A rapid method for detecting sulfur dioxide residues

Abstract

This invention discloses a rapid method for detecting sulfur dioxide residues. The method includes measuring the fluorescence intensity or color of the analyte using a ratiometric fluorescent probe 1; the ratiometric fluorescent probe 1 is 4-chloro-7-(diethylamine)-3-aldehyde coumarin. This method can rapidly and conveniently detect SO2 residues in food and pharmaceuticals, and is low in cost and simple to operate, making a significant contribution to the safety testing of food and pharmaceuticals.

Description

Technical Field

[0001] This invention belongs to the field of analytical testing, specifically relating to a method for rapid detection of sulfur dioxide residues. Background Technology

[0002] Sulfur dioxide (SO2) has insect-repellent, antioxidant, and dehumidifying functions and is often used as a preservative and antibacterial agent in the processing of food, beverages, and pharmaceuticals. However, excessive SO2 can irritate the respiratory and digestive tracts and lead to diseases such as hypertension, pulmonary atherosclerosis, and neuronal damage. Therefore, controlling SO2 residues in food and pharmaceuticals has received widespread attention. The Chinese Pharmacopoeia stipulates that, unless otherwise specified, the SO2 residue in Chinese medicinal materials and processed medicinal slices (excluding minerals) shall not exceed 150 mg / kg.

[0003] Currently, various analytical methods have been used for the detection of SO2 and its derivatives, such as colorimetry, titration, chromatography, electrochemical methods, and enzymatic spectrophotometry. However, these traditional analytical methods are mostly limited by expensive instruments, complex operating procedures, and the need for professional operators, which hinders their application in rapid analysis.

[0004] In recent years, fluorescent probes have attracted widespread attention due to their advantages such as simple operation, fast reaction speed, high sensitivity, and high selectivity. However, in order to eliminate the interference of thiols, which have similar chemical properties to SO2 and its derivatives, more complex organic synthesis steps or the addition of masking agents are usually required to improve the selectivity of fluorescent probes. Therefore, it is necessary to develop a simple and rapid method for detecting SO2 residues based on fluorescent probes. Summary of the Invention

[0005] To address the above problems, the present invention provides a method for rapid detection of sulfur dioxide residues in food and pharmaceuticals, the method comprising measuring the fluorescence intensity of the analyte using a ratiometric fluorescent probe 1;

[0006] The ratiometric fluorescent probe 1 is 4-chloro-7-(diethylamine)-3-aldehyde coumarin.

[0007] Furthermore, when measuring fluorescence intensity using ratiometric fluorescent probe 1, the pH of the solution is 5.0–6.0, preferably 6.0.

[0008] Furthermore, the method specifically includes the following steps:

[0009] ① Take a series of HSO3 concentrations respectively - The solution and the sample solution to be tested were reacted with ratiometric fluorescent probe 1 in a buffer solution for 20–60 min. The fluorescence intensity ratio was measured using a fluorescence spectrophotometer. 580 / I 505 ;

[0010] ② With HSO3 - Concentration to fluorescence intensity ratio I 580 / I 505 Plot a standard curve and calculate the SO2 content in the sample based on the standard curve.

[0011] Furthermore, the ratiometric fluorescent probe 1 is dissolved in acetonitrile, and its concentration in the buffer solution is 10–50 μmol / L;

[0012] The HSO3 - The concentration in the buffer solution is 0–200 μmol / L;

[0013] The buffer solution is any one of the following: disodium hydrogen phosphate-sodium dihydrogen phosphate buffer, disodium hydrogen phosphate-potassium dihydrogen phosphate buffer, potassium dihydrogen phosphate-sodium hydroxide buffer, citrate-sodium citrate buffer, citrate-sodium hydroxide-hydrochloric acid buffer, acetic acid-sodium acetate buffer, acetic acid-ammonium acetate buffer, Bis-Tris buffer, MES buffer, and disodium hydrogen phosphate-citrate buffer, preferably disodium hydrogen phosphate-citrate buffer.

[0014] The disodium hydrogen phosphate-citric acid buffer solution contains 5% acetonitrile.

