Efficient method for preparing l-borneol crystal from eisenia and product thereof

Abstract

The application discloses a kind of efficient preparation of left enantiomeric borneol crystal from Blumea Balsamifera and product, the method includes S1 supercritical CO2 extraction, S2 paste water separation, S3 impurity removal, S4 crystallization treatment and S5 crystal collection step.Using the method and the left enantiomeric borneol crystal prepared by the application, the whole preparation method is simple to operate, after supercritical CO2 extraction, the crude extract with less impurities can be obtained, then after column chromatography purification, Blumea Balsamifera crystal is obtained by induced crystallization, not only high preparation efficiency, and product quality is stable, far superior to traditional preparation method, greatly improve the comprehensive utilization rate of resources, also have guiding significance to left enantiomeric borneol product preparation and product application.

Description

Technical Field

[0001] This invention relates to the field of traditional Chinese medicine extraction technology, specifically to a highly efficient method and product for preparing L-borneol crystals from Artemisia annua. Background Technology

[0002] Artemisia argyi, also known as Dafeng Ai, Bingpian Ai, Dafengye, Niuer Ai, or Nalong, belongs to the Artemisia genus of the Asteraceae family. Artemisia argyi is an important raw material for obtaining artemisia flakes. L-borneol, also known as L-borneol, artemisia flakes, or L-borneol natural borneol, is a crystalline substance obtained by purifying and processing the sublimation of the leaves of Artemisia argyi. Its effects include clearing the orifices, dispersing heat, improving eyesight, relieving pain, warming the middle jiao and promoting blood circulation. It is mainly used to treat febrile diseases with delirium, convulsions with phlegm, suppurative otitis media, ulcerative stomatitis, burns, herpes zoster, pharyngitis, and cardiovascular diseases. It is a raw material for traditional Chinese medicine and a fragrance ingredient used in ophthalmology, dentistry, and cardiovascular medicine, and is widely used in the pharmaceutical and fragrance industries.

[0003] Using current extraction methods, the following prominent challenges are encountered in the processing and extraction stage: First, the existing technology and equipment are relatively outdated, resulting in low production efficiency, while the volatilization and conversion of L-borneol during processing is relatively large; Second, traditional production methods generate a lot of wastewater and pollutants.

[0004] With the development of extraction processes and technologies, the current extraction process for Artemisia argyi is increasingly unable to meet the requirements. The demands for purity and recovery rate of Artemisia argyi extract are also rising. Therefore, it is essential to improve the traditional extraction process to provide a more efficient preparation method. Summary of the Invention

[0005] The technical problem to be solved by this invention is to address the problems existing in the background technology, and thus provide an efficient method for preparing L-borneol crystals. This preparation method uses supercritical carbon dioxide extraction and induces crystallization to improve the extraction rate and content, thereby preparing L-borneol crystals with higher purity to meet the needs of L-borneol crystal use. Specifically, it is an efficient method and product for preparing L-borneol crystals from Artemisia annua.

[0006] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is: a highly efficient method for preparing L-borneol crystals from Artemisia annua, the method comprising the following steps: S1. Supercritical CO2 extraction: Using Artemisia as raw material, supercritical CO2 extraction is used to extract Artemisia to obtain a crude extract containing L-borneol; S2. Extract-water separation: The crude extract obtained in step S1 is subjected to extract-water separation, and the separated aqueous phase and oil phase are collected separately; S3. Impurity removal: The oil phase obtained in step S2 is subjected to impurity removal by column chromatography elution in order to remove water-soluble impurities and pigments from the Artemisia annua extract. After impurity removal, crude L-borneol is obtained. S4. Crystallization treatment: The crude levorotatory borneol obtained in step S3 is dissolved, seed crystals are added to the solution, and crystallization is carried out by induced crystallization to obtain a crystallization solution; S5. Crystal collection: After crystallization, the solution obtained in step S4 is filtered and dried to obtain high-purity L-carnitine crystals.

