A method for rapid detection of hydrogen sulfide in a solution

Abstract

The application discloses a method for rapidly detecting hydrogen sulfide in a solution, which comprises the following steps: firstly, dispersing nano AgI liquid in the solution to be detected under an acidic condition to obtain an iodine ion solution; then, introducing a CsPbBr3 quantum dot solution into the iodine ion solution to react; and finally, realizing visual detection of the content of hydrogen sulfide according to the change information of the fluorescence color of the solution after the reaction or the change value of the right shift of the fluorescence emission peak position. The application uses CsPbBr3 quantum dots as a fluorescence probe, can directly react with the iodine ion formed by the conversion of hydrogen sulfide, does not need to introduce other trigger media or conditions, can cause obvious changes of the fluorescence emission peak position and the fluorescence color, realizes efficient visual detection of the content of hydrogen sulfide, and has the advantages of simple operation, high sensitivity, rich color change and the like, and is suitable for popularization and application.

Description

Technical Field

[0001] This invention belongs to the field of chemical analysis and detection technology, specifically relating to a method for rapid detection of hydrogen sulfide in solution. Background Technology

[0002] Hydrogen sulfide (H2S) is an endogenous signaling molecule that plays a crucial role in biomedicine and food safety. Changes in its concentration are indicative of early disease diagnosis and food spoilage detection. In beer production, hydrogen sulfide is one of the key compounds affecting flavor. Appropriate amounts of hydrogen sulfide contribute to a full-bodied, rounded mouthfeel and harmonious aroma in beer, while excessive amounts can lead to a decline in the quality of fermented foods and beverages, producing unpleasant odors such as yeasty or rotten egg smells. This not only affects beer quality and consumer acceptance but may also cause food safety issues and economic losses. The hydrogen sulfide content in beer is strictly limited; high-quality beer typically has a hydrogen sulfide content controlled between 1-5 μg / L to avoid unpleasant odors. Therefore, developing a rapid, accurate, and sensitive method for detecting hydrogen sulfide is of significant practical value and importance for ensuring food safety and improving beer quality.

[0003] Currently, many methods have been developed for the detection of hydrogen sulfide, such as high performance liquid chromatography, electrochemical methods, gas chromatography, methylene blue spectrophotometry, and electrochemiluminescence. However, most of these methods rely on large and medium-sized instruments, are time-consuming, expensive, involve complex sample pretreatment processes, and require specialized technicians. They cannot meet the requirements for rapid, timely, and accurate assessment of the hydrogen sulfide content in solutions. Therefore, there is an urgent need to develop a rapid, sensitive, and accurate method for the detection of hydrogen sulfide in solutions. Summary of the Invention

[0004] The purpose of this invention is to address the shortcomings of existing technologies by providing a method for detecting hydrogen sulfide in solutions (such as beer) using perovskite quantum dots. This method has advantages such as simple operation, high sensitivity, and rich color changes, enabling rapid, quantitative, and visual identification of hydrogen sulfide in solutions, and is suitable for widespread application.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0006] A rapid method for detecting hydrogen sulfide in solution first utilizes AgI nanoparticles to react with hydrogen sulfide in the test solution, generating free iodine ions. Then, CsPbBr3 quantum dots are introduced as a fluorescence signal reporter. The method utilizes the change in the fluorescence color of the solution after the reaction or the rightward shift of the fluorescence emission peak position to achieve visual detection of the hydrogen sulfide content. The specific steps include:

[0007] An acidic buffer solution and the test solution are added to a nano AgI dispersion. After the reaction is complete, an iodide ion solution is obtained. Then, a CsPbBr3 quantum dot solution is introduced into the solution to obtain a fluorescent reaction solution. The solution is allowed to stand for reaction. Based on the fluorescence color information of the solution after the reaction or the change in the rightward shift of the fluorescence emission peak position, the hydrogen sulfide content can be visualized.

