Preparation method and application of dual-regulation chloropropanol molecularly imprinted column

Abstract

The invention provides a preparation method and application of a dual-regulation chloropropanol molecularly imprinted column. The double-regulation chloropropanol molecularly imprinted column is prepared by the following steps: dispersing silicon dioxide or a silicon dioxide modified material into N, N-dimethylformamide, adding triethylamine and 4-dimethylaminopyridine to form a suspension, and adding 2-bromoisobutyryl bromide into the suspension in a low-temperature environment for reaction to obtain SiO2-Br; the preparation method comprises the following steps: adding SiO2-Br, template molecule chloropropanol, a functional monomer and a cross-linking agent into an aqueous solution in sequence, incubating for more than 30 minutes in a low-temperature environment, then adding copper bromide, introducing nitrogen to prepare a polymerization product at low temperature, washing off the template 3-chloropropanol, carrying out vacuum drying to obtain a chloropropanol molecularly imprinted material, and filling the chloropropanol molecularly imprinted material into a solid-phase extraction empty column. According to the method, double-stranded DNA is introduced into organic imprinting polymerization to serve as a framework, and unwinding-renaturation of DNA chains is realized through temperature regulation, so that construction-damage-reconstruction of an imprinting cavity is realized, target molecules can be quickly analyzed, and a large amount of organic solvent does not need to be consumed.

Description

Technical Field

[0001] The invention relates to the field of new materials, and in particular to a preparation method and application of a double-regulated chloropropanol molecular imprinting column. Background Art

[0002] Chloropropanols generally refer to a series of isomers formed by the replacement of chlorine atoms on the hydroxyl group of glycerol. According to the position and number of chlorine substitutions, it can be divided into 2-chloro-1,3-propanediol (2-MCPD), 3-chloro-1,2-propanediol (3-MCPD), 1,3-dichloro-2-propanol (1,3-DCP) and 2,3-dichloro-1-propanol (2,3-DCP). Studies have shown that 3-MCPD can cause damage to the kidneys, testicles, liver, nerves, and immune systems, while 1,3-DCP has clear carcinogenicity and potential genotoxicity. Chloropropanol esters have been detected in soy sauce, formula milk powder, most heat-treated foods, and foods with high fat content, such as coffee, French fries, biscuits, cooking oil, bread, cakes, etc. In recent years, chloropropanols have also been commonly detected in some food contact paper products in domestic and foreign markets. Therefore, conducting trace analysis of chloropropanols in food is of great significance to food safety supervision and population exposure risk assessment.

[0003] At present, my country's latest national standard method recommends the use of sodium chloride solution extraction, diatomaceous earth column purification extraction, combined with gas chromatography-mass spectrometry analysis to detect chloropropanol in food. However, the standard method requires the consumption of 10 mL of n-hexane and 15 mL of ethyl acetate to analyze a sample, producing a large amount of laboratory waste liquid. Ethyl acetate is a flammable and explosive chemical, while n-hexane is highly volatile and is a neurotoxin that can cause irreversible health hazards to the population. In addition, when using diatomaceous earth columns, the liquid to be purified should be completely immersed in the filler and cannot penetrate. Therefore, the analysis of a sample also requires the consumption of a disposable extraction column (5g filler), which is costly. More importantly, due to the low selectivity of the diatomaceous earth column, it is inevitable that the sample matrix will interfere, and the quadrupole of the gas chromatography-mass spectrometer will often be contaminated.

[0004] As a polymer material, molecular imprinting adsorbent can selectively identify target molecules, significantly reduce sample matrix interference, and can be reused repeatedly, effectively reducing pretreatment costs. Many literatures have reported the preparation of imprinting materials with chloropropanol as a template. However, we found that the molecular weight of chloropropanol is only 94, and the outflow path in the imprinting pore is very long, resulting in 6-7 days of elution of the template, and a large amount of organic solvent is also required for elution during extraction. If we can adjust the selectivity of the imprinting pores so that it can release chloropropanol in a concentrated manner, the consumption of organic solvents will inevitably be reduced. The double helix structure of DNA molecules can be unwound into single-stranded DNA molecules (denaturation) at high temperatures, and can be twisted back into a double-stranded helix structure (renaturation) when the temperature is lowered.

