A hydrogel sensing material for detecting sulfite, a detection method, and its application.
By constructing a dual-modal signal hydrogel sensing material and utilizing a cross-validation method of color change and fluorescence enhancement, the problem of insufficient accuracy of sulfite detection in complex food matrices in existing technologies was solved, achieving a simple and efficient detection effect.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- KUNMING UNIV OF SCI & TECH
- Filing Date
- 2026-04-03
- Publication Date
- 2026-06-30
AI Technical Summary
Existing methods for detecting sulfites in complex food matrices suffer from complex pretreatment processes, are time-consuming, are easily affected by sample matrix color, and lack stability, making it difficult to guarantee accuracy. In particular, false positives or false negatives are prone to occur in dark-colored or complex samples.
A novel dual-modal signal hydrogel sensing material was constructed, which generates two independent signal responses—visible color change and fluorescence enhancement—after enriching sulfur dioxide (SO2) volatilized from sulfite. This enables cross-validation and high-accuracy detection, and a colorimetric fluorescence dual-modal signal response detection method was adopted.
This technology enables simple and rapid sulfite detection in complex matrices such as dairy products, alcoholic beverages, and dried vegetables. It exhibits excellent anti-interference capabilities and high accuracy, significantly improving the reliability and anti-interference ability of the test results.
Smart Images
Figure CN122302322A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of analytical detection technology, and in particular to a hydrogel sensing material for detecting sulfite, a detection method, and its application. Background Technology
[0002] Sulfites, a common food additive, are widely used in alcoholic beverages, dairy products, and dried vegetables for bleaching, preservation, and antioxidant effects. However, excessive intake of sulfites can trigger allergic reactions and pose risks to the respiratory system and overall health. Therefore, regulations in various countries have established strict limits on their residue levels in food. Establishing accurate, rapid, and applicable methods for sulfite detection in complex food matrices is crucial for ensuring consumer safety and meeting industry regulatory requirements. Currently, sulfite detection mainly relies on laboratory instruments, such as titration and ion chromatography as specified in national standards. These methods generally suffer from limitations such as complex pretreatment and time-consuming processes, making rapid on-site detection difficult. In recent years, sulfite detection methods have also faced challenges such as susceptibility to interference from sample matrix color and insufficient stability, especially in dark-colored, complex samples (such as dairy products and wine), where accuracy is difficult to guarantee and false positives or false negatives are highly likely. Summary of the Invention
[0003] This invention aims to at least solve one of the aforementioned technical problems existing in the prior art. Therefore, a first objective of this invention is to provide a hydrogel sensing material for detecting sulfite. A second objective of this invention is to provide a method for detecting sulfite. A third objective of this invention is to provide applications of this hydrogel sensing material.
[0004] The inventive concept of this invention is to construct a novel dual-modal signal hydrogel sensing material. After enriching with sulfur dioxide (SO2) volatilized from sulfite, this material generates two independent signal responses within the same system: a visible color change and enhanced fluorescence. This enables cross-validation and high-accuracy detection of sulfite. Furthermore, based on this hydrogel sensing material, a simple and rapid detection method for sulfite is developed. When applied to various typical and complex matrices of food samples, such as dairy products, alcoholic beverages, and dried vegetables, this method demonstrates good anti-interference capabilities and accurate detection results, facilitating rapid on-site screening of sulfite in experimental foods.
[0005] To achieve the above objectives, the present invention provides the following technical solutions.
[0006] In a first aspect, the present invention provides a hydrogel sensing material for detecting sulfite, the hydrogel sensing material having a colorimetric fluorescence dual-modal signal response; the raw materials for preparing the hydrogel sensing material include a long afterglow material, alginate, starch solution, iodine solution and crosslinking agent.
[0007] The principle of this invention is as follows: In the hydrogel sensing material of this invention, iodine solution and starch solution form a blue starch-iodine complex. The presence of this starch-iodine complex causes fluorescence quenching of the long-afterglow material. Therefore, when the hydrogel sensing material of this invention is not in contact with SO2, it appears blue under visible light and has no or weak fluorescence signal under ultraviolet light. When the hydrogel sensing material comes into contact with SO2 volatilized from sulfite, SO2 reacts with the starch-iodine complex in the hydrogel sensing material through a Karl Fischer reaction, gradually changing the hydrogel sensing material from blue to colorless, thus achieving a colorimetric signal response. Simultaneously, the fluorescence quenching of the long-afterglow material caused by the starch-iodine complex is relieved, and the fluorescence signal is restored, thus achieving a fluorescence signal response. Therefore, the hydrogel sensing material of this invention can produce two independent signal responses in the same system: a visible color change and fluorescence enhancement, enabling cross-validation and high-accuracy detection of sulfite. The higher the sulfite concentration, the stronger the sulfur dioxide reducing power, the lighter the color of the starch-iodine complex, and the stronger the fluorescence signal of the long-afterglow material. The two modal signals are independent of each other and verify each other.