[0008] Furthermore, the visualization detection steps based on solution fluorescence color information include: first, fully reacting a standard solution with known hydrogen sulfide content with a nano AgI dispersion to obtain an iodide ion solution; then, introducing a CsPbBr3 quantum dot solution into it to obtain a reaction solution; allowing the reaction to stand; obtaining the change pattern of solution fluorescence color corresponding to different hydrogen sulfide contents after the standing reaction; repeating the above steps; and achieving semi-quantitative detection of hydrogen sulfide content in the test solution based on the fluorescence color of the test solution after the standing reaction.

[0009] Furthermore, as the hydrogen sulfide content (iodide ion concentration) increases, the fluorescence color of the solution obtained after standing reaction changes from green to orange to red.

[0010] Furthermore, the visualization detection step based on solution fluorescence color information includes: firstly, fully reacting a standard solution with known hydrogen sulfide content with a nano AgI dispersion to obtain an iodide ion solution; then, introducing a CsPbBr3 quantum dot solution into the solution to obtain a reaction solution; allowing the reaction to stand; obtaining the RGB values ​​of solution images (using methods such as photography) corresponding to different hydrogen sulfide contents after the reaction; and establishing a stoichiometric relationship between hydrogen sulfide content and RGB values; then repeating the above steps; and using the RGB values ​​of the solution images after the reaction to achieve quantitative detection of hydrogen sulfide content in the detection solution.

[0011] Furthermore, the visualization detection steps based on the rightward shift of the fluorescence emission peak position include: first, fully reacting a standard solution with a known hydrogen sulfide content with a nano-AgI dispersion to obtain an iodide ion solution; then, introducing a CsPbBr3 quantum dot solution into the solution to obtain a reaction solution; allowing the reaction to stand; obtaining the stoichiometric relationship between different hydrogen sulfide contents and the corresponding rightward shift of the fluorescence emission peak position after the standing reaction; repeating the above steps; and achieving quantitative detection of the hydrogen sulfide content in the test solution based on the rightward shift of the fluorescence emission peak position after the standing reaction of the test solution.

[0012] Furthermore, the change in the position of the fluorescence emission peak shifted to the right was obtained in the range of 400–700 nm.

[0013] Furthermore, the chemometric relationship is a linear regression equation.

[0014] In the above scheme, the changes in fluorescence color and the rightward shift of the fluorescence emission peak position are observed and tested under ultraviolet lamp irradiation (320-400nm).

[0015] In the above scheme, the sufficient reaction time is 2 to 5 minutes.

[0016] In the above scheme, the concentration of the nano AgI dispersion is 0.7-1.0 mg / mL.

[0017] In the above scheme, the amount of nano-AgI introduced is excessive relative to the hydrogen sulfide content in the sample being tested.

[0018] In the above scheme, the acidic buffer solution is an acetate-sodium acetate buffer solution with a pH of 3.6 to 5.4.

[0019] In the above scheme, the concentration of CsPbBr3 quantum dots in the fluorescent reaction solution is 0.24–0.27 mg / mL.

[0020] Furthermore, the concentration of the CsPbBr3 quantum dot solution is 4.0–4.5 mg / mL.

[0021] Preferably, the volume ratio of CsPbBr3 quantum dot solution to iodide ion solution is 1:6 to 16.

[0022] In the above scheme, the static reaction time is 6 to 10 minutes.

[0023] In the above scheme, the CsPbBr3 quantum dots have a particle size of 5-20 nm and are rectangular.

[0024] Preferably, the preparation method of CsPbBr3 quantum dots includes the following steps:

[0025] (1) Mix Pb salt and Cs salt, add organic solvent, heat and stir to completely dissolve solid metal salt, then inject 5-bromopentanoic acid and oleylamine into the resulting solution, and carry out water bath stirring reaction to obtain precursor solution.

[0026] (2) The obtained precursor solution was injected into hot water within 10s to allow it to react fully. After refrigeration, the solution was centrifuged to remove the precipitate and obtain a CsPbBr3 dispersion.

