Polymer microextraction column with in-situ growth of MOF and preparation and application thereof

Abstract

The application discloses a polymer micro-extraction column with in-situ grown metal organic framework material (MOF), which is prepared by first preparing a polymer monolithic column matrix rich in metal oxide nanoparticles, and then introducing an organic linker solution into the monolithic column to realize self-assembly of the metal oxide and the organic linker on the polymer surface, thereby obtaining a hybrid polymer micro-extraction column with in-situ grown MOF. The polymer micro-extraction column prepared by the application combines the advantages of flexible porous polymer and rigid MOF, has continuous large through holes and rich micro-mesoporous action sites, and simultaneously, due to the fact that the micro-extraction column material is rich in fluorine atoms and open metal sites, can provide hydrogen bond, F-F affinity action and Lewis acid / base complexation action and the like, has specific enrichment effect on persistent organic fluorine pollutants such as perfluorinated compounds and fluorine aromatic compounds, and has very good application prospect in environmental and biological sample pretreatment.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of polymer materials, and particularly relates to a polymer micro-extraction column with in-situ growth of MOF in a capillary porous continuous bed, a preparation method thereof and application thereof in enrichment analysis of persistent organic pollutants. BACKGROUND

[0002] Monolithic column is a continuous porous monolithic material formed by in-situ polymerization or immobilization in the column, has an internal interconnected hierarchical porous network composed of through-pores, mesopores and micropores, and the material surface can be functionalized as needed, and is the preferred material for chromatography and catalysis applications. The polymer micro-extraction (PMME) technology based on capillary monolithic column has the advantages of simple column preparation, low cost, high mass transfer rate, and less sample consumption, and is widely used in the separation and analysis of trace organic pollutants. However, due to the fact that the polymer monolithic column generally lacks sufficient mesopores and interaction sites, the specific surface area and mechanical strength are relatively low, and the column body is prone to shrinkage or swelling in the presence of organic solvents, resulting in low extraction efficiency for small molecules and shortening the column life.

[0003] Introducing advanced porous materials with high stability, high specific surface area and adjustable porosity into organic polymer monolithic column is one of the ways to effectively increase the specific surface area of the stationary phase and the interaction sites with small molecules. Metal-organic frameworks (MOFs) are a class of inorganic-organic hybrid materials formed by self-assembly of metal ions (metal clusters) and organic ligands through coordination bonds, have the characteristics of high porosity, easy modification, large specific surface area, regular pore structure, etc., and can be regarded as a basic unit for constructing various functional materials. The synthesis method of MOF has high universality, and thousands of MOF structures have been found. However, due to the powder form and small particle size of MOF itself, its application in separation and analysis is limited. Studies have shown that MOF can affect the structure of polymer, and polymer can adjust the growth and properties of MOF. Therefore, hybridizing crystalline MOF with flexible polymer monolithic material will effectively combine the advantages of both, and provide an ideal extraction agent for PMME.

[0004] Currently, there are three methods for preparing MOF-based hybrid polymeric monolithic columns: (1) physical embedding method: pre-prepared MOF crystals are dispersed into a polymerization solution to prepare MOF hybrid monolithic materials by one-pot method; (2) chemical bonding method: the MOF is modified to have active sites for polymerization, and the modified MOF is used as a functional monomer to participate in the polymerization; (3) continuous layer-by-layer assembly method (LbL): the precursor solution of MOF is alternately passed through the polymer monolith multiple times to form a thin layer of MOF. However, due to the compatibility between MOF and polymer, the physical embedding and chemical bonding methods can only prepare low-content MOF hybrid monolithic materials, and the uniform distribution of MOF in the monolithic stationary phase is difficult to effectively control, and the pore structure of MOF may be embedded in the polymer support, which makes it difficult to achieve the expected separation or enrichment efficiency, and the advantages of MOF cannot be fully utilized. The tedious LbL method can better control the growth of MOF on the surface of the porous monolithic material, and is suitable for forming a MOF film. However, the assembly process is time-consuming and requires a large amount of organic solvent. Therefore, a new strategy for rapid and effective hybridization of MOF and porous polymer is needed. SUMMARY

