A method for purifying vitamin E

Abstract

The present invention discloses a method for purifying vitamin E, relating to the field of bioengineering technology. The method comprises the following steps: extracting raw vitamin E with solvent 1 and filtering to obtain a filter cake; mixing the filter cake, solvent 2, and silica gel to obtain a mixture; applying the mixture to a silica gel column, eluting with an eluent, and concentrating to obtain a crude vitamin E product; and mixing the crude vitamin E product with solvent 3, heating, cooling, and collecting the vitamin E layer to obtain purified vitamin E. The vitamin E purification method of the present invention is simpler, has higher product purity and yield, and has high process stability and good reproducibility.

Description

Technical Field

[0001] The present invention relates to the technical field of bioengineering, in particular to a method for purifying vitamin E, and further to a method for separating and purifying vitamin E from vitamin E powder. Background Art

[0002] Vitamin E (VE) is a fat-soluble vitamin and one of the most important antioxidants. It promotes reproduction and sex hormone secretion, increasing sperm motility and count in men; it increases estrogen levels in women, improving fertility and preventing miscarriage. It also slows aging, effectively reduces wrinkles, and maintains a youthful appearance. Vitamin E is a valuable vasodilator and anticoagulant, useful for preventing and treating varicose veins, preventing blood clotting, and reducing the appearance of streaky tissue.

[0003] Other functions of vitamin E include protecting T lymphocytes and red blood cells, resisting free radical oxidation, and inhibiting platelet aggregation, thereby reducing the risk of myocardial infarction and cerebral infarction. In addition, it has a good therapeutic effect on burns, frostbite, capillary bleeding, menopausal syndrome, and beauty.

[0004] Chinese patent CN105585552A discloses a method for decolorizing and purifying vitamin E, comprising the following steps: (a) providing a composite decolorizing agent to decolorize a vitamin E product; (b) eluting the decolorized vitamin E product obtained in step (a) with an eluent by column chromatography, collecting the eluate fraction; and (c) concentrating the eluate fraction obtained in step (b) to obtain decolorized and purified vitamin E. In step (a), the composite decolorizing agent comprises activated clay: activated carbon: diatomaceous earth: magnesium silicate in a ratio of 100:50-100:30-70:10-50, calculated by mass. The vitamin E decolorization and purification method of the invention can lighten the color of vitamin E, reduce viscosity, improve fluidity, and improve the purity of vitamin E. Furthermore, the decolorization and purification process has low loss and a high vitamin E recovery rate.

[0005] Chinese patent CN102584769A discloses a method for preparing natural vitamin E with a content of 99% or more. The method involves dissolving 40% natural vitamin E in a certain proportion with 99% ethanol, cooling the mixture to approximately 15°C, and filtering to remove ethanol-insoluble matter. A secondary adsorption process is then employed, first using a macroporous adsorption resin to adsorb acidic impurities and pigments. The effluent is then adsorbed with an anionic strong base resin to remove natural vitamin E. The anionic strong base resin is then washed with 99% ethanol to remove impurities such as unadsorbed methyl esters. The vitamin E is then removed with a stripping agent, and the eluate is cooled to a certain temperature and filtered through a microporous filter to remove ethanol-insoluble matter. A specific stripping agent is added to remove polycyclic aromatic hydrocarbons and adsorb other impurities. After filtering to remove the stripping agent, the mixture is concentrated, desolvated, and finally refined by three-stage molecular distillation. This invention provides a method for preparing a natural vitamin E containing 99% or more natural vitamin E, achieving a product with a content and purity that meets the quality requirements of EU countries.

[0006] At present, the purification of vitamin E is generally cumbersome and complex, and a simpler and more efficient purification process is needed. Summary of the Invention

[0007] The purpose of the present invention is to provide a method for purifying vitamin E, which can separate and purify vitamin E from vitamin E powder, has high yield and high purity, and is simple to operate.

[0008] In order to achieve the above-mentioned purpose of the invention, the technical solution of the present invention is as follows:

[0009] A method for purifying vitamin E comprises the following steps:

[0010] (1) extracting the raw vitamin E with solvent 1 and filtering to obtain a filter cake;

[0011] (2) mixing the filter cake obtained in step (1), solvent 2, and silica gel to obtain a mixture;

[0012] (3) applying the mixture obtained in step (2) to a silica gel column, eluting with an eluent, and concentrating to obtain crude vitamin E;

[0013] (4) Mixing the crude vitamin E obtained in step (3) with solvent 3, heating, cooling, and taking the vitamin E layer to obtain purified vitamin E.