[0027] In the above scheme, the Pb salt can be PbBr2; the Cs salt can be CsBr.

[0028] In the above scheme, the molar ratio of Pb salt to Cs salt is 1:1.

[0029] In the above scheme, the molar ratio of Pb salt, 5-bromopentanoic acid and oleylamine is 1:(4-5):(4-5).

[0030] In the above scheme, the heating and stirring are carried out at a temperature of 50-80℃ for a time of 40-60 minutes.

[0031] In the above scheme, the water bath stirring reaction is carried out at a temperature of 50-80℃ for a time of 10-30 minutes.

[0032] In the above scheme, in step (2), the temperature of the hot water is 50-80℃.

[0033] In the above scheme, in step (2), the refrigeration temperature is 2-8℃ and the time is 2-4h.

[0034] In the above scheme, the sufficient reaction time is 2 to 5 minutes.

[0035] In the above scheme, the nano-AgI is in the form of irregular ellipsoidal particles with a particle size of 200-500 nm.

[0036] Preferably, the preparation method of the AgI nanoparticles includes the following steps:

[0037] Polyvinylpyrrolidone was heated and dissolved in an alcohol solvent. Iodine salt was added and stirred until dissolved. Silver salt solution was then injected, and a gradient heating reaction was carried out. The resulting solution was then cooled to room temperature. The supernatant was removed by centrifugation, and the red precipitate was collected. After washing, centrifugation, and drying, AgI nanoparticles were obtained and stored in the dark.

[0038] In the above scheme, the alcohol solvent can be ethylene glycol or the like.

[0039] In the above scheme, the molar ratio of iodized salt, silver salt, and polyvinylpyrrolidone is 1:(1-1.25):(0.003-0.005).

[0040] In the above scheme, the molecular weight of the polyvinylpyrrolidone is 50,000 to 60,000.

[0041] In the above scheme, the heating and melting temperature is 50-80℃, and the time is 20-40 minutes.

[0042] In the above scheme, the gradient heating reaction step includes: first, holding at 50-80°C for 20-30 minutes, and then raising the temperature to 140-180°C and holding for 15-30 minutes.

[0043] In the above scheme, the solution to be tested is a water-based solution with an ethanol concentration of less than 8.7 wt%, specifically suitable for testing beverages such as beer.

[0044] The principle of this invention is as follows:

[0045] This invention utilizes the S-relationship between an unsaturated alkylamine containing a C=C double bond and 5-bromopentanoic acid. N The reaction forms zwitterionic ligands, and the preparation process is optimized. The synthesized CsPbBr3 exhibits excellent water stability and a high luminescence efficiency of up to 100%, which can effectively enhance the water dispersibility and surface potential of quantum dots and effectively promote their attraction to halide ions (I₂). - Driven by the capture and reaction of hydrogen sulfide, it enables highly sensitive and visual detection of hydrogen sulfide.

[0046] The CsPbBr3 fluorescent quantum dots were applied to the detection of hydrogen sulfide. First, AgI nanoparticles reacted with hydrogen sulfide in the test solution to generate free iodine ions. Then, CsPbBr3 quantum dots were introduced as a fluorescence signal reporter. By utilizing the change in the fluorescence color of the solution after the reaction or the change in the rightward shift of the fluorescence emission peak position, a highly sensitive and visual detection of the hydrogen sulfide content was achieved.

[0047] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0048] 1) This invention uses CsBr and PbBr as the main raw materials, combined with ligands such as 5-bromopentanoic acid and oleylamine, and optimizes its preparation process. The resulting fluorescent probe CsPbBr3 quantum dots have high chemical stability, high photostability, and a fluorescence quantum yield of nearly 100%, which helps to react stably with iodide ions in solution and promotes efficient and accurate detection of hydrogen sulfide content in complex solutions such as beer. In addition, the obtained CsPbBr3 quantum dots can be stored in a 4°C refrigerator for 1-2 months without the need for fresh preparation, which can effectively simplify application requirements and procedures and reduce detection costs.