[0008] Preferably, the precursor raw materials of the long afterglow material include ammonium germanate (Ce(NH4)4), zinc nitrate (Zn(NO3)2·6H2O), gallium nitrate (Ga(NO3)2), chromium nitrate (Cr(NO3)3·9H2O), ytterbium nitrate (Yb(NO3)3·5H2O), and erbium nitrate (Er(NO3)3·5H2O).
[0009] Preferably, the molar ratio of ammonium germanate, zinc nitrate, gallium nitrate, chromium nitrate, ytterbium nitrate, and erbium nitrate is (0.3~0.5):(0.3~0.6):(0.5~1):(0.05~0.2):(0.05~0.2):(0.05~0.2); more preferably, the molar ratio of ammonium germanate, zinc nitrate, gallium nitrate, chromium nitrate, ytterbium nitrate, and erbium nitrate is (0.35~0.5):(0.4~ 0.6): (0.6~1): (0.05~0.15): (0.05~0.12): (0.05~0.12); More preferably, the molar ratio of ammonium germanate, zinc nitrate, gallium nitrate, chromium nitrate, ytterbium nitrate, and erbium nitrate is (0.4~0.5): (0.5~0.6): (0.8~1): (0.1~0.15): (0.08~0.12): (0.06~0.1). Preferably, the long afterglow material is prepared by the following steps: mixing ammonium germanate solution, zinc nitrate solution, gallium nitrate solution, chromium nitrate solution, ytterbium nitrate solution, and erbium nitrate solution, adjusting the pH to form a white emulsion, stirring for 2 hours, adding oleic acid and toluene, and then carrying out a hydrothermal reaction, taking the precipitate after the reaction and calcining it to obtain the long afterglow material.
[0010] Preferably, the pH is adjusted to 7.8-9; more preferably, the pH is adjusted to 7.9-8.5; and even more preferably, the pH is adjusted to 8-8.2.
[0011] Preferably, the oleic acid accounts for 3% to 10% of the volume percentage of the final solution; more preferably, the oleic acid accounts for 4% to 8% of the volume percentage of the final solution.
[0012] Preferably, the toluene accounts for 30% to 50% of the final solution by volume; more preferably, the toluene accounts for 30% to 40% of the final solution by volume.
[0013] Preferably, the temperature of the hydrothermal reaction is 140℃~180℃; more preferably, the temperature of the hydrothermal reaction is 145℃~175℃; and even more preferably, the temperature of the hydrothermal reaction is 150℃~170℃.
[0014] Preferably, the hydrothermal reaction time is 18-30 h; more preferably, the hydrothermal reaction time is 20-28 h; and even more preferably, the hydrothermal reaction time is 22-26 h.
[0015] Preferably, the calcination temperature is 800~1200℃; more preferably, the calcination temperature is 850~1100℃; and even more preferably, the calcination temperature is 900~1000℃.
[0016] Preferably, the calcination time is 1-3 h; more preferably, the calcination time is 1.2-2.8 h; and even more preferably, the calcination time is 1.5-2.5 h.
[0017] Preferably, the alginate includes sodium alginate.
[0018] Preferably, the iodine solution comprises elemental iodine and an iodine compound; more preferably, the iodine compound comprises potassium iodide.
[0019] Preferably, the crosslinking agent includes at least one of calcium chloride, calcium carbonate and gluconolactone sustained-release system, and calcium sulfate.
[0020] Preferably, the mass ratio of the long-afterglow material to alginate is (0.5~2):1; more preferably, the mass ratio of the long-afterglow material to alginate is (0.6~1.8):1; and even more preferably, the mass ratio of the long-afterglow material to alginate is (0.8~1.2):1.
[0021] Preferably, the volume ratio of the starch solution to the iodine solution is (2~8):1; more preferably, the volume ratio of the starch solution to the iodine solution is (3~7):1; and even more preferably, the volume ratio of the starch solution to the iodine solution is (4~6):1.
[0022] Preferably, the mass ratio of the crosslinking agent to alginate is (0.5~5):60; more preferably, the mass ratio of the crosslinking agent to alginate is (1~4):60; and even more preferably, the mass ratio of the crosslinking agent to alginate is (1.5~3):60.
[0023] Preferably, the concentration of the starch solution is 0.001~0.02 mg / mL; more preferably, the concentration of the starch solution is 0.001~0.15 mg / mL; and even more preferably, the concentration of the starch solution is 0.001~0.1 mg / mL.
