Fluorescent test paper for detecting white spirit as well as preparation method and application of fluorescent test paper

Abstract

The invention provides white spirit detection fluorescent test paper as well as a preparation method and application thereof. The preparation method comprises the following steps: 1) preparing a mixed solution of polylactic acid and aggregation-induced emission molecules; (2) preparing a crystalline film of polylactic acid and aggregation-induced emission molecules by using the mixed solution in the step (1); and 3) carrying out heating and cold water rapid cooling amorphization treatment on the crystal film in the step 2). The polylactic acid and the crystal film of the aggregation-induced emission molecules are subjected to amorphization treatment of heating and rapid cooling with cold water, so that the test paper becomes transparent, the luminescent property and material characteristics are changed, and the fluorescent test paper with excellent white spirit detection performance is realized.

Description

Technical Field

[0001] The present invention belongs to the field of test paper detection, and particularly relates to a fluorescent test paper for detecting white liquor, a preparation method thereof, and an application thereof. Background Art

[0002] Compared with being dissolved in a solution, aggregation-induced emission (AIE) molecules produce stronger fluorescence in the aggregated state. Therefore, AIE molecules can be used to respond to changes in the environment, such as being formulated into a solution to detect specific chemical components in a liquid phase. In addition, when AIE molecules are combined with polymers, through the microenvironment changes brought about by the swelling or deformation of the polymers, the detection of specific substances in the liquid or gas phase and pressure sensing can be achieved. For the detection of the liquid-phase composition, the common method is to determine each component and its proportion through the combination of liquid chromatography and mass spectrometry, and the corresponding test cost and practicability are relatively low. For the liquid-phase detection of a simple binary system, its proportion can be determined by measuring the refractive index, but corresponding optical equipment is still required. Based on the special optical properties of AIE molecules, through molecular design, they can be attached to ordinary test papers for the detection of specific molecules. In life and production, the need for a rough determination and general composition determination of the solution composition is very common, such as identifying the components of a transparent solution, white liquor. Therefore, it is very necessary to design a test paper that can conveniently and quickly detect medium-polarity organic molecules in a solution.

[0003] The existing detection research related to AIE molecules mainly focuses on the detection of specific molecules. By designing the molecular structure, the binding with specific molecules is achieved, resulting in changes in optical signals, and thus detection is realized. However, in the commonly used detection scenarios in life, the components are often relatively complex, prone to generating interference signals, or unable to be analyzed. At the same time, it is difficult for the design of AIE molecules to accurately identify small molecules with fewer special functional groups. Therefore, there is an urgent need in this field to provide a test paper for detecting medium-polarity small-molecule substances in a liquid-phase environment to achieve the detection of ester substances in white liquor. Summary of the Invention

[0004] To solve the above problems, the present invention provides a preparation method of a fluorescent test paper for detecting white liquor.

[0005] The test paper provided by the present invention can detect ester substances in white liquor. Different from the common liquid chromatography analysis method, the fluorescent test paper of the present invention can achieve convenient and rapid liquid-phase detection, especially the components of white liquor. This method has a lower cost and is not restricted by equipment, and can be detected on-site. The preparation method of the present invention realizes the preparation of the fluorescent test paper for detecting white liquor by dissolving polylactic acid and tetraphenylethylene and then precipitating a crystal film, and then quickly immersing it in cold water after heating.

[0006] Specifically, the present invention provides the following technical solutions:

[0007] In a first aspect, the present invention provides a method for preparing a fluorescent test strip for detecting Chinese liquor, comprising the following steps:

[0008] 1) Prepare a mixed solution of polylactic acid and aggregation-induced emission molecules;

[0009] 2) Use the mixed solution in step 1) to prepare a crystalline film of polylactic acid and aggregation-induced emission molecules;

[0010] 3) Perform an amorphization treatment on the crystalline film in step 2) by heating and rapid cooling with cold water.