[0005] The present application aims to provide a polymer micro-extraction column with in-situ growth of MOF and a preparation method thereof, and the synthesized MOF hybrid polymer effectively integrates the crystallinity, porosity of metal organic framework and the flexibility and processability of polymer, has the characteristics of high specific surface area, stability and multiple interactions, and can be used as a polymer micro-extraction column combined with liquid chromatography, capillary liquid chromatography or LC-MS to realize high-sensitivity detection of trace persistent organic pollutants in the environment and biological samples.

[0006] To achieve the above-mentioned purpose, the present application adopts the following technical solutions:

[0007] One of the purposes of the present application is to protect a polymer micro-extraction column with in-situ growth of MOF, which is formed by in-situ self-assembly of a polymer monolithic column matrix hybridized with organic linking agents and metal oxide nanoparticles in a solvent; wherein the polymer monolithic column matrix hybridized with metal oxide nanoparticles is formed by thermal initiation of free radical polymerization of multi-functional monomers and nano metal oxide (MO-NPs) under the action of an initiator and an ionic liquid pore-forming agent system.

[0008] Further, the organic linking agent is any one of 2-methylimidazole, trimesic acid, terephthalic acid and 2,3-diamino-1,4-benzenedicarboxylic acid.

[0009] Further, the solvent is one of water, N,N-dimethylformamide and water, ethanol and water, or nitric acid, hydrogen fluoride and water.

[0010] Further, the multi-functional monomer is composed of one fluorine-functionalized and containing one double bond organic monomer and one or two double bond-containing organic monomers. Specifically, the fluorine-functionalized and containing one double bond organic monomer can be, for example, dodecafluoroheptyl methacrylate, 2-(trifluoromethyl)acrylic acid, 3-(perfluoro-3-methylbytyl)-2-hydroxypropyl acrylate; the double bond-containing organic monomer can be, for example, methacrylic acid, methyl acrylate, butyl methacrylate, 2-hydroxyethyl methacrylate, ethylene dimethacrylate, trimethylolpropane trimethacrylate, dodecyl methacrylate.

[0011] Further, the nano metal oxide is any one of MOF phase metal oxide of nano zinc oxide (ZnO), nano aluminum oxide (Al2O3), nano copper oxide (CuO), nano iron oxide (Fe2O3), etc.

[0012] Further, the initiator is azobisisobutyronitrile (AIBN).

[0013] Further, the ionic liquid porogen system is a mixture of 1-hexyl-3-methylimidazolium tetrafluoroborate, 1-butyl-3-methylimidazolium tetrafluoroborate or 1-octyl-3-methylimidazolium tetrafluoroborate and 1-propanol; the mass ratio of 1-propanol in the mixture is 23-48%.

[0014] The second object of the present application is to protect the preparation method of the polymer micro-extraction column with in-situ growth of MOF, which comprises the following steps:

[0015] 1) 3-9 mg of nano metal oxide, 30-60 mg of multi-functional monomer, and 1-3 mg of initiator are mixed, and 140-170 mg of ionic liquid pore-forming agent system is added, and the mixture is vortexed at room temperature for 5 min, and ultrasonic degassing is performed for 10 min to form a uniform pre-polymerization liquid;

[0016] 2) The pre-polymerization liquid obtained in step 1) is injected into a γ-methacryloxypropyl trimethyl silane (γ-MAPS) treated quartz capillary, both ends are sealed with silicone rubber plugs, and the capillary is placed in a 85-95 ℃ water bath for 5-15 min, and then washed with methanol to remove the ionic liquid pore-forming agent system and unreacted monomers, thereby obtaining a polymer monolithic column matrix rich in metal oxide nanoparticles on the surface;

[0017] 3) 10-20 mL of solvent is added to 40-400 mg of organic linker, and the mixture is ultrasonically dissolved at room temperature for 5-15 min to form a uniform transparent solution;

[0018] 4) The organic linker solution obtained in step 3) is pumped into the polymer monolithic column obtained in step 2), and the column is sealed at both ends after continuous pumping for 0.5-2 h;

[0019] 5) The monolithic column obtained in step 4) is placed in a 60-70 ℃ water bath for 16-24 h, and then washed with methanol for 1 h to remove the unreacted solution, thereby obtaining the polymer micro-extraction column.