[0024] Preferably, the concentration of elemental iodine in the iodine solution is 1.0~5.0 mg / mL; more preferably, the concentration of elemental iodine in the iodine solution is 1.5~4.5 mg / mL; and even more preferably, the concentration of elemental iodine in the iodine solution is 2~3.5 mg / mL.
[0025] Preferably, the concentration of iodine compound in the iodine solution is 5.0~12.0 mg / mL; more preferably, the concentration of iodine compound in the iodine solution is 6.0~12.0 mg / mL.
[0026] Preferably, the hydrogel sensing material is prepared by the following steps: accurately weighing alginate and long afterglow material, then adding starch solution and iodine solution to mix, obtaining a mixed solution, and then adding a crosslinking agent to crosslink and obtain the hydrogel sensing material.
[0027] Preferably, the concentration of alginate in the mixed solution is 10-30 mg / mL; more preferably, the concentration of alginate in the mixed solution is 12-28 mg / mL; and even more preferably, the concentration of alginate in the mixed solution is 15-25 mg / mL.
[0028] Preferably, in the mixed solution, the starch solution accounts for 60% to 90% of the volume percentage of the mixed solution; more preferably, in the mixed solution, the starch solution accounts for 70% to 90% of the volume percentage of the mixed solution.
[0029] Preferably, the crosslinking time is 10-30 min; more preferably, the crosslinking time is 10-25 min; even more preferably, the crosslinking time is 10-20 min.
[0030] Secondly, the present invention provides a method for detecting sulfites, comprising the following steps: S1: Heating the sulfite standard sample to enrich the SO2 generated by heating in the hydrogel sensing material described in the first aspect, taking pictures to obtain image data, and establishing colorimetric standard curves and fluorescence standard curves based on the relationship between image data and sulfite concentration. S2: Heat the sample to be tested, so that the SO2 generated by heating is enriched in the hydrogel sensing material, take a picture to obtain image data, and calculate the sulfite content in the sample to be tested based on the image data and the colorimetric standard curve and fluorescence standard curve in step S1.
[0031] This invention provides a method for detecting sulfite based on a hydrogel sensing material with a colorimetric fluorescence dual-modal signal response. This method is simple to operate and highly accurate. When applied to food samples with various typical and complex matrices, such as dairy products, alcoholic beverages, and dried vegetables, it can effectively identify systematic errors introduced by equipment or environmental fluctuations during sulfite detection, demonstrating good anti-interference ability and accurate detection results. This significantly improves the anti-interference ability and reliability of sulfite detection methods under complex real-world conditions, providing a new method for rapid on-site screening of sulfite in food.
[0032] Preferably, the sulfite standard sample includes a sodium sulfite standard solution and a sulfuric acid solution.
[0033] More preferably, the volume ratio of the sodium sulfite standard solution to the sulfuric acid solution is (5~10):1; even more preferably, the volume ratio of the sodium sulfite standard solution to the sulfuric acid solution is (6~10):1; even more preferably, the volume ratio of the sodium sulfite standard solution to the sulfuric acid solution is (8~10):1.
[0034] More preferably, the concentration of the sodium sulfite standard solution is 0.1~100.0 mg / L; even more preferably, the concentration of the sodium sulfite standard solution is 0.1~80.0 mg / L; and even more preferably, the concentration of the sodium sulfite standard solution is 0.1~60.0 mg / L. More preferably, the concentration of the sulfuric acid solution is 0.1~0.5 mol / L; even more preferably, the concentration of the sulfuric acid solution is 0.1~0.4 mol / L; even more preferably, the concentration of the sulfuric acid solution is 0.1~0.3 mol / L.
[0035] Preferably, in step S1, the method for establishing the colorimetric standard curve is to take an image of the SO2-enriched hydrogel sensing material under visible light, obtain the relationship between the R / B value of the image and the concentration of sulfite, and establish a colorimetric standard curve; the method for establishing the fluorescence standard curve is to take an image of the SO2-enriched hydrogel sensing material under ultraviolet light excitation, obtain the relationship between the R value of the image and the concentration of sulfite, and establish a fluorescence standard curve.
[0036] Thirdly, the present invention provides an apparatus for detecting sulfite, the apparatus comprising a heating device and a dual-modal imaging device; the heating device comprising a heating stage, multiple reaction vessels and multiple collection devices; the heating stage being used to heat the reaction vessels; the collection devices being connected to each of the reaction vessels, and the collection devices containing the hydrogel sensing material described in the first aspect.
[0037] Preferably, the reaction vessel includes a sample vial.
[0038] Preferably, the collection device includes a sample bottle cap.
[0039] Preferably, the heating device is a constant temperature heating device; more preferably, the cross-section of the constant temperature heating device is one of a circle, a rectangle, or a polygon.