[0007] Furthermore, the method for preparing L-carnitine crystals from Artemisia as described in this invention includes the following steps in the S1 supercritical CO2 extraction stage: raw material crushing, loading, carbon dioxide pump pressurization, separation in separation vessel I, separation in separation vessel II, collection in the tail gas buffer tank, and tail gas recovery in the intermediate storage tank.

[0008] Furthermore, in the efficient method for preparing L-borneol crystals from Artemisia as described in this invention, the specific extraction process in the S1 supercritical CO2 extraction stage includes the following steps: S11. Raw material pretreatment: First, crush the Artemisia argyi raw material into 50-80 mesh, and then load it into the extraction vessel at a loading density of 0.2-0.4 kg / L. S12. Supercritical CO2 Extraction: Supercritical CO2 dynamic extraction is carried out in an extraction vessel using a carbon dioxide pump at an extraction pressure of 20–40 MPa and a temperature of 38–45℃. When separation is carried out in separation vessel I, the pressure is controlled at 8–10 MPa and the temperature at 30–40℃; when separation is carried out in separation vessel II, the pressure is controlled at 4–5 MPa and the temperature at 20–30℃. Throughout the entire supercritical CO2 extraction process, the carbon dioxide flow rate is controlled at 80–120 kg / h and the extraction time is 2–3 h. S13. Collection of crude extract of Artemisia argyi: If Artemisia argyi extract is not completely separated in the separation vessel during each extraction using the extraction vessel, the crude extract of Artemisia argyi is collected in the tail gas buffer tank. During collection, the pressure of the tail gas buffer tank is controlled at 1-2 MPa and the temperature at 8-10℃. After extraction, the crude extract of Artemisia argyi is separated in the tail gas buffer tank, and the pressure of the tail gas buffer tank is controlled at 0 MPa and the temperature at 40-50℃.

[0009] Furthermore, in the efficient method for preparing L-carnitine crystals from Artemisia as described in this invention, during the collection of the crude Artemisia extract in S3, the tail gas buffer tank is equipped with a coil. During collection, it is necessary to connect a condensate circulation system or add a refrigeration unit for cooling to cool the carbon dioxide exiting the separation vessel. Simultaneously, the tail gas buffer tank is connected at the outlet of the precooler and at the inlet of the intermediate tank. The energy consumption for reducing carbon dioxide to the tail gas buffer tank at this connection point is the lowest. After the temperature and pressure decrease, the solubility of carbon dioxide decreases accordingly, thereby achieving the best analytical separation effect.

[0010] Furthermore, in the efficient method for preparing L-carnitine crystals from Artemisia annua described in this invention, during the S2 paste-water separation stage, the specific paste-water separation method is as follows: an oil-water separator is used to separate the crude Artemisia annua extract obtained from extraction. After controlling the jacket heating temperature in the oil-water separator to 50-60°C, the collected crude Artemisia annua extract is poured in and stirred using a stirring device until the material temperature reaches 50-60°C. Then, stirring is stopped, and the mixture is allowed to stand for 5-10 minutes. After that, the lower aqueous phase is slowly released and collected in a water tank. After continuing to keep it warm and stand for 10-20 minutes, the oil phase is released. At this point, the oil phase without residual water is collected, thus obtaining the supercritical extract paste.

[0011] Furthermore, in the efficient method for preparing L-borneol crystals from Artemisia as described in this invention, the specific operation method in the S3 impurity removal stage includes the following steps: S31. Raw material processing: Take the supercritical extract paste of Artemisia argyi after water removal, dissolve it in anhydrous ethanol at a mass ratio of 1:1 and perform ultrasonic treatment. Control the ultrasonic temperature at 50-60℃ and the ultrasonic time at 5-10 min, then filter out the impurities. S32. Column packing: Select 80-100 mesh D101 macroporous resin to pack 50-100 ml of chromatography column, soak in anhydrous ethanol for 24 h, wash with water until neutral, and then pack the column using the wet method. S33. Sample loading and adsorption: The treated solution is evenly dropped onto the chromatography column and waited for 30-60 minutes; S34. Cleaning: First, use pure water to wash away the water-soluble impurities and pigments remaining in the resin. Then, use 3-5 BV of pure water at a flow rate of 1-2 BV / h to rinse and collect the eluent. S35. Elution and Collection: Elute with 5-8 BV of 85-95% ethanol at a flow rate of 1-2 BV / h, collect the eluent in fractions, combine the concentrates, and recover the ethanol under reduced pressure to obtain the crude extract of L-borneol.

