Preparation method and application of molecularly imprinted composite filler

Abstract

The invention relates to a preparation method of a molecularly imprinted composite filler, and relates to the technical field of analytical chemistry and environmental monitoring technologies, the preparation method of the molecularly imprinted composite filler comprises the following steps: firstly dissolving template molecules and a first monomer, then adding a cross-linking agent and an initiator, carrying out deoxidation and water bath, and then centrifuging to obtain a template molecule solution; and eluting the precipitate with a flushing fluid, and drying to obtain the microspheres. And dissolving the ionic liquid, uniformly stirring with the obtained microspheres, and carrying out centrifugal separation, washing and vacuum drying to finally prepare the molecularly imprinted composite filler. Finally, the hydrophobic property of the molecularly imprinted composite filler is improved through modification of the ionic liquid and the second monomer. The method provided by the invention has excellent hydrophobic effect and enrichment capability on a target object.

Description

Technical Field

[0001] This application relates to the fields of analytical chemistry and environmental monitoring technology, and in particular to a method for preparing and applying a molecularly imprinted composite filler. Background Technology

[0002] Molecularly imprinted polymers (MIPs), as biomimetic materials with "molecular memory" capabilities, originated from the specific interactions between antigens and antibodies, and enzymes and substrates in biological systems. Molecular imprinting technology is essentially a "biomimetic customized" material preparation method. Its core is to construct a polymer framework with exclusive recognition capabilities around a specific target molecule, i.e., a template molecule. Specifically, the template molecule is first mixed with a functional monomer capable of polymerization. The two form a stable "template-monomer" complex through non-covalent interactions such as hydrogen bonding, electrostatic attraction, and hydrophobic interactions. Then, a cross-linking agent and initiator are added, and a cross-linking polymerization reaction is carried out under light or heat initiation. This fixes the complex structure within a three-dimensional cross-linked polymer network. Finally, the template molecule is completely removed from the polymer using a suitable elution solvent, yielding the molecularly imprinted polymer. The most significant characteristic of these polymers is the presence of "molecular imprint" sites that are highly complementary to the template molecule in terms of spatial configuration and functional group arrangement. Even after the template molecule is removed, these sites can still accurately recognize and bind to the original template molecule, like a "key matching a lock."

[0003] Therefore, thanks to this unique specific recognition capability, MIPs are widely used in solid-phase extraction for the separation and enrichment of target pollutants such as pesticide residues and antibiotics in environmental water samples, food, and biological fluids, achieving efficient purification to improve the accuracy of subsequent detection; as recognition elements in sensors to detect heavy metal ions, glucose, explosive molecules, etc., converting molecular recognition into electrochemical or optical signals; as intelligent carriers in drug controlled release to achieve targeted release of anticancer drugs in lesion areas; to construct catalytically active cavities to simulate the function of natural enzymes in enzyme catalysis; and to separate enantiomers of chiral drugs such as ibuprofen in chiral separation.

[0004] The core of molecular imprinting (MIP) technology is to construct a "molecular imprint" in a polymer matrix through the interaction of template molecules with functional monomers and cross-linking agents. This imprint highly matches the spatial structure and binding sites of the template molecules, enabling the specific recognition and separation of target substances. However, due to strong non-covalent interactions between template molecules and polymers, such as hydrogen bonds, hydrophobic interactions, electrostatic interactions, or partial covalent bonds, it is difficult to completely remove template molecules from the polymer interior and surface during subsequent template elution, even with conventional elution methods such as solvent extraction, heating, and ultrasound. This results in some template molecules remaining in the channels or binding sites of the MIPs. When these MIPs with template residues are applied to practical sample detection scenarios such as the detection of pollutants in environmental water samples, the analysis of harmful substances in food, and the quantification of target molecules in biological samples, the residual template molecules are released into the detection system during the detection process, such as sample adsorption, elution separation, and signal detection stages, causing secondary pollution.

[0005] On the one hand, if the target molecule and the template molecule are the same substance, the residual template will directly superimpose on the content of the target molecule in the actual sample, leading to a positive bias in the detection results and an overestimation of the actual pollutant concentration. On the other hand, residual template molecules may interact non-specifically with reagents in the detection system, such as components of the chromatographic mobile phase, or occupy the specific binding sites that MIPs should open to the target molecules in the sample, reducing the adsorption capacity and recognition efficiency of the MIPs for the target molecules in the actual sample, thereby interfering with the stability and accuracy of the detection signal. In chromatographic detection, this may lead to problems such as abnormal peak shape; in immunoblotting or fluorescence detection, it may cause an increase in background signal, ultimately affecting the reliability and precision of the detection results. Especially in trace detection scenarios, this secondary contamination caused by template residue has a more significant impact on detection accuracy. Summary of the Invention

[0006] The purpose of this application is to provide a molecularly imprinted composite filler that can efficiently enrich trace target analytes in complex matrices, and has excellent hydrophobic properties to reduce interference from oily substances in environmental samples, increase anti-interference performance, and thus improve recovery efficiency.

[0007] In a first aspect, this application provides a method for preparing a molecularly imprinted composite filler, which adopts the following technical solution: A method for preparing a molecularly imprinted composite filler includes the following steps: S1. Dissolve the template molecule and the first monomer in a solvent to obtain the first mixture; S2. Add crosslinking agent and initiator to the first mixture obtained in step S1, deoxygenate by passing nitrogen gas, and bathe in a constant temperature water bath to obtain the second mixture. S3. Centrifuge the second mixture obtained in step S2 to obtain a precipitate, wash the precipitate with rinsing solution, dry it, and obtain microspheres; S4. Add the ionic liquid solution to the microspheres obtained in step S3, stir at room temperature, centrifuge, wash, and vacuum dry to obtain the molecularly imprinted composite filler. The template molecule is a chlorinated alkane segment; the first monomer has a carboxyl functional group; and the ionic liquid has an imidazole ring and a long alkyl chain.

[0008] By employing the above technical solution, the carboxyl group of the first monomer, such as methacrylic acid in this application, forms hydrogen bonds or electrostatic interactions with the chlorine atoms of the template molecule, such as short-chain chlorinated paraffin in this application. The double bonds contained in the crosslinking agent, such as ethylene glycol dimethacrylate in this application, and the double bonds in the first monomer methacrylic acid are subjected to free radical polymerization under the action of an initiator, such as azobisisobutyronitrile in this application. Network microspheres containing the template molecule are then constructed using covalent bonds. Simultaneously, the microspheres are modified using an ionic liquid, such as 1-butyl-3-methylimidazolium hexafluorophosphate in this application. Modification is achieved through ionic bonds interacting with residual functional groups such as carboxyl groups on the microspheres, preserving specific recognition capabilities while enhancing adsorption and stability through the ionic liquid. This results in a molecularly imprinted composite filler with high selectivity, large adsorption capacity, and good elution efficiency for the target analyte. Furthermore, the high polarity of the ionic liquid enhances the electrostatic attraction of chlorine atoms in short-chain chlorinated paraffins. At the same time, the hydrophobic butyl group of 1-butyl-3-methylimidazolium hexafluorophosphate can repel water molecules and reduce interference in the hydration layer, thus giving the molecularly imprinted composite filler a hydrophobic effect.

