Sulfur dioxide detection method and application thereof

Abstract

The invention relates to the technical field of gas detection, and discloses a sulfur dioxide detection method and application thereof. The sulfur dioxide detection method comprises the following steps: S1, taking a sulfur dioxide standard sample and a reaction solution; s2, establishing a sulfur dioxide colorimetric standard curve and a surface enhanced Raman spectrum standard curve; s3, enriching sulfur dioxide gas in a to-be-detected sample in the reaction liquid by using a purge-trap method to obtain an absorption liquid; and S4, taking the absorption liquid, and respectively calculating the concentration of sulfur dioxide in the absorption liquid by utilizing the colorimetric standard curve and the surface enhanced Raman spectrum standard curve in the step S2 to obtain the content of sulfur dioxide in the sample to be detected. In the step S1, the reaction liquid comprises starch, an iodine compound and 4-mercaptopyridine. According to the detection method based on bimodal analysis of the colorimetric method and the surface enhanced Raman spectroscopy, provided by the invention, self-correction of a detection result can be realized, the accuracy of the detection result is improved, and the detection efficiency is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of gas detection, and in particular to a sulfur dioxide detection method and application thereof. Background Art

[0002] Sulfur dioxide (SO2) has many functions such as preservation, sterilization, stabilization, bleaching, clarification and anti-oxidation. It is widely used as a preservative and antioxidant in food to extend the shelf life of food and prevent food from turning brown. However, long-term intake of food with excessive sulfur dioxide content may cause adverse reactions such as headaches and nausea. Therefore, it is very important to determine the level of sulfur dioxide in food.

[0003] Wine is one of the two most popular alcoholic beverages in the world, and the wine trade it generates plays an important role in economic development. Sulfur dioxide (SO2) is widely used in the production and processing of wine, but the complexity of the wine sample matrix and the volatility of sulfur dioxide gas bring many inconveniences to the sample pretreatment and accurate analysis and detection of sulfur dioxide in wine samples. At present, the detection methods of sulfur dioxide in wine in China are mainly acid-base titration, spectrophotometry and ion chromatography. The above methods have many defects such as complex sample pretreatment process, time-consuming, and insufficient accuracy, and cannot meet the needs of rapid on-site detection. Therefore, it is of great significance to establish an accurate, efficient and economical detection and analysis method for sulfur dioxide in food. Summary of the invention

[0004] The present invention aims to solve at least one of the above-mentioned technical problems existing in the prior art. To this end, one of the purposes of the present invention is to provide a method for detecting sulfur dioxide; the second purpose of the present invention is to provide a purge and capture device for the method for detecting sulfur dioxide; the third purpose of the present invention is to provide an application of the method for detecting sulfur dioxide.

[0005] In order to achieve the above object, the technical solution adopted by the present invention is:

[0006] A first aspect of the present invention provides a method for detecting sulfur dioxide, comprising the following steps:

[0007] S1, take sulfur dioxide standard sample and reaction solution;

[0008] S2. Establishing the sulfur dioxide colorimetric standard curve and the surface enhanced Raman spectroscopy standard curve;

[0009] S3, using a purge-and-trap method to enrich the sulfur dioxide gas in the sample to be tested in the reaction solution to obtain an absorption solution;

[0010] S4, taking the absorption liquid, and using the colorimetric standard curve and the surface enhanced Raman spectroscopy standard curve described in S2 to respectively calculate the sulfur dioxide concentration in the absorption liquid, to obtain the sulfur dioxide content of the sample to be tested;

[0011] In the step S1, the reaction solution includes starch, an iodine compound and 4-mercaptopyridine.

[0012] Preferably, in step S1, the sulfur dioxide standard sample includes a sodium sulfite standard solution and a sulfuric acid solution.

[0013] Preferably, the concentration of the sodium sulfite standard solution is 0.1-1000 mg / L; further preferably, the concentration of the sodium sulfite standard solution is 0.1-500 mg / L.

[0014] Preferably, the concentration of the sulfuric acid solution is 0.05-0.5 mol / L; further preferably, the concentration of the sulfuric acid solution is 0.15-0.25 mol / L.

[0015] Preferably, the volume ratio of the sodium sulfite standard solution to the sulfuric acid solution is (5-20):1; further preferably, the volume ratio of the sodium sulfite standard solution to the sulfuric acid solution is (5-15):1.