[0011] By subjecting the crystalline film of polylactic acid and aggregation-induced emission molecules to an amorphization treatment of heating and rapid cooling with cold water, the test strip becomes transparent, and the luminescence properties and material characteristics change, realizing a fluorescent test strip with excellent Chinese liquor detection performance.

[0012] The method for preparing a fluorescent test strip for detecting Chinese liquor provided by the preferred embodiment of the present invention comprises the following steps:

[0013] 1) Mix polylactic acid, aggregation-induced emission molecules, and a solvent to obtain a mixed solution of polylactic acid and aggregation-induced emission molecules;

[0014] 2) Dry and volatilize the mixed solution in step 1) to obtain a crystalline film of polylactic acid and aggregation-induced emission molecules;

[0015] 3) Cut the crystalline film in step 2) and place it on a polytetrafluoroethylene film covering a glass slide. Then, place a copper foil on the surface of the crystalline film, cover it with a glass plate covered with a polytetrafluoroethylene film, and fix the template with a long-tail clip. Then, heat the template until the crystalline film becomes transparent, immerse it in cold water to cool, and take out the test strip in the template. The fluorescent test strip prepared from polylactic acid and tetraphenylethylene provided by the present invention, as discovered by the inventor, has its mixed solution dried and volatilized to obtain a crystalline film of polylactic acid and aggregation-induced emission molecules, which is placed on a polytetrafluoroethylene film covering a glass slide, a copper foil is placed on the surface of the crystalline film, a glass plate covered with a polytetrafluoroethylene film is covered, the template is fixed with a long-tail clip, the template is heated until the crystalline film becomes transparent, immersed in cold water to cool, and the test strip in the template is taken out. This method obtains an amorphous material by rapid cooling in a hot melt state. The amorphous polylactic acid will have a change in crystallization properties when affected by medium-polarity solvents such as ethyl acetate, ethyl hexanoate, and acetone. At the same time, the aggregation-induced emission molecules can reflect the internal structural changes of the polymer material, resulting in changes in fluorescence properties, and having excellent Chinese liquor detection effects.

[0016] Preferably, in step 1), in the mixed solution of polylactic acid and aggregation-induced emission molecule, the solvent is dichloromethane, the concentration of polylactic acid is 0.5 - 2 g / ml, and the concentration of aggregation-induced emission molecule is 0.05 - 0.5 g / ml; preferably, the weight-average molecular weight of the polylactic acid is 70000 - 100000. In the present invention, the selected polylactic acid and aggregation-induced emission molecule as the main materials, especially the polylactic acid, are the key to liquor detection. The ester substances in liquor act on amorphous polylactic acid, resulting in the phenomenon of induced crystallization, and the detection effect is better under the preferred ratio. Further preferably, the mass-volume ratio of polylactic acid, tetraphenylethylene and dichloromethane is 2 g: 0.5 g: 20 mL.

[0017] Further preferably, in step 1), the aggregation-induced emission molecule includes tetraphenylethylene or hexaphenylsilole, preferably tetraphenylethylene.

[0018] Further preferably, in step 2), the mixed solution in step 1) is poured into a container and naturally volatilized to obtain a crystal film of polylactic acid and aggregation-induced emission molecule; preferably, the natural volatilization is carried out by placing the container in a cool and ventilated place, preferably with little air disturbance to make the crystal film uniform.

[0019] Further preferably, to prepare a crystal film of polylactic acid and tetraphenylethylene: pour the dichloromethane solution of dissolved polylactic acid and tetraphenylethylene into a petri dish to spread it in the petri dish; cover the mouth of the petri dish with tin foil and poke holes with tweezers to prevent dust from falling in; then place the petri dish on a flat table and keep it in a cool and ventilated place for 1 - 2 days to make the components of the crystal film of polylactic acid and tetraphenylethylene uniform.

[0020] In the present invention, the template structure is that the glass plate provides mechanical support externally, the polytetrafluoroethylene film facilitates the separation of the test paper from the template, and the internal copper foil is used to adjust the thickness of the test paper.