[0040] Preferably, the dual-modal imaging device includes a visible light imaging module, a fluorescence imaging module, a partition, and a stage; the partition is disposed between the visible light imaging module and the fluorescence imaging module; the visible light imaging module has a white background and is provided with a visible light source and a first image acquisition area; the fluorescence imaging module has a black background and is provided with an ultraviolet light source and a second image acquisition area, and a filter is installed on the second image acquisition area.
[0041] In this invention, the white background in the visible light imaging module has a reflectivity close to 100%, reducing color difference. The black background and the installation of filters in the fluorescence imaging module reduce light scattering and other contaminants.
[0042] Preferably, the stage is made of highly transparent glass.
[0043] Preferably, the bottom of the stage is equipped with casters. The dual-modal hydrogel sensor can be moved between two imaging modes by moving the stage.
[0044] Preferably, the laser wavelength of the ultraviolet light source is 365 nm.
[0045] Preferably, the volume of the sample to be tested is 2-6 mL; more preferably, the volume of the sample to be tested is 2-5 mL; and even more preferably, the volume of the sample to be tested is 2-4 mL.
[0046] Fourthly, the present invention provides a kit for detecting sulfites, comprising the hydrogel sensing material described in the first aspect.
[0047] Fifthly, the present invention provides the application of the hydrogel sensing material described in the first aspect, the detection method described in the second aspect, the apparatus for detecting sulfite described in the third aspect, or the reagent kit for detecting sulfite described in the fourth aspect in the detection of sulfite content in food.
[0048] Preferably, the food includes liquid food and solid food.
[0049] Preferably, the liquid food includes one of fruit wine, yogurt, and milk; more preferably, the fruit wine includes one of red wine, white wine, and blueberry wine.
[0050] Preferably, the liquid food is mixed with sulfuric acid solution and then used as the sample to be tested.
[0051] Preferably, the volume ratio of the liquid food to the sulfuric acid solution is (5~10):1; more preferably, the volume ratio of the liquid food to the sulfuric acid solution is (6~10):1; even more preferably, the volume ratio of the liquid food to the sulfuric acid solution is (7~10):1.
[0052] Preferably, the concentration of the sulfuric acid solution is 0.1~0.5 mol / L; more preferably, the concentration of the sulfuric acid solution is 0.1~0.4 mol / L; even more preferably, the concentration of the sulfuric acid solution is 0.1~0.3 mol / L.
[0053] Preferably, the solid food includes white sugar.
[0054] Preferably, the solid food is dissolved in ultrapure water and then mixed with sulfuric acid solution to serve as the sample to be tested.
[0055] The beneficial effects of this invention are: (1) This invention constructs a novel hydrogel sensing material with dual-modal signals. When the hydrogel sensing material is not in contact with SO2, it exhibits a blue color under visible light and no or weak fluorescence signal under ultraviolet light. When the hydrogel sensing material comes into contact with SO2 volatilized from sulfite, SO2 reacts with the starch-iodine complex in the hydrogel sensing material via a Karl Fischer reaction, gradually changing the hydrogel sensing material from blue to colorless, thus achieving a colorimetric signal response. Simultaneously, the fluorescence quenching of the long-afterglow material caused by the starch-iodine complex is relieved, and the fluorescence signal is restored, thereby achieving a fluorescence signal response. Therefore, the hydrogel sensing material of this invention can produce two independent signal responses—visible color change and fluorescence enhancement—in the same system, enabling cross-validation and high-accuracy detection of sulfite.
[0056] (2) The sulfite detection method provided by this invention is simple to operate and has high detection accuracy. When applied to food samples with various typical and complex matrices such as dairy products, wines, and dried vegetables, it can effectively identify systematic errors introduced by equipment or environmental fluctuations during the sulfite detection process, showing good anti-interference ability and accurate detection results. It significantly improves the anti-interference ability and reliability of the sulfite detection method under actual complex conditions, and provides a new detection method for rapid on-site screening of sulfites in food. Attached Figure Description
[0057] Figure 1 This is an external schematic diagram of the constant temperature heating device used in the embodiment; Figure 2 This is a schematic diagram of the internal structure of the constant temperature heating device used in the embodiment; Figure 3 This is an external schematic diagram of the dual-modal imaging device used in the embodiment; Figure 4 This is a schematic diagram of the internal structure of the dual-modal imaging device used in the embodiment; Figure 5 Images of sulfite standard samples of different concentrations in Example 1 were captured under visible and ultraviolet light. Figure 6 The colorimetric and fluorescence standard curves established for Example 1; Figure 7 Colorimetric response bar charts for SO2 analogues, interfering substances and sulfites present in alcoholic beverages and dairy products; Figure 8 The fluorescence response bar charts for SO2 analogues, interfering substances and sulfites present in alcoholic and dairy products; Figure 9 The colorimetric response of sulfite after adding different interfering substances is shown in the bar graph. Figure 10 The bar chart shows the fluorescence response of sulfite after adding different interfering substances; Figure 11 Example 2: Detection of white wine in colorimetric and fluorescence images; Figure 12 Example 3: Detection of colorimetric and fluorescence images of blueberry wine; Reference numerals: 1-Heating stage, 2-Reaction vessel, 3-Collection device, 4-Visible light imaging module, 5-Fluorescence imaging module, 6-Separator, 7-Stage, 8-Visible light source, 9-First image acquisition area, 10-Ultraviolet light source, 11-Second image acquisition area, 12-Filter. Detailed Implementation
[0058] To enable those skilled in the art to more clearly understand this application, the present invention will be further described in detail below with reference to embodiments. However, it should be understood that the following embodiments are merely preferred embodiments of the present invention, and the scope of protection of the present invention should be determined by the scope defined in the claims. In the description of the present invention, it should be noted that unless specific conditions are specified in the embodiments, conventional conditions or conditions recommended by the manufacturer are followed. Reagents or instruments used that do not specify the manufacturer are all commercially available conventional products.
