Test paper detection method for rapidly determining sulfide content in Baijiu

Abstract

The invention discloses a test paper detection method for rapidly determining the content of sulfides in Baijiu. The method mainly comprises the following steps: preparing test paper, determining the content of different sulfides by using a national standard method, preparing a standard colorimetric card, comparing the fluorescence intensity of an unknown wine sample with naked eyes of the colorimetric card to obtain the content of the sulfides, and verifying the content of the sulfides by using a standard method. The invention provides a novel, simple, efficient and low-cost rapid detection method for sulfide substances in white spirit, the application range of the perovskite quantum dots is expanded, and a basis is provided for application of the perovskite quantum dots in the field of food safety.

Description

Technical Field

[0001] The present application relates to a test paper detection method for rapidly determining the sulfide content in liquor, and belongs to the field of food safety. Background Art

[0002] Liquor plays an important role in Chinese culture. It is regarded as one of the symbols of traditional Chinese culture, an important part of the Chinese dining table, and a common drink in social occasions. Sulfur compounds are produced during the brewing and aging process of liquor, and sulfide is an important flavor component of liquor. Some sulfur compounds can provide special fragrance to liquor in appropriate amounts, for example, some thiol compounds may have the smell of flowers, fruits or vegetables. 3-Methylthiopropanol and ethyl 3-methylthiopropionate in liquor have antioxidant activity and are one of the functional factors that are beneficial to human health. Excessive sulfur compounds will cause liquor to have odors, such as sulfur, hydrogen sulfide or onion, which reduce the quality and taste of liquor. In the liquor industry, one of the goals of quality control and technological improvement is to ensure that the content of sulfur compounds is within an appropriate range and does not negatively affect the quality of liquor. Sulfur compounds in liquor are volatile and have a low threshold. Common methods for determining the content of sulfur compounds in liquor include gas chromatography (GC), high performance liquid chromatography (HPLC), atomic absorption spectrometry (AAS) and mass spectrometry (MS). These methods require expensive instruments, are complex to operate, and are time-consuming. Moreover, most of these methods are only qualitative and not quantitative.

[0003] In recent years, perovskite nanocrystals have attracted people's attention and research due to their excellent optoelectronic properties. Compared with traditional inorganic semiconductor nanocrystals, perovskite nanocrystals have higher fluorescence quantum efficiency (PLQY), wider adjustable emission wavelength range, excellent photoelectric transmission performance, simple synthesis, low cost and other advantages, and have good application prospects in optoelectronic devices. At the same time, because of its high quantum yield and strong fluorescence signal and adjustable wavelength, it can be used as a light source to construct highly sensitive fluorescence sensors and applied in analytical chemistry or bioanalytical chemistry. However, perovskite nanocrystals are greatly affected by the environment and have poor stability. Factors such as air, humidity, temperature, and polar substances can cause the luminescence efficiency of perovskite nanocrystals to decrease or even completely quench. Using the unique property of being sensitive to sulfides, perovskite nanocrystals can be used for qualitative and quantitative analysis of sulfides. Fluorescence detection methods can overcome the above defects and have the advantages of high sensitivity and high stability. However, the fluorescence detection instruments used in traditional fluorescence detection methods are expensive and inconvenient to carry, showing obvious disadvantages in rapid detection. Compared with fluorescence instrument detection, fluorescence test strips have the advantages of easy portability, obvious phenomena, fast detection speed and low cost. Only a portable ultraviolet lamp is needed for on-site real-time naked eye rapid detection, and therefore it is increasingly valued by researchers. Summary of the invention

[0004] The purpose of the present invention is to make up for the shortcomings of the existing white wine sulfide detection method, and adopt the method of the present invention to measure the sulfide in the white wine.

[0005] According to one aspect of the present application, a test paper detection method for quickly determining the sulfide content in liquor is provided, and the test paper detection method comprises the following steps:

[0006] (1) preparing a solution a containing a perovskite precursor I;

[0007] (2) preparing a solution b containing a perovskite precursor II;

[0008] (3) adding 3-aminopropyltriethoxysilane to solution b and stirring for 1 to obtain solution c;

[0009] (4) adding solution a to solution c, stirring II, and centrifuging to obtain SiO2-coated perovskite nanocrystals;

[0010] (5) dropping the SiO2-coated perovskite nanocrystals onto a paper substrate, drying the paper substrate and storing the paper substrate in nitrogen to obtain a paper substrate containing the SiO2-coated perovskite nanocrystals;

[0011] (6) Add the wine sample with unknown sulfide content to the central sample addition area of ​​the paper substrate containing SiO2-coated perovskite nanocrystals, react, record the fluorescence intensity and compare it with the standard colorimetric card to determine the sulfide content in the wine sample;

[0012] The perovskite precursor I is selected from Cs2CO3 and / or MABr;

[0013] The perovskite precursor II is selected from at least one of PbBr2, PbI2, and PbCl2.