[0021] Further preferably, wrap the mouth of the container with tin foil and poke a plurality of ventilation holes on its surface.

[0022] Preferably, in step 3), the thickness of the copper foil is 0.025 - 0.2 mm, the thickness of the polytetrafluoroethylene film is 20 - 50 um, and the width of the long tail clip is 15 - 25 mm.

[0023] In the present invention, the thickness of the copper foil is 0.025 - 0.2 mm, such as 0.2 mm, 0.15 mm, 0.1 mm, 0.05 mm or 0.025 mm, etc., the thickness of the polytetrafluoroethylene film is 20 - 50 um, such as 20 um, 30 um, 40 um or 50 um, etc., and the width of the long tail clip is 15 - 25 mm, such as 15 mm, 19 mm or 25 mm, etc.

[0024] Further preferably, in step 3), the template is placed on a heating table with the temperature set at 300 - 400 °C for heating, and the heating time is 15 - 25 min. In the present invention, due to the height difference between the front and rear ends of the bulldog clip, there is a certain distance between the heated area and the surface of the heating table, and the actual heating temperature is slightly lower than the set temperature.

[0025] Further preferably, in step 3), the temperature of the cold water is 0 - 20 °C, and the soaking time is 20 - 60 s. In the present invention, when the template is quickly immersed in cold water, the amorphous state of the test paper at high temperature can be maintained by rapidly reducing the temperature.

[0026] Further preferably, the template is placed on a heating table with the temperature set at 350 - 400 °C and heated for 20 - 25 min to make the polylactic acid and tetraphenylethylene film transparent and evenly dispersed; then, the template is quickly immersed in cold water at 0 - 2 °C for 30 - 35 s to keep the test paper in an amorphous state. The test paper prepared under the above conditions can maintain a better amorphous state, especially significantly improving the detection effect of white liquor.

[0027] Preferably, it further includes trimming the part that overflows the template after cooling.

[0028] In the second aspect, the present invention provides a fluorescent test paper for detecting white liquor obtained by the preparation method of the above fluorescent test paper for detecting white liquor.

[0029] In the third aspect, the present invention provides the application of the fluorescent test paper for detecting white liquor obtained by the preparation method of the above fluorescent test paper for detecting white liquor or the above fluorescent test paper for detecting white liquor in the detection of white liquor.

[0030] The beneficial effects of the present invention are at least as follows:

[0031] 1) In the present invention, the polylactic acid and the aggregation-induced emission molecule are prepared into a test paper by an amorphous treatment method of heating and rapid cooling. Due to the solvent-induced crystallization effect of polylactic acid and the characteristic of enhanced crystallization emission of the aggregation-induced emission molecule, when the test paper contacts a solvent that can swell polylactic acid, the crystallinity of the whole test paper will be enhanced, showing the effects of enhanced fluorescence and whitening of the test paper. It can quickly and conveniently detect the content of medium-polar components in the solution without the need for detection under specific experimental conditions.

[0032] 2) Since the detection of the test paper of the present invention is achieved through solvent-induced crystallization, there is no discrimination ability for the types of detected substances, and medium-polar organic substances can all cause changes in the test paper. However, for the white liquor detection system mainly composed of water and ethanol, it has a good detection effect and can effectively detect the content of its ester substances. At the same time, the content of ester substances reflects the flavor type of the detected white liquor. Description of the Drawings

[0033] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the accompanying drawings required in the description of the embodiments or the prior art. The accompanying drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other accompanying drawings can be obtained based on these drawings.