[0009] Optionally, in a method for preparing a molecularly imprinted composite filler, step S4 may further involve adding an ionic liquid solution to the microspheres obtained in step S3, and then adding a second monomer, wherein the second monomer is silane.

[0010] By employing the above technical solution, ionic liquids such as 1-butyl-3-methylimidazolium hexafluorophosphate bind to the residual carboxyl groups of the microspheres via ionic bonds. Simultaneously, the long-chain alkyl group of the second monomer, such as 3-[tris(hexyloxy)silyl]propylamine in this application, synergistically with the hydrophobic structure of the ionic liquid to form a dense hydrophobic layer. The extended alkyl chains repel water molecules, reducing interference from the aqueous phase, thus enabling the molecularly imprinted composite filler to exhibit excellent hydrophobic properties. This further enhances the selective adsorption of hydrophobic target analytes, ultimately achieving highly efficient enrichment.

[0011] Optionally, the mass ratio of the ionic liquid to the second monomer is 25:(1-4).

[0012] By adopting the above technical solution, the hydrophobic synergistic effect of the molecularly imprinted composite filler is optimal when the mass ratio of ionic liquid to the second monomer is controlled at (5-20):1. The butyl chain of the ionic liquid, such as 1-butyl-3-methylimidazolium hexafluorophosphate in this application, provides the basic hydrophobicity, while the long-chain alkyl group of the second monomer, such as 3-[tris(hexyloxy)silyl]propylamine in this application, fills the gaps in the hydrophobic structure of the ionic liquid, forming a continuous and dense hydrophobic layer. If the ratio is too low, the second monomer is insufficient to cover the gaps; if it is too high, the excessive long chains are prone to entanglement and aggregation, destroying the integrity of the hydrophobic layer. Within this range, the hydrophobic groups of both are arranged in an orderly manner, synergistically repelling water molecules and significantly improving the hydrophobicity of the material.

[0013] Optionally, the molar ratio of the template molecule to the first monomer is 1:(1-16).

[0014] By employing the above technical solution, a molar ratio of 1:(1-16) between the template molecule and the first monomer achieves an optimal balance between the number of recognition sites and binding efficiency. When the ratio is too low, the first monomer provides insufficient functional groups, such as carboxyl groups, to form a sufficient number of specific sites matching the template, resulting in limited enrichment capacity. When the ratio is too high, excess first monomer easily forms random polymerization, and excess functional groups induce non-specific adsorption, and may also hinder template molecules from entering the sites due to steric hindrance. The 1:(1-16) range ensures that the first monomer is arranged orderly around the template molecule, forming a suitable number and precise configuration of recognition sites after cross-linking. This satisfies the binding requirements of the template molecule while avoiding interference from excess first monomer, thus achieving efficient enrichment.

[0015] Optionally, the template molecule is C 10 -C 13 Chlorinated paraffin; the first monomer is any one of methacrylic acid, itaconic acid, and maleic acid; the ionic liquid is any one of 1-butyl-3-methylimidazolium tetrafluoroborate and 1-butyl-3-methylimidazolium hexafluorophosphate.

[0016] By adopting the above technical solution, C is selected. 10 -C 13 Chlorinated paraffins, as chlorinated alkane segments, are short-chain chlorinated paraffins that can form stable interactions with the first monomer. Their moderate carbon chain length allows for precise matching of target recognition sites, enhancing the specific adsorption capacity of the molecularly imprinted material. The first monomer is selected from methacrylic acid, itaconic acid, or maleic acid, all of which contain carboxyl functional groups. These carboxyl groups can bind to the short-chain chlorinated paraffins, providing ample reaction sites for imprinting. The binary carboxyl groups in itaconic acid and maleic acid further enhance the binding strength, adapting to different adsorption requirements. The ionic liquid selected is 1-butyl-3-methylimidazolium tetrafluoroborate or hexafluorophosphate, which exhibits high thermal stability and improves the dispersibility and compatibility of the microspheres.

[0017] Optionally, the water bath temperature in step S2 is 50-70℃.

[0018] By adopting the above technical solution, the water bath temperature is controlled at 50-70℃. This temperature range can effectively activate the initiator and ensure that the microsphere preparation process proceeds smoothly, thereby obtaining microspheres with uniform size and good dispersibility.

[0019] Optionally, the rinsing solution is a mixture of methanol and acetic acid; the volume ratio of methanol to acetic acid is (8-10):1.

[0020] By employing the above technical solution, a methanol-acetic acid mixture with a volume ratio of (8-10):1 is used to wash the precipitate. The strong solubility of methanol effectively removes unreacted first or second monomers and crosslinking agents, among other impurities. A small amount of acetic acid provides an acidic environment, which, through protonation, disrupts the hydrogen bonds or electrostatic interactions between the template molecules and the first or second monomers, significantly improving the elution efficiency of the template molecules. This ratio ensures effective elution while avoiding damage to the imprinted site structure caused by excessive acidity, thus ensuring the stability of the material's subsequent enrichment performance.

[0021] Optionally, the solvent is a mixed solution of acetonitrile and water; the volume ratio of acetonitrile to water is (8-10):1.

[0022] By adopting the above technical solution, acetonitrile as the main phase can effectively dissolve template molecules, the first monomer and the crosslinking agent, ensuring uniform microsphere polymerization; the introduction of a small amount of water can adjust the overall polarity of the solvent and promote hydrogen bonding between template molecules and the first or second monomer.

[0023] Optionally, the stirring rate in step S4 is 500-1000 rpm.

[0024] By adopting the above technical solution and adjusting the stirring speed to 500-1000 rpm, microspheres with uniform particle size of 200-500 nm are prepared, thereby avoiding large particles from clogging the solid phase extraction column.

[0025] Secondly, the molecularly imprinted composite filler provided in this application has the following applications: Application of a molecularly imprinted composite filler in the efficient enrichment of trace template molecules in complex matrices.

[0026] In this preparation method, the raw materials and their functions are as follows: The template molecule is a short-chain chlorinated paraffin. As an imprinted template molecule, its chlorine-containing structure can be pre-assembled with the carboxyl group of methacrylic acid through hydrogen bonding or electrostatic interaction. After further polymerization into microspheres, it leaves specific recognition sites that match its spatial structure and polarity after elution, providing guidance for subsequent adsorption of target substances.

[0027] The first monomer is methacrylic acid. The carboxyl groups in methacrylic acid can form hydrogen bonds or electrostatic interactions with the chlorine atoms of the template molecule to achieve pre-assembly. At the same time, the carbon-carbon double bonds it contains can participate in free radical polymerization, and together with the crosslinking agent and the second monomer, they can construct the polymer skeleton, fix the configuration of the recognition sites in the network, and form microspheres.

[0028] The crosslinking agent is ethylene glycol dimethacrylate. The carbon-carbon double bonds at both ends of the molecule can undergo free radical polymerization with the double bonds of methacrylic acid under the action of an initiator. The first monomer is connected by covalent bonds to form a rigid network skeleton structure, which enhances the mechanical stability of the microspheres and fixes the spatial configuration of the recognition sites, ensuring that the pore structure matching the target can still be maintained after the template is eluted.