[0014] Optionally, in step (6), the method for preparing the standard colorimetric card comprises:

[0015] Step 1: Weigh the standard products dimethyl trisulfide, 3-methylmercaptopropanol, furfurylthiol, 3-methylmercaptopropionaldehyde, ethyl methylmercaptoacetate, ethyl 3-methylmercaptopropionate, dimethyl disulfide, and methylfurfuryl disulfide respectively, dissolve them in ethanol aqueous solution and then make up to volume to obtain a single standard solution;

[0016] Step 2: Mix the single standard solutions to obtain a mixed standard stock solution of sulfur-containing compounds;

[0017] Step 3: Add the sulfur-containing compound mixed standard stock solution to the wine sample, adjust the volume to obtain a spiked wine sample;

[0018] Step 4: Use an instrument to detect and record the sulfide content in the spiked wine sample, then drop the spiked wine sample into the central sampling area of ​​the paper base containing SiO2-coated perovskite nanocrystals, react and record the fluorescence intensity, and obtain a standard colorimetric card corresponding to the sulfide content and fluorescence intensity.

[0019] Optionally, the mass ratio of dimethyl trisulfide: 3-methylmercaptopropanol: furfuryl mercaptan: 3-methylmercaptopropionaldehyde: ethyl methylmercaptoacetate: ethyl 3-methylmercaptopropionate: dimethyl disulfide: methyl furfuryl disulfide is:

[0020] 0.24g: 0.24g: 0.24g: 0.12g: 0.12g: 0.12g: 0.06g: 0.06g.

[0021] Optionally, the ethanol concentration in the ethanol aqueous solution is 60% to 80%.

[0022] Optionally, in step (1), the concentration of the perovskite precursor I in the solution a is 0.05 to 0.2 mmol / L.

[0023] Optionally, the concentration of the perovskite precursor I in the solution a is any value among 0.05 mmol / L, 0.1 mmol / L, 0.15 mmol / L, 0.2 mmol / L, or a range between two values.

[0024] Optionally, in step (2), the concentration of the perovskite precursor II in the solution b is 0.05 to 0.2 mmol / L.

[0025] Optionally, the concentration of the perovskite precursor II in the solution b is any value of 0.05 mmol / L, 0.1 mmol / L, 0.15 mmol / L, 0.2 mmol / L, or a range between two values.

[0026] Optionally, the volume fraction of 3-aminopropyltriethoxysilane in the solution c is 0% to 10%.

[0027] Optionally, the volume fraction of 3-aminopropyltriethoxysilane in the solution c is any value of 0%, 3%, 5%, 7%, 10%, or a range between two values.

[0028] Optionally, the stirring time of I and II is independently selected from 5 min to 12 h.

[0029] Optionally, the stirring time I and stirring time II are independently selected from any value among 5 min, 10 min, 20 min, 30 min, 40 min, 1 h, 2 h, 4 h, 6 h, 8 h, 10 h, 12 min, or a range value between two values.

[0030] Optionally, in step (4), the volume ratio of solution a to solution c is 1:0.1-10.

[0031] Optionally, the volume ratio of solution a to solution c is any value of 1:0.1, 1:1, 1:3, 1:5, 1:7, 1:9, 1:10, or a range value between two values.

[0032] Optionally, in step (6), the sulfide content in the wine sample with unknown sulfide content is 300-2500 μg / L.

[0033] Optionally, the reaction time is 1 to 10 minutes.

[0034] Optionally, in step (6), the volume of the dropwise addition is 5 to 50 uL.

[0035] Optionally, in step (5), the paper substrate is selected from at least one of filter paper, nitrocellulose membrane, and polyvinylidene fluoride membrane.

[0036] Optionally, in step (6), the wine in the wine sample is one or more of light-flavor liquor, strong-flavor liquor, and sauce-flavor liquor.

