Method for evaluating purification capacity of purification material from molecular level

Abstract

The invention belongs to the field of purification capacity analysis of purification materials, and particularly relates to a method for evaluating the purification capacity of a purification material from the molecular level. The method comprises the following steps: (1) purifying an extracting solution by using a purifying material; respectively detecting the extracting solution before and after purification by adopting liquid chromatography-high resolution mass spectrometry to obtain mass spectrum response data of set matrix molecule types in the extracting solution before and after purification; and (2) evaluating the purification capability of the purification material on the set matrix molecule type according to the decline degree of the mass spectrum response data before and after purification. According to the invention, the purification effect of the QuEChERS purification material on various matrix interferents can be evaluated from the molecular level from the perspective of actual detection, and the fine evaluation of the purification material on a more subdivided matrix molecule level is realized.

Description

Technical Field

[0001] The invention belongs to the field of purification ability analysis of purification materials, and in particular relates to a method for evaluating the purification ability of purification materials at a molecular level. Background Art

[0002] The QuEChERS (Quick, Easy, Cheap, Effective, Rugged and Safe) method is a new rapid sample pretreatment technology developed by Professor Anastassiades of the United States Department of Agriculture and his collaborators in 2003. It has the advantages of being fast, simple, cheap, safe, reliable and having a high recovery rate. The principle of this method is similar to solid phase extraction. It mainly uses the interaction between the purification material and the impurities in the matrix to adsorb impurities and achieve the purpose of impurity removal and purification. The technology is simple to operate. When conducting sample pretreatment for pesticide residue detection, it mainly includes three steps: (1) extracting residual pesticides using acetonitrile; (2) adding salting-out agents such as anhydrous magnesium sulfate to separate layers; (3) adding purification materials such as ethylenediamine-N-propylsilane silica gel (PSA) to remove impurities. The QuEChERS technology has been widely used in the field of pesticide residue detection due to its advantages such as being fast, simple, cheap, effective, stable and safe. In view of the complex sample matrix and the high number of interferences, the impurity removal and purification steps are becoming increasingly important for the analysis and detection of pesticide residues. This is because impurity removal and purification can remove impurities in the matrix, thereby helping to reduce the detection limit and ensure the accuracy of the test results.

[0003] In the classic QuEChERS method, adsorbents such as ethylenediamine-N-propylsilane silica gel (PSA), octadecylsilane bonded silica gel (C18), and graphitized carbon black (GCB) are often used as purification materials, and a series of new purification materials have been developed subsequently. The evaporation residue weight method is currently widely used to evaluate the purification ability of purification materials for matrix interferences from an overall level. The evaporation residue weight method is to purify the extract (obtained by conventional sample pretreatment), evaporate and dry the extract before and after the purification treatment, and evaluate the purification ability of the purification material for the sample matrix by the difference in the mass of the evaporation residue before and after the purification treatment. The greater the difference in the mass of the evaporation residue, the better the overall purification effect of the purification material. It is not difficult to see from the evaluation process of the above evaporation residue weight method that this method only evaluates the overall purification ability, and it is unknown what specific reasons cause the difference in purification ability of different purification materials.

[0004] It should be noted that it is currently difficult to achieve efficient recovery of multiple residual pesticides simultaneously by relying on existing single purification materials, and different purification materials have different impurity removal effects. Therefore, researchers have tried to use a variety of purification materials in combination in order to obtain better impurity removal effects. The main combinations include PSA+MWCNTs (multi-walled carbon nanotubes), PSA+C18, PSA+GCB, PSA+C18+GCB and PSA+C18+MWCNTs. However, evaluation methods including the above-mentioned evaporation residue weight method cannot clearly explain the interaction between QuEChERS purification materials and matrix molecules, which leads to a certain degree of blindness in the selection and combined use of purification materials, let alone theoretically exploring purification materials that can efficiently remove matrix interferences, and it is impossible to feedback the influence of the structure and surface properties of purification materials on the removal of matrix molecules. Summary of the invention

[0005] The purpose of the present invention is to provide a method for evaluating the purification ability of purification materials at the molecular level, so as to solve the problem that the existing methods cannot explore the interaction between purification materials and matrix molecules and cannot effectively evaluate the purification ability of purification materials for specific types of matrix molecules.