[0029] The initiator is azobisisobutyronitrile (AIBN), which decomposes under water bath heating to generate free radicals, initiating the polymerization reaction between the monomer and the crosslinking agent.

[0030] The ionic liquid is 1-butyl-3-methylimidazolium hexafluorophosphate. Its high polarity enhances the electrostatic attraction to chlorine atoms in short-chain chlorinated paraffins. Alternatively, modification can be achieved by ionic bonding with residual carboxyl groups on the microsphere surface. Furthermore, the butyl chain provides hydrophobicity, repelling water molecules and reducing interference.

[0031] The second monomer is 3-[tris-(hexyloxy)silyl]propylamine. The amino group can crosslink with the residual carboxyl group of the microsphere. The long-chain alkyl group of trihexyloxysilane works synergistically with the hydrophobic structure of the ionic liquid to form a dense hydrophobic layer, which further repels the aqueous phase and enhances the affinity with the hydrophobic target, thus synergistically improving the hydrophobic effect of the molecularly imprinted composite filler.

[0032] In summary, this application includes at least one of the following beneficial technical effects: 1. Microspheres were prepared by using template molecules and a first monomer under the action of a crosslinking agent and an initiator. The microspheres were then modified with an ionic liquid and a second monomer to enhance the hydrophobicity and enrichment effect of the molecularly imprinted composite filler. The enrichment performance of the molecularly imprinted composite filler was controlled by changing the molar ratio of the first monomer to the template molecule, thereby enhancing the anti-interference ability of impurities.

[0033] 2. By optimizing the molecularly imprinted composite filler to reduce the amount of template molecules used and by using reusable ionic liquids, the overall cost is reduced. At the same time, the molecularly imprinted composite filler reduces the adsorption of oils and significantly improves the detection sensitivity of short-chain chlorinated paraffins in complex matrices. Detailed Implementation

[0034] The parameters for using specific chemical substances, and their sources.

[0035] C 12 H 17Cl6, purity ≥98%, brand: Sigma-Aldrich.

[0036] 1. Butyl-3-methylimidazolium hexafluorophosphate, CAS No.: 174501-64-5, Model: [BMIM][PF6], 99%, Brand: IoLiTec.

[0037] 3-[tris-(hexyloxy)silyl]propylamine, CAS No.: 94277-92-6, Brand: Dayang.

[0038] Short-chain chlorinated paraffins (SCCPs) are a class of persistent organic pollutants widely found in industrial products and environmental media. Due to their toxicity and bioaccumulation, they have been included in the Stockholm Convention's control list. However, the detection of SCCPs faces two major challenges: severe matrix interference; and the fact that environmental samples such as water, soil, and food packaging materials often contain large amounts of interfering substances such as oils and humic acids, which can easily cover the target analyte or clog analytical instruments. These two challenges make trace enrichment difficult. Furthermore, traditional solid-phase extraction packing materials such as C18 lack specific recognition capabilities, resulting in low enrichment efficiency and insufficient sensitivity.

[0039] Therefore, this application enhances the enrichment effect of short-chain chlorinated paraffins by preparing sub-imprinted composite fillers. The short-chain chlorinated paraffins in this application are C... 12 H 17 Cl6. Therefore, molecular imprinting technology is used to obtain C 12 H 17 Cl6 serves as the template molecule to construct a specific recognition site that matches the spatial structure and functional groups of the target analyte. Simultaneously, an ionic liquid and an optional second monomer are introduced. The hydrophobic chain of the ionic liquid repels water molecules, while the long-chain alkyl group of the second monomer further synergistically forms a dense hydrophobic layer with the ionic liquid, reducing interference from the aqueous phase and competition for matrix adsorption. Enhancing the enrichment effect is to accurately capture trace amounts of short-chain chlorinated paraffins to meet detection sensitivity requirements, while strengthening the hydrophobic effect is to resist hydrophilic interference in complex matrices, ultimately achieving highly efficient enrichment of trace amounts of short-chain chlorinated paraffins in complex matrices.

[0040] Example 1 A method for preparing a molecularly imprinted composite filler includes the following steps: S1. Mix 450 L of acetonitrile with 50 L of water to obtain an acetonitrile aqueous solution. Then add 1 mol C 12 H 17 Cl6 and 1 mol of methacrylic acid were dissolved in 500 L of acetonitrile aqueous solution and ultrasonicated at 200 W for 30 min to obtain the first mixture; S2. Add 20 mol of ethylene glycol dimethacrylate and 0.5 mol of azobisisobutyronitrile to the first mixture, purge with nitrogen for 15 min to deoxygenate, and incubate in a water bath at 60°C for 24 h to obtain the second mixture. S3. Centrifuge the second mixture at 10,000 rpm for 20 min, discard the supernatant, and collect the precipitate. Prepare an elution solution by mixing methanol and acetic acid at a volume ratio of 9:1. Add the precipitate to 20 L of the elution solution, sonicate at 8000 W for 2 min, then centrifuge at 10,000 rpm for 15 min. Repeat the above elution operation three times. Take the clear supernatant and analyze it by high-performance liquid chromatography (HPLC) until no residue is found. When no obvious chromatographic peaks appear in the HPLC chromatogram, or the peak area is below the HPLC detection limit, C can be considered precipitated. 12 H 17 Cl6 has been completely eluted. Otherwise, repeat the previous elution process. Then C 12 H 17 The precipitate obtained after complete elution of Cl6 was added to an autoclave. Liquid carbon dioxide was introduced into the autoclave, and the autoclave was closed. The carbon dioxide inside the autoclave was heated and pressurized to reach its supercritical point of 31.1℃ and 7.38MPa through external heating and pressurization. The temperature was then maintained for 2 hours. While maintaining the temperature of 31.1℃, the pressure inside the autoclave was reduced to atmospheric pressure to obtain microspheres.

[0041] S4. Dissolve 820g of 1-butyl-3-methylimidazolium hexafluorophosphate in 9.4L of acetonitrile. Add 100g of the microspheres prepared above, stir at 800rpm at 25℃; centrifuge at 10000rpm for 10min, collect the precipitate, wash the precipitate three times with acetonitrile, and vacuum dry at 60℃ for 12h to obtain the molecularly imprinted composite filler.

[0042] Example 2 A method for preparing a molecularly imprinted composite filler includes the following steps: S1. Mix 450 L of acetonitrile with 50 L of water to obtain an acetonitrile aqueous solution. Then add 1 mol C 12 H 17 Cl6 and 4 mol of methacrylic acid were dissolved in 500 L of acetonitrile aqueous solution and ultrasonicated at 200 W for 30 min to obtain the first mixture; S2. Add 20 mol of ethylene glycol dimethacrylate and 0.5 mol of azobisisobutyronitrile to the first mixture, purge with nitrogen for 15 min to deoxygenate, and incubate in a water bath at 60°C for 24 h to obtain the second mixture. S3. Centrifuge the second mixture at 10,000 rpm for 20 min, discard the supernatant, and collect the precipitate. Prepare an elution solution by mixing methanol and acetic acid at a volume ratio of 9:1. Add the precipitate to 20 L of the elution solution, sonicate at 8000 W for 2 min, then centrifuge at 10,000 rpm for 15 min. Repeat the above elution operation three times. Take the clear supernatant and analyze it by high-performance liquid chromatography (HPLC) until no residue is found. When no obvious chromatographic peaks appear in the HPLC chromatogram, or the peak area is below the HPLC detection limit, C can be considered precipitated. 12 H 17 Cl6 has been completely eluted. Otherwise, repeat the previous elution process. Then C 12 H 17 The precipitate obtained after complete elution of Cl6 was added to an autoclave, and liquid carbon dioxide was then introduced into the autoclave. The autoclave was then closed, and the carbon dioxide inside the autoclave was heated and pressurized to reach its supercritical point of 31.1℃ and 7.38MPa through external heating and pressurization. The temperature was then maintained for 2 hours. While maintaining the temperature of 31.1℃, the pressure inside the autoclave was reduced to atmospheric pressure, thus obtaining microspheres.