[0037] As a specific implementation, the present application is implemented through the following technical solutions:

[0038] The specific steps for determining sulfide in liquor are as follows:

[0039] Step (1): preparing a solution a containing a perovskite precursor I;

[0040] Step (2): preparing a solution b containing a perovskite precursor II;

[0041] Step (3): adding 3-aminopropyltriethoxysilane to solution b and stirring at room temperature to obtain solution c;

[0042] Step (4): adding solution a to solution c, stirring at room temperature, centrifuging to obtain SiO2-coated perovskite nanocrystals, and dispersing them in toluene;

[0043] Step (5): Preparation of liquor sulfide substance detection test paper: pipette the perovskite solution and drop it onto the paper base, dry it naturally at room temperature, and seal it in a nitrogen sealed bag for storage;

[0044] Step (6): preparing wine samples with different sulfide contents: weighing standard substances such as dimethyl trisulfide, 3-methylmercaptopropanol, and furfurylthiol 0.24 g, 3-methylmercaptopropionaldehyde, ethyl methylmercaptoacetate, and ethyl 3-methylmercaptopropionate 0.12 g, and dialkyl disulfide and methyl furfural disulfide 0.06 g respectively, dissolving them in 60% ethanol aqueous solution and then making the volume to 100 mL, so that the concentration of the standard stock solutions of dimethyl trisulfide, 3-methylmercaptopropanol, and furfurylthiol is 2.4 g / L, the concentration of 3-methylmercaptopropionaldehyde, ethyl methylmercaptoacetate, and ethyl 3-methylmercaptopropionate is 1.2 g / L, and the concentration of dialkyl disulfide and methyl furfural disulfide is 0.6 g / L, to prepare a mixed standard stock solution of sulfur-containing compounds.

[0045] Pipette 0-100uL of the sulfur compound mixed standard stock solution, add it to the wine sample, make up to 100mL, and use the national standard gas chromatography method to determine the sulfide content in all spiked wine samples;

[0046] Step (7): Pipette the spiked wine sample and drop it onto the paper base, allow it to react fully at room temperature, and place it under an ultraviolet lamp with an excitation wavelength of 365 nm. Due to the different sulfide contents, different wine samples have different degrees of quenching of quantum dot fluorescence, and the fluorescence intensity presented by the test paper is also different;

[0047] Use a digital camera to record the fluorescence photos of all wine samples after the reaction with quantum dot solutions, and make a standard colorimetric card.

[0048] Step (8): Compare the fluorescence intensity photograph of the wine sample with unknown sulfide content after the reaction on the test paper with the standard colorimetric card to achieve semi-quantitative detection of the sulfide content in the wine sample, and then use gas chromatography to verify the sulfide content in the wine sample.

[0049] In the present application, the fluorescent test paper for rapid determination of sulfide in liquor mainly includes the following steps: preparation of test paper, determination of different sulfide contents by national standard method, preparation of standard colorimetric card, naked eye comparison of fluorescence intensity of unknown liquor sample with colorimetric card, obtaining sulfide content, and verifying sulfide content by standard method. The present invention provides a novel, simple, efficient and low-cost rapid detection method for sulfide substances in liquor, and expands the application scope of perovskite quantum dots, providing a basis for the application of perovskite quantum dots in the field of food safety.

[0050] The beneficial effects of this application include:

[0051] 1) The method provided in this application is easy to operate. Compared with the traditional gas chromatography, it greatly shortens the detection time and reduces the amount of organic reagents used. Based on the fluorescence quenching principle of quantum dots, the reaction has high sensitivity, higher precision and good reproducibility.

[0052] 2) Compared with the previously reported detection methods and traditional fluorescence analysis methods, the method provided in this application is simple to operate, has clear and intuitive detection results, and is more operator-friendly.

[0053] 3) The present application provides a novel, simple, rapid, efficient and low-cost fluorescent test paper for sulfide substances in liquor, and expands the application scope of perovskite quantum dots, providing a basis for the application of perovskite quantum dots in the field of food safety. BRIEF DESCRIPTION OF THE DRAWINGS

[0054] Figure 1 This is the colorimetric chart of sulfide content and fluorescence intensity of Luzhou-flavor liquor in Example 1 of the present application.

[0055] Figure 2 This is the colorimetric card for the sulfide content and fluorescence intensity of Maotai-flavor liquor in Example 2 of the present application.

[0056] Figure 3 This is the colorimetric chart of sulfide content and fluorescence intensity of light-fragrance liquor in Example 3 of the present application. DETAILED DESCRIPTION

[0057] The present application is described in detail below with reference to embodiments, but the present application is not limited to these embodiments.

[0058] Unless otherwise specified, the raw materials in the examples of this application were purchased through commercial channels.

[0059] Example 1

[0060] Prepare 0.1mmol / L Cs2CO3 solution, prepare 0.1mmol / L PbBr2 solution, add 3-aminopropyltriethoxysilane (APTES) to the PbBr2 solution, and stir. The volume fraction of APTES added is 1%; the stirring time is 60 minutes;

[0061] 2 μL of the prepared perovskite solution was dropped onto the surface of the polyvinylidene fluoride (PVDF) membrane;

[0062] The spike method was used to prepare wine samples with different sulfide contents, which were 500, 600, 700, 800, and 900 μg / L respectively.