[0059] Figure 1 This is an external schematic diagram of the constant temperature heating device used in the embodiment. Figure 2 This is a schematic diagram of the internal structure of the constant-temperature heating device used in the embodiment. Figure 1 and Figure 2 It can be seen that the constant temperature heating device includes a heating platform 1, multiple reaction vessels 2, and multiple collection devices 3; the heating platform 1 is used to heat the reaction vessels 2; the reaction vessels 2 and the collection devices 3 are connected one by one, and the collection devices 3 are equipped with hydrogel sensing materials.
[0060] Figure 3 This is an external schematic diagram of the dual-modal imaging device used in the embodiment. Figure 4 This is a schematic diagram of the internal structure of the dual-modal imaging device used in the embodiment. Figure 3 and Figure 4It is known that the dual-modal imaging device includes a visible light imaging module 4, a fluorescence imaging module 5, a partition 6, and a stage 7; the partition 6 is movable and is located between the visible light imaging module 4 and the fluorescence imaging module 5 to prevent optical path crosstalk; the stage 7 is a movable platform used to place hydrogel sensing materials, and by moving the stage 7, the hydrogel sensing materials can be photographed between different imaging modules; the visible light imaging module 4 has a white background and is equipped with a visible light source 8 and a first image acquisition area 9; the visible light source 8 is a 5100 K LED light strip; the fluorescence imaging module 5 has a black background and is equipped with an ultraviolet light source 10 and a second image acquisition area 11, on which a filter 12 is installed.
[0061] The following will combine Figures 1-4 The detection of sulfites in the examples is described.
[0062] Example 1 The steps for establishing the colorimetric and fluorescence standard curves for sulfites are as follows: S1: Preparation of long afterglow material: Accurately weigh 1.4874 g of zinc nitrate into a 50 mL round-bottom flask, then add 10 mL of 0.47 mol / L ammonium germanate solution, 10 mL of 0.6 mol / L gallium nitrate solution, 300 μL of 0.1 mol / L chromium nitrate solution, 1500 μL of 0.1 mol / L ytterbium nitrate solution, and 150 μL of 0.1 mol / L erbium nitrate solution. Adjust the pH to 8 with tert-butylamine, stir for 2 h, then add 2 mL of oleic acid and 15 mL of toluene. After sonication, a white emulsion is formed and added to the liner of a polytetrafluoroethylene reactor. The reaction is carried out hydrothermally at 160℃ for 24 h. After the reaction is completed, after cooling, add anhydrous ethanol, mix well, centrifuge at 7000 rpm / min for 10 min to collect the precipitate, wash 2-3 times, and then place the centrifuged precipitate at 80℃ and vacuum dry for 3 h. After drying, the sample was coarsely ground and then transferred to a muffle furnace and calcined at 1000℃ for 2 hours to obtain a long afterglow material. S2: Preparation of hydrogel sensing material: Accurately weigh 60 mg of sodium alginate and 60 mg of long afterglow material, then add 2.5 mL of starch solution (0.005 mg / mL) and 0.5 mL of iodine solution (2 mg / mL iodine and 8 mg / mL potassium iodide), stir and mix to obtain a mixed solution. Then, pipette 60 μL of the mixed solution into a mold of a 4×4-well polytetrafluoroethylene (PTFE) plate. Add 200 μL of calcium chloride solution (0.02 mg / mL) to the mixed solution for crosslinking for 10 min to obtain the hydrogel sensing material. S3: Preparation of sodium sulfite standard samples: Sodium sulfite standard solutions with concentrations of 0 mg / L, 0.3 mg / L, 0.5 mg / L, 0.8 mg / L, 1.0 mg / L, 2.0 mg / L, 5.0 mg / L, 9.0 mg / L, and 10.0 mg / L were mixed with a 0.2 mol / L sulfuric acid solution at a volume ratio of 10:1 to prepare sodium sulfite standard samples. S4: Place the sodium sulfite standard sample prepared in S3 into the reactor of the constant temperature heating device, and place the hydrogel sensing material prepared in S2 into the collection device of the constant temperature heating device. Heat at 60℃ for 20 min, then take out the hydrogel sensing material and place it in the visible light imaging module of the dual-modal imaging device. Take a picture with a mobile phone to obtain the relationship between the R / B value of the colorimetric image and the concentration of sodium sulfite, and establish a colorimetric standard curve. Then place the hydrogel sensing material in the fluorescence imaging module of the dual-modal imaging device, irradiate it with an ultraviolet light source (365 nm ultraviolet lamp), take a picture with a mobile phone to obtain the relationship between the R value of the fluorescence image and the concentration of sodium sulfite, and establish a fluorescence standard curve.