[0015] Furthermore, the reaction time is 30 min, and the λ of the fluorescence spectrophotometer... ex It is 400nm.

[0016] Furthermore, the method specifically includes the following steps:

[0017] 1) Immobilize ratio fluorescent probe 1 onto the test strip, and fix the test strip inside the centrifuge tube cap to obtain an SO2 detection tube;

[0018] 2) Take the sample solution to be tested into the test tube obtained in step 1), add acid, tighten the cap and react for 15-30 minutes, then examine it under a 365nm ultraviolet lamp or sunlight.

[0019] Furthermore, the steps also include creating a colorimetric card or a standard curve;

[0020] The method for preparing the colorimetric card is as follows: take a series of HSO3 concentrations respectively - Add acid to the test tube obtained in step 1), tighten the cap and react for 15-30 minutes. Examine under 365nm ultraviolet light or sunlight. Arrange the test strips in the order of color change with concentration to form a colorimetric card.

[0021] The standard curve is prepared by taking a series of HSO3 concentrations respectively. -Add acid to the solution in the detection tube obtained in step 1), tighten the cap, and react for 15–30 minutes. Take an image under a 365 nm UV lamp or sunlight, extract the brightness value of the image, and determine the relationship between the brightness value and HSO3. - Plot a standard curve for the concentration.

[0022] Furthermore, the series of concentrations of HSO3 - The concentrations of the solutions ranged from 0 to 1.40 mmol / L, and the amount of acid added was 1 drop of hydrochloric acid per 2 mL of solution; the reaction time was 15 min.

[0023] Furthermore, the test strip after the sample has reacted is compared with the colorimetric card; the color similar to the colorimetric card corresponds to HSO3. - The concentration is used as the concentration of SO2 in the solution of the sample to be tested, and the SO2 content is calculated based on this concentration.

[0024] or:

[0025] The brightness value of the test strip image after the sample reaction is extracted, and the SO2 content is calculated according to the standard curve.

[0026] Furthermore, the test strips examined are blue under ultraviolet light (indicating the absence of SO2 in the sample) and green under ultraviolet light (indicating the presence of SO2 in the sample); under sunlight, they are light yellow (indicating the absence of SO2 in the sample) and dark yellow (indicating the presence of SO2 in the sample).

[0027] This invention is based on a fluorescent probe method. By developing a ratiometric fluorescent probe 1, SO2 is selectively identified based on the different pKa values ​​between bisulfite and thiols. SO2 residues in food and pharmaceuticals are detected using fluorescence spectrophotometry at pH 5.0-6.0. A portable detection tube made from this probe reacts the sample under specific conditions, enabling rapid detection of sulfur dioxide residues. This method offers advantages such as high selectivity, high sensitivity, and low detection limit. This invention provides a rapid and convenient method for detecting SO2 residues in food and pharmaceuticals, and is low in cost and simple to operate, making a significant contribution to the safety testing of food and pharmaceuticals.

[0028] Obviously, based on the above description of the present invention, and according to common technical knowledge and conventional methods in the field, various other modifications, substitutions or alterations can be made without departing from the basic technical concept of the present invention.

[0029] The following detailed embodiments further illustrate the above-described content of the present invention. However, this should not be construed as limiting the scope of the present invention to the following examples. All technologies implemented based on the above-described content of the present invention fall within the scope of the present invention. Attached Figure Description

[0030] Figure 1 The proton spectrum of probe 1;

[0031] Figure 2 Carbon spectrum of probe 1;

[0032] Figure 3 High-resolution mass spectrometry of probe 1;

[0033] Figure 4 Probe 1 and HSO3 - The working mechanism of the reaction;

[0034] Figure 5 (a) Emission spectrum of 1 at different pH values; (b) HSO3 - (c) Emission spectra of the reaction of thiols (200 μmol / L, Cys and GSH) with 1 (20 μmol / L) at different pH values; (d) Emission spectra of 1 with HSO3 added at different pH values. - Fluorescence intensity changes at 580 nm before and after; (e)1 and HSO3 - Changes in fluorescence intensity at 580 nm after different reaction times;