[0063] Pipette 10 μL of wine sample and add it to the center of the prepared test paper. React at room temperature for 3 minutes. Place it under an ultraviolet lamp with an excitation wavelength of 365 nm. Use a digital camera to record the fluorescence photos of all wine samples after the reaction with the quantum dot solution. Arrange them from strong to weak in fluorescence intensity to make a standard colorimetric card.

[0064] 50 μL of wine sample with unknown sulfide content is taken and added dropwise to the central sample addition area of ​​the prepared test paper. The sample is fully reacted at room temperature and placed under an ultraviolet lamp with an excitation wavelength of 365 nm. A digital camera is used to record the fluorescence photos of all wine samples and quantum dot solutions after the reaction. The photos of the test paper taken after the reaction are compared with the standard colorimetric card. The fluorescence intensity is close to the fluorescence intensity of the sulfide content of 900 μg / L on the colorimetric card. The wine sample is then verified by gas chromatography, and the result is 892 μg / L. This realizes the determination of the sulfide content of Luzhou-flavor liquor using rapid test paper based on perovskite quantum dot fluorescence quenching. Figure 1 It can be seen that as the sulfide content in the wine sample gradually increases, the fluorescence intensity decreases.

[0065] Example 2

[0066] Prepare 0.09mmol / L Cs2CO3 solution, prepare 0.09mmol / L PbBr2 solution, add APTES to the PbBr2 solution, and stir. The volume fraction of APTES added is 3%; the stirring time is 10 hours;

[0067] 2 μL of the prepared perovskite solution was dropped onto the surface of the polyvinylidene fluoride (PVDF) membrane;

[0068] The spike method was used to prepare wine samples with different sulfide contents, which were 1800, 1900, 2000, 2100, and 2200 μg / L respectively.

[0069] Pipette 50 μL of wine sample and add it dropwise to the center of the prepared test paper. Let it react at room temperature for 8 minutes. Place it under an ultraviolet lamp with an excitation wavelength of 365 nm. Use a digital camera to record the fluorescence photos of all wine samples after the reaction with the quantum dot solution. Arrange them from right to left according to the fluorescence intensity to make a standard colorimetric card.

[0070] 50 μL of wine sample with unknown sulfide content is taken and added dropwise to the central sample addition area of ​​the prepared test paper. The sample is fully reacted at room temperature and placed under an ultraviolet lamp with an excitation wavelength of 365 nm. A digital camera is used to record the fluorescence photos of all wine samples and quantum dot solutions after the reaction. The photos of the test paper taken after the reaction are compared with the standard colorimetric card. The fluorescence intensity is close to the fluorescence intensity of the sulfide content of 2200 μg / L on the colorimetric card. The wine sample is then verified by gas chromatography, and the result is 2164 μg / L. This realizes the determination of the sulfide content of Maotai-flavor liquor using rapid test paper based on perovskite quantum dot fluorescence quenching. Figure 2 It can be seen that as the sulfide content in the wine sample gradually increases, the fluorescence intensity decreases.

[0071] Example 3

[0072] Prepare 0.2mmol / L Cs2CO3 solution, prepare 0.15mmol / L PbBr2 solution, add APTES to the PbBr2 solution, and stir. The volume fraction of APTES added is 5%; the stirring time is 6 hours;

[0073] 2 μL of the prepared perovskite solution was dropped onto the surface of the polyvinylidene fluoride (PVDF) membrane;

[0074] The spike method was used to prepare wine samples with different sulfide contents, which were 300, 400, 500, 600, and 700 μg / L respectively.

[0075] Pipette 20 μL of wine sample and add it to the center of the prepared test paper. React at room temperature for 5 minutes. Place it under an ultraviolet lamp with an excitation wavelength of 365 nm. Use a digital camera to record the fluorescence photos of all wine samples and quantum dot solutions after the reaction. Arrange them from strong to weak in fluorescence intensity to make a standard colorimetric card.

[0076] 50 μL of wine sample with unknown sulfide content is taken and added dropwise to the central sample addition area of ​​the prepared test paper. The sample is fully reacted at room temperature and placed under an ultraviolet lamp with an excitation wavelength of 365 nm. A digital camera is used to record the fluorescence photos of all wine samples and quantum dot solutions after the reaction. The photos of the test paper after the reaction are compared with the standard colorimetric card. The fluorescence intensity is close to the fluorescence intensity of the sulfide content of 500 μg / L on the colorimetric card. The wine sample is then verified by gas chromatography, and the result is 532 μg / L. This realizes the determination of the sulfide content of light-fragrance liquor using rapid test paper based on perovskite quantum dot fluorescence quenching. Figure 3 It can be seen that as the sulfide content in the wine sample gradually increases, the fluorescence intensity decreases.