[0014] Wherein, the solvent 1, solvent 2 and solvent 3 are organic solvents, and the eluent is at least one of petroleum ether, ethyl acetate, dichloromethane and ethanol.

[0015] Preferably, the solvent 1 is at least one of methanol, petroleum ether, ethyl acetate, dichloromethane, ethanol, n-butanol, and acetone, more preferably at least one of methanol, petroleum ether, ethyl acetate, dichloromethane, and ethanol, and most preferably methanol.

[0016] Preferably, in step (1), the extraction conditions are: the ratio of solvent 1 to raw vitamin E is 4-10:1, L:kg, 1-3 extractions, each extraction time is 1-3 hours, and the extraction temperature is 40-80°C. More preferably, the ratio of solvent 1 to raw vitamin E is 5:1, L:kg, 2 extractions, each extraction time is 1 hour, and the extraction temperature is 50°C.

[0017] Preferably, in step (1), the filtering condition is: cooling to -10 to 10°C and filtering.

[0018] Preferably, the solvent 2 is at least one of petroleum ether, ethyl acetate, dichloromethane, ethanol, n-butanol, and acetone; more preferably, it is at least one of petroleum ether, ethyl acetate, dichloromethane, and ethanol, and most preferably, it is ethanol.

[0019] Preferably, in step (2), the mass ratio of the filter cake to the silica gel is 1-2:1-2, more preferably 1:1.

[0020] Preferably, in step (2), the mesh size of the silica gel is 100-300 mesh, more preferably 200-300 mesh.

[0021] Preferably, in step (3), the mesh size of the silica gel is 100-300 mesh, more preferably 100-200 mesh.

[0022] Preferably, in step (3), the weight ratio of the amount of silica gel to the filter cake is 5-12:1, more preferably 8:1.

[0023] Preferably, the eluent is a mixed solvent of petroleum ether and ethyl acetate. Further preferably, the volume ratio of petroleum ether to ethyl acetate is 1:3-10, and further preferably is 1:6.

[0024] Preferably, in step (3), the elution conditions are: flow rate 1-10V 柱体积 / h, elution volume is 1-5 times V 柱体积 , further preferably: flow rate 3V 柱体积 / h, elution volume 1.5-2 times V 柱体积 .

[0025] Preferably, in step (3), the concentration is concentration to a constant weight.

[0026] Preferably, in step (3), the concentration temperature is 30-70°C, more preferably 50°C.

[0027] Preferably, the solvent 3 is an ethanol aqueous solution, more preferably an ethanol aqueous solution with a volume fraction of 70-90%, and more preferably an ethanol aqueous solution with a volume fraction of 80%.

[0028] Preferably, in step (4), the mass ratio of the solvent 3 to the crude vitamin E is 1-5:1, more preferably 3:1.

[0029] Preferably, in step (4), the heating temperature is 40-80° C., and the heating time is 0.5-2 h. More preferably, the heating temperature is 60° C., and the heating time is 60 min.

[0030] Preferably, in step (4), the cooling temperature is -10 to 10°C, more preferably 0°C.

[0031] Preferably, in step (4), the concentration temperature is 30-70°C, more preferably 60°C.

[0032] The beneficial effects of the present invention are:

[0033] The vitamin E purification method of the present invention is simpler and more convenient. By selecting a process and specific solvents and conditions, the obtained vitamin E product has higher purity and higher yield, and the process is highly stable and has good repeatability. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 It is the chromatogram of vitamin E reference substance of the present invention.

[0035] Figure 2 This is a chromatogram of the purified vitamin E product in Example 1 of the present invention. DETAILED DESCRIPTION

[0036] Terms and Claims of the Present Invention:

[0037] 1. The articles "a", "an" and "the" include plural referents unless expressly limited to one or more referents otherwise.

[0038] 2. Numerical ranges: Unless expressly stated otherwise, all ranges or ratios disclosed herein are to be understood to include any and all subranges or subratios contained therein. For example, a range or ratio stated as 1 to 30 is to be considered inclusive of any and all subranges or subratios, integers, decimals, or subranges or subratios comprised therein, between a minimum of 1 and a maximum of 30, including any subranges or subratios, integers, decimals, or subranges or subratios comprised therein.