[0006] In order to achieve the above object, the technical solution adopted by the present invention is:

[0007] A method for evaluating the purification ability of a purification material at the molecular level comprises the following steps:

[0008] (1) purifying the extract using a purification material; detecting the extract before and after purification using a liquid chromatography-high resolution mass spectrometer to obtain mass spectrometry response data of set matrix molecule types in the extract before and after purification;

[0009] (2) Evaluating the purification ability of the purification material for the set matrix molecule types according to the degree of decrease in mass spectrometry response data before and after purification.

[0010] The present invention is a pioneering invention, which mainly uses liquid chromatography-high-resolution mass spectrometry to detect the extracts before and after purification, and can achieve the simultaneous rapid collection of target matrix molecules, non-target matrix molecules and unknown matrix molecules. It can evaluate the purification effect of QuEChERS purification materials on various matrix interferents from the molecular level from the perspective of actual detection, and realize the detailed evaluation of purification materials at a more detailed matrix molecule level.

[0011] The above evaluation results of the present invention can be used to explore the interaction relationship between purification materials and matrix molecules, determine the influence of the structure and surface properties of purification materials on the removal of matrix interferents, and provide a scientific basis for the directional construction of efficient QuEChERS purification materials or the establishment of combination strategies.

[0012] Preferably, in step (2), the purification capacity is quantitatively evaluated according to the following formula:

[0013] A=(I B -I A ) / I B ×100%

[0014] In the formula, I B and I A are the mass spectrometry response intensities of the matrix molecules in the extract before and after purification, respectively; the value range of A is 0% to 100%, and the larger the value, the stronger the purification ability.

[0015] Preferably, in step (1) and step (2), the set matrix molecule types include one or more of sugars, amino acids, pigments, and alkaloids, wherein sugars include monosaccharides, disaccharides, etc., amino acids include proline, valine, and asparagine, pigments include lutein and β-carotene, and alkaloids include nicotine and anabasine.

[0016] Preferably, in step (1), the chromatographic conditions of the liquid chromatography-high resolution mass spectrometry are: chromatographic column: Atlantis@T3 column; mobile phase A: 5 mM ammonium acetate solution with 0.1% formic acid, mobile phase B: acetonitrile; gradient elution: 0-1 min, 10%-50% B; 1-5 min, 50% B; 5-16 min, 50%-60% B; 16-25 min, 60%-80% B; 25-30 min, 80%-95% B; 30-40 min, 95% B; 40-40.1 min, 95%-10% B; 40.1-50.1 min, 10% B.

[0017] Further preferably, the mass spectrometry conditions of the liquid chromatography-high resolution mass spectrometry are: ion source: ESI source; scanning mode: positive ion scanning; scanning range: 100-1000 m / z; spray voltage: 5500 V; nebulizing gas pressure: 55 psi; curtain gas pressure: 35 psi; auxiliary gas pressure: 50 psi; ion source temperature: 500°C; cluster fragmentation voltage: 40 V; collision energy diffusion: 15 eV; detection mode: information association acquisition mode.

[0018] Preferably, the extract is used to detect residual pesticides in a sample to be tested; the extract is obtained by extracting the sample to be tested with a solvent. Further preferably, the sample to be tested includes tobacco leaves. More preferably, for every 2g of tobacco leaf sample, 10-15mL of water is first used for infiltration and allowed to stand, then 10-15mL of acetonitrile is used for oscillation extraction, and then a salting-out agent is added for salting-out and stratification, and the resulting supernatant is the extract.

[0019] Preferably, the purification treatment comprises mixing the extract and the purification material and then shaking the mixture, the volume of the extract is 0.5 to 3 mL, and the mass of the purification material is 3 to 300 mg.

[0020] More preferably, the amount of purification material used per milliliter of extract is 10 to 20 mg. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 This is a diagram showing the difference in purification ability of four purification materials for monosaccharides and polysaccharides in the embodiments of the present invention;

[0022] Figure 2 This is a diagram showing the difference in purification ability of four purification materials for nicotine and anabasine in the embodiments of the present invention;

[0023] Figure 3 This is a diagram showing the difference in purification ability of four purification materials for proline, valine and asparagine in the examples of the present invention;

[0024] Figure 4 Graph showing the differences in purification capabilities of four purification materials for lutein and β-carotene in the embodiments of the present invention. DETAILED DESCRIPTION

[0025] The technical concept of the present invention is to examine the relationship between purification materials and matrix molecules at the matrix molecular level, so as to finely characterize the internal mechanism of different purification materials with different purification performances, and realize the purification capacity evaluation at the matrix molecular level. The evaluation results at the molecular level can provide a basis for the combination strategy of different purification materials, for example, to achieve specific purposes by complementing or strengthening the purification capacity of matrix molecules.