[0035] Figure 6 (a) 1 and different concentrations of HSO3 - (a) emission spectrum; (b) fluorescence intensity ratio (I) 580 / I 505 ) and HSO3 - (c) shows the linear relationship between the concentrations; (d) is the fluorescence intensity ratio of a pair of different analytes at concentrations of 200 μM and 1000 μM (Ig). 580 / I 505 );

[0036] Figure 7 Schematic diagram and working process of portable detection tube;

[0037] Figure 8 (a) Detection of different concentrations of HSO3 using a portable detection tube - Images of the test strips under 365nm UV light and sunlight, respectively; (b) Brightness values ​​of the test strips under 365nm UV light and (c) sunlight, varying with HSO3. - Concentration change curve;

[0038] Figure 9 Images of test strips under ultraviolet and visible light after detecting different food and medicine homologous samples using portable test tubes. Detailed Implementation

[0039] Example 1: Quantitative Detection of Sulfur Dioxide Based on Fluorescence Spectrophotometer

[0040] 1. Create a standard curve

[0041] 1) Take 4-chloro-7-(diethylamine)-3-aldehyde coumarin, add acetonitrile to dissolve it, and obtain a 2 mmol / L probe 1 stock solution;

[0042] 2) Probe 1 concentration is 20 μmol / L, HSO3 - Concentrations of 0, 1, 5, 10, 20, 40, 60, 80, 100, and 200 μmol / L were reacted in disodium hydrogen phosphate-citrate buffer (5% acetonitrile, pH 6.0) for 30 min.

[0043] 3) Setting the λ of the fluorescence spectrophotometer ex =400nm, scan the emission spectrum of the solution in 2) above to establish HSO3 - Concentration to fluorescence intensity ratio I 580 / I 505 The linear fitting curve is used as the standard curve.

[0044] 2. Quantitative detection

[0045] 4) The concentration of probe 1 is 20 μmol / L, and it is reacted with the sample solution to be tested in disodium hydrogen phosphate-citric acid buffer (5% acetonitrile, pH 6.0) for 30 min.

[0046] 5) Set the λ of the fluorescence spectrophotometer ex =400nm, scan the emission spectrum of the solution in 1) above, and obtain the fluorescence intensity ratio of the solution to I. 580 / I 505 The SO2 content in the sample to be tested is calculated based on the standard curve.

[0047] Example 2 Qualitative Detection of Sulfur Dioxide

[0048] 1) Dissolve 4-chloro-7-(diethylamine)-3-aldehyde coumarin in acetonitrile to obtain a probe 1 solution with a concentration of 1.4 mmol / L;

[0049] 2) Cut the filter paper into 1×1cm pieces. 2 The paper strip is fixed to the cap of a 5mL centrifuge tube, and 5μL of probe 1 solution is added to the test paper to make an SO2 detection tube.

[0050] 3) Add 1g of the sample to be tested to the test tube and dissolve it in 2mL of water. Add 1 drop of hydrochloric acid, tighten the cap of the centrifuge tube, and heat it in 90℃ water for 15 minutes.

[0051] 4) After the paper strips are dried, examine them under a 365nm ultraviolet lamp or sunlight. Under ultraviolet light, the test strip is blue, indicating that the sample does not contain SO2; it is green, indicating that the sample contains SO2. Under sunlight, the test strip is light yellow, indicating that the sample does not contain SO2; it is dark yellow, indicating that the sample contains SO2.

[0052] Example 3 Semi-quantitative detection of sulfur dioxide

[0053] 1. Fabrication of SO2 detection tubes

[0054] ① Take 4-chloro-7-(diethylamine)-3-aldehyde coumarin, add acetonitrile to dissolve it, and obtain a probe 1 solution with a concentration of 1.4 mmol / L;

[0055] ② Cut the filter paper into 1×1cm pieces 2 The paper strip is fixed to the cap of a 5mL centrifuge tube, and 5μL of probe 1 solution is added to the test paper to make an SO2 detection tube.