[0012] Furthermore, in the efficient method for preparing L-borneol crystals from Artemisia as described in this invention, during the S4 crystallization stage, ethanol is selected as the crystallization solvent, the mass ratio of solvent to solute is 1:1 to 5, and the solvent concentration is 70 to 90%. During crystallization, a seed crystal induction method is adopted, in which seed crystals are added to the solution. The seed crystals are L-borneol crystals with a purity of 90 to 99%, and the amount added is 1 to 3% of the mass of the solute.

[0013] Furthermore, the specific steps of the crystallization process described in this invention for preparing L-borne borneol crystals from Artemisia annua are as follows: S41. Dissolution: Weigh the sample and solvent at a mass ratio of 1:2 to 4, mix them, and then perform ultrasonic dissolution. Control the ultrasonic temperature at 40°C and the ultrasonic time at 10 to 30 minutes. After dissolution, place the solution in a water bath at 40°C for stabilization for 30 minutes. The solvent used is ethanol with a concentration of 80 to 90%. S42. Induced crystallization: Take out the above solution, add 1-2% of solute by mass of levorotatory borneol as seed crystals, and induce crystallization. After adding the seed crystals, seal the container opening with plastic wrap, and at the same time, make a number of small holes in the plastic wrap. Place it at a temperature of 5°C and let it stand for 8-24 hours. Then take out the above solution and observe the crystallization.

[0014] Furthermore, in the efficient method for preparing L-borneol crystals from Artemisia as described in this invention, in the crystal collection stage of S5, the specific method for crystal collection is as follows: after the solution in step S4 crystallizes, the solution is first filtered and dried, and then placed in an oven at a temperature of 50°C to evaporate the solvent by drying, thereby obtaining high-purity L-borneol crystals.

[0015] The present invention also provides a levorotatory borneol crystal product, which is prepared by the above-described preparation method.

[0016] The method and product for preparing L-borneol crystals from Artemisia annua as described in this invention have the following advantages compared with the prior art: Supercritical CO2 extraction of Artemisia annua yields a crude extract with a high content of L-borneol. The crude extract is then subjected to paste-water separation. After removing a large amount of chlorophyll and flavonoid pigments using column chromatography, a crude L-borneol product with high purity is obtained. Finally, induced crystallization is used to prepare L-borneol crystals with even higher purity, reaching a purity of 95.65%, thus creating favorable conditions for expanding the application of L-borneol products.

[0017] Therefore, the preparation method described in this invention is simple to operate. After supercritical CO2 extraction, a crude extract with few impurities can be obtained. After purification by column chromatography, induced crystallization is used to obtain Artemisia argyi crystals. This method not only has high preparation efficiency but also stable product quality, which is far superior to traditional preparation methods. It greatly improves the comprehensive utilization rate of resources and has guiding significance for the preparation of L-carnitine products and the improvement of product applications. Attached Figure Description

[0018] The present invention will now be described in further detail with reference to the accompanying drawings.

[0019] Figure 1 This is a process flow diagram of the preparation method described in this invention; Figure 2 This is the GC-MS mass spectrum of levorotatory borneol obtained after crystallization in Example 1 of this invention; Figure 3 This is the GC-MS mass spectrum of levorotatory borneol obtained after crystallization in Example 2 of the present invention; Figure 4 This is the GC-MS mass spectrum of levorotatory borneol obtained after crystallization in Example 3 of the present invention. Detailed Implementation

[0020] The following specific embodiments illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification.