[0005] Therefore, if DNA molecules can be integrated into molecular imprinting polymers to prepare molecular imprinting composite materials based on double helix structures, it will be possible to achieve the purpose of quickly analyzing target molecules while retaining the highly selective recognition characteristics of molecular imprinting materials and reducing interference from sample matrices. Summary of the invention

[0006] The purpose of the present invention is to provide a preparation method and application of a double-regulated chloropropanol molecular imprinting column. The method integrates DNA molecules into molecular imprinting polymers to prepare a molecular imprinting composite material based on a double helix structure. The construction-destruction-reconstruction of the imprinting cavity can be achieved through temperature control. The interaction between target molecules, solvents and imprinting materials is combined to create a solvent and temperature double-regulated molecular imprinting solid phase extraction column. The column can not only retain the highly selective recognition characteristics of the molecular imprinting material and reduce the interference of the sample matrix, but also can quickly resolve the target molecules without consuming a large amount of organic solvents, thereby realizing green and efficient sample pretreatment, and providing technical support for the analysis of chloropropanols in food and the risk assessment of human exposure.

[0007] In order to solve the above technical problems, the present invention provides a method for preparing a double-regulated chloropropanol molecular imprinted column, which is characterized by comprising the following steps:

[0008] S1. dispersing silica or silica-modified material into N,N-dimethylformamide to form a silica solution, wherein the mass volume ratio of silica or silica-modified material to N,N-dimethylformamide is 1 g: 100-500 mL;

[0009] S2. Add triethylamine and 4-dimethylaminopyridine to the silica solution in step S1 to form a suspension, wherein the mass ratio of silica or silica-modified material, triethylamine and 4-dimethylaminopyridine in the mixed solution is 1:5-10:1-10; then add 2-bromoisobutyryl bromide to the suspension under low temperature to react, wherein the mass volume ratio of silica or silica-modified material to 2-bromoisobutyryl bromide is 1g:2-20mL;

[0010] S3. terminating the esterification reaction in step S2 with ethanol, washing the reaction product with N,N-dimethylformamide and ethanol for more than 2 times, modifying the initiator on the surface of silica or silica-modified material to form an initiator-modified silica material SiO2-Br,

[0011] S4. Add the SiO2-Br, template molecule chloropropanol, functional monomer and cross-linking agent in step S3 to the aqueous solution in sequence and incubate in a low temperature environment for more than 30 minutes, then add copper bromide, and introduce nitrogen into the reaction system for more than 30 minutes, and react at <40°C for more than 72 hours to prepare a polymer product; the mass ratio of SiO2-Br: template molecule: functional monomer: cross-linking agent is 100-500:1:2-8:10-50; the functional monomer is composed of methacrylic acid and 4-vinylbenzeneboronic acid, wherein the mass percentage of methacrylic acid is 0-100%; the cross-linking agent is composed of methylene bisacrylamide and two acrylamide-modified DNA sequences, wherein the mass percentage of methylene bisacrylamide is 0-80%; the mass ratio of copper bromide to functional monomer is 1:10-50;

[0012] S5. The polymer product prepared in step S4 is slowly heated to above 80° C., the template 3-chloropropanol is washed away with ethanol, and the 3-chloropropanol is vacuum dried to obtain a chloropropanol molecularly imprinted material;

[0013] S6. Fill 100-500 mg of the chloropropanol molecular imprinting material obtained in step S5 into a 3 mL commercial solid phase extraction empty column to obtain the dual-adjusted chloropropanol molecular imprinting column.

[0014] A preferred technical solution of the present invention: the acrylamide-modified DNA sequence is as follows: 5′-acrydite-AAATTCGCGCGCGAA-3′.