[0043] S4. Dissolve 820g of 1-butyl-3-methylimidazolium hexafluorophosphate in 9.4L of acetonitrile. Add 100g of the microspheres prepared above, stir at 800rpm at 25℃; centrifuge at 10000rpm for 10min, collect the precipitate, wash the precipitate three times with acetonitrile, and vacuum dry at 60℃ for 12h to obtain the molecularly imprinted composite filler.

[0044] Example 3 A method for preparing a molecularly imprinted composite filler includes the following steps: S1. Mix 450 L of acetonitrile with 50 L of water to obtain an acetonitrile aqueous solution. Then add 1 mol C 12 H 17 Cl6 and 8 mol of methacrylic acid were dissolved in 500 L of acetonitrile aqueous solution and ultrasonicated at 200 W for 30 min to obtain the first mixture; S2. Add 20 mol of ethylene glycol dimethacrylate and 0.5 mol of azobisisobutyronitrile to the first mixture, purge with nitrogen for 15 min to deoxygenate, and incubate in a water bath at 60°C for 24 h to obtain the second mixture. S3. Centrifuge the second mixture at 10,000 rpm for 20 min, discard the supernatant, and collect the precipitate. Prepare an elution solution by mixing methanol and acetic acid at a volume ratio of 9:1. Add the precipitate to 20 L of the elution solution, sonicate at 8000 W for 2 min, then centrifuge at 10,000 rpm for 15 min. Repeat the above elution operation three times. Take the clear supernatant and analyze it by high-performance liquid chromatography (HPLC) until no residue is found. When no obvious chromatographic peaks appear in the HPLC chromatogram, or the peak area is below the HPLC detection limit, C can be considered precipitated. 12 H 17 Cl6 has been completely eluted. Otherwise, repeat the previous elution process. Then C 12 H 17 The precipitate obtained after complete elution of Cl6 was added to an autoclave, and liquid carbon dioxide was then introduced into the autoclave. The autoclave was then closed, and the carbon dioxide inside the autoclave was heated and pressurized to reach its supercritical point of 31.1℃ and 7.38MPa through external heating and pressurization. The temperature was then maintained for 2 hours. While maintaining the temperature of 31.1℃, the pressure inside the autoclave was reduced to atmospheric pressure, thus obtaining microspheres.

[0045] S4. Dissolve 820g of 1-butyl-3-methylimidazolium hexafluorophosphate in 9.4L of acetonitrile. Add 100g of the microspheres prepared above, stir at 800rpm at 25℃; centrifuge at 10000rpm for 10min, collect the precipitate, wash the precipitate three times with acetonitrile, and vacuum dry at 60℃ for 12h to obtain the molecularly imprinted composite filler.

[0046] Example 4 A method for preparing a molecularly imprinted composite filler includes the following steps: S1. Mix 450 L of acetonitrile with 50 L of water to obtain an acetonitrile aqueous solution. Then add 1 mol C 12 H 17 Cl6 and 16 mol of methacrylic acid were dissolved in 500 L of acetonitrile aqueous solution and ultrasonicated at 200 W for 30 min to obtain the first mixture; S2. Add 20 mol of ethylene glycol dimethacrylate and 0.5 mol of azobisisobutyronitrile to the first mixture, purge with nitrogen for 15 min to deoxygenate, and incubate in a water bath at 60°C for 24 h to obtain the second mixture. S3. Centrifuge the second mixture at 10,000 rpm for 20 min, discard the supernatant, and collect the precipitate. Prepare an elution solution by mixing methanol and acetic acid at a volume ratio of 9:1. Add the precipitate to 20 L of the elution solution, sonicate at 8000 W for 2 min, then centrifuge at 10,000 rpm for 15 min. Repeat the above elution operation three times. Take the clear supernatant and analyze it by high-performance liquid chromatography (HPLC) until no residue is found. When no obvious chromatographic peaks appear in the HPLC chromatogram, or the peak area is below the HPLC detection limit, C can be considered precipitated. 12 H 17 Cl6 has been completely eluted. Otherwise, repeat the previous elution process. Then C 12 H 17 The precipitate obtained after complete elution of Cl6 was added to an autoclave, and liquid carbon dioxide was then introduced into the autoclave. The autoclave was then closed, and the carbon dioxide inside the autoclave was heated and pressurized to reach its supercritical point of 31.1℃ and 7.38MPa through external heating and pressurization. The temperature was then maintained for 2 hours. While maintaining the temperature of 31.1℃, the pressure inside the autoclave was reduced to atmospheric pressure, thus obtaining microspheres.

[0047] S4. Dissolve 820g of 1-butyl-3-methylimidazolium hexafluorophosphate in 9.4L of acetonitrile. Add 100g of the microspheres prepared above, stir at 800rpm at 25℃; centrifuge at 10000rpm for 10min, collect the precipitate, wash the precipitate three times with acetonitrile, and vacuum dry at 60℃ for 12h to obtain the molecularly imprinted composite filler.

[0048] Comparative Example 1 A method for preparing a molecularly imprinted composite filler includes the following steps: S1. Mix 450 L of acetonitrile with 50 L of water to obtain an acetonitrile aqueous solution. Then add 1 mol C 12 H 17 Cl6 was dissolved in 500 L of acetonitrile aqueous solution and ultrasonicated at 200 W for 30 min to obtain the first mixture; S2. Add 20 mol of ethylene glycol dimethacrylate and 0.5 mol of azobisisobutyronitrile to the first mixture, purge with nitrogen for 15 min to deoxygenate, and incubate in a water bath at 60°C for 24 h to obtain the second mixture. S3. Centrifuge the second mixture at 10,000 rpm for 20 min, discard the supernatant, and collect the precipitate. Prepare an elution solution by mixing methanol and acetic acid at a volume ratio of 9:1. Add the precipitate to 20 L of the elution solution, sonicate at 8000 W for 2 min, then centrifuge at 10,000 rpm for 15 min. Repeat the above elution operation three times. Analyze the clear supernatant using high-performance liquid chromatography (HPLC) until no residue is found. When no obvious chromatographic peaks appear in the HPLC chromatogram, or when the peak area is below the HPLC detection limit, C is considered precipitated. 12 H 17 Cl6 has been completely eluted. Otherwise, repeat the previous elution process. Then C 12 H 17 The precipitate obtained after complete elution of Cl6 was added to an autoclave. Liquid carbon dioxide was introduced into the autoclave, and the autoclave was closed. The carbon dioxide inside the autoclave was heated and pressurized to reach its supercritical point of 31.1℃ and 7.38MPa through external heating and pressurization. The temperature was then maintained for 2 hours. While maintaining the temperature of 31.1℃, the pressure inside the autoclave was reduced to atmospheric pressure to obtain microspheres.