[0016] Preferably, in step S1, the reaction solution includes a starch solution, an iodine solution, methanol, and a mixed solution of 4-mercaptopyridinemethanol.

[0017] Preferably, the volume ratio of the starch solution, iodine solution, methanol and 4-mercaptopyridinemethanol mixed solution is (50-800):(1-15):(50-500):1; further preferably, the volume ratio of the starch solution, iodine solution, methanol and 4-mercaptopyridinemethanol mixed solution is (100-120):(1-3):(80-120):1.

[0018] Preferably, the mass concentration of the starch solution is 1-20 mg / mL; further preferably, the mass concentration of the starch solution is 4-6 mg / mL.

[0019] Preferably, the concentration of the 4-mercaptopyridine-methanol mixed solution is 0.1-5 mmol / L; further preferably, the concentration of the 4-mercaptopyridine-methanol mixed solution is 0.4-0.8 mmol / L.

[0020] Preferably, the volume concentration of the methanol is 1-50% (v / v); further preferably, the volume concentration of the methanol is 5-12% (m / v).

[0021] Preferably, the iodine solution comprises elemental iodine and potassium iodide.

[0022] Preferably, in the iodine solution, the content of the iodine element is 0.01-0.05 mg / mL; more preferably, the content of the iodine element is 0.03-0.035 mg / mL.

[0023] Preferably, in the iodine solution, the content of potassium iodide is 0.05-0.12 mg / mL; further preferably, the content of potassium iodide is 0.08-0.10 mg / mL.

[0024] Preferably, in step S2, the specific operations of establishing the sulfur dioxide colorimetric standard curve and the surface enhanced Raman spectroscopy standard curve are: using the purge and trap method to enrich the sulfur dioxide gas in the standard sample in the reaction liquid, obtaining the relationship between the ultraviolet-visible characteristic absorption peak intensity of the reaction liquid and the concentration of sulfur dioxide, establishing a colorimetric standard curve, obtaining the relationship between the peak value at the characteristic Raman shift of 4-mercaptopyridine and the concentration of sulfur dioxide, and establishing a surface enhanced Raman spectroscopy standard curve.

[0025] Preferably, the surface enhanced Raman spectroscopy standard curve is established, and the surface enhanced Raman spectroscopy substrate (SERS substrate) includes nano-gold sol.

[0026] Preferably, the average particle size of the nano-gold sol is 30-70 nm; further preferably, the average particle size of the nano-gold sol is 35-45 nm.

[0027] Preferably, in step S3, the volume ratio of the sample to be tested to the reaction liquid is 1:(1-5); further preferably, the volume ratio of the sample to be tested to the reaction liquid is 1:(1-4.5).

[0028] The basic principle of the present invention is as follows: sulfur dioxide in the sample is separated and enriched by a purge-and-trap method, and a Karl Fischer reaction is performed with the sulfur dioxide reaction solution, thereby reducing the blue starch-iodine complex to colorless and enhancing the surface enhanced Raman spectroscopy signal of 4-mercaptopyridine. Therefore, the higher the sulfur dioxide concentration, the stronger the sulfur dioxide reducing property, the lighter the color of the starch-iodine complex, and the stronger the SERS signal of 4-mercaptopyridine.

[0029] The second aspect of the present invention provides a purging and trapping device for the sulfur dioxide detection method described in the first aspect of the present invention, the device comprising a circulation pump, a flow meter, an evaporation device and a sample collection device connected in sequence, and a heating device matching the evaporation device.

[0030] Preferably, the circulation pump comprises an air inlet end and an air outlet end.

[0031] Preferably, the rated voltage of the circulating pump power supply is 10-15V; further preferably, the rated voltage of the circulating pump power supply is 10-12V.

[0032] Preferably, the flow control range of the circulation pump is 0.1-5 L / min; further preferably, the flow control range of the circulation pump is 0.4-0.6 L / min.

[0033] Preferably, the flow meter comprises an air inlet end and an air outlet end.

[0034] Preferably, the flow control range of the flow meter is 0.1-5 L / min.

[0035] Preferably, the flow meter is a rotor flow meter.

[0036] Preferably, the evaporation device is a closed container; the evaporation device comprises an air inlet end and an air outlet end.

