Preparation method of molecularly imprinted polymer for separating asiaticoside

Abstract

The invention relates to the technical field of polymer separation and purification, in particular to a preparation method of a molecularly imprinted polymer for separating asiaticoside, and the method comprises the following steps: S1, under an anaerobic condition, sequentially adding asiaticoside and a functional monomer containing unsaturated double bonds and amido bonds into a reactor, and carrying out a reaction for 2-4 hours; carrying out self-assembly reaction on the asiaticoside and the functional monomer to obtain a prepolymer containing an asiaticoside structure and unsaturated double bonds; s2, continuing to add a cross-linking agent and an initiator into the reactor, so that the prepolymer is subjected to a polymerization reaction, and a mixed solution is obtained; s3, separating and filtering to obtain a precipitate, and washing to remove template molecules; and S4, collecting the asiaticoside molecularly imprinted polymer, and carrying out vacuum drying to obtain the asiaticoside-containing molecularly imprinted polymer. According to the present invention, with the molecular imprinting technology, the asiaticoside is specifically recognized by using the functional group so as to embody the specificity and the high selectivity of the method;

Description

Technical Field

[0001] The invention relates to the technical field of polymer extraction and preparation, and in particular to a method for preparing a molecular imprinting polymer for separating asiaticaside. Background Art

[0002] Centella asiatica contains triterpenoid saponins, volatile oils, polyacetylenes, flavonoids, sterols and other substances. Modern pharmacological research shows that saponins represented by asiatica glycoside have pharmacological effects such as anti-inflammatory, antioxidant, antifungal, promoting wound healing, protecting the liver and treating osteoporosis. With the deepening of pharmaceutical research on asiatica glycoside, the development of a practical and efficient asiatica glycoside extraction process has become an important part of its development and utilization.

[0003] Centella asiatica is a natural product with extensive medicinal value. The optimization of its extraction method is of great significance for improving the purity and yield of the product. At present, there are many studies on the extraction and separation process of Centella asiatica, mainly including water extraction, alcohol extraction, microwave method, ultrasound method, enzyme-assisted extraction, macroporous resin adsorption method refining, silica gel adsorption method refining, etc. Solvent extraction is the most traditional and commonly used extraction method. By selecting appropriate solvents (such as ethanol, methanol, etc.), the solubility difference of Centella asiatica in different solvents is utilized to achieve its extraction from the raw material. This method is simple to operate and low in cost, but the extraction time is long, and the extraction efficiency is affected by factors such as solvent type, temperature, and time. Ultrasonic-assisted extraction uses the cavitation effect, mechanical effect, and thermal effect generated by ultrasound to improve the solvent's penetration ability and dissolution rate to Centella asiatica, thereby accelerating the extraction process. This method has the advantages of short extraction time and high extraction efficiency, but the equipment cost is relatively high. Microwave-assisted extraction uses the heating effect of microwaves on solvents and raw materials to dissolve Centella asiatica from the raw materials in a relatively short time. This method has the characteristics of high extraction efficiency and simple operation, but the penetration of microwaves into raw materials is limited, which may affect the extraction effect. Enzyme-assisted extraction degrades the cell wall structure in the raw materials by adding specific enzymes (such as cellulase, pectinase, etc.) to increase the release rate of Centella asiatica glycoside. This method has the advantages of mild extraction conditions and good extraction effect, but the selection of enzymes and the conditions of use need to be optimized.

[0004] At present, the purity of asiaticoside extracted by the above method is low, and the application effect is poor. These impurities may affect the stability and activity of the product, and may even cause adverse reactions. At the same time, the above method has high production costs, which not only affects the market competitiveness of the product, but also may limit its application in certain fields. On the other hand, the reagents used in the above separation and purification method may also cause certain pollution to the environment. This is not conducive to environmental protection and sustainable development. Due to the existence of the above problems, the current extraction, separation and purification process of asiaticoside is difficult to achieve large-scale industrial production, which limits the supply and application scope of asiaticoside and cannot meet the growing market demand. Summary of the invention

[0005] The purpose of the invention is to solve the shortcomings of low purity, low efficiency, low stability and the like in the existing Centella asiatica preparation technology, and to propose a method for preparing a molecular imprinting polymer for separating Centella asiatica.