[0015] A preferred technical solution of the present invention: the silicon dioxide modified material in step S1 includes iron oxide nanoparticles wrapped in silicon dioxide film, graphene materials, carbon nanotube materials, nano-gold and metal organic framework materials.

[0016] A preferred technical solution of the present invention: the low temperature environment in step S2 and step S4 is a low temperature environment with a temperature ≤ 4°C.

[0017] A preferred technical solution of the present invention: in the step S4, the chloropropanol includes 2-chloro-1,3-propanediol, 3-chloro-1,2-propanediol, 1,3-dichloro-2-propanol or 2,3-dichloro-1-propanol.

[0018] The present invention also provides an application of a double-adjusted chloropropanol molecular imprinted column prepared by the method, and the double-adjusted chloropropanol molecular imprinted column is used for detecting chloropropanol in food.

[0019] A further technical solution of the present invention is as follows: the food comprises any one or a mixture of soy sauce, formula milk powder, cake, coffee, fried French fries, biscuits, edible oil, bread and cakes; the specific detection process is as follows: taking the above single or mixed food sample and using 20% ​​sodium chloride solution for ultrasonic extraction to obtain an analysis sample extract, wherein the mass volume ratio of the food sample to the 20% sodium chloride solution is 1g:20ml; at room temperature, using 20% ​​sodium chloride solution to activate the double-adjusted chloropropanol molecular imprinting column, and then slowly passing the analysis sample extract through the double-adjusted chloropropanol molecular imprinting column within 30 minutes, so that the target molecule is selectively adsorbed on the molecular imprinting material; then eluting the double-adjusted chloropropanol molecular imprinting column with 10% ethanol aqueous solution to remove sample impurities; finally, injecting 5mL of 50% ethanol aqueous solution into the double-adjusted chloropropanol molecular imprinting column, transferring it to an oven at 85-95°C for 2-3 minutes, collecting the effluent and blowing it to near dryness, and analyzing the content of chloropropanol by mass spectrometry after constant volume.

[0020] Conventional molecular imprinting columns mainly rely on the interaction between target molecules, solvents and imprinting materials to extract target molecules, but this force cannot be changed. Therefore, the target can be efficiently identified in the adsorption stage, but in the subsequent elution stage, a lot of time and solvent are needed to elute the target, and if necessary, acid, alkali, special reagents, etc. need to be added. The dual-regulatory molecular imprinting column of the present invention can regulate the interaction between target molecules, solvents and imprinting materials by temperature, so that the interaction force is enhanced in the adsorbent stage, which is conducive to identifying target molecules, and in the elution stage, the force is minimized, the target molecules are quickly eluted, and time and solvent consumption are reduced.

[0021] The filler of the molecular imprinted column prepared by the present invention is a kind of high molecular polymer formed by using chloropropanol as a template, anchoring functional groups through non-covalent recognition between template molecules and functional monomers, and imprinting the spatial conformation of template molecules with the help of organic polymerization. After washing away the template, the residual imprinted cavity can re-recognize the template molecule, showing a biomimetic recognition ability comparable to that of antibodies, and can achieve efficient adsorption of trace chloropropanol in complex sample matrices. At the same time, the present invention introduces double-stranded DNA as a skeleton in organic polymerization, realizes the unwinding-renaturation of DNA chains through temperature regulation, thereby realizing the construction-destruction-reconstruction of the imprinted cavity, combining the interaction between target molecules-solvent-imprinted materials, creating a solvent and temperature dual-regulation molecular imprinted solid phase extraction column, which can not only retain the highly selective recognition characteristics of molecular imprinted materials, reduce sample matrix interference, but also can quickly resolve target molecules, without the need to consume a large amount of organic solvents, and realize green and efficient sample pre-treatment.