[0039] The following non-limiting examples are provided to enable those skilled in the art to more fully understand the present invention, but are not intended to limit the present invention in any way. The following is merely an illustrative description of the scope of the present invention, and those skilled in the art may make various changes and modifications to the present invention based on the disclosed content, which should also fall within the scope of protection claimed in this application.

[0040] The present invention will be further described below by way of specific examples. The various chemical reagents used in the examples of the present invention were obtained through conventional commercial channels unless otherwise specified. Unless otherwise specified, the contents described below are all by weight. Unless otherwise specified, it is understood that the experiments were conducted at room temperature.

[0041] In the following examples, vitamin E powder was purchased from Zhengzhou Zhengyan Biotechnology Co., Ltd. with the product number 202401112.

[0042] Example 1

[0043] (1) Weigh 10 kg of 50% pure vitamin E powder and extract it twice with 50 L of methanol, each extraction temperature at 50°C for 1 hour. Combine the two extracts; cool the extract to 5°C and filter to obtain a filter cake.

[0044] (2) 6.5 kg of the filter cake was obtained, dissolved in 6.5 L of ethanol, mixed with 6.5 kg of 200-300 mesh silica gel, and stirred to obtain a mixture;

[0045] (3) Weigh 52 kg of 100-200 mesh silica gel to pack the column, compact it, and elute it with a mixture of petroleum ether and ethyl acetate (volume ratio 1:6) at a flow rate of 3V. 柱体积 / h, elution volume 1.5 times V 柱体积 , collect the eluate containing vitamin E, concentrate at 50°C to obtain 5.5 kg of crude vitamin E;

[0046] (4) The crude vitamin E product was mixed with 3 times the mass of 80% ethanol, heated at 60°C for 60 min, cooled to 0°C, separated into layers, and the vitamin E layer was concentrated at 60°C to obtain 4.75 kg of vitamin E product.

[0047] Example 2

[0048] (1) Weigh 100 kg of 50% pure vitamin E powder and extract it twice with 500 L of methanol, each extraction temperature at 50°C for 1 hour. Combine the two extracts; cool the extract to 5°C and filter to obtain a filter cake.

[0049] (2) 66.2 kg of the filter cake was obtained, dissolved in 65 L of ethanol, mixed with 66 kg of 200-300 mesh silica gel, and stirred to obtain a mixture;

[0050] (3) Weigh 530 kg of 100-200 mesh silica gel to pack the column, compact it, and elute it with a mixture of petroleum ether and ethyl acetate (volume ratio 1:6) at a flow rate of 1 V. 柱体积 / h, elution volume 2 times V 柱体积 , collect the eluate containing vitamin E, concentrate at 50°C to obtain 54.8 kg of crude vitamin E;

[0051] (4) The crude vitamin E product was mixed with 1 times the mass of 80% ethanol, heated at 60°C for 60 min, cooled to 0°C, separated into the vitamin E layer, and then concentrated at 60°C to obtain 47.6 kg of vitamin E product.

[0052] Example 3

[0053] (1) Weigh 500 kg of 50% pure vitamin E powder and extract it twice with 2500 L of methanol, each extraction temperature at 50°C for 1 hour. Combine the two extracts; cool the extract to 5°C and filter to obtain a filter cake;

[0054] (2) 325 kg of the filter cake was obtained, dissolved in 325 L of ethanol, mixed with 325 kg of 200-300 mesh silica gel, and stirred to obtain a mixture;

[0055] (3) Weigh 2600 kg of 100-200 mesh silica gel and pack it into the column, compact it, and elute it with a mixture of petroleum ether and ethyl acetate (volume ratio 1:6) at a flow rate of 3V. 柱体积 / h, elution volume 1.5 times V 柱体积 , collect the eluate containing vitamin E, concentrate at 50°C to obtain 276.5 kg of crude vitamin E;

[0056] (4) The crude vitamin E product was mixed with 5 times the mass of 80% ethanol, heated at 60°C for 60 min, cooled to 0°C, separated into layers, and the vitamin E layer was concentrated at 60°C to obtain 235.5 kg of vitamin E product.

[0057] Example 4

[0058] (1) Weigh 10 kg of 50% pure vitamin E powder and extract it twice with 50 L of methanol, each extraction temperature at 50°C for 1 hour. Combine the two extracts; cool the extract to 5°C and filter to obtain a filter cake.