[0056] 2. Make a color matching card

[0057] ① Add 2 mL of HSO3 at concentrations of 0, 0.28, 0.56, 0.84, 1.12, and 1.40 mmol / L to the test tubes, respectively. - Add the solution and a drop of hydrochloric acid, tighten the centrifuge tube cap, and heat in 90°C water for 15 minutes;

[0058] ② After the paper strips are dried, they are inspected under a 365nm UV lamp or sunlight. Under the UV lamp, along with HSO3... - As the concentration increases, the color of the test strip changes from blue to green. Arrange the test strips in order of color change to create a colorimetric chart. Under sunlight, as the HSO3 content increases... - As the concentration increases, the color of the test strip changes from light yellow to dark yellow. The test strips are arranged in order of color gradient to form a colorimetric card.

[0059] 3. Semi-quantitative detection

[0060] ① Add 1g of the sample to be tested to the test tube and dissolve it in 2mL of water. Add 1 drop of hydrochloric acid, tighten the cap of the centrifuge tube, and heat it in 90℃ water for 15 minutes.

[0061] ② After the paper strips are dried, examine them under a 365nm UV lamp or sunlight. Compare the color development of the test strips with the colorimetric card. The color similar to the colorimetric card corresponds to HSO3. - The concentration is used as the concentration of SO2 in the solution of the sample to be tested, and the SO2 content is calculated based on this concentration.

[0062] Example 4 Semi-quantitative detection of sulfur dioxide

[0063] 1. Fabrication of SO2 detection tubes

[0064] ① Take 4-chloro-7-(diethylamine)-3-aldehyde coumarin, add acetonitrile to dissolve it, and obtain a probe 1 solution with a concentration of 1.4 mmol / L;

[0065] ② Cut the filter paper into 1×1cm pieces 2 The paper strip is fixed to the cap of a 5mL centrifuge tube, and 5μL of probe 1 solution is added to the test paper to make an SO2 detection tube.

[0066] 2. Create a standard curve

[0067] ① Add 2 mL of HSO3 at concentrations of 0, 0.28, 0.56, 0.84, 1.12, and 1.40 mmol / L to the test tubes, respectively. - Add the solution and a drop of hydrochloric acid, tighten the centrifuge tube cap, and heat in 90°C water for 15 minutes.

[0068] ② After the paper strips are dried, images are taken under a 365nm ultraviolet lamp or sunlight. The brightness values ​​(L) of these images are extracted using Adobe Photoshop software, and L and HSO3 are constructed respectively. - The linear fitting curve of the concentration is used as a standard curve;

[0069] 3. Semi-quantitative detection

[0070] ① Add 1g of the sample to be tested to the test tube and dissolve it in 2mL of water. Add 1 drop of hydrochloric acid, tighten the cap of the centrifuge tube, and heat it in 90℃ water for 15 minutes.

[0071] ②After the paper strips are dried, images are taken under a 365nm ultraviolet lamp or sunlight. The brightness values ​​(L) of these images are extracted using Adobe Photoshop software, and the SO2 content in the sample is calculated based on the standard curve.

[0072] The following experimental examples illustrate the beneficial effects of the present invention.

[0073] Experimental Example 1: Study on SO2 Residue Detection Method Based on Fluorescent Probes

[0074] 1. Synthesis of Probe 1

[0075] Synthesis route of probe 1:

[0076]

[0077] Specific synthesis steps:

[0078] 1) Slowly add POCl3 (11-12 mL) to a mixture of malonic acid (10-11 g) and phenol (19.5-20.5 g) at 0 °C. Heat the mixture at 110-120 °C for about 1-2 h. Pour the supernatant into 140-160 mL of water, extract three times with ethyl acetate, and evaporate to dryness to obtain diphenylmalonate diester.

[0079] 2) Add 3-N,N-diethylaminophenol (8.0-8.5 g) to a solution of diphenylmalonate (12.5-13.5 g) in toluene (45-55 mL). After refluxing the reaction mixture for 6-8 hours, wash the product with hexane and dry it under vacuum to give a pale yellow solid 7-(diethylamino)-4-hydroxycoumarin.