[0037] Preferably, the sample collection device comprises an air inlet end and an air outlet end.

[0038] Preferably, the temperature control range of the heating device is 25-180°C; further preferably, the temperature control range of the heating device is 40-60°C.

[0039] Preferably, the heating device comprises a power supply, a switch and a heating jacket; the heating jacket is wrapped around the outer wall of the evaporation device.

[0040] Preferably, the rated voltage of the power supply of the heating device is 10-15V; further preferably, the rated voltage of the power supply of the heating device is 10-12V.

[0041] Preferably, the switch of the heating device is a digital display switch.

[0042] Preferably, the heating cover of the heating device is made of high temperature resistant cloth.

[0043] Preferably, the device also includes a silicone tube; the air outlet end of the circulation pump and the air inlet end of the flow meter, the air outlet end of the flow meter and the air inlet end of the evaporation device, and the air outlet end of the evaporation device and the air inlet end of the sample collection device are respectively connected by the silicone tube.

[0044] The third aspect of the present invention provides application of the sulfur dioxide detection method described in the first aspect of the present invention in the detection of sulfur dioxide content in food.

[0045] Preferably, the food includes solid food and liquid food.

[0046] Preferably, the liquid food comprises wine.

[0047] Preferably, the solid food is a soluble food; further preferably, the solid food includes white sugar.

[0048] Preferably, when the food is liquid food, the liquid food is mixed with a sulfuric acid solution to be used as a sample to be tested.

[0049] Preferably, the concentration of the sulfuric acid solution is 0.05-0.5 mol / L; further preferably, the concentration of the sulfuric acid solution is 0.15-0.25 mol / L.

[0050] Preferably, the volume ratio of the liquid food to the sulfuric acid solution is (5-20):1; further preferably, the volume ratio of the liquid food to the sulfuric acid solution is (5-15):1.

[0051] Preferably, when the food is a solid food, the process includes first dissolving the solid food.

[0052] Compared with the prior art, the present invention has the following beneficial effects:

[0053] 1) The sulfur dioxide detection method provided by the present invention is a dual-modal analysis method based on colorimetry and surface-enhanced Raman spectroscopy, which can quickly and preliminarily determine the sulfur dioxide concentration by naked eyes, and can simultaneously obtain the detection results of the two methods, so that the detection results of the two detection methods can be self-corrected, thereby improving the accuracy of the detection results and the detection efficiency;

[0054] 2) The purge and capture device provided by the present invention can realize the rapid separation of sulfur dioxide in the sample to be tested, and exhibits good selectivity and anti-interference properties for sulfur dioxide, which is conducive to improving the accuracy of sulfur dioxide detection results;

[0055] 3) The method for detecting sulfur dioxide provided by the present invention can be used for detecting sulfur dioxide in solid and liquid foods, and has good practicability. BRIEF DESCRIPTION OF THE DRAWINGS

[0056] Figure 1 Schematic diagram of the structure of the sulfur dioxide purge capture device in the embodiment, wherein 100-circulation micro pump, 200-rotor flow meter, 300-evaporation bottle, 400-micro heating jacket, 401-power adapter, 402-temperature control switch, 403-heating jacket, 500-sample collection bottle, 600-silicone tube;

[0057] Figure 2 The UV-visible absorption spectrum response diagram (a) and the surface enhanced Raman spectrum response diagram (b) of the sulfur dioxide standard sample in Example 1;

[0058] Figure 3The colorimetric standard curve (a) and the surface enhanced Raman spectroscopy standard curve (b) established in Example 1;

[0059] Figure 4 The UV-visible spectrophotometric detection diagram of the dry white wine and plum wine samples in Examples 2 and 3;

[0060] Figure 5 This is the surface enhanced Raman spectroscopy detection image of the dry white wine and plum wine samples in Examples 2 and 3;

[0061] Figure 6 is a histogram of the UV-visible spectrophotometric responses of sulfur dioxide analogs and sulfur dioxide;

[0062] Figure 7 The surface enhanced Raman spectroscopy response bar graphs of sulfur dioxide analogs and sulfur dioxide;

[0063] Figure 8 The UV-visible spectrophotometric response bar graph of sulfur dioxide interfering substances and sulfur dioxide;

[0064] Fig. 9 This is a bar graph showing the surface enhanced Raman spectroscopy response of sulfur dioxide and sulfur dioxide. DETAILED DESCRIPTION

[0065] The present invention is further described in detail below by specific examples. Unless otherwise specified, the raw materials, reagents or devices used in the examples and comparative examples can be obtained from conventional commercial sources or can be obtained by prior art methods. Unless otherwise specified, the experiments or test methods are conventional methods in the art.