[0034] Figure 1 It is a flowchart for the preparation of a fluorescence test strip for detecting Chinese liquor provided by the present invention;

[0035] Figure 2 It is a schematic structural diagram of a template provided in Embodiment 1 of the present invention, which includes a glass plate, a polytetrafluoroethylene film, a copper foil, a polylactic acid crystal film, and a long-tail clip;

[0036] Figure 3 It is a fluorescence spectrogram of the fluorescence test strip for detecting ethanol aqueous solutions with various volume fractions in Test Example 1 of the present invention;

[0037] Figure 4 It is a fluorescence spectrogram of the fluorescence test strip before and after detecting a 50% vol ethanol aqueous solution containing 2% ethyl hexanoate in Test Example 2 of the present invention;

[0038] Figure 5 It is a standard curve of the fluorescence test strip for detecting 50% vol ethanol aqueous solutions containing various concentrations of ethyl hexanoate in Test Example 3 of the present invention;

[0039] Figure 6 It is a fluorescence spectrogram of the fluorescence test strip before and after detecting Xifeng liquor in Test Example 4 of the present invention. Detailed implementation manners

[0040] To clearly express the content of the present invention, the following will make a detailed description of the present invention. The following examples and comparative examples are used to illustrate the present invention, but not to limit the scope of the present invention. To make the purpose, technical solutions, and advantages of the present invention clearer, the following further details the present invention.

[0041] For those not specified in the examples in terms of specific technologies or conditions, they shall be in accordance with the technologies or conditions described in the literature in this field or in accordance with the product instructions. The implementation conditions in the examples can be further adjusted according to specific experimental conditions or factory conditions. Those not specified in the implementation conditions are usually the conditions in conventional experiments. If not specifically indicated, the technical means used in the examples are the conventional means well-known to those skilled in the art, and the raw materials used are all commercially available products.

[0042] Embodiment 1

[0043] The fluorescence test strip provided in this embodiment is prepared as follows:

[0044] Prepare a dichloromethane solution of polylactic acid and tetraphenylethylene: Weigh 2 g of polylactic acid and 0.5 g of tetraphenylethylene separately using a balance. Put the weighed polylactic acid and tetraphenylethylene into a 20 mL glass bottle, and add a magnetic stir bar and 20 mL of dichloromethane. Place the glass bottle on a magnetic stirring platform and stir for 6 hours until the solution becomes transparent, dissolving the polylactic acid and tetraphenylethylene.

[0045] Prepare a crystalline film of polylactic acid and tetraphenylethylene: Pour the dissolved dichloromethane solution of polylactic acid and tetraphenylethylene into a petri dish to spread it in the petri dish. Cover the mouth of the petri dish with tin foil and poke holes with tweezers to prevent dust from falling in. Then place the petri dish on a flat table and keep it in a cool and ventilated place for 2 days to ensure that the components of the crystalline film of polylactic acid and tetraphenylethylene are evenly distributed.

[0046] Amorphization treatment of the crystalline film of polylactic acid and tetraphenylethylene: Cut the crystalline film into 1.5 cm × 3 cm thin slices, and sandwich the thin slices of the crystalline film and a 50 μm thick copper foil between two 40 μm thick polytetrafluoroethylene films to facilitate subsequent detachment from the template. Then attach glass plates on both sides to provide mechanical support and act as a template. Finally, use a long-tail clip with a size of 15 mm to fix both sides of the glass plate carrying the film, ensuring that the crystalline film continuously thins during heating until it is close to the thickness of the copper foil. Place the entire template on a heating table with a temperature set to 400 °C and heat for 20 minutes to make the polylactic acid and tetraphenylethylene film transparent and evenly dispersed. Then, quickly immerse the template in ice-cold water at 0 °C for 30 seconds to keep the test paper in an amorphous state.

[0047] Cutting and use of the fluorescent test paper of polylactic acid and tetraphenylethylene: Cut off the yellow or black parts extruded by the template and keep the test paper inside the template. At this time, the test paper is in a semi-transparent state and the fluorescent color is green. Cut the test paper obtained by the method of Example 1 into 0.5 cm × 1.5 cm strips for the following test examples to test solutions.