[0022] The present invention introduces double-stranded DNA as a skeleton in organic imprinting polymerization, realizes unwinding and renaturation of the DNA chain through temperature regulation, thereby realizing construction, destruction and reconstruction of the imprinting cavity, and can quickly resolve target molecules without consuming a large amount of organic solvents; the prepared molecular imprinting column can quickly resolve chloropropanol molecules in the detection process of chloropropanol in complex samples such as soy sauce, formula milk powder, fried French fries, cakes, etc. without consuming a large amount of organic solvents, thereby realizing green and efficient sample pre-treatment.

[0023] The present invention extracts the target object through the interaction among the target molecule, the solvent and the imprinting material, and realizes the intelligent transformation from the recognition material with high adsorption capacity to the material with low adsorption capacity by adjusting the temperature, which is beneficial to the green and efficient extraction of chloropropanol in complex samples; the extraction process not only avoids the use of organic solvents, but also reduces the volume of the extraction solvent by temperature regulation, thereby realizing the efficient extraction of chloropropanol in complex samples, and meeting the sample pretreatment requirements of on-site sensor analysis and laboratory mass spectrometry analysis. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a schematic diagram of the principle of preparing the dual-regulatory molecular imprinted column filler in the present invention;

[0025] Figure 2 is an electron microscope image of the dual-regulatory molecularly imprinted column filler prepared in Example 3 of the present invention;

[0026] Figure 3 It is a comparative curve diagram of the adsorption effect of double-adjusted molecular imprinted column at room temperature, non-imprinted column at room temperature and double-adjusted molecular imprinted column at high temperature on chloropropanol;

[0027] Figure 4 It is a comparison curve of the adsorption and desorption effects of the double-adjusted molecular imprinting column on chloropropanol at room temperature and high temperature;

[0028] Figure 5 This is a statistical table of the selective extraction ability of the double-regulated molecular imprinting column for chloropropanol. DETAILED DESCRIPTION

[0029] The present invention is further described in detail below in conjunction with embodiments and drawings, but the embodiments of the present invention are not limited thereto.

[0030] The preparation method of a dual-regulated chloropropanol molecular imprinted column provided in Example 1 comprises the following specific steps:

[0031] (1) Disperse 1 g of silica or silica-modified material in 100 mL of N,N-dimethylformamide, add triethylamine and 4-dimethylaminopyridine, and make the mass ratio of silica or silica-modified material, triethylamine and 4-dimethylaminopyridine be 1:5:1; then, add 2 mL of 2-bromoisobutyryl bromide to the suspension in a low temperature environment (4°C), and after completion, terminate the esterification reaction with more than 100 mL of ethanol, and wash the reaction product with N,N-dimethylformamide and ethanol for more than 2 times, so that the initiator can be modified on the surface of silica or silica-modified material to form initiator-modified silica material SiO2-Br.

[0032] (2) 100 mg of SiO2-Br in step (1), template molecule 2-chloro-1,3-propanediol, functional monomer methacrylic acid and cross-linking agent are added in sequence to the aqueous solution, wherein the cross-linking agent is two acrylamide-modified DNA sequences (5′-acrydite-AAATTCGCGCGCGAA-3′, the mutually recognizing sequence in the frame), the two acrylamide-modified DNA sequences are the same and are directly purchased commodities, and incubated in a low temperature environment (≤4°C) for more than 30 minutes; wherein the mass ratio of the template molecule: functional monomer: cross-linking agent is 1:2:10.

[0033] (3) Then, copper bromide is added so that the mass ratio of copper bromide to the functional monomer is 1:10, and nitrogen is introduced into the reaction system for more than 30 minutes, and the reaction is carried out at a temperature of <40° C. for more than 72 hours.

[0034] (4) slowly heating the polymer product prepared in step (3) to an environment above 80° C., washing away the template 3-chloropropanol with ethanol, and vacuum drying to obtain a chloropropanol molecular imprinting material.