[0021] It should be noted that the term "comprising" or any other variation is intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus. Example 1

[0022] This embodiment provides an efficient method for preparing L-borne borneol crystals from arugula, such as... Figure 1 As shown, the preparation method includes five steps: supercritical CO2 extraction → paste-water separation → impurity removal → crystallization → crystal collection. The supercritical CO2 extraction includes the following steps: raw material crushing, loading, carbon dioxide pump pressurization, separation in separation vessel I, separation in separation vessel II, collection in tail gas buffer tank, and tail gas recovery in intermediate storage tank.

[0023] The oil-water separation is achieved by using an oil-water separator to separate the crude extract of Artemisia argyi obtained from extraction. After oil-water separation, the oil phase is collected.

[0024] The impurity removal is performed by column chromatography elution, mainly to remove a large amount of chlorophyll and flavonoid pigments from the Artemisia annua extract in order to obtain a crude extract of L-borneol.

[0025] The crystallization process involves dissolving the crystals in a solvent and then adding seed crystals to induce crystallization, thereby obtaining crystals with high purity.

[0026] The crystal collection process involves filtering and drying the crystallized solution, and then evaporating the solvent by drying to obtain L-carnitine crystals.

[0027] The specific preparation methods for the above five steps are as follows: The selected Artemisia argyi raw material was first pulverized to 50 mesh and then loaded at a density of 0.2 kg / L. The supercritical CO2 extraction process parameters were as follows: extraction pressure 25 MPa, extraction temperature 38℃; pressure of separation vessel I 8 MPa, temperature 30℃; pressure of separation vessel II 4.5 MPa, temperature 23℃; carbon dioxide flow rate 80 kg / h; extraction time 2 h. Approximately 15 minutes before the end of each extraction, the extraction product was collected at the outlet of the separation vessel, and the products from all separation vessels were combined into a product container.

[0028] Set the jacket heating temperature of the oil-water separator to 50℃, pour in the crude extract of Artemisia argyi, and stop stirring when the material temperature reaches 50℃. Let it stand and heat for more than 5 minutes, then slowly release the lower aqueous phase, continue to keep it warm and stand for more than 10 minutes, and then release the oil phase. At this time, the collected oil phase has almost no water residue.

[0029] An 80ml chromatography column was packed with 80-mesh D101 macroporous resin. The column was soaked in anhydrous ethanol for 24 hours, washed with water until neutral, and the dehydrated supercritical extract of *Artemisia argyi* was collected. This extract was dissolved in anhydrous ethanol at a 1:1 mass ratio and sonicated at 50℃ for 5 minutes. Impurities were then filtered out. The treated sample was then evenly dropped onto the chromatography column and allowed to stand for 30 minutes. Water-soluble impurities and pigments remaining in the resin were eluted with purified water at a flow rate of 1 BV / h using 3 BV (3 times the volume of purified water to the stationary phase). The eluent was collected and then eluted with 1 BV / h of 80% ethanol at a flow rate of 5 BV (5 times the volume of ethanol to the stationary phase). The eluent was collected in fractions, and the concentrates were combined. Ethanol was recovered under reduced pressure to obtain the crude L-borneol extract.

[0030] The crude extract of L-borneol was dissolved in 70% ethanol at a mass ratio of 1:1 using ultrasonication at 40°C for 10 minutes. After dissolution, the solution was placed in a 40°C water bath and stabilized for 30 minutes. Then, 1% by weight of the crude extract of L-borneol and 90% pure L-borneol seed crystals were added. The container was sealed with plastic wrap, with a few small holes punched in the wrap, and left to stand at 5°C for 8 hours.

[0031] Take out the above solution and observe the crystallization. After crystallization is complete, filter the solution and dry it. Then place it in an oven at 50°C to evaporate the solvent. After weighing, pure L-carnitine crystals are obtained and can be subjected to gas chromatography-mass spectrometry. Example 2

