Phosphate detection reagent, detection kit and detection method

Abstract

A phosphate detection reagent, a detection kit and a detection method. The detection reagent comprises a reagent A and a reagent B. The reagent A comprises a strong acid reagent, a molybdate and a weighting agent, at a mass ratio of the strong acid reagent to the molybdate to the weighting agent of (2-98) : (0.2-20.0) : (0-50.0). The reagent B comprises a strong acid reagent, a masking agent, a reducing agent, an accelerant and a weighting agent, at a mass ratio of the strong acid reagent to the masking agent to the reducing agent to the accelerant to the weighting agent of (2-98) : (1.0-30.0) : (0.5-50.0) : (0.1-50.0) : (0-50.0). The detection reagent has no special environmental requirements, no special three-waste pollution, low costs, simple and non-interfering detection steps with a higher accuracy, a short color development time and high portability.

Description

A phosphate detection reagent, detection kit and detection method Technical Field

[0001] The present invention belongs to the technical field of analytical chemistry, and in particular relates to a phosphate detection reagent, a detection kit and a detection method. Background Art

[0002] Phosphorus is an essential element for biological growth, but excessive phosphorus levels in water can interfere with the coagulation process in water plants. Phosphorus is a key element for algae growth, and excessive phosphorus levels can lead to excessive algae growth, eutrophication, and impact the ecological balance of the water. Phosphate levels are generally low in natural water, primarily coming from domestic sewage, fertilizer, smelting, organophosphorus pesticides, and industrial wastewater from synthetic detergent industries. Phosphorus is a key indicator for evaluating water quality.

[0003] Currently, phosphate is commonly determined using methods such as gravimetric, titration, ion chromatography, spectrophotometry, atomic absorption spectrophotometry, and Raman spectroscopy. Spectrophotometry is the most commonly used method and is widely used in the water quality testing industry. Its advantages are simplicity, speed, accuracy, and the availability of comprehensive standard analytical methods. However, this method is associated with high reagent consumption, significant environmental pollution, tediousness, time-consuming procedures, high technical requirements, and difficulties in emergency response, limiting its application in rapid testing. The gravimetric method offers the advantage of high accuracy and is still recommended as a standard method both domestically and internationally, making it suitable for standard laboratories and research institutions. However, its disadvantage is its slow analysis speed, making it impractical for on-site analysis in enterprises. Titration offers the advantage of highly accurate phosphorus content, unlike instrumental analysis, which requires multiple absorption tests due to high phosphorus concentrations exceeding the measurement range, leading to experimental error. Its disadvantage is its cumbersome, time-consuming, and labor-intensive traditional chemical titration, which does not meet current scientific and technological requirements. The advantages of the rapid test kit method are that it is cheap, only a few hundred yuan is needed to test dozens of times, it is fast, and the results can be obtained in just 5 minutes, and it is light and convenient. Its disadvantage is that it is not accurate enough and can only estimate a large range of values.

[0004] Ammonium molybdate spectrophotometry is commonly used to detect phosphate content in water systems. This method includes the molybdenum yellow method or the molybdenum blue method. The ammonium molybdate spectrophotometry method is simple to operate and inexpensive. The molybdenum yellow method directly measures the phosphate content of a heteropolyacid, phosphovanadomolybdate yellow, formed by the reaction of phosphoric acid with vanadic acid or molybdic acid. However, existing molybdenum yellow methods generally use liquid solutions of strong acids such as sulfuric acid or nitric acid. These strong acid liquid solutions require high transportation requirements, are cumbersome to operate, are unsafe, and pose certain risks. The molybdenum blue method reacts active phosphate with molybdate to form phosphomolybdate yellow. This is then reduced to phosphomolybdate blue using a reducing agent. The color depth of the blue is proportional to the available phosphorus concentration and conforms to the Lambert-Beer law within a certain range, allowing for colorimetric determination. Reducing agents used include stannous chloride, ascorbic acid, hydrazine sulfate, and sulfite. However, these methods have drawbacks, such as the need for specialized equipment, high cost, cumbersome operation, high technical requirements, and difficulty in emergency response, which limit their application in rapid detection. To address these shortcomings, rapid, accurate, portable, simple-to-use, and quick phosphate detection kits have been developed in recent years. However, in practice, these kits have been found to have a high false-positive rate and are unable to eliminate interference from elements such as arsenic and silicon.