[0066] Figure 1 is a schematic diagram of the structure of the sulfur dioxide purge and capture device in the embodiment, Figure 1 It can be seen that the sulfur dioxide purging and capturing device in the embodiment includes a circulating micro pump 100, a rotor flow meter 200, an evaporating bottle 300, a micro heating jacket 400, a sample collecting bottle 500 and a silicone tube 600; wherein the micro heating jacket 400 includes a power adapter 401, a digital display temperature control switch 402, and a heating jacket 403 coated on the outer wall of the evaporating bottle 300; the gas outlet end of the circulating micro pump 100 and the gas inlet end of the rotor flow meter 200, the gas outlet end of the rotor flow meter 200 and the gas inlet end of the evaporating bottle 300, and the gas outlet end of the evaporating bottle 300 and the gas inlet end of the sample collecting bottle 500 are respectively connected by the silicone tube 600.

[0067] The rated voltage of the power supply of the circulating micro pump 100 is 12V, and the gas flow control range is 0.4-0.6L / min; the flow control range of the rotor flowmeter 200 is 0.1-5L / min; the evaporating flask 300 is a sealed glass bottle with a cover and a capacity of 100mL, and the upper end of the cover is a threaded mouth; the temperature control range of the micro heating sleeve 400 is 40-60℃, the rated voltage of the power adapter 401 is 12V, the temperature control switch 402 is a digital display temperature control switch, and the material of the heating sleeve 403 is high temperature resistant cloth; the sample collection bottle 500 is a sealed glass bottle with a cover and a capacity of 50mL, and the upper end of the cover is a frosted mouth.

[0068] The following will be combined Figure 1 The detection of sulfur dioxide in the embodiment is described:

[0069] Example 1

[0070] The steps to establish the sulfur dioxide colorimetric standard curve and the surface enhanced Raman spectroscopy standard curve are as follows:

[0071] S11. Mix 10 mL of sodium sulfite standard solutions with concentrations of 0.1 mg / L, 0.5 mg / L, 1 mg / L, 10 mg / L, 50 mg / L, 100 mg / L, 200 mg / L, and 500 mg / L with 1 mL of sulfuric acid solution with a concentration of 0.2 mol / L to prepare sulfur dioxide standard samples;

[0072] S12, 10 mL of 5 mg / mL starch solution, 0.2 mL of iodine solution prepared from 0.0325 mg / mL elemental iodine and 0.0875 mg / mL potassium iodide, 9.9 mL of 10% (v / v) methanol, and 0.1 mL of 5 mmol / L 4-mercaptopyridine methanol solution were mixed to prepare a sulfur dioxide reaction solution;

[0073] S21. Add the sulfur dioxide standard sample prepared in S11 and the sulfur dioxide reaction solution prepared in S12 to the evaporating bottle 300 and the sample collection bottle 500 of the purge and capture device respectively, start the circulating micro pump 100 and the temperature control switch 402 in the purge and capture device, and after continuous heating for 6 minutes, turn off the circulating micro pump 100 and the temperature control switch 402, take out 1 mL of the reaction solution in the sample collection bottle 500 and test it by UV-visible spectrophotometry to obtain the relationship between the UV-visible characteristic absorption peak intensity of the reaction solution and the concentration of sulfur dioxide, and establish a colorimetric standard curve; take out 160 μL of the reaction solution and mix it with 160 μL of nano gold sol (average particle size 35-45 nm) to perform surface enhanced Raman spectroscopy test, obtain the relationship between the peak value at the characteristic Raman shift of 4-mercaptopyridine and the concentration of sulfur dioxide, and establish a surface enhanced Raman spectroscopy standard curve.