[0049] 2) The CsPbBr3 quantum dots described in this invention can react directly with free iodine ions without the need for other triggering media or other conditions, causing the fluorescence emission peak position of the solution to shift to the right and the fluorescence color to change. In particular, the fluorescence color change information is more obvious and intuitive (fluorescence intensity changes are usually difficult to compare directly with the naked eye), which is more conducive to realizing the visual detection of hydrogen sulfide.

[0050] 3) This invention introduces nano-AgI material as an anion exchanger, which has excellent anti-interference properties. It releases iodine ions and initiates a reaction with CsPbBr3 quantum dots when hydrogen sulfide is present in the environment, thereby producing fluorescence shift and color change, which can ensure high accuracy.

[0051] 4) The detection method described in this invention provides a sensitive fluorescence platform for the determination of hydrogen sulfide in solution. It has high accuracy, high sensitivity, and good linear range. Compared with existing detection methods, it avoids the defects of large equipment and long time consumption, and does not require high professional skills from operators. It provides a new approach for the low-cost and efficient determination of hydrogen sulfide in beer and has great application potential. Attached Figure Description

[0052] Figure 1 The fluorescence spectrum of the CsPbBr3 quantum dots of this invention is shown on the x-axis, which represents wavenumber and the y-axis, which represents fluorescence intensity.

[0053] Figure 2 This is a transmission electron microscope image of the CsPbBr3 quantum dots of this invention.

[0054] Figure 3 This is a schematic flowchart of a rapid method for detecting hydrogen sulfide according to the present invention.

[0055] Figure 4 The CsPbBr3 quantum dots described in Example 2 of this invention and their reactions with AgI nanosolution (+AgI), AgCl nanosolution (+AgCl), and AgI + hydrogen sulfide (+AgI + S) respectively. 2- ) solution system and AgCl + hydrogen sulfide (+AgCl + S) 2- Fluorescence spectrum of the system after reaction.

[0056] Figure 5 A. Color and fluorescence emission peak position changes after the CsPbBr3 quantum dots described in Example 3 of this invention react with gradient concentrations of hydrogen sulfide (iodide ions converted from AgI NPs); B. Linear fitting results of hydrogen sulfide concentration with RGB values ​​and fluorescence emission peak position changes. Detailed Implementation

[0057] The applicant will now provide a more detailed description of the present invention with reference to specific embodiments, so that those skilled in the art can more clearly understand the present invention. However, the following content should not be construed as limiting the scope of protection claimed in the claims of the present invention.

[0058] All chemical reagents and solvents used in the examples were of analytical grade.

[0059] The fluorescence spectroscopy measurement conditions were all for an emission wavelength of 400-700 nm, an excitation wavelength of 365 nm, and a slit width of 10 nm.

[0060] In the following embodiments, the preparation method of the CsPbBr3 quantum dots includes the following steps:

[0061] 1) Weigh 0.0734g PbBr2 (0.2mmol) and 0.0425g CsBr (0.2mmol) and mix them in an ep tube. Then add 5mL DMF and stir in a water bath at 60℃ for 1h to completely dissolve the solid metal salt.

[0062] 2) Take 0.0181 g of 5-bromopentanoic acid (1 mmol) and 329 μL of OA solution (1 mmol) and inject them into the above solution. Continue to stir and react in a 60℃ water bath for 20 min to obtain the precursor solution.

[0063] 3) Inject 2 mL of the obtained precursor solution into 25 mL of deionized water at 60 °C, react for 2 min, and refrigerate at 4 °C for 2 h; centrifuge at 10000 rpm for 10 min to remove the bottom phase precipitate and collect the upper phase CsPbBr3 dispersion (concentration of 4.3 mg / mL).