[0049] S4. Dissolve 820g of 1-butyl-3-methylimidazolium hexafluorophosphate in 9.4L of acetonitrile. Add 100g of the microspheres prepared above, stir at 800rpm at 25℃; centrifuge at 10000rpm for 10min, collect the precipitate, wash the precipitate three times with acetonitrile, and vacuum dry at 60℃ for 12h to obtain the molecularly imprinted composite filler.

[0050] Application Examples The molecularly imprinted composite fillers prepared in Examples 1-4 and Comparative Example 1 were applied to the enrichment and determination of short-chain chlorinated paraffins.

[0051] Packing and preparation of solid-phase extraction (SPE) column: A polyethylene sieve plate was installed at the bottom of a hollow polypropylene column and compacted. 50 mg of molecularly imprinted composite packing material and 50 mg of silica gel were weighed and mixed at 200 rpm for 2 min. The mixture was then packed into a 6 mL hollow polypropylene column. A polyethylene sieve plate was installed at the top of the polymer packing material and compacted to obtain a molecularly imprinted composite packing solid-phase extraction column.

[0052] Loading of short-chain chlorinated paraffin samples: The molecularly imprinted composite solid-phase extraction column was rinsed with 5 mL of methanol, followed by 5 mL of water. 50 mL of blank sample matrix soil leachate was added to 2.5 μL of a 1 μg / mL short-chain chlorinated paraffin standard solution, and mixed at 100 rpm for 10 min. A 25 wt% hydrochloric acid aqueous solution was added to the above solution to adjust the pH to 4, thus preparing the sample to be tested. The sample was passed through the molecularly imprinted composite solid-phase extraction column at a uniform rate of 5 mL / min, and the liquid remaining at the bottom of the column was collected.

[0053] Elution and Concentration: The elution step involves mixing 2.5 mL of n-hexane and 2.5 mL of dichloromethane at 200 rpm for 2 min to obtain the eluent. This eluent is then added dropwise at 1 mL / min to the top of the molecularly imprinted composite solid-phase extraction column. After the first round of eluent has mostly dissipated, the elution step is repeated twice to ensure complete removal of the short-chain chlorinated paraffins. The concentration step involves combining all collected eluents and placing them in a water bath of a nitrogen evaporator at 30°C. Nitrogen evaporation is then initiated until the eluent is reduced to 0.5 mL.

[0054] Test Example 1 The 0.5 mL products obtained after elution and concentration in Examples 1-4 and Comparative Example 1 were tested respectively, and detected using GC-MS / MS (Agilent 7000D). The chromatographic column was DB-5MS 30m×0.25mm×0.25μm, and the temperature was kept at 80℃ for 1 min, then increased to 300℃ at 25℃ / min and held for 10 min. The mass spectrometry conditions were electron impact source (EI), ion monitoring (SIM) mode, and quantitative ion mass-to-charge ratio m / z = 225. The recovery method was used, and the recovery rate (%) was calculated as (detected spike amount / actual spike amount) × 100%. In this application, the actual spike amount was 0.005 mg / kg. The test results are shown in Table 1. Table 1 Recovery rate test results Experimental group Recovery rate (%) Example 1 87.12 Example 2 95.54 Example 3 92.82 Example 4 85.36 Comparative Example 1 1.33 By observing the recovery rate test data in Examples 1-5 and Comparative Example 1 in Table 1, it was found that the molecularly imprinted composite filler prepared in Example 2 had the highest recovery rate for short-chain chlorinated paraffins. This may be because the carboxyl groups on methacrylic acid are key functional groups that form electrostatic forces such as hydrogen bonds or halogen bonds with hydrogen or chlorine atoms on the CH bonds in short-chain chlorinated paraffin molecules. When the amount of methacrylic acid in Example 1 and Comparative Example 1 is too low, the number of carboxyl groups in the polymer that can react with short-chain chlorinated paraffins is insufficient, resulting in few effective recognition sites and an inability to fully capture short-chain chlorinated paraffin molecules in the sample, thus exhibiting a low recovery rate. This is especially true when the amount of methacrylic acid in Comparative Example 1 is so low that it cannot form a polymer, which significantly reduces the recovery rate. As the amount of methacrylic acid increases to the 1:4 ratio in Example 2, sufficient methacrylic acid monomers accumulate around the template molecules, forming a sufficient number of recognition sites under the action of ethylene glycol dimethacrylate. At this point, both the number of binding sites and the strength of the interaction are ideal, thus exhibiting the highest enrichment efficiency. Therefore, the recovery effect of short-chain chlorinated paraffin molecules in Example 2 is better.

[0055] However, when the amount of methacrylic acid is further excessive, as in Examples 3 and 4, although theoretically the number of carboxyl groups is greater, the excessively high monomer concentration leads to the formation of a large number of free carboxyl groups that do not directly interact with short-chain chlorinated paraffin molecules during polymerization. These excess carboxyl groups are distributed on the polymer backbone and pore surface, which may interfere with the target molecule's entry into specific sites through steric hindrance. Excess methacrylic acid may also cause the polymer network structure to be too dense or disordered, affecting the recovery efficiency. Therefore, in Example 2, when the ratio of functional monomer to template molecule is appropriate, the number of recognition sites and the microstructure of the molecularly imprinted composite filler achieve the best enrichment effect.

[0056] Examples 5-9 and Comparative Example 2 described below are further examples based on Example 2.

[0057] Example 5 A method for preparing a molecularly imprinted composite filler includes the following steps: S1. Mix 450 L of acetonitrile with 50 L of water to obtain an acetonitrile aqueous solution. Then add 1 mol C 12 H 17 Cl6 and 4 mol of methacrylic acid were dissolved in 500 L of acetonitrile aqueous solution and ultrasonicated at 200 W for 30 min to obtain the first mixture; S2. Add 20 mol of ethylene glycol dimethacrylate and 0.5 mol of azobisisobutyronitrile to the first mixture, purge with nitrogen for 15 min to deoxygenate, and incubate in a water bath at 60°C for 24 h to obtain the second mixture. S3. Centrifuge the second mixture at 10,000 rpm for 20 min, discard the supernatant, and collect the precipitate. Prepare an elution solution by mixing methanol and acetic acid at a volume ratio of 9:1. Add the precipitate to 20 L of the elution solution, sonicate at 8000 W for 2 min, then centrifuge at 10,000 rpm for 15 min. Repeat the above elution operation three times. Take the clear supernatant and analyze it by high-performance liquid chromatography (HPLC) until no residue is found. When no obvious chromatographic peaks appear in the HPLC chromatogram, or the peak area is below the HPLC detection limit, C can be considered precipitated. 12 H 17 Cl6 has been completely eluted. Otherwise, repeat the previous elution process. Then C 12 H 17 The precipitate obtained after complete elution of Cl6 was added to an autoclave. Liquid carbon dioxide was introduced into the autoclave, and the autoclave was closed. The carbon dioxide inside the autoclave was heated and pressurized to reach its supercritical point of 31.1℃ and 7.38MPa through external heating and pressurization. The temperature was then maintained for 2 hours. While maintaining the temperature of 31.1℃, the pressure inside the autoclave was reduced to atmospheric pressure to obtain microspheres.