[0074] Figure 2The UV-Vis absorption spectrum response diagram (a) and the surface enhanced Raman spectrum response diagram (b) of the sulfur dioxide standard sample in Example 1 are shown in FIG. Figure 2 It can be seen that when using UV-visible spectrophotometry and surface-enhanced Raman spectroscopy to quantitatively analyze sulfur dioxide molecules, the best response is at 346nm in the UV-visible absorption spectrum, and at 1000cm in the surface-enhanced Raman spectrum. -1 The best response.

[0075] Figure 3 The colorimetric standard curve (a) and the surface enhanced Raman spectroscopy standard curve (b) established in Example 1 are shown.

[0076] Example 2

[0077] To detect the sulfur dioxide content in dry white wine samples, the steps are as follows:

[0078] S31, add 10mL of dry white wine and 1mL of 0.2mol / L sulfuric acid solution into the evaporating bottle 300 of the purge and trap device, add the sulfur dioxide reaction solution prepared in step S12 of Example 1 into the sample collection bottle 500 of the purge and trap device, start the circulating micro pump 100 and the temperature control switch 402 in the purge and trap device, and after continuous heating for 6 minutes, turn off the circulating micro pump 100 and the temperature control switch 402, take out 1mL of the reaction solution from the sample collection bottle 500 and test it by UV-visible spectrophotometry to obtain the UV-visible characteristic absorption peak intensity of the reaction solution at 346nm, measure it 3 times in total, and calculate the average value and relative standard deviation of the UV-visible absorption peak at 346nm of the 3 data; take 160μL of the reaction solution and mix it with 160μL of nano gold sol (average particle size 35-45nm) to perform surface enhanced Raman spectroscopy test, obtain the peak at the characteristic Raman shift of 4-mercaptopyridine, measure it 3 times in total, and calculate the 1000cm -1 The peak value average and relative standard deviation;

[0079] S41. The UV-visible characteristic absorption peak intensity of the reaction solution obtained in S31 is substituted into the colorimetric standard curve in step S21 of Example 1 to calculate the sulfur dioxide concentration in the dry white wine; the peak value at the characteristic Raman shift of 4-mercaptopyridine obtained in S31 is substituted into the surface enhanced Raman spectroscopy standard curve in step S21 of Example 1 to calculate the sulfur dioxide concentration in the dry white wine.

[0080] Example 3

[0081] To detect the sulfur dioxide content in plum wine samples, the steps are as follows:

[0082] S31, add 10mL plum wine and 1mL 0.2mol / L sulfuric acid solution into the evaporating bottle 300 of the purge and trap device, add the sulfur dioxide reaction solution prepared in step S12 of Example 1 into the sample collection bottle 500 of the purge and trap device, start the circulating micro pump 100 and the temperature control switch 402 in the purge and trap device, and after continuous heating for 6 minutes, turn off the circulating micro pump 100 and the temperature control switch 402, take out 1mL of the reaction solution from the sample collection bottle 500 and test it by ultraviolet-visible spectrophotometry to obtain the ultraviolet-visible characteristic absorption peak intensity of the reaction solution at 346nm, measure it 3 times in total, and calculate the average value and relative standard deviation of the ultraviolet-visible absorption peak at 346nm of the 3 data; take 160μL of the reaction solution and mix it with 160μL of nano gold sol (average particle size 35-45nm) to perform surface enhanced Raman spectroscopy test, obtain the peak at the characteristic Raman shift of 4-thiopyridine, measure it 3 times in total, and calculate the 1000cm -1 The peak value average and relative standard deviation;

[0083] S41. The UV-visible characteristic absorption peak intensity of the reaction solution obtained in S31 is substituted into the colorimetric standard curve in step S21 of Example 1 to calculate the sulfur dioxide concentration in plum wine; the peak value at the characteristic Raman shift of 4-mercaptopyridine obtained in S31 is substituted into the surface enhanced Raman spectroscopy standard curve in step S21 of Example 1 to calculate the sulfur dioxide concentration in plum wine.