[0005] Chinese patent publication number CN106442511A discloses a rapid phosphate detection kit and method. Using this kit and its accompanying test strips, the entire phosphate detection process can be reduced to just 2 minutes, significantly simplifying the process and extending the shelf life to two years. However, the method lacks the ability to eliminate interference from elements such as arsenic and silicon. Furthermore, it uses a liquid solution of a strong acid, such as sulfuric acid or nitric acid. This liquid solution of a strong acid is demanding to transport, cumbersome to operate, unsafe, and potentially dangerous.

[0006] Therefore, improving the measurement sensitivity of the test kit and eliminating the interference of other elements is a key issue that needs to be solved at present.

[0007] Summary of the Invention

[0008] The purpose of the present invention is to overcome the shortcomings and deficiencies of the prior art and to provide a phosphate detection reagent, a detection kit and a detection method.

[0009] The specific technical solutions of the present invention are as follows:

[0010] In one aspect, the present invention provides a phosphate detection reagent, comprising reagent A and reagent B;

[0011] The reagent A comprises a strong acidic reagent, a molybdate and a weighting agent, wherein the mass ratio of the strong acidic reagent, the molybdate and the weighting agent is (2-98): (0.2-20.0): (0-50.0);

[0012] The reagent B includes a strong acidic reagent, a masking agent, a reducing agent, an accelerating agent and a weighting agent, wherein the mass ratio of the strong acidic reagent, the masking agent, the reducing agent, the accelerating agent and the weighting agent is (2-98): (1.0-30.0): (0.5-50.0): (0.1-50.0): (0-50.0).

[0013] Furthermore, the mass ratio of the strong acid reagent, molybdate and weighting agent in the reagent A is (5-10): (0.5-2.0): (0-5.0);

[0014] The mass ratio of the strong acid reagent, the masking agent, the reducing agent, the speed increasing agent and the weighting agent in the reagent B is (5-10): (1.0-5.0): (0.5-1.5): (0.1-0.5): (0-5.0).

[0015] Preferably, the mass ratio of the strong acid reagent, molybdate and weighting agent in the reagent A is 7:1:2;

[0016] The mass ratio of the strong acid reagent, the masking agent, the reducing agent, the speed increasing agent and the weighting agent in the reagent B is 5:1:1:0.2:2.

[0017] Furthermore, the strong acidic agent is selected from one or more of sulfamic acid, citric acid, and glycolic acid;

[0018] The molybdate includes one or more of sodium molybdate, ammonium molybdate and potassium molybdate;

[0019] The masking agent includes one or more of potassium sodium tartrate, citric acid, oxalic acid, tartaric acid, and EDTA;

[0020] The reducing agent includes at least one of ascorbic acid, hydrazine sulfate, tin dichloride, sodium chloride-stannous chloride, hydrazine sulfate, 1-amino-2-naphthalene-4-sulfonic acid, p-aminophenol sulfate, hydroquinone, phenylthiocarbamide, ammonium ferrous sulfate-fructose, ammonium ferrous sulfate-glucose, sodium metabisulfite, metol, sodium formaldehyde hyposulfite, titanium trichloride, sulfite-iron salt, ammonium ferrous sulfate, sodium sulfite, sodium bisulfite and antimony (III);

[0021] The speed increasing agent is at least one of potassium antimony tartrate and bismuth nitrate;

[0022] The weighting agent includes one or more of sodium chloride, sodium sulfate, and potassium sulfate.

[0023] Furthermore, the strong acidic reagent is aminosulfonic acid, the molybdate is sodium molybdate, the masking agent is potassium sodium tartrate, the reducing agent is ascorbic acid, the speed increasing agent is potassium antimony tartrate, and the weighting agent is sodium chloride.

[0024] Another aspect of the present invention provides a phosphate detection kit, which comprises reagent A, reagent B, and a standard colorimetric card.

[0025] Another aspect of the present invention provides a method for preparing the above-mentioned detection kit, comprising the steps of:

[0026] Prepare Reagent A: Grind the strong acid reagent, molybdate, and weighting agent thoroughly according to the above mass ratio. The ground mixture should pass through an 80-mesh standard sieve. After packaging, evacuate or seal with inert gas.