[0063] Figure 5 Images of sulfite standard samples of different concentrations in Example 1 were captured under visible and ultraviolet light. Figure 5 In the image, a is the image obtained under visible light, and b is the image obtained under ultraviolet light. Figure 5 It is known that sulfite standard samples of different concentrations can produce colorimetric and fluorescence signals of varying intensities. The higher the concentration of the sulfite standard sample, the more SO2 is generated upon heating, causing the blue color of the starch-iodine complex in the hydrogel sensing material to become increasingly lighter until it turns colorless. As the starch-iodine complex is reduced to a higher degree by SO2, the fluorescence suppression of the long-persistent material in the hydrogel sensing material is gradually relieved, and the fluorescence signal of the hydrogel sensing material under ultraviolet light becomes increasingly stronger.
[0064] A colorimetric standard curve was established based on the relationship between the R / B value of the colorimetric image and the concentration of sulfite. A fluorescence standard curve was established based on the relationship between the R value of the fluorescence image and the concentration of sulfite. The standard curves are as follows: Figure 6 As shown. Figure 6 In the diagram, a is the colorimetric standard curve, and b is the fluorescence standard curve. The linear range for both colorimetric and fluorescence standards is 0.3–9 mg / L. 2 The values are 0.9965 and 0.9964, respectively.
[0065] Example 2 A method for detecting sulfites in white wine, in addition to steps S1 to S4 as described in Example 1, also includes the following steps: S5: A white wine sample was mixed with a 0.2 mol / L sulfuric acid solution at a volume ratio of 10:1 to prepare the test sample. 3 mL of the test sample was placed in the reactor of a constant-temperature heating device. The hydrogel sensing material prepared in S2 was placed in the collecting device of the constant-temperature heating device and heated for 20 min. Then, the hydrogel sensing material was removed and placed in the visible light imaging module of a dual-modal imaging device. A mobile phone was used to take an image, obtaining the R / B value of the colorimetric image of the test sample. Three images were taken, and the average and relative standard deviation of the three R / B values were calculated. Next, the hydrogel sensing material was placed in the fluorescence imaging module of the dual-modal imaging device. After irradiation with ultraviolet light, a mobile phone was used to take an image, obtaining the R value of the fluorescence image of the test sample. Three images were taken, and the average and relative standard deviation of the three R values were calculated. S6: Substitute the obtained R / B value and R value of the sample to be tested into the colorimetric standard curve and fluorescence standard curve respectively to calculate the concentration of sulfite in white wine.
[0066] Example 3 This embodiment provides a method for detecting sulfites in blueberry wine, replacing the white wine in Example 2 with blueberry wine, while all other aspects remain the same as in Example 2.
[0067] Example 4 This embodiment provides a method for detecting sulfites in milk, replacing the white wine in Example 2 with milk, while all other aspects remain the same as in Example 2.
[0068] Example 5 This embodiment provides a method for detecting sulfites in yogurt, replacing the white wine in Example 2 with yogurt, while all other aspects remain the same as in Example 2.
[0069] Data representation I. Anti-interference test The detection method of Example 2 was used to detect SO2 analogs, interfering substances (methanol, ethanol, formic acid, acetic acid, tannic acid, lactose, ethyl acetate, n-butanol), and sulfites (i.e., sodium sulfite) present in alcoholic and dairy products. The white wine sample in Example 2 was replaced with samples containing SO2 analogs, interfering substances in alcoholic and dairy products, and sulfites. Colorimetric and fluorescence response bar charts were obtained for SO2 analogs, interfering substances in alcoholic and dairy products, and sulfites, respectively. Figure 7 The bar chart shows the colorimetric response of SO2 analogs, interfering substances in alcoholic beverages and dairy products, and sulfites. Figure 8This is a bar chart showing the fluorescence response of SO2 analogues, interfering substances in alcoholic beverages and dairy products, and sulfites. Anti-interference tests were conducted by adding interfering substances to sulfites at concentrations 200 times higher than the sulfite concentration, resulting in colorimetric and fluorescence response bar charts of sulfites after adding different interfering substances. Figure 9 The bar chart shows the colorimetric response of sulfite after adding different interfering substances. Figure 10 The bar chart shows the fluorescence response of sulfite after adding different interfering agents. Figure 7 and Figure 9 , Figure 8 and Figure 10 The comparison shows that for low concentrations of sulfite, the R value and R / B value obtained after adding different interfering substances did not change significantly. This indicates that the sulfite detection method of the present invention has good selectivity and anti-interference ability.