[0006] To achieve the above-mentioned purpose, the present invention is implemented by the following technical solutions: In a first aspect, the present invention first provides a method for preparing a molecularly imprinted polymer for separating asiaticaside, comprising the following steps: S1: under anaerobic conditions, sequentially adding asiatica glycoside and a functional monomer containing an unsaturated double bond and an amide group into a reactor, so that asiatica glycoside and the functional monomer undergo a self-assembly reaction to obtain a prepolymer containing an asiatica glycoside structure and an unsaturated double bond; S2: Continue to add the crosslinking agent and the initiator into the reactor to make the prepolymer undergo a polymerization reaction to obtain a mixed solution; S3: separation and filtration to obtain precipitate, and washing to remove template molecules; S4: collecting the asiaticaoside molecular imprinted polymer and vacuum drying it to obtain the asiaticaoside molecular imprinted polymer.

[0007] Molecular imprinting is a method that forms polymers with specific recognition capabilities by polymerizing specific molecular templates with functional monomers under appropriate conditions. Compared with traditional extraction, macroporous resin adsorption, countercurrent extraction combined with membrane separation and other methods on the market, molecular imprinting has the following advantages: High selectivity: Molecular imprinting polymers are highly selective and can recognize and adsorb target molecules based on the structural characteristics of template molecules, thereby improving the purity of the target substance. High efficiency: Molecular imprinting can prepare polymers with specific recognition capabilities in a shorter time, thereby improving the extraction efficiency of the target substance. Stability: Molecular imprinting polymers have good stability and regeneration, can be used multiple times, and reduce production costs.

[0008] Molecularly imprinted polymers provide a new means for the rapid and accurate determination of asiaticoside. Polymer molecular imprinting is a new type of polymer material with specific recognition function. The specific recognition of the template molecule asiaticoside is mainly attributed to the functional groups in the imprinting pores. Therefore, the polymer molecular imprinting has a binding site that matches the target in terms of functional groups and spatial structure, thereby achieving the rapid and efficient preparation and production effect of asiaticoside molecular imprinting polymers.

[0009] The asiaticoside of S1 of the present invention contains a hydroxyl group, which is a functional group with active hydrogen. In the self-assembly reaction, the hydroxyl group usually acts as a reaction site and interacts with other functional groups. The functional monomer contains an amide group. In the self-assembly reaction, the amide group can act as a hydrogen bond acceptor or donor to participate in the interaction between molecules. The amino group of the functional monomer and the hydroxyl group of asiaticoside undergo a self-assembly reaction and are tightly connected by hydrogen bonds to obtain a prepolymer.

[0010] The crosslinking agent of S2 of the present invention is a compound that can initiate or promote the formation of chemical bonds between polymer molecules. The initiator is a compound that can decompose to produce free radicals or ions, which are used to start the polymerization reaction. During the polymerization reaction, the free radical reaction and the functional group reaction work together to form a crosslinked structure.

[0011] Preferably, the functional monomer is acrylamide; the cross-linking agent is ethylene glycol dimethacrylate; and the initiator is azobisisobutyronitrile.

[0012] Preferably, the molar ratio of asiatica glycoside, functional monomer, cross-linking agent and initiator is 1:3-7:10:0.2.

[0013] The present invention has the above requirements for the ratio of the above-mentioned reactants, and the most preferred molar ratio of asiatica glycoside, functional monomer, crosslinking agent and initiator is 1:3:10:0.2.

[0014] Preferably, the reaction time of the prepolymerization in S1 is 8-14 hours.

[0015] Preferably, the heating temperature of the polymerization reaction of S2 is 50°C-60°C.

[0016] Preferably, the polymerization reaction of S2 is carried out for 8h-14h.

[0017] Preferably, the separation method of the S3 mixed solution is centrifugal drying and suction filtration.

[0018] Preferably, the purification method of the S3 mixed solution is elution, and the elution time is 2-4h.

[0019] The invention adopts methanol:acetic acid solution to elute and remove the template molecule Centella asiatica in a certain proportion to obtain pure Centella asiatica molecular imprinting polymer.

[0020] In a second aspect, the present invention also provides a molecular imprinted polymer of asiaticaside prepared according to the above method.