[0032] This embodiment provides an efficient method for preparing L-borne borneol crystals from Artemisia annua. The preparation process is the same as in Example 1, except that in the five implementation steps, firstly, a tail gas buffer tank is used for collection, and secondly, the dosage and process parameters are different. The specific preparation method is as follows: The selected Artemisia argyi raw material was first pulverized to 60 mesh and then loaded at a density of 0.3 kg / L. The supercritical CO2 extraction process parameters were as follows: extraction pressure 30 MPa, extraction temperature 40℃; separation vessel I pressure 9 MPa, temperature 30℃; separation vessel II pressure 4.5 MPa, temperature 23℃; carbon dioxide flow rate 100 kg / h, extraction time 2 h. During each extraction, any Artemisia argyi extract not completely separated in the separation vessel was collected in a tail gas buffer tank. During collection, the tail gas buffer tank pressure was controlled at 2 MPa and the temperature at 10℃. After extraction, the Artemisia argyi crude extract was separated in the tail gas buffer tank, with the tail gas buffer tank pressure controlled at 0 MPa and the temperature at 40℃. All separated products were then combined in a product container.

[0033] Set the jacket heating temperature of the oil-water separator to 50℃, pour in the crude extract of Artemisia argyi, and stop stirring when the material temperature reaches 50℃. Let it stand and heat for more than 5 minutes, then slowly release the lower aqueous phase, continue to keep it warm and stand for more than 10 minutes, and then release the oil phase. At this time, the collected oil phase has almost no water residue.

[0034] An 80ml chromatography column was packed with 90-mesh D101 macroporous resin. The column was soaked in anhydrous ethanol for 24 hours, washed with water until neutral, and the dehydrated supercritical extract of *Artemisia annua* was dissolved in anhydrous ethanol at a 1:1 mass ratio. The extract was then sonicated at 50℃ for 5 minutes, followed by filtration to remove impurities. The treated sample was then evenly dropped onto the chromatography column and allowed to stand for 30 minutes. Water-soluble impurities and pigments remaining in the resin were eluted with purified water at a flow rate of 1.5 BV / h using 4 BV (four times the volume of purified water to the stationary phase). The eluent was collected and then eluted with 85% ethanol at a flow rate of 1.5 BV / h using 6 BV (six times the volume of ethanol to the stationary phase). The eluent was collected in fractions, and the concentrates were combined. Ethanol was recovered under reduced pressure to obtain a crude L-borneol extract.

[0035] The crude extract of L-borneol was dissolved in 80% ethanol at a mass ratio of 1:2 using ultrasonication at 40℃ for 10 minutes. After dissolution, the solution was placed in a 40℃ water bath and stabilized for 30 minutes. Then, 1.5% by weight of the crude extract of L-borneol, with a purity of 90%, was added. The container was sealed with plastic wrap, with a few small holes punched in the wrap, and left to stand at 5℃ for 18 hours.

[0036] Take out the above solution and observe the crystallization. After crystallization is complete, filter the solution and dry it. Then place it in an oven at 50°C to evaporate the solvent. After weighing, pure L-carnitine crystals are obtained and can be subjected to gas chromatography-mass spectrometry. Example 3

[0037] This embodiment provides an efficient method for preparing L-borne borneol crystals from Artemisia annua. The preparation process is the same as in Example 1, except that in the five implementation steps, firstly, a tail gas buffer tank is used for collection, and secondly, the dosage and process parameters are different. The specific preparation method is as follows: The selected Artemisia argyi raw material was first pulverized to 80 mesh and then loaded at a density of 0.35 kg / L. The supercritical CO2 extraction process parameters were as follows: extraction pressure 38 MPa, extraction temperature 45℃; separation vessel I pressure 10 MPa, temperature 35℃; separation vessel II pressure 5 MPa, temperature 25℃; carbon dioxide flow rate 90 kg / h, extraction time 3 h. During each extraction, any Artemisia argyi extract not completely separated in the separation vessel was collected in a tail gas buffer tank. During collection, the pressure in the tail gas buffer tank was controlled at 1 MPa and the temperature at 8℃. After extraction, the Artemisia argyi crude extract was separated in the tail gas buffer tank, with the pressure controlled at 0 MPa and the temperature at 50℃. All separated products were then combined in a product container.

[0038] Set the jacket heating temperature of the oil-water separator to 50℃, pour in the crude extract of Artemisia argyi, and stop stirring when the material temperature reaches 50℃. Let it stand and heat for more than 5 minutes, slowly release the lower water phase, continue to keep it warm and stand for more than 10 minutes, and then release the oil phase. At this time, the collected oil phase has basically no water residue.