[0084] Example 4

[0085] To detect the sulfur dioxide content in the white sugar sample, the steps are as follows:

[0086] S31, weigh 2.04g potassium hydrogen phthalate and dissolve it in a small amount of water, add 5.5mL 36-38% (v / v) formaldehyde solution, 20mL 0.05mol / L EDTA-2Na solution, dilute with water and make up to 100mL, and finally dilute 100 times with water to obtain formaldehyde buffer; weigh 10g white sugar, add 100mL formaldehyde buffer, shake and soak for 2h, then filter, and take the filtrate as the white sugar sample to be tested; add 10mL white sugar sample to be tested and 1mL 0.2mol / L sulfuric acid solution into the evaporating bottle 300 of the purge and trap device, add the sulfur dioxide reaction solution prepared in step S12 of Example 1 into the sample collection bottle 500 of the purge and trap device, start the circulating micro pump 100 and the temperature control switch 402 in the purge and trap device, and continue heating for 6m in, close the circulating micro pump 100 and the temperature control switch 402, take out 1mL of the reaction solution from the sample collection bottle 500 and test it by UV-visible spectrophotometry to obtain the UV-visible characteristic absorption peak intensity of the reaction solution at 346nm, measure it 3 times in total, calculate the average value and relative standard deviation of the UV-visible absorption peak at 346nm of the 3 data; take 160μL of the reaction solution and mix it with 160μL of nano-gold sol (average particle size 35-45nm) to perform surface enhanced Raman spectroscopy test, obtain the peak at the characteristic Raman shift of 4-mercaptopyridine, measure it 3 times in total, calculate the 1000cm -1 The peak value average and relative standard deviation;

[0087] S41. The UV-visible characteristic absorption peak intensity of the reaction solution obtained in S31 is substituted into the colorimetric standard curve in step S21 of Example 1 to calculate the concentration of sulfur dioxide in white sugar; the peak value at the characteristic Raman shift of 4-mercaptopyridine obtained in S31 is substituted into the surface enhanced Raman spectroscopy standard curve in step S21 of Example 1 to calculate the concentration of sulfur dioxide in white sugar.

[0088] Comparative Example 1

[0089] The spike method was used to verify the accuracy of the test results of the sulfur dioxide content in the dry white wine sample of Example 2, and the steps were as follows:

[0090] 1 mg / kg, 10 mg / kg and 100 mg / kg of sulfur dioxide standard solution were added to the dry white wine samples respectively, and then UV-visible spectrophotometry and surface enhanced Raman spectroscopy were performed for detection. The test was performed three times in a row, and the average value and relative standard deviation of the UV-visible absorption peak at 346 nm of the three data were calculated. The colorimetric standard curve in step S21 of Example 1 was substituted to obtain the sulfur dioxide concentration in the spiked sample, and the sample spike recovery rate and relative standard deviation were calculated. The 1000 cm -1The peak value average value and relative standard deviation are substituted into the surface enhanced Raman spectroscopy standard curve in step S21 of Example 1 to obtain the sulfur dioxide concentration in the spiked sample, and the sample spiked recovery rate and relative standard deviation are calculated.

[0091] Comparative Example 2

[0092] The accuracy of the test results of the sulfur dioxide content in the plum wine sample of Example 3 was verified by the spiked method, and the steps were as follows:

[0093] 1 mg / kg, 10 mg / kg and 100 mg / kg of sulfur dioxide standard solution were added to the plum wine samples respectively, and then UV-visible spectrophotometry and surface enhanced Raman spectroscopy were performed for detection. The test was performed three times in a row, and the average value and relative standard deviation of the UV-visible absorption peak at 346 nm of the three data were calculated. The colorimetric standard curve in step S21 of Example 1 was substituted to obtain the sulfur dioxide concentration in the spiked sample, and the sample spike recovery rate and relative standard deviation were calculated; the 1000 cm -1 The peak value average value and relative standard deviation are substituted into the surface enhanced Raman spectroscopy standard curve in step S21 of Example 1 to obtain the sulfur dioxide concentration in the spiked sample, and the sample spiked recovery rate and relative standard deviation are calculated.

[0094] Comparative Example 3

[0095] The sulfur dioxide content in the same dry white wine sample as in Example 2 was detected by a commercial sulfur dioxide ELISA kit.

[0096] Comparative Example 4

[0097] The sulfur dioxide content in the same plum wine sample as in Example 3 was detected by a commercial sulfur dioxide ELISA kit.