[0080] 3) Under nitrogen protection, distilled N,N-dimethylformamide (DMF, 2.5-3.5 mL) was added dropwise to phosphorus oxychloride (POCl3, 2.5-3.5 mL) at room temperature and stirred for 30 min. The compound obtained in steps (1-3) (2.0-2.5 g) was dissolved in DMF (13.0-13.5 mL) and added dropwise to the above solution. The entire system was stirred at 60-80 °C for 5-7 hours and then cooled to room temperature. The reaction system was then transferred to ice water (90-110 mL), and NaOH solution was added to adjust the pH to obtain a large amount of precipitate. The crude product was washed with water and purified by preparative liquid chromatography (methanol / water, v / v = 7:3) to obtain an orange powder.

[0081] 2. Characterization of Probe 1

[0082] Orange powder was obtained, and proton, carbon, and high-resolution mass spectrometry were performed. See details below. Figures 1-3 From the figure, it can be determined that the orange powder is pure 4-chloro-7-(diethylamine)-3-aldehyde coumarin (1), i.e., probe 1.

[0083] 3. Probe 1 and HSO3 - Verification of the reaction mechanism and optimization of spectroscopic experimental conditions

[0084] 3.1 Probe 1 and HSO3 - The reaction mechanism was investigated using HRMS. 1 H NMR, theoretical calculations, and spectroscopic experiments confirmed that the chlorine atom on probe 1 reacted with HSO3. - Nucleophilic substitution occurs. See details. Figure 4

[0085] 3.2 The optimization of conditions for the spectral experiment includes pH investigation and time investigation.

[0086] pH value is probe 1 and HSO3 -An important factor in the reaction between probe 1 and the aldehyde group is its reactivity, which affects the reactivity of the Cl atom and the aldehyde group on probe 1. The reaction of probe 1 with HSO3 was investigated in disodium hydrogen phosphate-citrate buffer solutions at different pH values. - Spectral characteristics with and without presence (λ) ex =400nm). From Figure 5 As can be seen from ab and d, the fluorescence spectrum of free ion 1 is basically stable in the pH range of 3.0–8.0; with the addition of HSO3 - Subsequently, when the pH value is ≤5.0, the emission intensity of probe 1 increases, and when the pH value is ≥6.0, the emission spectrum shows a significant red shift. Low pH values ​​(pH ≤5.0) favor nucleophilic addition reactions of aldehydes / ketones, while high pH values ​​(pH ≥6.0) promote the dissolution of sulfites, sulfides, and thiols, making them more susceptible to nucleophilic substitution reactions with electron-withdrawing groups. pH value not only affects the reaction between probe 1 and HSO3... - The type of reaction can also affect the reactivity of certain typical interfering substances (such as thiols). For example... Figure 5 As shown in c, after the addition of thiol, the emission spectrum of 1 remained essentially unchanged when the pH value was ≤6.0, but showed a significant change at the pH value of 7.4. Furthermore, the effect of reaction time on the results was further investigated. Figure 5 e), Probe 1 in HSO3 - When present, the fluorescence intensity at 580 nm remained relatively stable after 30 minutes.

[0087] Therefore, considering various factors, pH 6.0 was chosen as the optimal pH value, and the reaction time was 30 min. This not only eliminates interference but also allows compound 1 to be used as a ratiometric fluorescent probe to detect SO2, generating compound 2 with a redshifted emission spectrum. Figure 4 right).

[0088] 4. Establishment of a method for detecting SO2 residues based on probe 1 of a fluorescence spectrophotometer

[0089] Based on a fluorescence spectrophotometer, the effect of probe 1 on HSO3 was investigated. - The sensing performance was assessed using fluorescence spectroscopy titration. Results are shown below. Figure 6 ,from Figure 6 It can be seen that when the excitation wavelength is 400 nm, probe 1 recognizes HSO3. - Subsequently, its emission wavelength redshifted from 505 nm to 580 nm, and it has an isoabsorption point at 535 nm. The fluorescence intensity ratio (I...) 580 / I 505 ) and HSO3 - There is a good linear relationship in the concentration range of 0-200 μmol / L (R0). 2 =0.9972), proving that 1 applies to HSO3. -Quantitative detection.

[0090] 5. Preparation of a portable detection tube for rapid detection of sulfur dioxide residues

[0091] 5.1 Portable detection tubes and their operating procedures are described in [reference needed]. Figure 7 .