[0035] (5) 100 mg of the chloropropanol molecular imprinting material prepared in step (4) was filled into a 3 mL commercial solid phase extraction empty column to obtain a double-adjusted chloropropanol molecular imprinting column, which can achieve efficient extraction of chloropropanol in complex samples.

[0036] The preparation method of a dual-regulated chloropropanol molecular imprinted column provided in Example 2 comprises the following specific steps:

[0037] (1) Disperse 1 g of silica or silica-modified material in 500 mL of N,N-dimethylformamide, add triethylamine and 4-dimethylaminopyridine, and make the mass ratio of silica or silica-modified material, triethylamine and 4-dimethylaminopyridine be 1:10:10; then, add 20 mL of 2-bromoisobutyryl bromide dropwise to the suspension in a low temperature environment (≤4°C), and after completion, terminate the esterification reaction with more than 100 mL of ethanol, and wash the reaction product with N,N-dimethylformamide and ethanol for more than 2 times, so that the initiator can be modified on the surface of silica or silica-modified material (initiator modified silica material SiO2-Br).

[0038] (2) 500 mg of SiO2-Br prepared in step (1), template molecule 1,3-dichloro-2-propanol, functional monomer methacrylic acid 4-vinylbenzene boronic acid, cross-linking agent methylenebisacrylamide and two acrylamide-modified DNA sequences (5′-acrydite-AAATTCGCGCGCGAA-3′, the box is a mutual recognition sequence) were added to the aqueous solution in sequence, the two acrylamide-modified DNA sequences were the same and were directly purchased commodities, the mass percentage of methylenebisacrylamide was 80%, and the mixture was incubated in a low temperature environment (≤4°C) for more than 30 minutes, wherein the mass ratio of template molecule: functional monomer: cross-linking agent was 1:8:50.

[0039] (3) Then, copper bromide is added so that the mass ratio of copper bromide to the functional monomer is 1:50, and nitrogen is introduced into the reaction system for more than 30 minutes, and the reaction is carried out at a temperature of <40° C. for more than 72 hours.

[0040] (4) slowly heating the polymer product prepared in step (3) to an environment above 80° C., washing away the template 3-chloropropanol with ethanol, and vacuum drying to obtain a chloropropanol molecular imprinting material.

[0041] (5) Fill 500 mg of the chloropropanol molecular imprinting material obtained in step (4) into a 3 mL commercial solid phase extraction empty column to obtain a double-adjusted chloropropanol molecular imprinting column, which can achieve efficient extraction of chloropropanol in complex samples.

[0042] The preparation method of a dual-regulated chloropropanol molecular imprinted column provided in Example 3 comprises the following specific steps:

[0043] (1) Disperse 1 g of silica or silica-modified material in 200 mL of N,N-dimethylformamide, add triethylamine and 4-dimethylaminopyridine, and make the mass ratio of silica or silica-modified material, triethylamine and 4-dimethylaminopyridine be 1:8:6; then, add 10 mL of 2-bromoisobutyryl bromide dropwise to the suspension in a low temperature environment (4°C); after completion, terminate the esterification reaction with more than 100 mL of ethanol, and wash the reaction product with N,N-dimethylformamide and ethanol for more than 2 times, so that the initiator can be modified on the surface of silica or silica-modified material.

[0044] (2) 300 mg of initiator modified on silica or silica modified material, template molecule 3-chloro-1,2-propanediol, functional monomers methacrylic acid and 4-vinylbenzene boronic acid, crosslinker methylenebisacrylamide and two acrylamide modified DNA sequences (5′-acrydite-AAATTCGCGCGCGAA-3′, the box is a mutual recognition sequence) were added to the aqueous solution in sequence. The two acrylamide modified DNA sequences were the same and were directly purchased commodities. The mass percentage of methylenebisacrylamide was 40%, and the mixture was incubated in a low temperature environment (4°C) for more than 30 minutes. The mass ratio of template molecule: functional monomer: crosslinker was 1:6:20. The mass ratio of methacrylic acid in the functional monomer was 50%; the mass ratio of methylenebisacrylamide in the crosslinker was 50%.