[0026] At the same time, the use of liquid chromatography-high-resolution mass spectrometry to detect the extracts before and after purification can enhance the anti-interference ability under complex matrices and achieve rapid collection of target matrix molecules, non-target matrix molecules and unknown matrix molecules at the same time. Under this method, the number of matrix molecules that can be detected is not limited, and the acquired data can be reprocessed and retrospectively analyzed as the research on matrix molecules continues to deepen, so as to achieve comprehensive screening of matrix molecules that affect pesticide residue detection and accurately evaluate the purification ability of QuEChERS purification materials for specific matrix molecules.

[0027] In the above method, the extract can be obtained by conventional pesticide residue detection pre-treatment steps. For example, the extract can be obtained by solvent extraction, salting out and stratification (if necessary). The purified material and the extract are oscillated together, centrifuged, and the obtained supernatant is filtered through a membrane, and the obtained filtrate is the purified extract.

[0028] The high-resolution mass spectrometry in liquid chromatography-high-resolution mass spectrometry can adopt time-of-flight mass spectrometry, orbital trap mass spectrometry, magnetic mass spectrometry, Fourier transform ion cyclotron resonance mass spectrometry, and the full scan mode is adopted for detection, and the secondary mass spectrometry or multi-stage mass spectrometry is collected synchronously.

[0029] The implementation process of the present invention is described in detail below in conjunction with specific embodiments.

[0030] 1. Specific embodiments of the method of evaluating the purification ability of purification materials at the molecular level of the present invention

[0031] Example 1

[0032] The method of evaluating the purification ability of the purification material at the molecular level in this embodiment is specifically described as follows:

[0033] (1) Treat the sample to be tested to obtain an extract.

[0034] Weigh about 2.00g of tobacco dust sample into a 50mL stoppered centrifuge tube, add 10mL of water and shake until the sample is fully soaked, then let it stand for 10min, then add 10mL of acetonitrile and shake at 2000rpm for 2min. After freezing the centrifuge tube at -20℃ for 10min, add 4g of anhydrous magnesium sulfate, 1g of sodium chloride, 1g of sodium citrate and 0.5g of disodium hydrogen citrate in sequence, immediately shake at 2000rpm for 2min, then centrifuge at 5000rpm for 3min, collect the supernatant, which is the tobacco extract before purification.

[0035] This step is a routine pre-treatment operation for pesticide residue detection. Anhydrous magnesium sulfate, sodium chloride, sodium citrate and disodium hydrogen citrate are used as salting-out agents; the centrifuge tube is placed in a -20℃ freezer for 10 minutes for pre-cooling to prevent the subsequent addition of the salting-out agent from causing heat release and causing the extract temperature to be too high.

[0036] (2) Use purification materials to purify the extract.

[0037] Here we use the homemade CZIF purification material as an example. There is no restriction or requirement on the type of purification material. Any purification material with purification ability is suitable for this method. CZIF is a carbon-based adsorption material obtained by high-temperature pyrolysis of MOF materials with zeolite structure. Purification and adsorption are achieved by using its pores and surface properties. The specific operation process is as follows:

[0038] Take 1 mL of the tobacco extract before purification in a 2 mL centrifuge tube, add 10 mg of the purification material CZIF, shake for 2 minutes and then centrifuge, filter the supernatant through a membrane, and the filtrate obtained is the purified tobacco extract.

[0039] (3) The tobacco extract before and after purification was tested by high performance liquid chromatography-quadrupole time-of-flight mass spectrometry. The specific testing method is as follows:

[0040] Chromatographic conditions:

[0041] Chromatographic column: Atlantis@T3 column (150mm×2.1mm×3μm, Waters, USA); column temperature: 40°C; flow rate: 0.2mL / min; injection volume: 10μL; mobile phase A: 0.1% formic acid aqueous solution (containing 5mM ammonium acetate); mobile phase B: acetonitrile; elution gradient: 0-1min, 10%-50% B; 1-5min, 50% B; 5-16min, 50%-60% B; 16-25min, 60%-80% B; 25-30min, 80%-95% B; 30-40min, 95% B; 40-40.1min, 95%-10% B; 40.1-50.1min, 10% B. All "%" involved in the chromatographic conditions are volume percentages.