[0039] A 100ml chromatography column was packed with 100-mesh D101 macroporous resin. The column was soaked in anhydrous ethanol for 24 hours, washed with water until neutral, and the dehydrated supercritical extract of *Artemisia annua* was dissolved in anhydrous ethanol at a 1:1 mass ratio. The extract was then sonicated at 50℃ for 5 minutes, followed by filtration to remove impurities. The treated sample was then evenly dropped onto the chromatography column and allowed to stand for 30 minutes. Water-soluble impurities and pigments remaining in the resin were eluted with purified water at a flow rate of 2BV / h using 5BV (5 times the volume of purified water to the stationary phase). The eluent was collected and then eluted with 90% ethanol at a flow rate of 2BV / h using 8BV (8 times the volume of ethanol to the stationary phase). The eluent was collected in fractions, and the concentrates were combined. Ethanol was recovered under reduced pressure to obtain the crude L-borneol extract.

[0040] The crude extract of L-borneol was dissolved in 85% ethanol at a mass ratio of 1:4 using ultrasonication at 40°C for 10 minutes. After dissolution, the solution was placed in a 40°C water bath and stabilized for 30 minutes. Then, 2% by weight of the crude extract of L-borneol (90% purity) was added. The container was sealed with plastic wrap, with a few small holes punched in the wrap, and left to stand at 5°C for 20 hours.

[0041] Take out the above solution and observe the crystallization. After crystallization is complete, filter the solution and dry it. Then place it in an oven at 50°C to evaporate the solvent. After weighing, pure L-carnitine crystals are obtained and can be subjected to gas chromatography-mass spectrometry.

[0042] To illustrate the GC-MS percentage content of L-carnitine obtained by the preparation method described in this invention, the GC-MS percentage content of L-carnitine obtained by the preparation method described in Examples 1 to 3 at three different stages—after supercritical extraction, after column chromatography elution to remove impurities, and after crystallization—was determined. Table 1 shows the detection results after supercritical extraction, Table 2 shows the detection results after column chromatography elution to remove impurities, and Table 3 shows the detection results after crystallization. The specific detection results are shown in Tables 1 to 3.

[0043] Table 1. Percentage content of levorotatory borneol after supercritical extraction by GC-MS

[0044] Table 2. Percentage content of levorotatory borneol after impurity removal by column chromatography GC-MS

[0045] Table 3. Percentage content of levorotatory borneol after crystallization (GC-MS)

[0046] As can be seen from the results in Tables 1 to 3, the L-borneol crystal product obtained by the preparation method described in this invention uses Artemisia argyi as raw material. Through supercritical extraction, column chromatography elution and induced crystallization, impurities can be effectively reduced. The content of L-borneol gradually increases, indicating that its purity is getting higher and higher, thus obtaining a high-purity L-borneol crystal product.

[0047] In addition, to illustrate the purity of the levorotatory borneol obtained using the preparation method described in this invention, the levorotatory borneol crystal products obtained by the preparation methods described in Examples 1 to 3 were subjected to gas chromatography-mass spectrometry (GC-MS) analysis. The specific test results are as follows: Figures 2 to 4 As shown in the gas chromatography-mass spectrometry results, the L-carnitine crystal product obtained by the preparation method described in this invention can not only effectively reduce impurities, but also greatly improve the purity of the product.

[0048] Therefore, the preparation method described in this invention, which uses supercritical CO2 extraction of Artemisia annua, can yield a crude extract of L-borneol with a high content. The crude extract is then subjected to extract-water separation, and after removing a large amount of chlorophyll and flavonoid pigments using column chromatography, a crude L-borneol product with high purity can be obtained. Finally, through induced crystallization, L-borneol crystals with even higher purity can be prepared, achieving a crystal purity of 96.43%, thus creating favorable conditions for expanding the application of L-borneol products.