[0059] (2) 6.4 kg of the filter cake was obtained, dissolved in 6.4 L of dichloromethane, mixed with 6.4 kg of 200-300 mesh silica gel, and stirred to obtain a mixture;

[0060] (3) Weigh 51.2 kg of 100-200 mesh silica gel to pack the column, compact it, and elute it with a mixture of petroleum ether and ethyl acetate (volume ratio 1:6) at a flow rate of 3V. 柱体积 / h, elution volume 1.5 times V 柱体积 , collect the eluate containing vitamin E, concentrate at 50°C to obtain 5.8 kg of crude vitamin E;

[0061] (4) The crude vitamin E product was mixed with 3 times the mass of 70% ethanol, heated at 60°C for 60 min, cooled to 0°C, separated into layers, and the vitamin E layer was concentrated at 60°C to obtain 4.53 kg of vitamin E product.

[0062] Example 5

[0063] (1) Weigh 10 kg of 50% pure vitamin E powder and extract it twice with 50 L of ethyl acetate, each extraction temperature at 50°C for 1 hour. Combine the two extracts; cool the extract to 5°C and filter to obtain a filter cake.

[0064] (2) 7.1 kg of filter cake was obtained, dissolved in 7.1 L of petroleum ether, mixed with 7.1 kg of 200-300 mesh silica gel, and stirred to obtain a mixture;

[0065] (3) Weigh 56.8 kg of 100-200 mesh silica gel to pack the column, compact it, and elute it with a mixture of petroleum ether and ethyl acetate (volume ratio 1:10) at a flow rate of 3V. 柱体积 / h, elution volume 1.5 times V 柱体积 , collect the eluate containing vitamin E, concentrate at 50°C to obtain 5.1 kg of crude vitamin E;

[0066] (4) The crude vitamin E product was mixed with 3 times the mass of 70% ethanol, heated at 60°C for 60 min, cooled to 0°C, separated into the vitamin E layer, and then concentrated at 60°C to obtain 4.67 kg of vitamin E product.

[0067] Comparative Example 1

[0068] (1) Weigh 10 kg of 50% pure vitamin E powder and extract it once with 50 L of methanol at 30°C for 1 hour. Cool the extract to 5°C and filter to obtain a filter cake.

[0069] (2) 4.5 kg of the filter cake was obtained, dissolved in 4.5 L of methanol, mixed with 4.5 kg of 200-300 mesh silica gel, and stirred to obtain a mixture;

[0070] (3) Weigh 36 kg of 100-200 mesh silica gel to pack the column, compact it, and elute it with a mixture of petroleum ether and ethyl acetate (volume ratio 1:6) at a flow rate of 3V. 柱体积 / h, elution volume 1.5 times V 柱体积 , collect the eluate containing vitamin E, concentrate at 50°C to obtain 3.5 kg of crude vitamin E;

[0071] (4) The crude vitamin E product was mixed with 3 times the mass of 80% ethanol, heated at 60°C for 60 min, cooled to 0°C, separated into layers, and the vitamin E layer was concentrated at 60°C to obtain 2.8 kg of vitamin E product.

[0072] Comparative Example 2

[0073] (1) Weigh 10 kg of 50% pure vitamin E powder and extract it five times with 50 L of methanol, each extraction temperature at 40°C for 0.5 h. Combine the two extracts, cool the extract to 5°C, and filter to obtain a filter cake.

[0074] (2) 6.5 kg of the filter cake was obtained, dissolved in 6.5 L of ethanol, mixed with 6.5 kg of 200-300 mesh silica gel, and stirred to obtain a mixture;

[0075] (3) Weigh 20 kg of 100-200 mesh silica gel to pack the column, compact it, and elute it with a mixture of petroleum ether and ethyl acetate (volume ratio 1:6) at a flow rate of 3V. 柱体积 / h, elution volume 1.5 times V 柱体积 , collect the eluate containing vitamin E, concentrate at 50°C to obtain 3.5 kg of crude vitamin E;

[0076] (4) The crude vitamin E product was mixed with 3 times the mass of 80% ethanol, heated at 60°C for 60 min, cooled to 0°C, separated into the vitamin E layer, and then concentrated at 60°C to obtain 3.42 kg of vitamin E product.