[0042] Mass spectrometry conditions:

[0043] Ion source: ESI source; scanning mode: positive ion scanning; scanning range: 100-1000 m / z; spray voltage: 5500 V; nebulizer gas pressure: 55 psi; curtain gas pressure: 35 psi; auxiliary gas pressure: 50 psi; ion source temperature: 500 ° C; cluster fragmentation voltage: 40 V; collision energy: 10 eV (collision energy of primary mass spectrometry, MS), 35 eV (collision energy of secondary mass spectrometry, MS / MS); collision energy diffusion: 15 eV; detection mode: information correlation acquisition mode (intensity threshold: 10 cps; m / z range: 10-1000 Da; mass tolerance, 50 mDa; dynamic background subtraction).

[0044] (4) Analyze the degree of decrease in mass spectrometric response data of different matrix molecular types in the extract before and after purification and evaluate the purification ability.

[0045] In this step, the following formula is used to quantitatively evaluate the purification ability of the purification material for different matrix molecular species at the molecular level:

[0046] A=(I B -I A ) / I B ×100%

[0047] In the above formula, I B and I A are the mass spectrometry response intensities of matrix molecules in tobacco extract before and after the purification material is used, respectively. A represents the purification performance, and the value range is 0% to 100%. The larger the value, the stronger the purification ability.

[0048] Through the above-mentioned high performance liquid chromatography-quadrupole time-of-flight mass spectrometry detection process, mass spectrometry response data of different matrix molecular types can be obtained. Different matrix molecular types include sugars, amino acids, pigments and alkaloids. Here, sugars are illustrated by monosaccharides and disaccharides; amino acids and proline, valine and asparagine are illustrated as examples. Pigments are illustrated by lutein and β-carotene. Alkaloids are illustrated by nicotine and anabasine as examples.

[0049] The purification performance evaluation results of the purification material CZIF on the above different matrix molecular types are as follows Figure 1 to Figure 4 shown.

[0050] Example 2

[0051] The method of evaluating the purification ability of the purification material at the molecular level in this embodiment is based on the embodiment 1, and directly performs the same treatment as steps (2) to (4), the only difference being that the purification material CZIF is replaced by PSA in equal amounts.

[0052] Example 3

[0053] The method for evaluating the purification ability of the purification material at the molecular level in this embodiment is based on the method of Example 1, and directly performs the same treatment as steps (2) to (4), with the only difference being that the purification material CZIF is replaced by GCB in equal amounts.

[0054] Example 4

[0055] The method of evaluating the purification ability of the purification material at the molecular level in this embodiment is based on the method of Example 1, and directly performs the same treatment as steps (2) to (4), with the only difference being that the purification material CZIF is replaced by C18 in equal amounts.

[0056] The purification performance evaluation results of the purification materials PSA, GCB, and C18 on the above different matrix molecular types are collected in Figure 1 to Figure 4 shown.

[0057] For carbohydrate matrix molecules, Figure 1 It can be seen that the purification ability of the four purification materials for disaccharides is better than that for monosaccharides; the purification ability of the four purification materials for disaccharides is good, about 86% to 90%, while for monosaccharides, there is no obvious difference in the purification ability of the three traditional purification materials, about 63% to 66%, and the purification ability of CZIF is slightly lower, about 54%.

[0058] For alkaloid matrix molecules, Figure 2It can be seen that the purification abilities of the four purification materials for nicotine and anabasine are average, not exceeding 10% and 26% respectively. Among them, the purification abilities for nicotine are: CZIF>C18>PSA≈GCB; the purification abilities for anabasine are: CZIF>GCB>C18>PSA.