[0021] The present invention has the following beneficial effects: (1) The preparation method of the present invention adopts molecular imprinting technology and utilizes the functional groups in the imprinting pores to specifically recognize the template molecule Centella asiatica, thereby improving the specificity and efficiency of separating and purifying Centella asiatica molecular imprinting polymers, and is conducive to the rapid and efficient preparation of high-quality Centella asiatica molecular imprinting polymers; (2) The preparation method of the present invention requires less equipment and is simple and convenient to operate. One person alone can complete the preparation of the molecular imprinted polymer containing asiaticaside. In addition, the preparation process is simple, safe and stable, which can effectively reduce the risk of safety accidents. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 This is a scanning electron microscope image of the MIPs of the present invention.

[0023] Figure 2 FT-IR spectra of MIPs and NIPs of the present invention.

[0024] Figure 3 is the SEM of the MIPs of the present invention.

[0025] Figure 4 The pseudo-first-order kinetic model (a) and the pseudo-second-order kinetic model (b) of MIPs and NIPs of the present invention are shown.

[0026] Figure 5 The adsorption thermodynamic curves (a) and the Langmuir model (b) of the MIPs and NIPs of the present invention.

[0027] Figure 6 The invention discloses the adsorption performance of asiaticaside and madecassoside on imprinted polymer and non-imprinted polymer. DETAILED DESCRIPTION

[0028] The following is an explanation of the embodiments of the present invention by specific specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied by other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that, in the absence of conflict, the features in the following embodiments and embodiments can be combined with each other. In the embodiments of the present invention, the methods used are all conventional methods unless otherwise specified, and the reagents used can be obtained from commercial sources.

[0029] Example 1 A method for preparing a molecularly imprinted polymer for separating asiaticaside comprises the following steps: S1: evacuate the reactor and fill it with nitrogen three times in a row to make the reaction system in the reactor oxygen-free and obtain the environment required for the reaction; S2: Adding asiaticaside and acrylamide into the reactor in sequence, and stirring the reaction solution at 200 r / min for 12 h with a magnetic stirring bar to prepolymerize the reaction solution, while maintaining an oxygen-free environment during the reaction; S3: After the prepolymerization is completed, ethylene glycol dimethacrylate and azobisisobutyronitrile are added to the reactor, and the amounts of the Centella asiatica glycoside, acrylamide, ethylene glycol dimethacrylate and azobisisobutyronitrile are set to 1:3:10:0.2 respectively, and the bottom of the reactor is immersed in a water bath for water bath heating and reflux reaction, and the oxygen-free environment is maintained during the reaction process until white turbidity appears after a period of reaction, and the heating cross-linking time is 8 h, and the temperature is 55 ° C; S4: Observe the white turbid object, record the real-time state of the white turbid object, and then continue to react for a period of time until white microspherical substances appear in the reactor. After the white turbid state continues to react for 6 hours, white microspherical substances can be obtained, and a mixed solution can be obtained at this time; S5: taking out the mixed solution and filtering the precipitate by suction filtration; S6: washing with methanol:acetic acid = 9:1 solution to remove the template molecule Centella asiatica glycoside, the elution solvent volume is 50 mL, and the elution is carried out at room temperature for 3 h; S7: When the pH value of methanol after washing is 7, the washing is stopped, and the washing method is flowing washing. The washing oven is set to 55 °C and heated in vacuum drying for 12 h.

[0030] Example 2 A method for preparing a molecularly imprinted polymer for separating asiaticaside comprises the following steps: S1: evacuate the reactor and fill it with nitrogen three times in a row to make the reaction system in the reactor oxygen-free and obtain the environment required for the reaction; S2: Adding asiaticaside and acrylamide into the reactor in sequence, and stirring the reaction solution at 200 r / min for 12 h with a magnetic stirring bar to prepolymerize the reaction solution, while maintaining an oxygen-free environment during the reaction; S3: After the prepolymerization is completed, ethylene glycol dimethacrylate and azobisisobutyronitrile are added to the reactor, and the amounts of the Centella asiatica glycoside, acrylamide, ethylene glycol dimethacrylate and azobisisobutyronitrile are set to 1:5:10:0.2 respectively, and the bottom of the reactor is immersed in a water bath for water bath heating and reflux reaction, and the oxygen-free environment is maintained during the reaction process until white turbidity appears after a period of reaction, and the heating cross-linking time is 8 h, and the temperature is 55 ° C; S4: Observe the white turbid object, record the real-time state of the white turbid object, and then continue to react for a period of time until white microspherical substances appear in the reactor. After the white turbid state continues to react for 6 hours, white microspherical substances can be obtained, and a mixed solution can be obtained at this time; S5: taking out the mixed solution and filtering the precipitate by suction filtration; S6: washing with methanol:acetic acid = 9:1 solution to remove the template molecule Centella asiatica glycoside, the elution solvent volume is 50 mL, and the elution is carried out at room temperature for 3 h; S7: When the pH value of methanol after washing is 7, the washing is stopped, and the washing method is flowing washing. The washing oven is set to 55 °C and heated in vacuum drying for 12 h.