[0077] Comparative Example 3

[0078] (1) Weigh 10 kg of 50% pure vitamin E powder and extract it twice with 50 L of n-butanol, each extraction temperature at 50°C for 1 hour. Combine the two extracts; cool the extract to 5°C and filter to obtain a filter cake.

[0079] (2) 5.5 kg of the filter cake was obtained, dissolved in 5.5 L of ethanol, mixed with 5.5 kg of 200-300 mesh silica gel, and stirred to obtain a mixture;

[0080] (3) Weigh 44 kg of 100-200 mesh silica gel to pack the column, compact it, and elute it with a mixture of petroleum ether and ethyl acetate (volume ratio 1:6) at a flow rate of 3V. 柱体积 / h, elution volume 1.5 times V 柱体积 , collect the eluate containing vitamin E, concentrate at 50°C to obtain 4.5 kg of crude vitamin E;

[0081] (4) The crude vitamin E product was mixed with 60% ethanol, heated at 60°C for 60 min, cooled to 0°C, separated into layers, and the vitamin E layer was concentrated at 60°C to obtain 3.95 kg of vitamin E product.

[0082] Comparative Example 4

[0083] (1) Weigh 10 kg of 50% pure vitamin E powder and extract it twice with 50 L of methanol, each extraction temperature at 50°C for 1 hour. Combine the two extracts; cool the extract to 5°C and filter to obtain a filter cake.

[0084] (2) 6.5 kg of the filter cake was obtained, dissolved in 6.5 L of ethanol, mixed with 6.5 kg of 200-300 mesh silica gel, and stirred to obtain a mixture;

[0085] (3) Weigh 52 kg of 100-200 mesh silica gel to pack the column, compact it, and elute it with a mixture of petroleum ether and ethanol in a volume ratio of 1:6 at a flow rate of 3V 柱体积 / h, elution volume 1.5 times V 柱体积 , collect the eluate containing vitamin E, concentrate at 50°C to obtain 4.6 kg of crude vitamin E;

[0086] (4) The crude vitamin E product was mixed with 80% ethanol, heated at 60°C for 60 min, cooled to 0°C, separated into layers, and the vitamin E layer was separated. The layer was then concentrated at 60°C to obtain 4.05 kg of vitamin E product.

[0087] Comparative Example 5

[0088] (1) Weigh 10 kg of 50% pure vitamin E powder and extract it twice with 30 L of methanol, each extraction temperature at 50°C for 1 hour. Combine the two extracts; cool the extract to 5°C and filter to obtain a filter cake.

[0089] (2) 4.5 kg of the filter cake was obtained, dissolved in 4.5 L of ethanol, mixed with 4.5 kg of 200-300 mesh silica gel, and stirred to obtain a mixture;

[0090] (3) Weigh 36 kg of 100-200 mesh silica gel to pack the column, compact it, and elute it with a mixture of petroleum ether and ethyl acetate (volume ratio 1:6) at a flow rate of 3V. 柱体积 / h, elution volume 1.5 times V 柱体积 , collect the eluate containing vitamin E, concentrate at 50°C to obtain 2.9 kg of crude vitamin E;

[0091] (4) The crude vitamin E product was mixed with 80% ethanol, heated at 60°C for 60 min, cooled to 0°C, separated into layers, and the vitamin E layer was concentrated at 60°C to obtain 1.75 kg of vitamin E product.

[0092] Comparative Example 6

[0093] (1) Weigh 10 kg of 50% pure vitamin E powder and extract it twice with 50 L of ethanol, each extraction temperature at 50°C for 1 hour. Combine the two extracts; cool the extract to 5°C and filter to obtain a filter cake.

[0094] (2) 5.6 kg of the filter cake was obtained, dissolved in 5.6 L of methanol, mixed with 5.6 kg of 200-300 mesh silica gel, and stirred to obtain a mixture;

[0095] (3) Weigh 44.8 kg of 100-200 mesh silica gel to pack the column, compact it, and elute it with a mixture of petroleum ether and methanol (volume ratio 1:6) at a flow rate of 3V. 柱体积 / h, elution volume 1.5 times V 柱体积 , collect the eluate containing vitamin E, concentrate at 50°C to obtain 4.5 kg of crude vitamin E;

[0096] (4) The crude vitamin E product was mixed with 80% ethanol, heated at 60°C for 60 min, cooled to 0°C, separated into layers, and the vitamin E layer was concentrated at 60°C to obtain 3.25 kg of vitamin E product.