[0070] II. Testing of Commercially Available Products The detection methods of Examples 2-5 and commercially available total sodium sulfite (e.g., SO2) ELISA kits were used to detect sulfites in commercially available white wine, blueberry wine, milk, and yogurt.
[0071] Figure 11 Example 2: Detection of white wine in colorimetric images ( Figure 11 a) and fluorescence images ( Figure 11 (b) The R / B value obtained from the colorimetric image was substituted into the colorimetric standard curve to calculate the sulfite content in the white wine as 421.84 mg / kg. The R value obtained from the fluorescence image was substituted into the fluorescence standard curve to calculate the sulfite content in the white wine as 414.16 mg / kg. The sulfite concentration in the white wine was detected by a sulfur dioxide ELISA kit as 442.90 mg / kg.
[0072] Figure 12 The colorimetric image of blueberry wine detected in Example 3 ( Figure 12 a) and fluorescence images ( Figure 12 (b) The R / B value obtained from the colorimetric image was substituted into the colorimetric standard curve to calculate the sulfite content in the blueberry wine as 107.65 mg / kg. The R value obtained from the fluorescence image was substituted into the fluorescence standard curve to calculate the sulfite content in the blueberry wine as 105.60 mg / kg. The sulfite concentration in the blueberry wine was 107.74 mg / kg as detected by a sulfur dioxide ELISA kit.
[0073] In the tests conducted using Examples 4 and 5, as well as the sulfur dioxide ELISA kit, no sulfites were detected in milk and yogurt.
[0074] The results above show that, for the same sample, the relative deviation between colorimetric and fluorescence detection results is <5%, indicating that self-calibration can be achieved between the colorimetric and fluorescence detection results, thus improving detection accuracy. The relative deviation between the detection method of this invention and commercially available kits is less than 8%, demonstrating the reliability of the detection method in this embodiment.
[0075] III. Test Spike Recovery Rate To verify the accuracy of the detection method of this invention, the white wine sample from Example 2, the blueberry wine sample from Example 3, the milk sample from Example 4, and the yogurt sample from Example 5 were spiked. The spiked samples were prepared by adding sodium sulfite standard solutions of 0.5 mg / kg, 1.0 mg / kg, and 5.0 mg / kg, respectively. The spiked samples were then tested using the same method, with three parallel tests to obtain three R / B values and three R values. The average of the three R / B values was calculated and substituted into the colorimetric standard curve to obtain the sulfite concentration in the spiked sample. The sample recovery rate and relative standard deviation were then calculated using the colorimetric method. Similarly, the average of the three R values was calculated and substituted into the fluorescence standard curve to obtain the sulfite concentration in the spiked sample. The sample recovery rate and relative standard deviation were then calculated using the fluorescence method. The test results are shown in Table 1.
[0076] Table 1. Accuracy verification of test results for different samples
[0077] As shown in Table 1, both colorimetric and fluorescence methods demonstrated excellent performance in actual sample detection, confirming the great potential of this method in practical applications.
[0078] IV. Verifying the superiority of the colorimetric fluorescence dual-modal response To verify the superiority of the colorimetric fluorescence dual-modal response of the present invention, the detection method was tested to see if interference with the fluorescence signal channel would cause false positives / false negatives, thereby determining the superiority of the colorimetric fluorescence dual-modal response.
[0079] The detection method of Example 2 was used, replacing the white wine sample of Example 2 with a 5.0 mg / L sodium sulfite standard solution. Colorimetric and fluorescence images were obtained, and the tests were performed in triplicate. The mean and relative standard deviation of the three R / B values of the colorimetric image were calculated, and the recovery rate was found to be 96.62%. The mean and relative standard deviation of the three R values of the fluorescence image were calculated, and the recovery rate was found to be 101.3%. The difference between the colorimetric and fluorescence recoveries was <5%.