[0098] Comparative Example 5

[0099] The accuracy of the test results of the sulfur dioxide content in the white sugar sample of Example 4 was verified by the spiked method, and the steps were as follows:

[0100] Take the white sugar sample to be tested in step S31 of Example 4, add 1 mg / kg, 10 mg / kg and 100 mg / kg of sulfur dioxide standard solution, and then perform UV-visible spectrophotometry and surface enhanced Raman spectroscopy detection, test three times in a row, calculate the average value and relative standard deviation of the UV-visible absorption peak at 346 nm of the three data, substitute the colorimetric standard curve in step S21 of Example 1, obtain the sulfur dioxide concentration in the spiked sample, calculate the sample spike recovery rate and relative standard deviation; calculate the 1000 cm -1The peak value average value and relative standard deviation are substituted into the surface enhanced Raman spectroscopy standard curve in step S21 of Example 1 to obtain the sulfur dioxide concentration in the spiked sample, and the sample spiked recovery rate and relative standard deviation are calculated.

[0101] Table 1 below shows the test results of sulfur dioxide content in each sample in Examples 2-4 and Comparative Examples 3 and 4:

[0102] Table 1 Test results of sulfur dioxide content in each sample in Examples 2-4 and Comparative Examples 3 and 4

[0103]

[0104]

[0105] Table 2 below is the accuracy verification results of the sulfur dioxide content detection results of Example 2-4:

[0106] Table 2 Accuracy verification results of sulfur dioxide content detection results of Example 2-4

[0107]

[0108] Table 1 shows the detection results of the sulfur dioxide content in each sample in Examples 2-4 and Comparative Examples 3 and 4. It can be seen from Table 1 that the sulfur dioxide detection method based on colorimetry / surface-enhanced Raman spectroscopy dual-modal analysis provided by the present invention can be used to detect the sulfur dioxide content in liquid foods such as wine and plum wine, and solid foods such as white sugar; the relative deviation of the detection results of the colorimetric method and the surface-enhanced Raman spectroscopy method is 3.3%-5.8%, and the relative deviation is small, indicating that the two detection methods can realize the verification and self-correction of the detection results, and improve the accuracy of the detection results; compared with the detection results of the commercial sulfur dioxide ELISA kit, the relative deviations of the colorimetric method and the surface-enhanced Raman spectroscopy analysis method are less than 5.1% and 0.8%, respectively, indicating that this method has high accuracy and practical value. Figure 4 The UV-visible spectrophotometric detection diagram of the dry white wine and plum wine samples in Examples 2 and 3, Figure 5 The surface enhanced Raman spectroscopy detection diagram of the dry white wine and plum wine samples in Examples 2 and 3 is shown in FIG. Figure 2 and Figure 3 It can also be known that the detection results of UV-Vis spectrophotometry and surface-enhanced Raman spectroscopy can achieve self-correction to improve the accuracy of detection.

[0109] Table 2 is the accuracy verification result of the sulfur dioxide content detection results of Examples 2-4. It can be seen from Table 2 that the accuracy of the colorimetric / surface enhanced Raman spectroscopy dual-modal sulfur dioxide detection method is verified by the spiked method, and the data of the sample spiked recovery rate and the relative standard deviation are within a reasonable range, which can prove that the detection results of the method provided by the present invention are highly accurate and the method has good reliability.

[0110] In order to verify the separation and detection results of the purge and capture device provided by the present invention, the ultraviolet-visible spectrophotometry and surface-enhanced Raman spectroscopy responses of sulfur dioxide analogues (methanol, ethanol, formic acid, acetic acid, formaldehyde, acetaldehyde, ethyl acetate, and n-butanol) and sulfur dioxide were analyzed; the ultraviolet-visible spectrophotometry and surface-enhanced Raman spectroscopy responses of sulfur dioxide interferors (methanol, ethanol, formic acid, acetic acid, tartaric acid, tannic acid, ethyl acetate, n-butanol, and a mixture of the above interferors) and sulfur dioxide were analyzed.