[0058] S4. Dissolve 820g of 1-butyl-3-methylimidazolium hexafluorophosphate in 9.4L of acetonitrile. Add 100g of the microspheres prepared above to obtain a third mixture. Then add 32.8g of 3-[tris-(hexyloxy)silyl]propylamine to the third mixture. Stir at 800rpm at 25℃; centrifuge at 10000rpm for 10min, collect the precipitate, wash the precipitate three times with acetonitrile, and dry under vacuum at 60℃ for 12h to obtain the molecularly imprinted composite filler.

[0059] Example 6 A method for preparing a molecularly imprinted composite filler includes the following steps: S1. Mix 450 L of acetonitrile with 50 L of water to obtain an acetonitrile aqueous solution. Then add 1 mol C 12 H 17 Cl6 and 4 mol of methacrylic acid were dissolved in 500 L of acetonitrile aqueous solution and ultrasonicated at 200 W for 30 min to obtain the first mixture; S2. Add 20 mol of ethylene glycol dimethacrylate and 0.5 mol of azobisisobutyronitrile to the first mixture, purge with nitrogen for 15 min to deoxygenate, and incubate in a water bath at 60°C for 24 h to obtain the second mixture. S3. Centrifuge the second mixture at 10,000 rpm for 20 min, discard the supernatant, and collect the precipitate. Prepare an elution solution by mixing methanol and acetic acid at a volume ratio of 9:1. Add the precipitate to 20 L of the elution solution, sonicate at 8000 W for 2 min, then centrifuge at 10,000 rpm for 15 min. Repeat the above elution operation three times. Take the clear supernatant and analyze it by high-performance liquid chromatography (HPLC) until no residue is found. When no obvious chromatographic peaks appear in the HPLC chromatogram, or the peak area is below the HPLC detection limit, C can be considered precipitated. 12 H 17 Cl6 has been completely eluted. Otherwise, repeat the previous elution process. Then C 12 H 17 The precipitate obtained after complete elution of Cl6 was added to an autoclave, and liquid carbon dioxide was then introduced into the autoclave. The autoclave was then closed, and the carbon dioxide inside the autoclave was heated and pressurized to reach its supercritical point of 31.1℃ and 7.38MPa through external heating and pressurization. The temperature was then maintained for 2 hours. While maintaining the temperature of 31.1℃, the pressure inside the autoclave was reduced to atmospheric pressure, thus obtaining microspheres.

[0060] S4. Dissolve 820g of 1-butyl-3-methylimidazolium hexafluorophosphate in 9.4L of acetonitrile. Add 100g of the microspheres prepared above to obtain a third mixture. Then add 43.1g of 3-[tris-(hexyloxy)silyl]propylamine to the third mixture. Stir at 800rpm at 25℃; centrifuge at 10000rpm for 10min, collect the precipitate, wash the precipitate three times with acetonitrile, and dry under vacuum at 60℃ for 12h to obtain the molecularly imprinted composite filler.

[0061] Example 7 A method for preparing a molecularly imprinted composite filler includes the following steps: S1. Mix 450 L of acetonitrile with 50 L of water to obtain an acetonitrile aqueous solution. Then add 1 mol C 12 H 17 Cl6 and 4 mol of methacrylic acid were dissolved in 500 L of acetonitrile aqueous solution and ultrasonicated at 200 W for 30 min to obtain the first mixture; S2. Add 20 mol of ethylene glycol dimethacrylate and 0.5 mol of azobisisobutyronitrile to the first mixture, purge with nitrogen for 15 min to deoxygenate, and incubate in a water bath at 60°C for 24 h to obtain the second mixture. S3. Centrifuge the second mixture at 10,000 rpm for 20 min, discard the supernatant, and collect the precipitate. Prepare an elution solution by mixing methanol and acetic acid at a volume ratio of 9:1. Add the precipitate to 20 L of the elution solution, sonicate at 8000 W for 2 min, then centrifuge at 10,000 rpm for 15 min. Repeat the above elution operation three times. Take the clear supernatant and analyze it by high-performance liquid chromatography (HPLC) until no residue is found. When no obvious chromatographic peaks appear in the HPLC chromatogram, or the peak area is below the HPLC detection limit, C can be considered precipitated. 12 H 17 Cl6 has been completely eluted. Otherwise, repeat the previous elution process. Then C 12 H 17 The precipitate obtained after complete elution of Cl6 was added to an autoclave, and liquid carbon dioxide was then introduced into the autoclave. The autoclave was then closed, and the carbon dioxide inside the autoclave was heated and pressurized to reach its supercritical point of 31.1℃ and 7.38MPa through external heating and pressurization. The temperature was then maintained for 2 hours. While maintaining the temperature of 31.1℃, the pressure inside the autoclave was reduced to atmospheric pressure, thus obtaining microspheres.

[0062] S4. Dissolve 820g of 1-butyl-3-methylimidazolium hexafluorophosphate in 9.4L of acetonitrile. Add 100g of the microspheres prepared above to obtain a third mixture. Then add 52.2g of 3-[tris-(hexyloxy)silyl]propylamine to the third mixture. Stir at 800rpm at 25℃; centrifuge at 10000rpm for 10min, collect the precipitate, wash the precipitate three times with acetonitrile, and dry under vacuum at 60℃ for 12h to obtain the molecularly imprinted composite filler.

[0063] Example 8 A method for preparing a molecularly imprinted composite filler includes the following steps: S1. Mix 450 L of acetonitrile with 50 L of water to obtain an acetonitrile aqueous solution. Then add 1 mol C 12 H 17 Cl6 and 4 mol of methacrylic acid were dissolved in 500 L of acetonitrile aqueous solution and ultrasonicated at 200 W for 30 min to obtain the first mixture; S2. Add 20 mol of ethylene glycol dimethacrylate and 0.5 mol of azobisisobutyronitrile to the first mixture, purge with nitrogen for 15 min to deoxygenate, and incubate in a water bath at 60°C for 24 h to obtain the second mixture. S3. Centrifuge the second mixture at 10,000 rpm for 20 min, discard the supernatant, and collect the precipitate. Prepare an elution solution by mixing methanol and acetic acid at a volume ratio of 9:1. Add the precipitate to 20 L of the elution solution, sonicate at 8000 W for 2 min, then centrifuge at 10,000 rpm for 15 min. Repeat the above elution operation three times. Take the clear supernatant and analyze it by high-performance liquid chromatography (HPLC) until no residue is found. When no obvious chromatographic peaks appear in the HPLC chromatogram, or the peak area is below the HPLC detection limit, C can be considered precipitated. 12 H 17 Cl6 has been completely eluted. Otherwise, repeat the previous elution process. Then C 12 H 17 The precipitate obtained after complete elution of Cl6 was added to an autoclave, and liquid carbon dioxide was then introduced into the autoclave. The autoclave was then closed, and the carbon dioxide inside the autoclave was heated and pressurized to reach its supercritical point of 31.1℃ and 7.38MPa through external heating and pressurization. The temperature was then maintained for 2 hours. While maintaining the temperature of 31.1℃, the pressure inside the autoclave was reduced to atmospheric pressure, thus obtaining microspheres.