[0027] Prepare reagent B: Grind the strong acid reagent, masking agent, reducing agent, weighting agent and speed increasing agent thoroughly according to the above mass ratio. The mixed components after grinding can pass through an 80-mesh standard sieve. After packaging, vacuum or seal with inert gas.

[0028] Preparation of standard colorimetric card: prepare phosphate standard solutions with concentrations of 0 mg / L, 2.0 mg / L, 5.0 mg / L, 10.0 mg / L, 20 mg / L, 50 mg / L, 100 mg / L, 200 mg / L, 500 mg / L, and 1000 mg / L, take 1-5 mL of various phosphate standard solutions, add the reagent A described above, shake well, then add reagent B, shake well, and develop color for 1-5 minutes to prepare the standard colorimetric card.

[0029] Furthermore, reagent A and reagent B are packaged into 0.1-0.5 g per tube.

[0030] On the other hand, the present invention also provides a method for detecting phosphate, which uses the detection kit for detection, comprising the steps of: adding 1-5 mL of a water sample to be tested to reagent A, shaking well, then adding reagent B, shaking well, and after 1-5 minutes, comparing with a standard colorimetric card to determine the concentration of phosphate in the water sample to be tested.

[0031] The test kit of this invention should be stored in a cool, dry place, preferably below 26°C. If the temperature is above 25°C, unused test strips should be stored in the refrigerator in a fresh-keeping layer and packaged in a light-proof and moisture-proof container. The test kit of this invention has an effective shelf life of approximately one year.

[0032] The beneficial effects of the present invention are:

[0033] 1. The phosphate detection method of the present invention is based on the phosphomolybdenum blue method. It is a fast and flexible phosphate rapid detection method that does not require instruments and equipment and has low production and use costs. The kit of the present invention has no special environmental requirements, no special three wastes pollution, low cost, simple detection steps without interference, more accurate determination, short color development time and strong mobility. Compared with traditional methods or other determination forms, the present invention is more convenient to use and does not require specialized technicians to perform determinations. The reagents used in the present invention are all common chemical reagents, which are safe, reliable and inexpensive. It has a wide range of applications and can be used to determine the phosphate content of water bodies such as chemical wastewater, surface water, urban sewage recycling-landscape environment water and urban miscellaneous water, especially in the monitoring of phosphate in the field of environmental protection.

[0034] 2. The present invention eliminates interference from elements such as arsenic and silicon by adding a large amount of acid to reagent A. Phosphate in the water sample reacts with the molybdate in reagent A to produce a pale yellow phosphomolybdate yellow. The masking agent in reagent B then chelates the molybdenum in the molybdate, thereby improving detection sensitivity. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] FIG1 is a standard colorimetric card of the detection kit of Example 1.

[0036] FIG2 is the color development result of Example 1;

[0037] FIG3 is the color development result of Example 2;

[0038] FIG4 is the color development result of Example 3;

[0039] FIG5 is the color development result of Example 4. DETAILED DESCRIPTION

[0040] To more clearly understand the present invention, the present invention is further described with reference to the following examples and accompanying drawings. The examples are intended to illustrate the present invention only and are not intended to limit the present invention in any way. In the examples, all raw materials and reagents are commercially available. Experimental methods without specific conditions are conventional methods and conditions well known in the art, or according to the conditions recommended by the instrument manufacturer.

[0041] This embodiment provides a phosphate detection kit, which includes reagent A, reagent B, and a standard colorimetric card. The specific preparation method is as follows:

[0042] Preparation of Reagent A: According to the mass ratio of strongly acidic reagent, molybdate and weighting agent is (2-98): (0.2-20.0): (0-50.0), prepare strongly acidic reagent, molybdate, and weighting agent, add the above components to a mortar, fully grind until all raw materials can pass through an 80-mesh standard sieve, then pack into 0.1-0.5 gram per tube, evacuate or seal with inert gas. In a preferred embodiment, the mass ratio of strongly acidic reagent, molybdate and weighting agent is (5-10): (0.5-2.0): (0-5.0).