[0049] In summary, the product prepared by the method described in this invention is simple to operate. After supercritical CO2 extraction, a crude extract with few impurities can be obtained. After purification by column chromatography, induced crystallization is used to obtain Artemisia argyi crystals. This method not only has high preparation efficiency but also stable product quality, which is far superior to traditional preparation methods. It greatly improves the comprehensive utilization rate of resources and has guiding significance for the preparation of L-carnitine products and the improvement of their applications.

[0050] Other aspects of this invention that are not detailed herein are all conventional techniques known to those skilled in the art.

[0051] The scope of protection of this invention is not limited to the technical solutions disclosed in the specific embodiments. The above description is only a preferred embodiment of this invention and does not limit this invention. Any minor modifications, equivalent substitutions and improvements made based on the technical solutions of this invention should be included within the scope of protection of the technical solutions of this invention.

Claims

1. A highly efficient method for preparing L-borneol crystals from Artemisia annua, characterized in that, The method includes the following steps: S1. Supercritical CO2 extraction: Using Artemisia as raw material, supercritical CO2 extraction is used to extract Artemisia to obtain a crude extract containing L-borneol; S2. Extract-water separation: The crude extract obtained in step S1 is subjected to extract-water separation, and the separated aqueous phase and oil phase are collected separately; S3. Impurity removal: The oil phase obtained in step S2 is subjected to impurity removal by column chromatography elution in order to remove water-soluble impurities and pigments from the Artemisia annua extract. After impurity removal, crude L-borneol is obtained. S4. Crystallization treatment: The crude levorotatory borneol obtained in step S3 is dissolved, seed crystals are added to the solution, and crystallization is carried out by induced crystallization to obtain a crystallization solution; S5. Crystal collection: After crystallization, the solution obtained in step S4 is filtered and dried to obtain high-purity L-carnitine crystals.

2. The method for preparing L-borne borneol crystals from Artemisia as described in claim 1, characterized in that: The S1 supercritical CO2 extraction stage includes the following steps: raw material crushing, loading, carbon dioxide pump pressurization, separation in separation vessel I, separation in separation vessel II, collection in tail gas buffer tank, and tail gas recovery in intermediate storage tank.

3. The method for preparing L-borne borneol crystals from Artemisia as described in claim 2, characterized in that: In the S1 supercritical CO2 extraction stage, the specific extraction process includes the following steps: S11. Raw material pretreatment: First, crush the Artemisia argyi raw material into 50-80 mesh, and then load it into the extraction vessel at a loading density of 0.2-0.4 kg / L. S12. Supercritical CO2 Extraction: Supercritical CO2 dynamic extraction is carried out in an extraction vessel using a carbon dioxide pump at an extraction pressure of 20–40 MPa and a temperature of 38–45℃. When separation is carried out in separation vessel I, the pressure is controlled at 8–10 MPa and the temperature at 30–40℃; when separation is carried out in separation vessel II, the pressure is controlled at 4–5 MPa and the temperature at 20–30℃. Throughout the entire supercritical CO2 extraction process, the carbon dioxide flow rate is controlled at 80–120 kg / h and the extraction time is 2–3 h. S13. Collection of crude extract of Artemisia argyi: If Artemisia argyi extract is not completely separated in the separation vessel during each extraction using the extraction vessel, the crude extract of Artemisia argyi is collected in the tail gas buffer tank. During collection, the pressure of the tail gas buffer tank is controlled at 1-2 MPa and the temperature at 8-10℃. After extraction, the crude extract of Artemisia argyi is separated in the tail gas buffer tank, and the pressure of the tail gas buffer tank is controlled at 0 MPa and the temperature at 40-50℃.

4. The method for preparing L-borne borneol crystals from Artemisia as described in claim 3, characterized in that: During the collection of the crude extract of S3 Artemisia annua, the tail gas buffer tank is equipped with a coil. During collection, it is necessary to connect a condensate circulation system or add a refrigeration unit for cooling to cool the carbon dioxide coming out of the separation vessel. At the same time, the connection position of the tail gas buffer tank is at the outlet end of the precooler and at the inlet end of the intermediate storage tank. The energy consumption for reducing the carbon dioxide to the tail gas buffer tank at the connection position is the lowest. After the temperature and pressure decrease, the solubility of carbon dioxide decreases accordingly, thereby achieving the best desorption and separation effect.