[0045] (3) Then, copper bromide is added so that the mass ratio of copper bromide to the functional monomer is 1:30, and nitrogen is introduced into the reaction system for more than 30 minutes, and the reaction is carried out at a temperature of <40° C. for more than 72 hours.

[0046] (4) slowly heating the polymer product prepared in step (3) to an environment above 80° C., washing away the template 3-chloropropanol with ethanol, and vacuum drying to obtain a chloropropanol molecular imprinting material.

[0047] (5) 100-500 mg of the chloropropanol molecular imprinting material obtained in step (4) is filled into a 3 mL commercial solid phase extraction empty column to obtain a double-adjusted chloropropanol molecular imprinting column, which can achieve efficient extraction of chloropropanol in complex samples.

[0048] The present invention is further described below in conjunction with specific experiments. Figure 2 The electron microscope image of the molecular imprinted material synthesized on the surface of silica using 3-chloro-1,2-propanediol as a template prepared in Example 3 is shown. The results show that the prepared molecular imprinted film is evenly distributed on the surface of the silica material, has a regular shape, a smooth surface and stable binding.

[0049] Experiment 1: The dual-regulatory molecular imprinting filler prepared in Example 3 was used to extract 3-chloro-1,2-propanediol from the sample. Specifically, 50 mg of the dual-regulatory molecular imprinting filler prepared in Example 3 was incubated in 10 ml of an aqueous solution containing different concentrations of 3-chloro-1,2-propanediol, and oscillated at room temperature or high temperature (90°C) for 1 hour. After the filler was washed with deionized water, the content of 3-chloro-1,2-propanediol in the supernatant was determined by gas chromatography, and the effect of different temperatures on the selective adsorption capacity of the imprinting material was evaluated. The results are as follows: Figure 3 As shown, at room temperature, the adsorption capacity of the dual-regulatory molecular imprinting material for TBBPA reached 52.9 mg / g, while the adsorption capacity of the non-imprinting material as a control was 12.1 mg / g, and the selectivity factor reached 4.4, which is higher than the selectivity factor of the imprinting material reported in the literature (2.9, Anal Bioanal Chem, 2014, 406, 6319-6327), and close to the selectivity of the imprinting material reported by us (4.5, Food Chem, 2019, 274: 156-161), proving that the preparation method proposed in this patent has an excellent selective adsorption effect on chloropropanol. However, under high temperature conditions (90 ° C), the DNA in the imprinting material skeleton is unwound, the molecular imprinting cavity is destroyed, and the selective adsorption capacity is drastically reduced, and the adsorption capacity is only 2.27 mg / g, which is conducive to the rapid analysis and release of the target molecules in the imprinting material. The imprinting materials reported in the literature are all synthesized under high temperature conditions, have high temperature stability, and will not reduce the adsorption capacity, so a large amount of organic solvent is required for elution.

[0050] Experiment 2: 50 mg of the dual-regulatory molecular imprinting material prepared in Example 3 was incubated in an aqueous solution of 3-chloro-1,2-propanediol (10 mg / L), shaken at room temperature for 80 minutes, and the supernatant was collected at different time periods. The content of 3-chloro-1,2-propanediol in the supernatant was determined by gas chromatography. Subsequently, the imprinting material with the adsorbed target was incubated in a 50% ethanol aqueous solution (5 / 5, v / v), transferred to a 90°C oven, and the supernatant was continued to be collected at different time periods to determine the content of 3-chloro-1,2-propanediol. The results are as follows: Figure 4 As shown, Figure 4 The adsorption and desorption curves of the dual-regulatory molecular imprinting material proposed in Example 3 are shown. Figure 4 It can be seen that due to the small molecular weight, the target molecule has a long way to reach the imprinted cavity. The imprinted material needs about 30 minutes to achieve efficient adsorption of the target molecule in the sample extract, and the recovery rate reaches more than 90%. It can be seen that it takes a long time for the target molecule to be eluted from the imprinted column at room temperature. However, for the double-regulated imprinted column, the double-stranded DNA unwinds under high temperature, the polymer backbone becomes sparse, and the molecular imprinted cavity is fully opened, and the efficient analysis of the target molecule can be achieved in 2 minutes, effectively shortening the sample pretreatment time.