[0077] The above are only a few embodiments of the present application and do not constitute any form of limitation to the present application. Although the present application is disclosed as above with preferred embodiments, it is not intended to limit the present application. Any technician familiar with the profession, without departing from the scope of the technical solution of the present application, using the technical content disclosed above to make slight changes or modifications are equivalent to equivalent implementation cases and fall within the scope of the technical solution.

Claims

1. A test paper detection method for rapidly determining the sulfide content in liquor, characterized in that: The test paper detection method comprises the following steps: (1) preparing a solution a containing a perovskite precursor I; (2) preparing a solution b containing a perovskite precursor II; (3) adding 3-aminopropyltriethoxysilane to solution b and stirring for 1 to obtain solution c; (4) adding solution a to solution c, stirring II, and centrifuging to obtain SiO2-coated perovskite nanocrystals; (5) dropping the SiO2-coated perovskite nanocrystals onto a paper substrate, drying the paper substrate and storing the paper substrate in nitrogen to obtain a paper substrate containing the SiO2-coated perovskite nanocrystals; (6) Add the wine sample with unknown sulfide content to the central sample addition area of ​​the paper substrate containing SiO2-coated perovskite nanocrystals, react, record the fluorescence intensity and compare it with the standard colorimetric card to determine the sulfide content in the wine sample; The perovskite precursor I is selected from Cs2CO3 and / or MABr; The perovskite precursor II is selected from at least one of PbBr2, PbI2, and PbCl2.

2. The test paper detection method according to claim 1, characterized in that: In the step (6), the method for preparing the standard colorimetric card comprises: Step 1: Weigh the standard products dimethyl trisulfide, 3-methylmercaptopropanol, furfurylthiol, 3-methylmercaptopropionaldehyde, ethyl methylmercaptoacetate, ethyl 3-methylmercaptopropionate, dimethyl disulfide, and methylfurfuryl disulfide respectively, dissolve them in ethanol aqueous solution and then make up to volume to obtain a single standard solution; Step 2: Mix the single standard solutions to obtain a mixed standard stock solution of sulfur-containing compounds; Step 3: Add the sulfur-containing compound mixed standard stock solution to the wine sample, adjust the volume to obtain a spiked wine sample; Step 4: Use an instrument to detect and record the sulfide content in the spiked wine sample, then drop the spiked wine sample into the central sampling area of ​​the paper base containing SiO2-coated perovskite nanocrystals, react and record the fluorescence intensity, and obtain a standard colorimetric card corresponding to the sulfide content and fluorescence intensity.

3. The test paper detection method according to claim 2, characterized in that: The mass ratio of dimethyl trisulfide: 3-methylmercaptopropanol: furfurylthiol: 3-methylmercaptopropionaldehyde: ethyl methylmercaptoacetate: ethyl 3-methylmercaptopropionate: dimethyl disulfide: methyl furfuryl disulfide is: 0.24g: 0.24g: 0.24g: 0.12g: 0.12g: 0.12g: 0.06g: 0.06g.

4. The test paper detection method according to claim 2, characterized in that: The ethanol concentration in the ethanol aqueous solution is 60% to 80%.

5. The test paper detection method according to claim 1, characterized in that: In the step (1), the concentration of the perovskite precursor I in the solution a is 0.05 to 0.2 mmol / L; Preferably, in the step (2), the concentration of the perovskite precursor II in the solution b is 0.05 to 0.2 mmol / L.

6. The test paper detection method according to claim 1, characterized in that: The volume fraction of 3-aminopropyltriethoxysilane in the solution c is 0% to 10%; Preferably, the stirring time of I and II is independently selected from 5 min to 12 h.

7. The test paper detection method according to claim 1, characterized in that: In the step (4), the volume ratio of solution a to solution c is 1:0.1-10.

8. The test paper detection method according to claim 1, characterized in that: In the step (6), the sulfide content in the wine sample with unknown sulfide content is 300 to 2500 μg / L; Preferably, the reaction time is 1 to 10 minutes.

9. The test paper detection method according to claim 1, characterized in that: In the step (6), the volume of the dropwise addition is 5 to 50 uL.

10. The test paper detection method according to claim 1, characterized in that: In the step (5), the paper substrate is selected from at least one of filter paper, nitrocellulose membrane, and polyvinylidene fluoride membrane.

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