[0064] S4. Dissolve 820g of 1-butyl-3-methylimidazolium hexafluorophosphate in 9.4L of acetonitrile. Add 100g of the microspheres prepared above to obtain a third mixture. Then add 61.6g of 3-[tris-(hexyloxy)silyl]propylamine to the third mixture. Stir at 800rpm at 25℃; centrifuge at 10000rpm for 10min, collect the precipitate, wash the precipitate three times with acetonitrile, and dry under vacuum at 60℃ for 12h to obtain the molecularly imprinted composite filler.

[0065] Example 9 A method for preparing a molecularly imprinted composite filler includes the following steps: S1. Mix 450 L of acetonitrile with 50 L of water to obtain an acetonitrile aqueous solution. Then add 1 mol C 12 H 17 Cl6 and 4 mol of methacrylic acid were dissolved in 500 L of acetonitrile aqueous solution and ultrasonicated at 200 W for 30 min to obtain the first mixture; S2. Add 20 mol of ethylene glycol dimethacrylate and 0.5 mol of azobisisobutyronitrile to the first mixture, purge with nitrogen for 15 min to deoxygenate, and incubate in a water bath at 60°C for 24 h to obtain the second mixture. S3. Centrifuge the second mixture at 10,000 rpm for 20 min, discard the supernatant, and collect the precipitate. Prepare an elution solution by mixing methanol and acetic acid at a volume ratio of 9:1. Add the precipitate to 20 L of the elution solution, sonicate at 8000 W for 2 min, then centrifuge at 10,000 rpm for 15 min. Repeat the above elution operation three times. Take the clear supernatant and analyze it by high-performance liquid chromatography (HPLC) until no residue is found. When no obvious chromatographic peaks appear in the HPLC chromatogram, or the peak area is below the HPLC detection limit, C can be considered precipitated. 12 H 17 Cl6 has been completely eluted. Otherwise, repeat the previous elution process. Then C 12 H 17 The precipitate obtained after complete elution of Cl6 was added to an autoclave, and liquid carbon dioxide was then introduced into the autoclave. The autoclave was then closed, and the carbon dioxide inside the autoclave was heated and pressurized to reach its supercritical point of 31.1℃ and 7.38MPa through external heating and pressurization. The temperature was then maintained for 2 hours. While maintaining the temperature of 31.1℃, the pressure inside the autoclave was reduced to atmospheric pressure, thus obtaining microspheres.

[0066] S4. Dissolve 820g of 1-butyl-3-methylimidazolium hexafluorophosphate in 9.4L of acetonitrile. Add 100g of the microspheres prepared above to obtain a third mixture. Then add 65.6g of 3-[tris-(hexyloxy)silyl]propylamine to the third mixture. Stir at 800rpm at 25℃; centrifuge at 10000rpm for 10min, collect the precipitate, wash the precipitate three times with acetonitrile, and dry under vacuum at 60℃ for 12h to obtain the molecularly imprinted composite filler.

[0067] Comparative Example 2 A method for preparing a molecularly imprinted composite filler includes the following steps: S1. Mix 450 L of acetonitrile with 50 L of water to obtain an acetonitrile aqueous solution. Then add 1 mol C 12 H 17 Cl6 and 4 mol of methacrylic acid were dissolved in 500 L of acetonitrile aqueous solution and ultrasonicated at 200 W for 30 min to obtain the first mixture; S2. Add 20 mol of ethylene glycol dimethacrylate and 0.5 mol of azobisisobutyronitrile to the first mixture, purge with nitrogen for 15 min to deoxygenate, and incubate in a water bath at 60°C for 24 h to obtain the second mixture. S3. Centrifuge the second mixture at 10,000 rpm for 20 min, discard the supernatant, and collect the precipitate. Prepare an elution solution by mixing methanol and acetic acid at a volume ratio of 9:1. Add the precipitate to 20 L of the elution solution, sonicate at 8000 W for 2 min, then centrifuge at 10,000 rpm for 15 min. Repeat the above elution operation three times. Take the clear supernatant and analyze it by high-performance liquid chromatography (HPLC) until no residue is found. When no obvious chromatographic peaks appear in the HPLC chromatogram, or the peak area is below the HPLC detection limit, C can be considered precipitated. 12 H 17 Cl6 has been completely eluted. Otherwise, repeat the previous elution process. Then C 12 H 17 The precipitate obtained after complete elution of Cl6 was added to an autoclave, and liquid carbon dioxide was then introduced into the autoclave. The autoclave was then closed, and the carbon dioxide inside the autoclave was heated and pressurized to reach its supercritical point of 31.1℃ and 7.38MPa through external heating and pressurization. The temperature was then maintained for 2 hours. While maintaining the temperature of 31.1℃, the pressure inside the autoclave was reduced to atmospheric pressure, thus obtaining microspheres.

[0068] S4. Add 52.2g of 3-[tris-(hexyloxy)silyl]propylamine and 9.4L of acetonitrile to 100g of the microspheres prepared above. Then stir at 800rpm at 25℃; centrifuge at 10000rpm for 10min, collect the precipitate, wash the precipitate three times with acetonitrile, and dry under vacuum at 60℃ for 12h to obtain the molecularly imprinted composite filler.

[0069] Application Examples The molecularly imprinted composite fillers prepared in Examples 5-9 and Comparative Example 2 were applied to the enrichment and determination of short-chain chlorinated paraffins, as described in the above application examples.

[0070] Test Example 2 The contact angles between the surface of the molecularly imprinted composite filler in Examples 5-9 and Comparative Example 2 and water were measured using a KSVCM20 contact angle meter.