[0043] The preparation of reagent B: according to the mass ratio of strongly acidic reagent, screening agent, reducing agent, speed-increasing agent and weighting agent, be (2~98): (1.0~30.0): (0.5~50.0): (0.1~50.0): (0~50.0), prepare strongly acidic reagent, screening agent, reducing agent, speed-increasing agent and weighting agent, above-mentioned components are joined in mortar, fully grind to all raw materials and all can pass through 80 mesh standard sieves, then be divided into every tube 0.1-0.5 gram, vacuumize or lead to inert gas sealing. In a preferred embodiment, the mass ratio of strongly acidic reagent, screening agent, reducing agent, speed-increasing agent and weighting agent is (5~10): (1.0~5.0): (0.5~1.5): (0.1~0.5): (0~5.0).

[0044] Preparation of standard colorimetric card: Use phosphate stock solution (1000 mg / L) to prepare phosphate standard solutions with concentrations of 0 mg / L, 2.0 mg / L, 5.0 mg / L, 10.0 mg / L, 20 mg / L, 50 mg / L, 100 mg / L, 200 mg / L, 500 mg / L, and 1000 mg / L. Take 1-5 mL of various phosphate standard solutions, add solid reagent A respectively, shake well, then add solid reagent B, shake well, and color will develop for 1-5 minutes until the color is basically stable to prepare the standard colorimetric card.

[0045] Wherein, the strong acidic agent is selected from one or more of sulfamic acid, citric acid, and glycolic acid;

[0046] Molybdate includes one or more of sodium molybdate, ammonium molybdate and potassium molybdate;

[0047] The masking agent includes one or more of potassium sodium tartrate, citric acid, oxalic acid, tartaric acid, and EDTA, and the masking agent is used to chelate molybdenum in molybdate;

[0048] The reducing agent includes at least one of ascorbic acid, hydrazine sulfate, tin dichloride, sodium chloride-stannous chloride, hydrazine sulfate, 1-amino-2-naphthalene-4-sulfonic acid, p-aminophenol sulfate, hydroquinone, thiophenylaminourea, ammonium ferrous sulfate-fructose, ammonium ferrous sulfate-glucose, sodium metabisulfite, metol, sodium formaldehyde hyposulfite, titanium trichloride, sulfite-iron salt, ammonium ferrous sulfate, sodium sulfite, sodium bisulfite and antimony (III);

[0049] The speed increasing agent is at least one of potassium antimony tartrate and bismuth nitrate;

[0050] The weighting agent includes one or more of sodium chloride, sodium sulfate, and potassium sulfate. The weighting agent facilitates the weighing of reagent A and reagent B.

[0051] The prepared test kit should be stored in a cool, dry place, preferably below 26°C. If the temperature is above 25°C, the unused test paper bag should be stored in the refrigerator in the fresh-keeping layer and stored in a light-proof and moisture-proof packaging.

[0052] This embodiment further provides a method for detecting phosphate, which is performed using a prepared detection kit, comprising the steps of adding 1-5 mL of a water sample to be tested to reagent A, shaking well, then adding reagent B, shaking well, and after 1-5 minutes, if phosphate is present in the water, a blue-green color is displayed. The depth of the color is related to the concentration of phosphate in the water, and the concentration of phosphate in the water sample to be tested is determined by comparing with a standard colorimetric card.

[0053] Example 1

[0054] This example provides a detection kit. The raw materials for Reagent A are: 7 g sulfamic acid, 1 g sodium molybdate, and 2 g sodium chloride. The raw materials for Reagent B are: 5 g sulfamic acid, 1 g potassium sodium tartrate, 1 g ascorbic acid, 0.2 g potassium antimony tartrate, and 2 g sodium chloride. Reagents A and B are prepared according to the above method and packaged in 0.2 g tubes.

[0055] Phosphate standard solutions with concentrations of 0 mg / L, 0.1 mg / L, 0.2 mg / L, 0.5 mg / L, 1 mg / L, 2.0 mg / L, 5.0 mg / L, 10.0 mg / L, 20 mg / L, 30 mg / L, 50 mg / L, 100 mg / L, 200 mg / L, 500 mg / L, and 1000 mg / L were prepared using phosphate stock solution (1000 mg / L). 1-5 mL of various phosphate standard solutions were added to solid reagent A, shaken well, and then solid reagent B was added, shaken well, and the color was substantially stable after 1-5 minutes of color development. The color development results of phosphate standard solutions of different concentrations are shown in Figure 2, and the standard colorimetric card prepared based on reagent A and reagent B according to the kit of this embodiment is shown in Figure 1.