[0051] Experiment 3: The double-adjustment non-imprinted column and the double-adjustment imprinted column of the present invention were used to test and compare the selective extraction ability of the double-adjustment molecular imprinted column. The preparation method of the double-adjustment non-imprinted column is basically the same as that of the double-adjustment imprinted column, except that no template molecule is added during the synthesis process. Since there is no chloropropanol as a guide for the template molecule, the adsorbent does not form an imprinted cavity for highly selective recognition of the target molecule; although the double-adjustment non-imprinted column can also adjust the changes in the polymer skeleton, there is no selective imprinted cavity, and the recognition performance of the target is lost. Therefore, it is used as a control to evaluate the selective recognition ability of the double-adjustment imprinted column. In the experiment, the target molecule is 3-chloro-1,2-propanediol, and the molecular imprinting material is prepared using 3-chloro-1,2-propanediol as a template; other compounds are 2-chloro-1,3-propanediol, 1,3-dichloro-2-propanol, 2,3-dichloro-1-propanol and propylene glycol. The experiment specifically used the dual-regulatory molecular imprinting column proposed in Example 3. The content of 3-chloro-1,2-propanediol and structural analogs in the experiment was 10 mg / L. The analysis sample was a mixed matrix of soy sauce, formula milk powder and cake (1 g, mass ratio, 1:1:1), and ultrasonic extraction was performed with 20 mL of 20% sodium chloride solution. At room temperature, the dual-regulatory molecular imprinting column was first activated with 5 mL of 20% sodium chloride solution, and then the sample extract was slowly passed through the dual-regulatory molecular imprinting column within 30 minutes to selectively adsorb the target molecule on the molecular imprinting material of the dual-regulatory molecular imprinting column. The solid phase extraction column was further eluted with 3 mL of 10% ethanol aqueous solution (1 / 9, v / v) to remove sample impurities. Finally, 5 mL of 50% ethanol aqueous solution (5 / 5, v / v) was injected into the dual-regulatory molecular imprinting column, which was transferred to a 90°C oven for 2 minutes, the effluent was collected and blown to near dryness, and then the volume was fixed and analyzed by mass spectrometry. The analysis results are as follows Figure 5 As shown in the figure, the recovery rate of the target molecule can reach 87.11%, and the recovery rate of the structural analogs at the same concentration is less than 30%, indicating that the selectivity of the analytical method is extremely high and can be truly used for actual sample analysis. To analyze a sample, this method only consumes 2.8mL of ethanol, which is only about one-tenth of the organic solvent used in the standard method (25mL), and does not require the more toxic n-hexane / ethyl acetate.