5. The method for preparing L-borne borneol crystals from Artemisia as described in claim 1, characterized in that: In the S2 paste-water separation stage, the specific paste-water separation method is as follows: the crude extract of Artemisia argyi obtained by extraction is separated using an oil-water separator. After controlling the jacket heating temperature in the oil-water separator to 50-60°C, the collected crude extract of Artemisia argyi is poured in and stirred using a stirring device until the material temperature reaches 50-60°C. Then, stirring is stopped, and the mixture is allowed to stand for 5-10 minutes. After that, the lower aqueous phase is slowly released and collected in a water tank. After continuing to keep it warm and stand for 10-20 minutes, the oil phase is released. At this time, the oil phase without water residue is collected, which yields the supercritical extract paste.

6. The method for preparing L-borne borneol crystals from Artemisia as described in claim 1, characterized in that: The specific operation method in the S3 impurity removal stage includes the following steps: S31. Raw material processing: Take the supercritical extract paste of Artemisia argyi after water removal, dissolve it in anhydrous ethanol at a mass ratio of 1:1 and perform ultrasonic treatment. Control the ultrasonic temperature at 50-60℃ and the ultrasonic time at 5-10 min, then filter out the impurities. S32. Column packing: Select 80-100 mesh D101 macroporous resin to pack 50-100 ml of chromatography column, soak in anhydrous ethanol for 24 h, wash with water until neutral, and then pack the column using the wet method. S33. Sample loading and adsorption: The treated solution is evenly dropped onto the chromatography column and waited for 30-60 minutes; S34. Cleaning: First, use pure water to wash away the water-soluble impurities and pigments remaining in the resin. Then, use 3-5 BV of pure water at a flow rate of 1-2 BV / h to rinse and collect the eluent. S35. Elution and Collection: Elute with 5-8 BV of 85-95% ethanol at a flow rate of 1-2 BV / h, collect the eluent in fractions, combine the concentrates, and recover the ethanol under reduced pressure to obtain the crude extract of L-borneol.

7. The efficient method for preparing L-borneol crystals from Artemisia as described in claim 1, characterized in that: In the S4 crystallization process, ethanol is selected as the crystallization solvent, the mass ratio of solvent to solute is 1:1 to 5, and the solvent concentration is 70 to 90%. During crystallization, a seed crystal is added to induce crystallization. The seed crystal is a 90 to 99% pure L-carnitine crystal, and the amount added is 1 to 3% of the mass of the solute.

8. The efficient method for preparing L-borneol crystals from Artemisia as described in claim 6, characterized in that, The specific steps of the crystallization process are as follows: S41. Dissolution: Weigh the sample and solvent at a mass ratio of 1:2 to 4, mix them, and then perform ultrasonic dissolution. Control the ultrasonic temperature at 40°C and the ultrasonic time at 10 to 30 minutes. After dissolution, place the solution in a water bath at 40°C for stabilization for 30 minutes. The solvent used is ethanol with a concentration of 80 to 90%. S42. Induced crystallization: Take out the above solution, add 1-2% of solute by mass of levorotatory borneol as seed crystals, and induce crystallization. After adding the seed crystals, seal the container opening with plastic wrap, and at the same time, make a number of small holes in the plastic wrap. Place it at a temperature of 5°C and let it stand for 8-24 hours. Then take out the above solution and observe the crystallization.

9. The efficient method for preparing L-borneol crystals from Artemisia as described in claim 7, characterized in that, In the S5 crystal collection stage, the specific method of crystal collection is as follows: after the solution in step S4 crystallizes, the solution is first filtered and dried, and then placed in an oven at a temperature of 50°C to evaporate the solvent by drying, thereby obtaining high-purity L-carnitine crystals.

10. A L-carnitine crystal product, characterized in that: The product is prepared by the method described in any one of claims 1 to 8.

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