[0031] Example 3 A method for preparing a molecularly imprinted polymer for separating asiaticaside comprises the following steps: S1: evacuate the reactor and fill it with nitrogen three times in a row to make the reaction system in the reactor oxygen-free and obtain the environment required for the reaction; S2: Adding asiaticaside and acrylamide into the reactor in sequence, and stirring the reaction solution at 200 r / min for 12 h with a magnetic stirring bar to prepolymerize the reaction solution, while maintaining an oxygen-free environment during the reaction; S3: After the prepolymerization is completed, ethylene glycol dimethacrylate and azobisisobutyronitrile are added to the reactor, and the amounts of the Centella asiatica glycoside, acrylamide, ethylene glycol dimethacrylate and azobisisobutyronitrile are set to 1:7:10:0.2 respectively, and the bottom of the reactor is immersed in a water bath for water bath heating and reflux reaction, and the oxygen-free environment is maintained during the reaction process until white turbidity appears after a period of reaction, and the heating cross-linking time is 8 h, and the temperature is 55 ° C; S4: Observe the white turbid object, record the real-time state of the white turbid object, and then continue to react for a period of time until white microspherical substances appear in the reactor. After the white turbid state continues to react for 6 hours, white microspherical substances can be obtained, and a mixed solution can be obtained at this time; S5: taking out the mixed solution and filtering the precipitate by suction filtration; S6: washing with methanol:acetic acid = 9:1 solution to remove the template molecule Centella asiatica glycoside, the elution solvent volume is 50 mL, and the elution is carried out at room temperature for 3 h; S7: When the pH value of methanol after washing is 7, the washing is stopped, and the washing method is flowing washing. The washing oven is set to 55 °C and heated in vacuum drying for 12 h.

[0032] Example 4 A method for preparing a molecularly imprinted polymer for separating asiaticaside comprises the following steps: S1: evacuate the reactor and fill it with nitrogen three times in a row to make the reaction system in the reactor oxygen-free and obtain the environment required for the reaction; S2: Adding asiaticaside and acrylamide into the reactor in sequence, and stirring the reaction solution at 200 r / min for 8 h with a magnetic stirring bar to prepolymerize the reaction solution, while maintaining an oxygen-free environment during the reaction; S3: After the prepolymerization is completed, ethylene glycol dimethacrylate and azobisisobutyronitrile are added to the reactor, and the amounts of the Centella asiatica glycoside, acrylamide, ethylene glycol dimethacrylate and azobisisobutyronitrile are set to 1:3:10:0.2 respectively, and the bottom of the reactor is immersed in a water bath for water bath heating and reflux reaction, and the oxygen-free environment is maintained during the reaction process until white turbidity appears after a period of reaction, and the heating cross-linking time is 7 h, and the temperature is 50 ° C; S4: observing the white turbid object, recording the real-time state of the white turbid object, and then continuing the reaction for a period of time until a white microspherical substance appears in the reactor. After the white turbid state continues to react for 6 hours, a white microspherical substance can be obtained, and at this time, an asiaticaside molecularly imprinted polymer mixed solution can be obtained; S5: taking out the mixed solution and filtering the precipitate by suction filtration; S6: washing with methanol:acetic acid = 9:1 solution to remove the template molecule Centella asiatica glycoside, the elution solvent volume is 50 mL, and the elution is carried out at room temperature for 2 h; S7: When the pH value of methanol after washing is 7, the washing is stopped, and the washing method is flowing washing. The washing oven is set to 55 °C and heated in vacuum drying for 12 h.