[0092] 5.2 Detection using portable detection tubes

[0093] 1) Cut the filter paper into 1×1cm pieces. 2 The paper strip was fixed to the cap of a 5 mL centrifuge tube, and 5 μL of 1.4 mmol / L probe 1 solution (dissolved in acetonitrile) was added to the test paper to make an SO2 detection tube.

[0094] 2) Add 2 mL of HSO3 at concentrations of 0, 0.28, 0.56, 0.84, 1.12, and 1.40 mmol / L to centrifuge tubes, respectively. - The solution contains one drop of hydrochloric acid.

[0095] 3) Tightly close the centrifuge tube cap and heat in 90℃ water for 15 minutes.

[0096] 4) After the paper strips are dried, photos are taken under a 365nm UV lamp and sunlight. Under the UV lamp, with HSO3... - As the concentration increases, the color of the test strip changes from blue to green; under sunlight, the color of the test strip changes from light yellow to dark yellow. Figure 8 a).

[0097] 5) Extract the brightness values ​​(L) of these images using Adobe Photoshop, and construct L and HSO3 values ​​respectively. - The linear fitting curve for concentration is shown in the figure. Figure 8 bc, as can be seen from the figure: the height of R 2 (~0.98) indicates that L and HSO3 - There is a good linear relationship between the contents, and the detection tube can be used for semi-quantitative detection of SO2 residues.

[0098] 6. Application of Probe 1 in Actual Samples

[0099] 6.1 Detection of SO2 Residues Using Probe 1 Based on Fluorescence Spectrophotometer

[0100] Based on the above results, SO2 residues in four actual food and medicinal samples were detected using a fluorescence spectrophotometer according to the method in Example 1. The accuracy of the method was evaluated by spiked recovery, with recoveries ranging from 90.1% to 103.4% and relative standard deviations (RSD) ≤ 2.8% (Table 1). Based on the established linear fitting equation, the HSO3 content in the samples of yam, gastrodia elata, angelica dahurica, and codonopsis pilosula was calculated. -The contents were 0.04, 0.03, 0.17, and 0.18 g / kg, respectively. Meanwhile, the four samples were determined using the first method (acid-base titration) for the determination of sulfur dioxide residues in the 2020 edition of the Chinese Pharmacopoeia, and the results were consistent with those obtained using the method of this invention (Table 1).

[0101] Table 1. HSO3 in four different food and medicinal samples - The determination (n=3).

[0102]

[0103] 6.2 Detection of SO2 Residue Using Probe 1 Based on Portable Detection Tube

[0104] Based on the above results, SO2 residues in actual food and medicine homologous samples were detected using portable detection tubes. Figure 8 Using 'a' as the standard colorimetric card, the samples of yam, gastrodia, and angelica were tested according to the method in Example 3. Figure 9 As shown, the test strip for detecting yam appears light green under ultraviolet light and light yellow under sunlight, which is consistent with... Figure 8 Comparison of standard colorimetric cards for HSO3 in yam - A concentration below 0.28 mmol / L translates to approximately 35 mg / kg of residual SO2. The test strip for Gastrodia elata appears blue-green under UV light and pale yellow under sunlight. Figure 8 Comparison of standard colorimetric charts for HSO3 in Gastrodia elata. - A concentration below 0.28 mmol / L translates to approximately 35 mg / kg of residual SO2. The test strip for Angelica dahurica appears dark green under UV light and dark yellow under sunlight. Figure 8 Compared with the standard colorimetric card, Angelica dahurica has a relatively high residual SO2 content and HSO3 content. - The concentration was approximately 1.4 mmol / L, which translates to approximately 180 mg / kg of residual SO2. These results are essentially consistent with those obtained using acid-base titration and method 6.1 of this invention.

[0105] In summary, the ratiometric fluorescent probe 1 and portable detection tube prepared by this invention not only possess excellent selectivity but also enable rapid and convenient detection of SO2 residues in actual samples, effectively solving the problems of complex operation and high cost of current SO2 residue detection methods. This invention achieves a simple, rapid, convenient, and low-cost detection of SO2 residues using a portable detection tube based on probe 1, making a significant contribution to food and drug safety testing.