[0064] The obtained CsPbBr3 quantum dots (initial peak position 520 nm, fluorescence spectrum shown in [reference]) were subjected to fluorescence spectroscopy. Figure 1 Transmission electron microscopy characterization revealed that the obtained product consisted of uniformly dispersed cubic particles (see...). Figure 2 ).

[0065] The preparation method of the AgI nanoparticles includes the following steps:

[0066] 1) Measure 12 mL of ethylene glycol into a round-bottom flask, place it in a 60°C oil bath and heat for 30 min. Then add 54 mg of polyvinylpyrrolidone (PVP, molecular weight 58000), stir and heat to dissolve. Add 45 mg of KI (0.27 mM), continue stirring until completely dissolved, and then slowly pour in 1 mL of AgNO3 solution (concentration 57 mg / mL, solvent ethylene glycol). Heat in a 60°C oil bath for 30 min, then continue heating at 160°C for 20 min. Cool the solution to room temperature.

[0067] (2) Transfer the cooled solution to an ep tube, centrifuge at 13000 rpm for 5 min, remove the supernatant, and take the purple precipitate as the bottom phase. Wash the precipitate with ethanol and water respectively (the volume of solvent used for each wash is 5 mL). After each wash, centrifuge at 13000 rpm for 5 min, discard the supernatant, dry the precipitate at 60℃ for 12 h, and store the obtained AgI nanoparticles in the dark.

[0068] Example 1

[0069] A method for rapid detection of hydrogen sulfide in beer, the schematic diagram of its detection principle is shown below. Figure 3 Specifically, it includes the following steps:

[0070] 1) First, 100 μL of a standard solution with a known hydrogen sulfide content was mixed with 100 μL of AgI nanoparticle solution (0.7 mg / mL), 20 μL of acetate-sodium acetate buffer solution (pH 3.6, 1 mmol), and 15 μL of deionized water. The mixture was allowed to stand for 2 min. Then, 15 μL of CsPbBr3 quantum dot solution was added and allowed to stand for 8 min. The fluorescence color information of the solutions with different concentrations (0–400 μM) of hydrogen sulfide was obtained under ultraviolet light (365 nm) excitation conditions. The specific change pattern was that as the concentration of hydrogen sulfide in the solution increased, the fluorescence color of the solution after the reaction was green-orange-red.

[0071] 2) Mix 100 μL of the beer to be tested with 100 μL of AgI nanoparticle solution (0.7 mg / mL), 20 μL of acetate-sodium acetate buffer solution (pH 3.6, 1 mmol), and 15 μL of deionized water. Let the mixture stand for 2 min, then add 15 μL of SPbBr3 quantum dot solution and let it stand for 8 min. Observe the fluorescence color of the solution after the reaction with the naked eye to achieve a visual detection of the hydrogen sulfide content in the beer to be tested.

[0072] Example 2

[0073] A method for quantitative detection of hydrogen sulfide based on CsPbBr3 quantum dots includes the following steps:

[0074] Prepare a 1 mmol hydrogen sulfide solution. Mix different volumes of hydrogen sulfide solution with water (total volume of hydrogen sulfide solution and water is 100 μL) to obtain hydrogen sulfide dilutions of different concentrations (40 μM, 80 μM, 120 μM, 160 μM, 200 μM, 240 μM, 280 μM, 320 μM, 360 μM, and 400 μM). Add 100 μL of AgI nanosol (0.7 mg / mL) and 15 μL of buffer solution (acetic acid-sodium acetate buffer solution, pH 3.6, 1 mmol). Let the reaction stand for 2 min. Add 15 μL of CsPbBr3 quantum dot solution and let the reaction stand for another 8 min. Under ultraviolet light (365 nm) excitation, detect the fluorescence spectrum in the range of 400-700 nm. Obtain the peak position information of the corresponding CsPbBr3 quantum dot fluorescence emission peaks before and after the addition of hydrogen sulfide, and establish a linear relationship between the change in peak position and hydrogen sulfide concentration.