Claims

1. A method for preparing a double-regulated chloropropanol molecular imprinted column, characterized in that The steps include: S1. dispersing silica or silica-modified material into N,N-dimethylformamide to form a silica solution, wherein the mass volume ratio of silica or silica-modified material to N,N-dimethylformamide is 1 g: 100-500 mL; S2. Add triethylamine and 4-dimethylaminopyridine to the silica solution in step S1 to form a suspension, wherein the mass ratio of silica or silica-modified material, triethylamine and 4-dimethylaminopyridine in the mixed solution is 1:5-10:1-10; then add 2-bromoisobutyryl bromide to the suspension under low temperature to react, wherein the mass volume ratio of silica or silica-modified material to 2-bromoisobutyryl bromide is 1g:2-20mL; S3. terminating the esterification reaction in step S2 with ethanol, washing the reaction product with N,N-dimethylformamide and ethanol for more than 2 times, modifying the initiator on the surface of silica or silica-modified material to form an initiator-modified silica material SiO2-Br, S4. Add the SiO2-Br, template molecule chloropropanol, functional monomer and cross-linking agent in step S3 to the aqueous solution in sequence and incubate in a low temperature environment for more than 30 minutes, then add copper bromide, and introduce nitrogen into the reaction system for more than 30 minutes, and react at <40°C for more than 72 hours to prepare a polymer product; the mass ratio of SiO2-Br: template molecule: functional monomer: cross-linking agent is 100-500:1:2-8:10-50; the functional monomer is composed of methacrylic acid and 4-vinylbenzeneboronic acid, wherein the mass percentage of methacrylic acid is 0-100%; the cross-linking agent is composed of methylene bisacrylamide and two acrylamide-modified DNA sequences, wherein the mass percentage of methylene bisacrylamide is 0-80%; the mass ratio of copper bromide to functional monomer is 1:10-50; S5. The polymer product prepared in step S4 is slowly heated to above 80° C., the template 3-chloropropanol is washed away with ethanol, and the 3-chloropropanol is vacuum dried to obtain a chloropropanol molecularly imprinted material; S6. Fill 100-500 mg of the chloropropanol molecular imprinting material obtained in step S5 into a 3 mL commercial solid phase extraction empty column to obtain the dual-adjusted chloropropanol molecular imprinting column.

2. The method for preparing a double-regulated chloropropanol molecularly imprinted column according to claim 1, characterized in that: The acrylamide modified DNA sequence is as follows: 5′-acrydite-AAATTCGCGCGCGAA-3′.

3. The method for preparing a dual-regulated chloropropanol molecularly imprinted column according to claim 1 or 2, characterized in that: The silicon dioxide modified material in step S1 includes ferrosoferric oxide nanoparticles wrapped in silicon dioxide film, graphene materials, carbon nanotube materials, nano-gold and metal organic framework materials.

4. The method for preparing a dual-regulated chloropropanol molecularly imprinted column according to claim 1 or 2, characterized in that: The low temperature environment in the step S2 and the step S4 is a low temperature environment with a temperature ≤ 4°C.

5. The method for preparing a dual-regulated chloropropanol molecularly imprinted column according to claim 1 or 2, characterized in that: The chloropropanol in step S4 includes 2-chloro-1,3-propanediol, 3-chloro-1,2-propanediol, 1,3-dichloro-2-propanol or 2,3-dichloro-1-propanol.

6. Use of the double-adjusted chloropropanol molecular imprinted column prepared according to any one of claims 1 to 5, wherein the double-adjusted chloropropanol molecular imprinted column is used for the detection of chloropropanol in food.

7. The use of a double-regulated chloropropanol molecular imprinted column according to claim 6, characterized in that: The food comprises any one or a mixture of soy sauce, formula milk powder, cake, coffee, fried French fries, biscuits, edible oil, bread and pastry; the specific detection process is as follows: taking the above single or mixed food sample and using 20% ​​sodium chloride solution for ultrasonic extraction to obtain an analytical sample extract, wherein the mass volume ratio of the food sample to the 20% sodium chloride solution is 1g:20ml; at room temperature, using 20% ​​sodium chloride solution to activate a double-adjusted chloropropanol molecular imprinting column, and then slowly passing the analytical sample extract through the double-adjusted chloropropanol molecular imprinting column within 30 minutes, so that the target molecule is selectively adsorbed on the molecular imprinting material; then eluting the double-adjusted chloropropanol molecular imprinting column with 10% ethanol aqueous solution to remove sample impurities; finally, injecting 5mL of 50% ethanol aqueous solution into the double-adjusted chloropropanol molecular imprinting column, transferring it to an oven at 85-95°C for 2-3 minutes, collecting the effluent and blowing it to near dryness, and analyzing the content of chloropropanol by mass spectrometry after constant volume.

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