Claims

1. A method for rapid detection of sulfur dioxide residues in food and pharmaceuticals, characterized in that: The method specifically includes the following steps: ① Take a series of HSO3 concentrations respectively - The solution and the sample solution to be tested were reacted with ratiometric fluorescent probe 1 in a buffer solution for 20–60 min. The fluorescence intensity ratio was measured using a fluorescence spectrophotometer. 580 / I 505 ; ② With HSO3 - Concentration to fluorescence intensity ratio I 580 / I 505 Plot a standard curve and calculate the SO2 content in the sample based on the standard curve; The ratiometric fluorescent probe 1 is dissolved in acetonitrile, and the concentration in the buffer solution is 10–50 μmol / L; The HSO3 - The concentration in the buffer solution is 0–200 μmol / L; The buffer solution is a disodium hydrogen phosphate-citric acid buffer solution containing 5% acetonitrile; the pH value is 6.

0. The ratiometric fluorescent probe 1 is 4-chloro-7-(diethylamine)-3-aldehyde coumarin.

2. The method according to claim 1, characterized in that: The reaction time was 30 min, and the λex of the fluorescence spectrophotometer was 400 nm.

3. A method for rapid detection of sulfur dioxide residues in food and pharmaceuticals, characterized in that: The method specifically includes the following steps: 1) Immobilize ratio fluorescent probe 1 onto the test strip, and fix the test strip inside the centrifuge tube cap to obtain an SO2 detection tube; 2) Take the sample solution to be tested into the test tube obtained in step 1), add acid, tighten the cap and react for 15-30 minutes, then examine it under a 365nm ultraviolet lamp or sunlight. The ratiometric fluorescent probe 1 is 4-chloro-7-(diethylamine)-3-aldehyde coumarin; The steps also include creating a colorimetric card or standard curve; The method for preparing the colorimetric card is as follows: take a series of HSO3 concentrations respectively - Add acid to the test tube obtained in step 1), tighten the cap and react for 15-30 minutes. Examine under 365nm ultraviolet light or sunlight. Arrange the test strips in the order of color change with concentration to form a colorimetric card. The standard curve is prepared by taking a series of HSO3 concentrations respectively. - Add acid to the solution in the detection tube obtained in step 1), tighten the cap, and react for 15–30 minutes. Take an image under a 365 nm UV lamp or sunlight, extract the brightness value of the image, and determine the relationship between the brightness value and HSO3. - Plot a standard curve for concentration; The test strip after the sample reaction is compared with the colorimetric card. The color similar to that on the colorimetric card corresponds to HSO3. - The concentration is used as the concentration of SO2 in the solution of the sample to be tested, and the SO2 content is calculated based on this concentration. Alternatively: Extract the brightness value from the image of the test strip after the sample has reacted, and calculate the SO2 content based on the standard curve.

4. The method according to claim 3, characterized in that: The series of concentrations of HSO3 - The concentrations of the solutions ranged from 0 to 1.40 mmol / L, and the amount of acid added was 1 drop of hydrochloric acid per 2 mL of solution; the reaction time was 15 min.

5. A method for rapid detection of sulfur dioxide residues in food and pharmaceuticals, characterized in that: The method specifically includes the following steps: 1) Immobilize ratio fluorescent probe 1 onto the test strip, and fix the test strip inside the centrifuge tube cap to obtain an SO2 detection tube; 2) Take the sample solution to be tested into the test tube obtained in step 1), add acid, tighten the cap and react for 15-30 minutes, then examine it under a 365nm ultraviolet lamp or sunlight. The ratiometric fluorescent probe 1 is 4-chloro-7-(diethylamine)-3-aldehyde coumarin; The test strips tested are blue under ultraviolet light (indicating the absence of SO2 in the sample), green under ultraviolet light (indicating the presence of SO2 in the sample), and light yellow under sunlight (indicating the absence of SO2 in the sample) and dark yellow under sunlight (indicating the presence of SO2 in the sample).

6. The method according to claim 5, characterized in that: The acid added is 1 drop of hydrochloric acid per 2 mL of solution; the reaction time is 15 min.

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