[0056] Example 2

[0057] This example provides a detection kit. The raw materials for each component of Reagent A are: 1 g sulfamic acid, 1 g sodium molybdate, and 8 g sodium chloride. The raw materials for each component of Reagent B are: 1 g sulfamic acid, 1 g potassium sodium tartrate, 1 g ascorbic acid, 0.2 g potassium antimony tartrate, and 7 g sodium chloride. Reagents A and B are prepared according to the above method and packaged in 0.2 g tubes.

[0058] Silica standard solutions at concentrations of 0 mg / L, 0.1 mg / L, 0.2 mg / L, 0.5 mg / L, 1 mg / L, 2.0 mg / L, 5.0 mg / L, 10.0 mg / L, 20 mg / L, 30 mg / L, 50 mg / L, and 100 mg / L were prepared from a 1000 mg / L silica stock solution. 1-5 mL of each silica standard solution was added to solid reagent A and shaken well. Solid reagent B was then added and shaken well. The color developed for 1-5 minutes and stabilized. The results are shown in Figure 3. This indicates that even with reduced acid concentration, the kit was unable to eliminate interference from elements such as silicon.

[0059] Example 3

[0060] This example provides a detection kit. The raw materials for Reagent A are: 7 g sulfamic acid, 1 g sodium molybdate, and 2 g sodium chloride. The raw materials for Reagent B are: 5 g sulfamic acid, 0.2 g potassium antimony tartrate, and 4 g sodium chloride. Reagents A and B are prepared according to the above method and packaged in 0.2 g tubes.

[0061] Silica standard solutions at concentrations of 0.25 mg / L, 0.5 mg / L, 1.0 mg / L, 2.0 mg / L, 4.0 mg / L, 8.0 mg / L, 15.0 mg / L, 30 mg / L, 60 mg / L, 120 mg / L, 250 mg / L, and 500 mg / L were prepared using a silica stock solution (1000 mg / L). 1-5 mL of each silica standard solution was added to solid reagent A and shaken well. Solid reagent B was then added and shaken well. The color developed for 1-5 minutes and stabilized. The results are shown in Figure 4. This indicates that without the addition of a masking agent, the kit cannot eliminate interference from elements such as silicon.

[0062] Example 4

[0063] This example provides a detection kit. The raw materials for Reagent A are: 7 g sulfamic acid, 1 g sodium molybdate, and 2 g sodium chloride. The raw materials for Reagent B are: 5 g sulfamic acid, 0.2 g potassium antimony tartrate, and 4 g sodium chloride. Reagents A and B are prepared according to the above method and packaged in 0.2 g tubes.

[0064] Silica stock solution (1000 mg / L) was used to prepare silica standard solutions with concentrations of 0.02 mg / L, 0.05 mg / L, 0.1 mg / L, 0.2 mg / L, 0.4 mg / L, 0.8 mg / L, 1.5 mg / L, 3.0 mg / L, 6.0 mg / L, 12.0 mg / L, 25 mg / L, and 50 mg / L. 1-5 mL of each silica standard solution was added to solid reagent B, shaken well, and then solid reagent A was added, shaken well, and the color was basically stable after 1-5 minutes of color development. The results are shown in Figure 5. This shows that without adding a masking agent, the kit cannot eliminate the interference of elements such as silicon. The results are shown in Figure 5. Changing the order of adding the reagents cannot eliminate the interference of elements such as silicon.

[0065] Obviously, the above embodiments are merely examples for clarity of explanation and are not intended to limit the implementation methods. Those skilled in the art will readily appreciate that other variations or modifications based on the above descriptions are possible. It is not necessary and impossible to enumerate all implementation methods here. Obvious variations or modifications arising therefrom remain within the scope of protection of the present invention.