[0033] Example 5 A method for preparing a molecularly imprinted polymer for separating asiaticaside comprises the following steps: S1: evacuate the reactor and fill it with nitrogen three times in a row to make the reaction system in the reactor oxygen-free and obtain the environment required for the reaction; S2: Adding asiaticaside and acrylamide into the reactor in sequence, and stirring the reaction solution at 200 r / min for 14 h with a magnetic stirring bar to prepolymerize the reaction solution, while maintaining an oxygen-free environment during the reaction; S3: After the prepolymerization is completed, ethylene glycol dimethacrylate and azobisisobutyronitrile are added to the reactor, and the amounts of the Centella asiatica glycoside, acrylamide, ethylene glycol dimethacrylate and azobisisobutyronitrile are set to 1:3:10:0.2 respectively, and the bottom of the reactor is immersed in a water bath for water bath heating and reflux reaction, and the oxygen-free environment is maintained during the reaction process until white turbidity appears after a period of reaction, and the heating cross-linking time is 9 hours, and the temperature is 60°C; S4: Observe the white turbid object, record the real-time state of the white turbid object, and then continue to react for a period of time until white microspherical substances appear in the reactor. After the white turbid state continues to react for 6 hours, white microspherical substances can be obtained, and a mixed solution can be obtained at this time; S5: taking out the mixed solution and filtering the precipitate by suction filtration; S6: washing with methanol:acetic acid = 9:1 solution to remove the template molecule Centella asiatica glycoside, the elution solvent volume is 50 mL, and the elution is carried out at room temperature for 4 h; S7: When the pH value of methanol after washing is 7, the washing is stopped, and the washing method is flowing washing. The washing oven is set to 55 °C and heated in vacuum drying for 12 h.

[0034] The molecular imprinted polymers (MIPs) prepared in the examples were tested, and the test methods and results are shown below. In order to make a clearer comparison between the molecular imprinted polymers (MIPs), the applicant also prepared comparative polymers (NIPs) by not adding asiaticoside during the preparation process based on Example 1.

[0035] Asiaticoside molecularly imprinted polymers (MIPs) were prepared by cross-linking asiaticaside (AS) and acrylamide (AM). Figure 1 is a scanning electron micrograph of the asiatica glycoside molecularly imprinted polymer; Figure 1 It can be seen that the Centella asiatica molecular imprinted polymer material is spherical particles with holes of different sizes on the surface and a certain degree of collapse; the surface structure of the polymer not only helps the mass transfer of the liquid, but also makes them better exposed to the interaction position, thereby promoting adsorption. The successful synthesis of the Centella asiatica material was verified by FT-IR. The results are as follows Figure 2As shown in the FTIR spectra, the spectra of MIPs and NIPs are similar. -1 The COC stretching vibration absorption peak at 1731 cm -1 The -C=O stretching vibration absorption peak at 3411.7 cm is the characteristic peak of the coupling agent (EGDMA), which confirms that the functional monomer and the cross-linking agent are well polymerized. −1 and 3414.0 cm −1 The peak at is attributed to the stretching vibration absorption of the free -OH group. In order to determine the porous characteristics of molecular imprinting, nitrogen adsorption-desorption analysis was performed on MIPs and NIPs. The results are shown in Figure 3 As shown in the figure, the adsorption-desorption isotherm of the material has a hysteresis phenomenon, indicating that the material has a mesoporous structure. According to the adsorption isotherm calculated by the Barrett-Joyner-Halenda (BJH) method, the pore size of MIPs is 10.81 nm. The BET surface area and total pore volume of MIPs are calculated to be 8.414 m 2 / g and 0.0340cm 3 / g.

[0036] Adsorption properties of asiaticaside molecularly imprinted polymer: To explore the adsorption behavior of the adsorbent material, the initial asiaticoside concentration of 1.0 mg mL -1 The contact time and adsorption kinetics of the adsorbent are controlled by the mass transfer process, including the equilibrium time and the physical and chemical properties of the adsorbent. Figure 4 It can be seen that the adsorption capacity of asiaticaside molecular imprinting composite material for asiaticaside increases significantly with time, until the adsorbent reaches equilibrium time, and the adsorption capacity of the adsorbent material does not change significantly with time. The adsorption of asiaticaside on MIP (polymer described in Example 1) increases with the increase of contact time and reaches equilibrium within 90 min.