[0080] Interference conditions were set up, and the ultraviolet light source in the dual-modal imaging device was adjusted to have insufficient power supply, with the light source brightness only 50% of normal operation. Under this insufficient power supply condition, a 5.0 mg / L sodium sulfite standard solution was tested using the same detection method. Colorimetric and fluorescence images were obtained, and the tests were performed in triplicate. The mean and relative standard deviation were calculated based on the three R / B values of the colorimetric image, resulting in a recovery rate of 97.62%. The mean and relative standard deviation were calculated based on the three R values of the fluorescence image, resulting in a recovery rate of 87.63%. The difference between the colorimetric and fluorescence recovery rates was 11.41%, indicating an anomaly in the data.
[0081] The results above show that under interference conditions, the colorimetric / fluorescence recovery rates exhibit significant differences, indicating abnormal data. Therefore, using a single signal for judgment can lead to false negatives. Thus, the colorimetric and fluorescence dual-modal signals of this invention, through mutual verification, can effectively identify systematic errors introduced by equipment or environmental fluctuations and issue early warnings, thereby significantly improving the anti-interference capability and reliability of the detection method under complex real-world conditions.
[0082] In summary, the sulfite detection method provided in this invention is simple to operate and highly accurate. When applied to food samples with various typical and complex matrices, such as dairy products and alcoholic beverages, it can effectively identify systematic errors introduced by equipment or environmental fluctuations during sulfite detection, demonstrating good anti-interference ability and accurate detection results. This significantly improves the anti-interference ability and reliability of the sulfite detection method under actual complex conditions.
[0083] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.
Claims
1. A hydrogel sensing material for detecting sulfite, characterized by, The raw materials for preparing the hydrogel sensing material include long afterglow material, alginate, starch solution, iodine solution and crosslinking agent.
2. The hydrogel sensing material of claim 1, wherein, The precursor raw materials for the long afterglow material include at least one of ammonium germanate, zinc nitrate, gallium nitrate, chromium nitrate, ytterbium nitrate, and erbium nitrate. And / or, the alginate includes sodium alginate; And / or, the iodine solution comprises elemental iodine and iodine compounds; And / or, the crosslinking agent includes at least one of calcium chloride, calcium carbonate and gluconolactone sustained-release system, and calcium sulfate.
3. The hydrogel sensing material of claim 1, wherein, The mass ratio of the long afterglow material to the alginate is (0.5~2):1; the volume ratio of the starch solution to the iodine solution is (2~8):1; And / or, the mass ratio of the crosslinking agent to the alginate is (0.5~5):
60.
4. The hydrogel sensing material of claim 1, wherein, The hydrogel sensing material is prepared by the following steps: mixing alginate, long afterglow material, starch solution and iodine solution, and then adding a crosslinking agent to crosslink the hydrogel sensing material.
5. A method for detecting sulfite, characterized by, Includes the following steps: S1: Heating a sulfite standard sample to enrich the SO2 generated during heating in the hydrogel sensing material described in any one of claims 1 to 4, taking pictures to obtain image data, and establishing a colorimetric standard curve and a fluorescence standard curve based on the relationship between the image data and the concentration of sulfite. S2: Heat the sample to be tested, so that the SO2 generated by heating is enriched in the hydrogel sensing material, take a picture to obtain image data, and calculate the sulfite content in the sample to be tested based on the image data and the colorimetric standard curve and fluorescence standard curve in step S1.
6. The detection method according to claim 5, characterized in that, In step S1, the method for establishing the colorimetric standard curve is to take an image of the SO2-enriched hydrogel sensing material under visible light, obtain the relationship between the R / B value of the image and the concentration of sulfite, and establish the colorimetric standard curve; the method for establishing the fluorescence standard curve is to take an image of the SO2-enriched hydrogel sensing material under ultraviolet light excitation, obtain the relationship between the R value of the image and the concentration of sulfite, and establish the fluorescence standard curve.
7. A device for detecting sulfites, characterized in that The device includes a heating device and a dual-modal imaging device; the heating device includes a heating stage, multiple reaction containers and multiple collection devices; the heating stage is used to heat the reaction containers; the collection devices are connected to each of the reaction containers, and the collection devices are provided with the hydrogel sensing material according to any one of claims 1 to 4.
8. The apparatus of claim 7, wherein, The dual-modal imaging device includes a visible light imaging module, a fluorescence imaging module, a partition, and a stage; the partition is located between the visible light imaging module and the fluorescence imaging module; the visible light imaging module has a white background and is equipped with a visible light source and a first image acquisition area; the fluorescence imaging module has a black background and is equipped with an ultraviolet light source and a second image acquisition area, and a filter is installed on the second image acquisition area.
9. A kit for detecting sulfite, characterized by, Includes the hydrogel sensing material according to any one of claims 1 to 4.
10. The application of the hydrogel sensing material according to any one of claims 1 to 4, the detection method according to any one of claims 5 to 6, the apparatus according to any one of claims 7 to 8, or the kit according to claim 9 in the detection of sulfite content in food.