[0059] For amino acid matrix molecules, Figure 3 It can be seen that the purification ability of the four purification materials for proline, valine and asparagine is quite different. According to the matrix molecule: 1) The four purification materials all show good purification ability for proline, about 77% to 92%, which is in line with the trend of CZIF>PSA>C18>GCB; 2) For valine, CZIF has the best purification ability (about 85%), followed by PSA (about 48%), while the purification abilities of GCB and C18 can be ignored; 3) PSA has no obvious purification ability for asparagine, and the purification abilities of the other three purification materials are in line with the trend of CZIF>GCB>C18, and the purification ability of CZIF for asparagine can reach 81%. In terms of purification materials: 1) CZIF has good purification ability for proline, valine and asparagine, and conforms to the rule of proline>valine>asparagine; 2) PSA has no obvious purification ability for asparagine, and its purification ability for proline (89%) is stronger than that for valine (48%); 3) GCB has a weak purification ability for valine (2%), which can be ignored, and its purification ability for proline (77%) is stronger than that for asparagine (23%); 4) C18 has a weak purification ability for valine (5%), which can be ignored, and its purification ability for proline (83%) is stronger than that for asparagine (15%).

[0060] For pigment matrix molecules, Figure 4 It can be seen that the purification ability of the four purification materials for lutein and β-carotene is quite different. According to the matrix molecule: 1) The four purification materials have a certain purification ability for lutein, about 11% to 36%, which is in line with the trend of C18≈GCB>CZIF>PSA; 2) For β-carotene, the four purification materials have a certain purification ability, about 20% to 76%, which is in line with the trend of CZIF>GCB>C18>PSA. According to the purification materials, the purification ability of CZIF, PSA, and GCB for β-carotene is better than that for lutein, while the purification ability of C18 for lutein and β-carotene is equivalent.

[0061] Based on the above detailed evaluation of different purification materials on different matrix molecules, we can provide a basis for the scientific formulation of purification material combination strategies, thereby reducing the blindness of the use of QuEChERS purification materials. Based on the above detailed evaluation results, we can further study the influence of the structure and surface properties of purification materials on the removal of matrix interferences, or guide the directional construction of efficient QuEChERS purification materials.

[0062] In studying the influence of the structure and surface properties of purification materials on the removal of matrix interferences, the following conclusions can be drawn:

[0063] Depend on Figure 2 It can be seen that compared with the three traditional purification materials PSA, GCB and C18, CZIF has slightly better purification performance for nicotine and pseudoequisetine, which is mainly attributed to the electrostatic interaction between the COOH site on the surface of CZIF and the nitrogen-containing groups in nicotine and pseudoequisetine. In addition, CZIF and GCB, which can provide π adsorption, have better purification performance for pseudoequisetine than for nicotine. Through density functional theory simulation of the spatial molecular configuration of nicotine and pseudoequisetine, it can be seen that pseudoequisetine has a higher degree of coplanarity, so it is easier to interact with CZIF and GCB by π-π, which leads to better purification performance of CZIF and GCB for pseudoequisetine; from the electrostatic potential distribution of nicotine and pseudoequisetine, it can also be seen that the steric hindrance of nicotine is greater, which also weakens the π-π effect of CZIF and GCB on nicotine to a certain extent.

[0064] Depend on Figure 3 It can be seen that compared with the three traditional purification materials PSA, GCB and C18, CZIF shows better purification performance for proline, valine and asparagine, and the purification performance for proline is the best, up to 92%. This is mainly attributed to the following two aspects: First, CZIF has a variety of adsorption sites, including the π-π effect of the main carbon material, the electrostatic effect of N doping on the acidic groups of the target, and the electrostatic effect of COOH surface sites on the basic groups of the target; second, proline, valine and asparagine have both acidic groups and basic groups, and the proline molecule has a ring structure, especially there is a five-membered ring between the amino side chain and the carboxyl group, the nitrogen atom on the pyrrole ring is not only combined with a hydrogen atom, but also forms two coplanar π bonds with the two carbon atoms on the ring.

[0065] Depend on Figure 4It can be seen that, on the one hand, the purification ability of the four purification materials for β-carotene generally conforms to the trend of CZIF>GCB>C18>PSA. This is because β-carotene is a linear polyene molecule with a π-π conjugated double bond straight chain structure, which can show a strong π-π conjugation effect. In view of the strong π-π interaction between CZIF and GCB and β-carotene, both can achieve efficient purification of β-carotene, and C18 can achieve a certain degree of purification of β-carotene through its octadecyl group, an effective adsorption site, through non-polar interactions; on the other hand, the purification ability of CZIF and GCB for lutein is significantly weaker than that for β-carotene. This is because compared with β-carotene, the effective conjugation length of lutein is reduced, and the π-π interaction between it and CZIF and GCB is weakened.