Claims

1. A detection reagent for phosphate radical, characterized in that, The detection reagent includes reagent A and reagent B; The reagent A comprises a strong acid reagent, a molybdate and a weighting agent, wherein the mass ratio of the strong acid reagent, the molybdate and the weighting agent is (2-98): (0.2-20.0): (0-50.0); The reagent B comprises a strong acidic reagent, a masking agent, a reducing agent, an accelerating agent and a weighting agent, wherein the mass ratio of the strong acidic reagent, the masking agent, the reducing agent, the accelerating agent and the weighting agent is (2-98): (1.0-30.0): (0.5-50.0): (0.1-50.0): (0-50.0).

2. The detection reagent according to claim 1, wherein The mass ratio of the strong acid reagent, molybdate and weighting agent in the reagent A is (5-10): (0.5-2.0): (0-5.0); The mass ratio of the strong acid reagent, the masking agent, the reducing agent, the speed increasing agent and the weight increasing agent in the reagent B is (5-10): (1.0-5.0): (0.5-1.5): (0.1-0.5): (0-5.0).

3. The detection reagent according to claim 1, wherein The mass ratio of the strong acid reagent, molybdate and weighting agent in the reagent A is 7:1:2; The mass ratio of the strong acid reagent, the masking agent, the reducing agent, the speed increasing agent and the weight increasing agent in the reagent B is 5:1:1:0.2:

2.

4. The detection reagent according to any one of claims 1 to 3, characterized in that, The strong acidic reagent is selected from one or more of aminosulfonic acid, citric acid, and glycolic acid; The molybdate includes one or more of sodium molybdate, ammonium molybdate and potassium molybdate; The masking agent includes one or more of potassium sodium tartrate, citric acid, oxalic acid, tartaric acid, and EDTA; The reducing agent includes at least one of ascorbic acid, hydrazine sulfate, tin dichloride, sodium chloride-stannous chloride, hydrazine sulfate, 1-amino-2-tetraphenol-4-sulfonic acid, p-aminophenol sulfate, hydroquinone, thiophenylamine, ammonium ferrous sulfate-fructose, ammonium ferrous sulfate-glucose, sodium pyrosulfite, metol, sodium formaldehyde hyposulfite, titanium trichloride, sulfite-iron salt, ammonium ferrous sulfate, sodium sulfite, sodium bisulfite and antimony (III); The speed increasing agent is at least one of potassium antimony tartrate and bismuth nitrate; The weighting agent includes one or more of sodium chloride, sodium sulfate and potassium sulfate.

5. The detection reagent according to any one of claims 1-3, characterized in that, The strong acid reagent is aminosulfonic acid, the molybdate is sodium molybdate, the masking agent is potassium sodium tartrate, the reducing agent is ascorbic acid, the speed increasing agent is potassium antimony tartrate, and the weighting agent is sodium chloride.

6. A detection kit for phosphate radicals, characterized in that, The kit comprises the reagent A and reagent B described in claim 1, and a standard colorimetric card.

7. The preparation method of the detection kit according to claim 6, characterized in that, Includes steps: Preparation of reagent A: fully grinding the strong acid reagent, molybdate and weighting agent according to the mass ratio of claim 1, the mixed components after grinding can pass through an 80-mesh standard sieve, and after packaging, vacuuming or sealing with inert gas; Preparation of reagent B: fully grinding the strong acid reagent, masking agent, reducing agent, speed increasing agent and weighting agent according to the mass ratio of claim 1, the mixed components after grinding can pass through an 80-mesh standard sieve, and after packaging, vacuuming or sealing with inert gas; Preparation of standard color comparison card: Prepare phosphate standard solutions with concentrations of 0 mg / L, 2.0 mg / L, 5.0 mg / L, 10.0 mg / L, 20 mg / L, 50 mg / L, 100 mg / L, 200 mg / L, 500 mg / L, and 1000 mg / L. Take 1 - 5 mL of each phosphate standard solution, add them to the reagent A respectively, shake well, then add reagent B, shake well. After color development for 1 - 5 minutes, a standard color comparison card is prepared.

8. The preparation method according to claim 7, characterized in that, Reagent A and reagent B are dispensed into tubes of 0.1 - 0.5 g each.

9. A method for detecting phosphate radicals, characterized in that, Detection is carried out using the detection kit described in claim 6, including the steps: Add 1 - 5 mL of the water sample to be tested to reagent A, shake well, then add reagent B, shake well. After 1 - 5 minutes, compare with the standard color comparison card to determine the concentration of phosphate in the water sample to be tested.

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