[0111] Since the UV-visible spectrum absorption value is negatively correlated with the sulfur dioxide concentration, that is, the higher the sulfur dioxide concentration, the lower the UV-visible spectrum absorption value, the concentration of the sulfur dioxide analog is similar to the blank, and the intensity decreases after adding sulfur dioxide. In the anti-interference test, sulfur dioxide interfering substances are mixed with sulfur dioxide and then measured to examine whether the presence of interfering substances will affect the detection of sulfur dioxide. The closer the intensity of the interfering substance is to the intensity of sulfur dioxide tested alone, the less the presence of the interfering substance will affect the detection of sulfur dioxide. Figure 6 is a histogram of the UV-visible spectrophotometric response of sulfur dioxide analogs and sulfur dioxide, Figure 7 The surface enhanced Raman spectroscopy response histogram of sulfur dioxide analogs and sulfur dioxide is shown in Figure 2. Figure 8 The UV-Vis spectrophotometric response histogram of sulfur dioxide interference and sulfur dioxide is shown in Figure 2. Fig. 9 The above is the histogram of the surface enhanced Raman spectroscopy response of sulfur dioxide and sulfur dioxide interference. Figure 6-Figure 9 It can be seen that the purge and capture device provided by the present invention has a good separation and detection effect, and can ensure that the detection method using this device exhibits good selectivity and anti-interference in sulfur dioxide detection.

Claims

1. A method for detecting sulfur dioxide, characterized in that: The following steps are involved: S1, take sulfur dioxide standard sample and reaction solution; S2. Establishing the sulfur dioxide colorimetric standard curve and the surface enhanced Raman spectroscopy standard curve; S3, using a purge-and-trap method to enrich the sulfur dioxide gas in the sample to be tested in the reaction solution to obtain an absorption solution; S4, taking the absorption liquid, and using the colorimetric standard curve and the surface enhanced Raman spectroscopy standard curve described in S2 to respectively calculate the sulfur dioxide concentration in the absorption liquid, to obtain the sulfur dioxide content of the sample to be tested; In the step S1, the reaction solution includes starch, an iodine compound and 4-mercaptopyridine.

2. The detection method according to claim 1, characterized in that: In the step S1, the sulfur dioxide standard sample includes a sodium sulfite standard solution and a sulfuric acid solution; Preferably, the concentration of the sodium sulfite standard solution is 0.1-1000 mg / L; Preferably, the concentration of the sulfuric acid solution is 0.05-0.5 mol / L; Preferably, the volume ratio of the sodium sulfite standard solution to the sulfuric acid solution is (5-20):

1.

3. The detection method according to claim 1, characterized in that: In step S1, the reaction solution includes a starch solution, an iodine solution, methanol, and a mixed solution of 4-mercaptopyridinemethanol; Preferably, the volume ratio of the starch solution, the iodine solution, the methanol and the 4-mercaptopyridinemethanol mixed solution is (50-800): (1-15):(50-500):1。 4. The detection method according to claim 3, characterized in that: The concentration of the starch solution is 1-20 mg / mL; And / or, the concentration of the 4-mercaptopyridinemethanol mixed solution is 0.1-5mmol / L; And / or, the volume concentration of the methanol is 1-50%.

5. The detection method according to claim 3, characterized in that: The iodine solution comprises elemental iodine and potassium iodide; Preferably, in the iodine solution, the content of the iodine element is 0.01-0.05 mg / mL, and the content of the potassium iodide is 0.05-0.12 mg / mL.

6. The detection method according to claim 3, characterized in that: In step S2, the specific operations of establishing the sulfur dioxide colorimetric standard curve and the surface enhanced Raman spectroscopy standard curve are: using the purge and trap method to enrich the sulfur dioxide gas in the standard sample in the reaction liquid, obtaining the relationship between the ultraviolet-visible characteristic absorption peak intensity of the reaction liquid and the concentration of sulfur dioxide, establishing a colorimetric standard curve, obtaining the relationship between the peak value at the characteristic Raman shift of 4-mercaptopyridine and the concentration of sulfur dioxide, and establishing a surface enhanced Raman spectroscopy standard curve.

7. The detection method according to claim 1, characterized in that: In step S3, the volume ratio of the sample to be tested to the reaction solution is 1:(1-5).

8. A purge and capture device for the sulfur dioxide detection method according to any one of claims 1 to 7, characterized in that: The device comprises a circulation pump, a flow meter, an evaporation device and a sample collection device which are connected in sequence, and a heating device matched with the evaporation device.

9. The purge and capture device according to claim 7, characterized in that: The flow control ranges of the circulation pump and the flow meter are respectively selected from 0.1-5L / min; And / or, the temperature control range of the heating device is 25-180°C.

10. Use of the method for detecting sulfur dioxide according to any one of claims 1 to 7 in detecting sulfur dioxide content in food.

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