, additions to auxiliary technical features, and selections of specific methods, etc., fall within the scope of protection and disclosure of the present invention.

Claims

1. A pH test composition, characterized in that The pH test composition includes a pH indicator, a dechlorinating agent, and an additive; Wherein, the dechlorination agent includes any one of sodium thiosulfate, sodium sulfite or sodium ascorbate, or a combination of at least two of them.

2. The pH test composition according to claim 1, wherein The mass ratio of the dechlorinating agent to the pH indicator is (10-50):1; The pH indicator comprises any one of phenol red, bromothymol blue or m-cresol purple or a combination of at least two thereof; The mass percentage of the pH indicator in the pH test composition is 0.03-0.4%.

3. The pH test composition according to claim 1 or 2, characterized in that The additives include fillers and binders; the additives may also optionally include disintegrants and / or lubricants.

4. The pH test composition according to claim 3, wherein The filler includes any one or a combination of at least two of soluble starch, sucrose, mannitol, lactose or inorganic salts; The inorganic salt includes any one of NaCl, KCl, Na2SO4 or K2SO4 or a combination of at least two; The filler preferably comprises a combination of sucrose and an inorganic salt; The mass ratio of sucrose to inorganic salt is (3-5):1; The content of the filler in the pH test composition is 92-99 wt %.

5. The pH test composition according to claim 3, characterized in that The binder comprises any one of methylcellulose, hydroxypropyl cellulose, hydroxypropyl methylcellulose or polyethylene glycol, or a combination of at least two thereof; The content of the binder in the pH test composition is 0.2-0.5 wt %.

6. The pH test composition according to claim 3, characterized in that The disintegrant includes low-substituted hydroxypropyl cellulose and / or sodium carboxymethyl starch; The proportion of hydroxypropyl in the low-substituted hydroxypropyl cellulose is 5-16%.

7. The pH test composition according to claim 6, characterized in that The mass ratio of low-substituted hydroxypropyl cellulose and sodium carboxymethyl starch in the disintegrant is (0.7-0.9):1; The content of the disintegrant in the pH test composition is 0.5-2 wt %.

8. The pH test composition according to claim 3, wherein The lubricant includes polyethylene glycol; The weight average molecular weight of the polyethylene glycol in the lubricant is 4000 to 6000; The content of the lubricant in the pH test composition is 0.2-4 wt %.

9. A pH test tablet, characterized in that The pH test tablet comprises the pH test composition according to any one of claims 1 to 8.

10. Use of the pH test composition according to any one of claims 1 to 8 and / or the pH test tablet according to claim 7, characterized in that: The pH test composition and / or pH test tablet is used for pH detection in an aqueous phase; Preferably, the aqueous phase contains chlorine; Preferably, the aqueous phase comprises tap water and / or swimming pool water; Preferably, the application method comprises: mixing the pH test tablet and the aqueous phase to be tested, and measuring the pH value of the aqueous phase to be tested according to a colorimetric method or a pH electrode.

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