[0048] Test Example 1

[0049] Fix a 0.5 cm × 1.5 cm test paper in the optical path of an RF-5301 fluorescence spectrometer. Select an excitation wavelength of 365 nm, a detection wavelength range of 400 nm - 600 nm, both the excitation and emission slit widths are 1.5, the detection speed is set to Fast, and the step size is 0.2 nm to measure the initial fluorescence spectrum of the test paper. Then successively immerse the fluorescent test paper in ethanol aqueous solutions with volume fractions of 5%, 10%, 20%, 50%, 70%, and 80% for 3 minutes, and then measure its fluorescence spectrum in the fluorescence spectrometer. The results are as Figure 3 shown.

[0050] The results show that the fluorescence test paper of polylactic acid / tetraphenylethylene maintains stable properties in an environment of ethanol and water, and its fluorescence intensity and peak wavelength are not affected by ethanol.

[0051] Test Example 2

[0052] Fix a test paper of 0.5 cm × 1.5 cm in the optical path of an RF-5301 fluorescence spectrometer. Select the excitation wavelength to be 365 nm, the detection wavelength range to be 400 nm - 600 nm, the slit widths of both excitation and emission to be 1.5, the detection speed to be set as Fast, and the step size to be 0.2 nm. Start the fluorescence spectrometer to obtain its initial fluorescence spectrum (solid line). Then, immerse the test paper in an ethanol aqueous solution (50% vol) containing 2% ethyl hexanoate for three minutes, and then blot the liquid on its surface dry. Start the fluorescence spectrometer again under the same conditions to obtain its fluorescence spectrum after detection (dashed line), and the results are as Figure 4 shown.

[0053] The results show that the fluorescence test paper of polylactic acid / tetraphenylethylene will have obvious changes in optical properties in an environment containing ethyl hexanoate. Its central wavelength blue-shifts from 468 nm to 454 nm, and the intensity increases from 189 a.u. to 238 a.u. Combining with Test Example 1 indicates that the fluorescence test paper has a good response to ethyl hexanoate in water and ethanol environments.

[0054] Test Example 3

[0055] Fix a test paper of 0.5 cm × 1.5 cm in the optical path of an RF-5301 fluorescence spectrometer. Select the excitation wavelength to be 365 nm, the detection wavelength range to be 400 nm - 600 nm, the slit widths of both excitation and emission to be 1.5, the detection speed to be set as Fast, and the step size to be 0.2 nm. Start the fluorescence spectrometer to obtain its initial fluorescence spectrum. Then, immerse the test paper in an ethanol aqueous solution (50% vol) containing 2% ethyl hexanoate for three minutes, and then blot the liquid on its surface dry. Start the fluorescence spectrometer again under the same conditions to obtain its fluorescence spectrum after detection. Test the ethanol aqueous solutions (50% vol) containing 0.1%, 0.25%, 0.5%, and 1% ethyl hexanoate according to the same method, and organize the data of the ratio of the fluorescence intensity change to the initial fluorescence intensity (labeled as ΔI / I 0 ) to obtain the relationship curve between ΔI / I 0 and the content of ethyl hexanoate, and the results are as Figure 5 shown.

[0056] The results show that the fluorescence test paper of polylactic acid / tetraphenylethylene will have obvious changes in optical properties in an environment containing ethyl hexanoate. As the concentration of ethyl hexanoate increases, ΔI / I 0The corresponding value increases accordingly. This result indicates that the fluorescent test paper of polylactic acid / tetraphenylethylene has excellent detection ability for the concentration change of ethyl hexanoate in water and ethanol environments.

[0057] Test Example 4

[0058] Fix a test paper of 0.5 cm×1.5 cm in the optical path of an RF-5301 fluorescence spectrometer. Select the excitation wavelength to be 365 nm, the detection wavelength range to be 400 nm - 600 nm, the slit widths of both excitation and emission to be 1.5, set the detection speed to Fast, the step size to be 0.2 nm, and measure the initial fluorescence spectrum of the test paper. Immerse the test paper in Fengxiang-style Xifeng liquor with an alcohol content of 45% vol for 3 minutes, then take it out and blot the liquid on the surface dry, and test its fluorescence spectrum after detection under the same conditions. Detect in the same way for strong-flavor liquor, light-flavor liquor, and sauce-flavor liquor multiple times. The test results are as Figure 6 shown.