[0097] Result detection

[0098] Determined according to high performance liquid chromatography (General Rule 0512);

[0099] Chromatographic conditions and system suitability test:

[0100] Column: C18 5μm 150x 4.6mm;

[0101] Chromatographic conditions:

[0102] Mobile phase: methanol-water (volume ratio 98:2);

[0103] Flow rate: 1 mL / min;

[0104] Injection volume: 20 μL;

[0105] Column temperature: 25°C;

[0106] The number of theoretical plates calculated based on peaks should not be less than 2000.

[0107] Preparation of reference solution: Accurately weigh an appropriate amount of vitamin E reference solution and add methanol to make a solution containing 0.1 mg per 1 mL.

[0108] Preparation of test solution: Take 2 parts of vitamin E prepared in each of the above examples and comparative examples (accurately weighed, placed in a stoppered conical flask, accurately add 10 mL of methanol, weigh the weight, sonicate (power 250 W, frequency 25 kHz) for 15 minutes, let cool, weigh again, make up the loss with methanol, shake well, filter, and obtain;

[0109] Determination method: Accurately aspirate 10 μL of reference solution and test solution respectively, inject into liquid chromatograph, and determine.

[0110] The content test results and vitamin E yield results are shown in Table 1 below:

[0111] Table 1

[0112] Sample name content Quality product yield Example 1 99.1％ 95.0％ Example 2 99.5％ 95.2％ Example 3 99.2％ 94.2％ Example 4 99.1％ 90.6％ Example 5 98.9％ 93.4％ Comparative Example 1 98.9％ 56.0％ Comparative Example 2 99.1％ 68.4％ Comparative Example 3 98.12％ 79.5％ Comparative Example 4 97.25％ 81.0％ Comparative Example 5 98.53％ 35.0％ Comparative Example 6 99.12％ 65.0％

[0113] The results show that the determination results are relatively stable, the vitamin E product of the embodiment has high purity, high yield of vitamin E product, high process stability and good repeatability. Comparative Examples 1 and 2 show that the extraction conditions and the amount of silica gel used will significantly affect the yield of fine products. Comparative Examples 3, 4, and 6 show that the type of solvent and eluent has a great influence on both purity and yield. Comparative Example 5 verifies that when the amount of solvent used in step (1) is reduced, the yield will decrease significantly.

[0114] Although the embodiments of the present invention have been disclosed above, they are not limited to the applications listed in the description and implementation methods. They can be fully applied to various fields suitable for the present invention. For those familiar with the art, additional modifications can be easily implemented. Therefore, without departing from the general concept defined by the claims and the scope of equivalents, the present invention is not limited to specific details.

Claims

1. A method for purifying vitamin E, characterized in that: The following steps are involved: (1) extracting the raw vitamin E with solvent 1 and filtering to obtain a filter cake; (2) mixing the filter cake obtained in step (1), solvent 2, and silica gel to obtain a mixture; (3) The mixture obtained in step (2) is applied to a silica gel column, eluted with an eluent, and concentrated to obtain crude vitamin E; (4) Mixing the crude vitamin E obtained in step (3) with solvent 3, heating, cooling, and taking the vitamin E layer to obtain purified vitamin E. Wherein, the eluent is petroleum ether and ethyl acetate in a volume ratio of 1:3-10; The solvent 1 is methanol; The solvent 2 is at least one of petroleum ether, ethyl acetate, dichloromethane, and ethanol; The solvent 3 is an ethanol aqueous solution with a volume fraction of 70-90%; The extraction conditions are as follows: the ratio of the amount of the solvent to the vitamin is 4-5, L:kg, the extraction is performed 2-3 times, the extraction time for each time is 1-3 hours, and the extraction temperature is 50°C.

2. The purification method according to claim 1, wherein In step (1), the method further includes cooling to -10~10°C and filtering.

3. The purification method according to claim 1, wherein In step (2), the mass ratio of the filter cake to the silica gel is 1-2:1-2.

4. The purification method according to claim 1, wherein In step (2), the mesh size of the silica gel is 100-300 mesh; in step (3), the mesh size of the silica gel is 100-300 mesh, and the weight ratio of the silica gel to the filter cake is 5-12:

1.

5. The purification method according to claim 1, wherein In step (3), the elution conditions are: a flow rate of 1-10 V column volumes / h and an elution volume of 1-5 times V column volumes.

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