[0037] The adsorption time and adsorption capacity data of Centella asiatica glycoside molecularly imprinted polymer adsorbent were fitted with pseudo-first-order kinetic and pseudo-second-order kinetic models ( Figure 4 ) is used to illustrate its adsorption behavior. From the fitting curve, it can be seen that the adsorption kinetics of asiaticoside molecular imprinting composites conforms to the pseudo-first-order kinetic model, rather than the pseudo-second-order kinetic model. This conclusion shows that the adsorption rate of asiaticoside molecules adsorbed by the organic functional groups of the interlayer spacing of asiaticoside molecular imprinting composites mainly depends on the rate at which asiaticoside binds to the material surface.

[0038] The thermodynamic adsorption behavior of asiatica glycoside molecularly imprinted polymers was studied and the maximum adsorption capacity of the materials was evaluated. The adsorption performance of the adsorbent materials at different asiatica glycoside concentrations at 30 °C was investigated. Figure 5 a. It can be seen from the figure that the adsorption capacity of the asiaticoside molecular imprinting composite material increases with the increase of asiaticoside concentration. On the one hand, due to the increase of asiaticoside concentration in the solution, more active sites in the adsorbent are used for adsorption. From the fitting curve ( Figure 5 As can be seen from b), the thermodynamics of the asiaticaside molecular imprinting composite material conforms to the Langmuir model, indicating that nicotine is uniformly and monolayer adsorbed on the adsorption sites on the surface of the asiaticaside molecular imprinting composite material, and the binding energy is evenly distributed on the entire surface of the material.

[0039] Selectivity of Molecularly Imprinted Polymers Containing Centella asiatica: The selectivity of asiatica glycoside molecular imprinting composites was investigated by selective adsorption experiments using hydroxy-madecassoside as a competitive molecule. The adsorption results of molecular imprinting composites and non-molecular imprinting composites showed that ( Figure 6 ), the molecularly imprinted polymer has very good selective adsorption for asiaticoside, and the adsorption selectivity coefficients for asiaticoside and madecassoside are 2.29 and 1.47, respectively. This shows that it is effective to construct selective recognition sites in molecularly imprinted composites. The results show that the prepared molecularly imprinted cavities have a high recognition ability for asiaticoside.

Claims

1. A method for preparing a molecularly imprinted polymer for separating asiaticaside, characterized in that: The following steps are involved: S1: under anaerobic conditions, sequentially adding asiatica glycoside and a functional monomer containing an unsaturated double bond and an amide group into a reactor, so that asiatica glycoside and the functional monomer undergo a self-assembly reaction to obtain a prepolymer containing an asiatica glycoside structure and an unsaturated double bond; S2: Continue to add the crosslinking agent and the initiator into the reactor to make the prepolymer undergo a polymerization reaction to obtain a mixed solution; S3: separation and filtration to obtain precipitate, and washing to remove template molecules; S4: collecting the asiaticaoside molecular imprinted polymer and vacuum drying it to obtain the asiaticaoside molecular imprinted polymer.

2. The method for preparing a molecularly imprinted polymer for separating asiaticaside according to claim 1, characterized in that: The functional monomer is acrylamide; the cross-linking agent is ethylene glycol dimethacrylate; and the initiator is azobisisobutyronitrile.

3. The method for preparing a molecularly imprinted polymer for separating asiaticaside according to claim 2, characterized in that: The molar ratio of the asiaticoside, the functional monomer, the crosslinking agent and the initiator is 1:3-7:10:0.

2.

4. The method for preparing a molecularly imprinted polymer for separating asiaticaside according to claim 1 or 2, characterized in that: The reaction time of the S1 prepolymerization is 8-14 h.

5. The method for preparing a molecularly imprinted polymer for separating asiaticaside according to claim 1 or 2, characterized in that: The heating temperature of the polymerization reaction of S2 is 40°C-60°C.

6. The method for preparing a molecularly imprinted polymer for separating asiaticaside according to claim 5, characterized in that: The polymerization reaction time of S2 is 8-14h.

7. The method for preparing a molecularly imprinted polymer for separating asiaticaside according to claim 1 or 2, characterized in that: The separation method of the S3 mixed solution is centrifugal drying and suction filtration.

8. The method for preparing a molecularly imprinted polymer for separating asiaticaside according to claim 7, characterized in that: The S3 mixed solution is eluted, and the elution time is 2-4h.

9. A molecularly imprinted polymer of Centella asiatica, characterized in that: It is prepared by the method described in claims 1-8.

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