[0066] In guiding the directional construction of efficient QuEChERS purification materials:

[0067] The influence of the structure and surface properties of the purification materials listed above on the removal of matrix interferents achieved by the present invention can further guide the directional construction of efficient QuEChERS purification materials. For example, for application scenarios mainly focusing on the purification of β-carotene and lutein, the construction of purification materials should focus on achieving a stronger π-π conjugation effect; for application scenarios mainly focusing on the purification of amino acid matrix molecules with both acidic and basic groups, the construction of purification materials should focus on loading more acidic and basic groups to achieve stronger electrostatic effects; for application scenarios focusing on the purification of multiple types of matrix molecules, the purification materials should be modified with diversified surface functional groups based on similar experiences summarized by the present invention to provide abundant adsorption sites, thereby achieving enhanced removal of a wider range of matrix interferents.

[0068] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for evaluating the purification ability of a purification material at the molecular level, characterized in that: The following steps are involved: (1) purifying the extract using a purification material; detecting the extract before and after purification using a liquid chromatography-high resolution mass spectrometer to obtain mass spectrometry response data of set matrix molecule types in the extract before and after purification; (2) Evaluating the purification ability of the purification material for the set matrix molecule types according to the degree of decrease in mass spectrometry response data before and after purification.

2. The method for evaluating the purification ability of a purification material at the molecular level according to claim 1, characterized in that: In step (2), the purification capacity is quantitatively evaluated according to the following formula: A=(I B -I A ) / I B ×100% In the formula, I B and I A are the mass spectrometry response intensities of the matrix molecules in the extract before and after purification, respectively; the value range of A is 0% to 100%, and the larger the value, the stronger the purification ability.

3. The method for evaluating the purification ability of a purification material at the molecular level as claimed in claim 1, characterized in that: In step (1) and step (2), the set matrix molecule types include one or more of sugars, amino acids, pigments, and alkaloids.

4. The method for evaluating the purification ability of a purification material at a molecular level as claimed in claim 1, characterized in that: In step (1), the chromatographic conditions of the liquid chromatography-high resolution mass spectrometry are as follows: chromatographic column: Atlantis@T3 column; mobile phase A: 5 mM ammonium acetate solution with 0.1% formic acid, mobile phase B: acetonitrile; gradient elution: 0-1 min, 10%-50% B; 1-5 min, 50% B; 5-16 min, 50%-60% B; 16-25 min, 60%-80% B; 25-30 min, 80%-95% B; 30-40 min, 95% B; 40~40.1min, 95%~10%B; 40.1~50.1min, 10%B.

5. The method for evaluating the purification ability of a purification material at the molecular level as claimed in claim 4, characterized in that: The mass spectrometry conditions of the liquid chromatography-high resolution mass spectrometry are as follows: ion source: ESI source; scanning mode: positive ion scanning; scanning range: 100-1000 m / z; spray voltage: 5500 V; nebulizing gas pressure: 55 psi; curtain gas pressure: 35 psi; Auxiliary gas pressure: 50 psi; ion source temperature: 500 °C; cluster fragmentation voltage: 40 V; collision energy spread: 15 eV; Detection mode: information association collection mode.

6. The method for evaluating the purification ability of a purification material at the molecular level as claimed in claim 1, characterized in that: The extract is used to detect residual pesticides in the sample to be tested; the extract is prepared by extracting the sample to be tested with a solvent.

7. The method for evaluating the purification ability of a purification material at the molecular level according to claim 6, characterized in that: The sample to be tested includes tobacco leaves.

8. The method for evaluating the purification ability of a purification material at the molecular level according to claim 7, characterized in that: For every 2 g of tobacco leaf sample, 10-15 mL of water is first used for soaking and allowed to stand, then 10-15 mL of acetonitrile is used for oscillation extraction, and then a salting-out agent is added for salting-out and stratification, and the obtained supernatant is the extract.

9. The method for evaluating the purification ability of a purification material at a molecular level as claimed in claim 1, characterized in that: The purification process comprises mixing the extract and the purification material and then shaking the mixture. The volume of the extract is 0.5 to 3 mL, and the mass of the purification material is 3 to 300 mg.

10. The method for evaluating the purification ability of a purification material at the molecular level according to claim 9, characterized in that: The amount of purification material used per milliliter of extract is 10 to 20 mg.

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