[0071] The 0.5 mL products obtained after elution and concentration in Examples 5-9 and Comparative Example 2 were tested respectively, and detected using GC-MS / MS (Agilent 7000D). The chromatographic column was DB-5MS 30m×0.25mm×0.25μm, and the temperature was kept at 80℃ for 1 min, then increased to 300℃ at a rate of 25℃ / min, and held for 10 min. The mass spectrometry conditions were electron impact source (EI), ion monitoring (SIM) mode, and quantitative ion mass-to-charge ratio m / z = 225. The recovery method was used, and the recovery rate (%) was calculated as (detected spike amount / actual spike amount) × 100%. In this application, the actual spike amount was 0.005 mg / kg. The test results are shown in Table 2. Table 2. Results of Contact Angle and Recovery Rate Tests Experimental group Contact angle (°) Recovery rate (%) Example 5 123.7 101.4 Example 6 126.9 102.5 Example 7 143.4 103.2 Example 8 122.8 102.7 Example 9 121.5 101.8 Comparative Example 2 104.6 85.2 By observing the test data in Table 2 and comparing the contact angle data of Examples 5-9 and Comparison 2, it can be found that the molecularly imprinted composite filler prepared in Example 7 has the largest contact angle value and the best hydrophobic effect. The reason for these differences in contact angle values ​​may be that 3-[tris-(hexyloxy)silyl]propylamine needs to achieve uniform modification and directional arrangement on the surface of microspheres through the medium of ionic liquid. When the amount of 3-[tris-(hexyloxy)silyl]propylamine added in Examples 5-6 is too low, the ionic liquid in the system is insufficient to fully coat the active sites on the surface of microspheres, and the hydrophobic silane is difficult to effectively anchor and spread, resulting in insufficient exposure of hydrophobic groups and weak hydrophobic effect. When the amount of ionic liquid added is increased to 820g, the ionic liquid can form a suitable adsorption layer on the surface of microspheres, providing a uniform adhesion interface for the hydrophobic silane, so that the hydrophobic long chains can be arranged in an orderly manner and form a dense hydrophobic layer, thereby achieving optimal hydrophobic performance. When an excess of ionic liquid was used in Examples 8-9, the excessive ionic liquid molecules formed multilayer adsorption on the microsphere surface, which sterically hindered the directional arrangement of the hydrophobic silane. Some hydrophobic groups were encapsulated by the ionic liquid, reducing the integrity of the hydrophobic layer and weakening the hydrophobic effect. In Comparative Example 2, no ionic liquid was added, and the hydrophobic silane was difficult to stably bind on the microsphere surface through physical mixing alone, resulting in the worst hydrophobic effect.

[0072] Further observation of the recovery rate changes in Examples 5-9 and Comparative Example 2 in Table 2 reveals that the data for Examples 5-9 are not significantly different, while Example 7 shows better overall recovery performance. This may be because the content of 1-butyl-3-methylimidazolium hexafluorophosphate is fixed, while only the content of 3-[tris-(hexyloxy)silyl]propylamine is varied. The change in the content of 3-[tris-(hexyloxy)silyl]propylamine primarily reflects the hydrophobic effect, hence the minimal difference in recovery rates between Examples 5-9.

[0073] Analysis of the recovery rates in Example 7 and Comparative Example 2 revealed that Example 7 exhibited a better recovery rate. The difference in recovery rates is likely due to the absence of 1-butyl-3-methylimidazolium hexafluorophosphate in Comparative Example 2. The high polarity of 1-butyl-3-methylimidazolium hexafluorophosphate enhances the electrostatic attraction to the chlorine atoms of the short-chain chlorinated paraffin, thus Example 7 demonstrates a better recovery rate, while Example 2 shows a worse recovery. Furthermore, the hydrophobic chain (butyl) in 1-butyl-3-methylimidazolium hexafluorophosphate repels water molecules, reducing interference from the hydration layer and thus exhibiting a hydrophobic effect. Therefore, the hydrophobic effect in Example 7 is better than that in Comparative Example 2.

[0074] Furthermore, comparing the recovery rates in Example 2 and Example 7 reveals that Example 7 exhibits a better recovery rate. This difference in data may be due to the absence of 3-[tris(hexyloxy)silyl]propylamine in Example 2. The introduction of 3-[tris(hexyloxy)silyl]propylamine optimizes the hydrophilicity / hydrophobicity and molecular recognition environment of the molecularly imprinted composite filler surface. The propylamine group in this molecular structure interacts strongly with the residual carboxyl groups on the microsphere surface through acid-base interactions or hydrogen bonding, firmly binding the entire molecule to the microsphere surface. Meanwhile, the tris(hexyloxy)silyl group at the other end, with its strong hydrophobic structure composed of long-chain alkyl groups, spontaneously extends outwards and interweaves with each other, forming a dense, low-surface-energy hydrophobic protective film on the microsphere surface. This film physically repels water molecules, significantly reducing the surface free energy of the molecularly imprinted composite filler, thereby effectively inhibiting the contact and wetting of water molecules with the surface of the molecularly imprinted composite filler in the aqueous system, ultimately achieving optimal hydrophobicity. Meanwhile, 3-[tris(hexyloxy)silyl]propylamine and 1-butyl-3-methylimidazolium hexafluorophosphate synergistically exhibit excellent hydrophobic properties. In Example 2, because 3-[tris(hexyloxy)silyl]propylamine was not added, the hydrophobic effect of the molecularly imprinted composite filler was even worse. The synergistic effect of 3-[tris(hexyloxy)silyl]propylamine and 1-butyl-3-methylimidazolium hexafluorophosphate demonstrates excellent hydrophobic and recyclability.

[0075] The above are all preferred embodiments of this application, and are not intended to limit the scope of protection of this application. Therefore, all equivalent changes made to the structure, shape and principle of this application should be covered within the scope of protection of this application.

Claims

1. A method for preparing a molecularly imprinted composite filler, characterized in that, Includes the following steps: S1. Dissolve the template molecule and the first monomer in a solvent to obtain the first mixture; S2. Add crosslinking agent and initiator to the first mixture obtained in step S1, deoxygenate by passing nitrogen gas, and bathe in a constant temperature water bath to obtain the second mixture. S3. Centrifuge the second mixture obtained in step S2 to obtain a precipitate, wash the precipitate with rinsing solution, dry it, and obtain microspheres; S4. Add the ionic liquid solution to the microspheres obtained in step S3, stir at room temperature, centrifuge, wash, and vacuum dry to obtain the molecularly imprinted composite filler. The template molecule is a chlorinated alkane segment; the first monomer has a carboxyl functional group; and the ionic liquid has an imidazole ring and a long alkyl chain.

2. The method for preparing the molecularly imprinted composite filler according to claim 1, characterized in that, Step S4 may also involve adding an ionic liquid solution to the microspheres obtained in step S3, and then adding a second monomer, wherein the second monomer is silane.

3. The method for preparing the molecularly imprinted composite filler according to claim 2, characterized in that, The mass ratio of the ionic liquid to the second monomer is 25:(1-4).

4. The method for preparing the molecularly imprinted composite filler according to claim 1, characterized in that, The molar ratio of the template molecule to the first monomer is 1:(1-16).

5. The method for preparing the molecularly imprinted composite filler according to claim 1, characterized in that, The template molecule is C. 10 -C 13 Chlorinated paraffin; the first monomer is any one of methacrylic acid, itaconic acid, and maleic acid; the ionic liquid is any one of 1-butyl-3-methylimidazolium tetrafluoroborate and 1-butyl-3-methylimidazolium hexafluorophosphate.

6. The method for preparing the molecularly imprinted composite filler according to claim 1, characterized in that, The water bath temperature in step S2 is 50-70℃.

7. The method for preparing the molecularly imprinted composite filler according to claim 1, characterized in that, The rinsing solution is a mixture of methanol and acetic acid; the volume ratio of methanol to acetic acid is (8-10):

1.

8. The method for preparing the molecularly imprinted composite filler according to claim 1, characterized in that, The solvent is a mixed solution of acetonitrile and water; the volume ratio of acetonitrile to water is (8-10):

1.

9. The method for preparing the molecularly imprinted composite filler according to claim 1, characterized in that, The stirring rate in step S4 is 500-1000 rpm.

10. Application of a molecularly imprinted composite filler in the efficient enrichment of trace template molecules in complex matrices.