[0059] The results show that the fluorescent test paper of polylactic acid / tetraphenylethylene has significantly distinguishable fluorescence intensity changes for white liquors of different flavors. Combining the results of Test Example 1 and Test 3, it can be known that the fluorescent test paper responds to ester flavor substances such as ethyl hexanoate in white liquor. Combining the corresponding concentration relationship curves, the content of the corresponding substances can be roughly detected.

[0060] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements for some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A preparation method of a fluorescent test paper for detecting Chinese liquor, characterized in that, it includes: 1) Prepare a mixed solution of polylactic acid and aggregation-induced emission molecules; 2) Use the mixed solution in step 1) to prepare a crystalline film of polylactic acid and aggregation-induced emission molecules; 3) Perform an amorphous treatment on the crystalline film in step 2) by heating and rapid cooling with cold water.

2. The preparation method of the fluorescent test paper for detecting Chinese liquor according to claim 1, characterized in that, it includes the following steps: 1) Mix polylactic acid, aggregation-induced emission molecules and a solvent to obtain a mixed solution of polylactic acid and aggregation-induced emission molecules; 2) Dry and volatilize the mixed solution in step 1) to obtain a crystalline film of polylactic acid and aggregation-induced emission molecules; 3) Cut the crystalline film in step 2) and place it on a polytetrafluoroethylene film covering a glass slide. Then place a copper foil on the surface of the crystalline film, cover it with a glass plate covered with a polytetrafluoroethylene film, and fix the template with a long-tailed clip; then heat the template until the crystalline film becomes transparent, immerse it in cold water to cool, and take out the test paper in the template.

3. The preparation method of the fluorescent test paper for detecting Chinese liquor according to claim 2, characterized in that, in step 1), in the mixed solution of polylactic acid and aggregation-induced emission molecules, the solvent is dichloromethane, the concentration of polylactic acid is 0.5 - 2 g / ml, and the concentration of aggregation-induced emission molecules is 0.05 - 0.5 g / ml; preferably, the molecular weight of the polylactic acid is 70000 - 100000.

4. The preparation method of the fluorescent test paper for detecting Chinese liquor according to claim 3, characterized in that, in step 1), the aggregation-induced emission molecules include tetraphenylethylene or hexaphenylsilole.

5. The preparation method of the fluorescent test paper for detecting Chinese liquor according to claim 2, characterized in that, in step 2), pour the mixed solution in step 1) into a container and let it volatilize naturally to obtain a crystalline film of polylactic acid and aggregation-induced emission molecules.

6. The preparation method of the fluorescent test paper for detecting Chinese liquor according to claim 2, characterized in that, in step 3), the thickness of the copper foil is 0.025 - 0.2 mm, the thickness of the polytetrafluoroethylene film is 20 - 50 μm, and the width of the long-tailed clip is 15 - 25 mm.

7. The preparation method of the fluorescent test paper for detecting Chinese liquor according to any one of claims 2 - 6, characterized in that, in step 3), place the template on a heating table with the temperature set at 300 - 400 °C for heating, and the heating time is 15 - 25 min.

8. The preparation method of the fluorescent test paper for detecting Chinese liquor according to any one of claims 1 - 7, characterized in that, in step 3), the temperature of the cold water is 0 - 20 °C, and the soaking time is 20 - 60 s.

9. A fluorescent test paper for detecting Chinese liquor obtained by the preparation method of the fluorescent test paper for detecting Chinese liquor according to any one of claims 1 - 8.

10. Application of the fluorescent test paper for detecting Chinese liquor obtained by the preparation method of the fluorescent test paper for detecting Chinese liquor according to any one of claims 1 - 8 or the fluorescent test paper for detecting Chinese liquor according to claim 9 in detecting Chinese liquor.

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