[0075] Figure 4 The CsPbBr3 quantum dots described in Example 2 of this invention and their reactions with AgI nanosolution (+AgI), AgCl nanosolution (+AgCl), and AgI + hydrogen sulfide (+AgCl + S) respectively. 2- ) solution system and AgCl + hydrogen sulfide (+AgI + S)2- The fluorescence spectrum of the system after the reaction was shown. The results indicate that the peak position of the CsPbBr3 quantum dot solution without hydrogen sulfide was 520 nm. Simply adding AgI nanosolution (+AgI) did not cause a rightward shift in the fluorescence emission peak position of the CsPbBr3 quantum dots. However, when hydrogen sulfide reacted with AgI nanosolution to generate free iodide ions (+AgI+S), the peak position shifted to the right. 2- This will cause the fluorescence emission peak of CsPbBr3 quantum dots to shift to the right, introducing AgCl or AgCl+S. 2- Although the system can cause a leftward shift in the peak position, the linear relationship after fitting is poor.

[0076] Example 3

[0077] A method for visually detecting hydrogen sulfide based on CsPbBr3 quantum dots includes the following steps:

[0078] Different volumes of hydrogen sulfide solution were mixed with water in 96-well plates to maintain a final volume of 100 μL, resulting in hydrogen sulfide dilutions of varying concentrations (40 μM, 80 μM, 120 μM, 160 μM, 200 μM, 240 μM, 280 μM, 320 μM, 360 μM, and 400 μM). Then, 100 μL of AgI nanoparticle solution (0.7 mg / mL) and 20 μL of buffer solution (acetic acid-sodium acetate buffer, pH 3.6, 1 mmol) were added. After reacting for 2 min, 15 μL of... The CsPbBr3 quantum dot solution was thoroughly mixed and reacted at room temperature for 8 minutes. The color change of the solution before and after the reaction was observed visually under a UV lamp (365nm), and the corresponding RGB values ​​were extracted. At the same time, the fluorescence spectrum in the range of 400-700nm was detected to obtain the peak position information of the fluorescence emission peak of CsPbBr3 quantum dots before and after the addition of hydrogen sulfide. A linear relationship between the extracted RGB values ​​and the change in peak position and the concentration of hydrogen sulfide was established.

[0079] The results showed that the CsPbBr3 quantum dot solution was green without the addition of hydrogen sulfide, and the color of the CsPbBr3 quantum dot solution gradually changed from green to orange to red after the addition of different concentrations of hydrogen sulfide solution. Figure 5 A) Visual semi-quantitative detection of sodium sulfide can be achieved based on the abundant fluorescence color changes in the solution. The linear fitting results obtained by comparing RGB values ​​and peak position changes with hydrogen sulfide concentration are shown below. Figure 5 B, the linear fitting effect is better.

[0080] Comparative Example

[0081] A method for visual detection of hydrogen sulfide based on CsPbBr3 quantum dots is provided. This method is largely the same as that in Example 1, except that the synthesis step (2) was not adequately refrigerated before centrifugation.

[0082] The quantum dots obtained by the above method have weaker stability and luminescence efficiency than the CsPbBr3 quantum dots obtained in the example, and the FAE color change reaction is weaker, with reduced fluorescence intensity, which is not conducive to the visual detection of hydrogen sulfide in solution.

[0083] Example 4

[0084] A rapid method for detecting hydrogen sulfide in beer, which involves applying obtained CsPbBr3 quantum dots to detect hydrogen sulfide in the beer matrix, specifically includes the following steps:

[0085] Beer concentrate was diluted 10 times with deionized water. Different concentrations of beer matrix were prepared by varying the ratio of beer to water, with a final volume of 100 μL. Then, 100 μL of AgI nanoparticle solution and 20 μL of buffer solution were added, and the mixture was allowed to stand for 2 min. Next, 15 μL of CsPbBr3 quantum dot solution was added, mixed, and reacted at room temperature for 8 min. Fluorescence spectra in the 400-700 nm range were measured under UV (365 nm) excitation. The wavelengths of the CsPbBr3 quantum dot fluorescence emission peaks before and after introducing hydrogen sulfide into the beer matrix at different concentrations were measured. The changes in peak wavelength positions were substituted into the linear equation obtained in Example 3 to calculate the predicted hydrogen sulfide concentration in the beer matrix and its recovery rate. The results are shown in Tables 1 and 2.

[0086] Table 1. Determination results of hydrogen sulfide in beer matrix based on wavelength shift method.

[0087]

[0088] Table 2. Determination results of hydrogen sulfide in beer matrix based on colorimetric difference method.

[0089]

[0090]

[0091] The results showed that the recovery rates of three different concentrations of hydrogen sulfide in the beer matrix remained between 92.5% and 116.4% (as shown in Tables 1 and 2), enabling the specific identification and quantification of hydrogen sulfide in the beer matrix.

[0092] Traditional fluorescent probe detection of hydrogen sulfide is generally based on fluorescence quenching, using changes in fluorescence intensity to quantify hydrogen sulfide. However, changes in fluorescence intensity are not easily distinguishable to the naked eye and require the support of large instruments. The fluorescence detection system established in this paper is based on a dual readout mode of color and wavelength shift, which enables real-time detection. Furthermore, the synthesis of CsPbBr3 has been optimized to achieve higher luminescence efficiency and greater stability.

[0093] The above embodiments are merely illustrative examples and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations; therefore, any obvious variations or modifications derived therefrom remain within the scope of protection of this invention.

Claims

1. A method for rapid detection of hydrogen sulfide in solution, characterized in that, Includes the following steps: An acidic buffer solution and the test solution were added to a nano AgI dispersion and allowed to react fully to obtain an iodide ion solution. Then, a CsPbBr3 quantum dot solution was introduced into the solution to obtain a fluorescent mixture. The mixture was allowed to stand and react. Based on the fluorescence color information of the solution after the reaction or the change in the rightward shift of the fluorescence emission peak position, the hydrogen sulfide content was visualized. The changes in fluorescence color and the rightward shift of the fluorescence emission peak position were observed under ultraviolet light irradiation conditions of 320~400nm; The change in the position of the fluorescence emission peak shifted to the right was obtained in the range of 400~700 nm; The preparation method of the CsPbBr3 quantum dots includes the following steps: (1) Mix Pb salt and Cs salt, add organic solvent, heat and stir to completely dissolve solid metal salt, then inject 5-bromopentanoic acid and oleylamine into the resulting solution, and carry out water bath stirring reaction to obtain precursor solution; (2) The obtained precursor solution was injected into hot water, allowed to react fully, refrigerated, centrifuged to remove the bottom phase precipitate, and CsPbBr3 quantum dot dispersion was obtained; the refrigeration temperature was 2-8℃ and the time was 2-4h. The particle size of the nano-AgI is 200~500nm; The preparation method of the AgI nanoparticles includes the following steps: heating and dissolving polyvinylpyrrolidone in an alcohol solvent, adding iodine salt, stirring and dissolving, then injecting silver salt solution, carrying out a gradient heating reaction, and then cooling the reaction solution to room temperature; The supernatant was removed by centrifugation, and the red precipitate was collected. After washing, centrifugation, and drying, AgI nanoparticles were obtained and stored in the dark.

2. The method according to claim 1, characterized in that, The sufficient reaction time is 2-5 minutes.

3. The method according to claim 1, characterized in that, The pH value of the acidic buffer solution is 3.6~5.

4.

4. The method according to claim 1, characterized in that, The concentration of CsPbBr3 quantum dots in the fluorescent reaction solution is 0.24~0.27 mg / mL.

5. The method according to claim 1, characterized in that, The static reaction time is 6-10 minutes.

6. The method according to claim 1, characterized in that, The CsPbBr3 quantum dots have a particle size of 5-20 nm and are rectangular.

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