[0020] The third object of the present application is to protect the application of the polymer micro-extraction column with in-situ growth of MOF in the enrichment analysis of persistent organic pollutants.

[0021] Further, the persistent organic pollutants include persistent organic fluorine pollutants such as perfluorinated compounds and fluorine aromatic compounds.

[0022] The present application has the following advantages and positive effects:

[0023] (1) The metal oxide nanoparticles are added to a prepolymerization liquid to prepare a monolithic column material, and the controllable growth of the MOF coating in the tube is realized through in-situ self-assembly. Different structures of metal oxides can grow expected MOFs as metal sources of the MOFs, and the in-situ growth of the MOFs can be regulated by simply adjusting parameters affecting the dissolution of the metal oxides and the crystallization of the MOFs. Meanwhile, by introducing different organic linking agents on the basis of the same metal oxides, the MOFs can be further regulated. The preparation method is simple, economical and easy to operate, and has good universality.

[0024] (2) A new strategy for efficient and rapid hybridization of MOFs and porous polymer monolithic materials is developed. The prepared hybrid polymer micro-extraction column has the advantages of MOFs and flexible porous polymer materials, has a large specific surface area, a high mass transfer rate, suitable porosity and good thermal and chemical stability. Meanwhile, the micro-extraction column is rich in F atoms and open metal sites, can provide hydrogen bonding, F-F affinity and Lewis acid / base complexation, and has high enrichment effect on persistent organic fluorine pollutants such as perfluorinated compounds and fluorine aromatic compounds, and has wide application prospects in environmental and biological sample pretreatment. BRIEF DESCRIPTION OF DRAWINGS

[0025] Figure 1 Scanning electron microscope morphology diagrams of ZnO NPs hybrid polymer monolithic columns prepared by different amounts of ZnO NPs (wherein a-d are magnified by 1000, e-h are magnified by 10000, and i-l are magnified by 30000).

[0026] Figure 2 N2 adsorption-desorption isotherms of polymer micro-extraction columns of ZIF-8 prepared by different amounts of 2-methyl imidazole.

[0027] Figure 3 Scanning electron microscope diagrams of ZnO NPs hybrid polymer monolithic columns and polymer micro-extraction columns of in-situ grown ZIF-8.

[0028] Figure 4 XRD diffraction diagrams of ZnO NPs hybrid polymer monolithic columns and polymer micro-extraction columns of in-situ grown ZIF-8.

[0029] Figure 5 N2 adsorption-desorption isotherms of ZnO NPs hybrid polymer monolithic columns and polymer micro-extraction columns of in-situ grown ZIF-8.

[0030] Figure 6 TIC chromatograms of three perfluoroalkyl phosphates (PFPAs) analyzed by ZnO NPs hybrid polymer monolithic columns (a) and polymer micro-extraction columns of in-situ grown ZIF-8 (b).

[0031] Figure 7 TIC chromatograms of spiked serum samples containing three PFPAs were analyzed using the polymer microextraction column with in-situ growth of ZIF-8, wherein a is perfluorohexylphosphonic acid (PFHP), b is perfluorooctylphosphonic acid (PFOP), and c is perfluorodecylphosphonic acid (PFDP). DETAILED DESCRIPTION

[0032] A polymer microextraction column with in-situ growth of MOF, the preparation of which comprises the following steps:

[0033] 1) 3-9 mg of nano-metal oxide, 30-60 mg of multi-functional monomer, and 1-3 mg of initiator azobisisobutyronitrile are mixed, and 140-170 mg of an ionic liquid pore-forming agent system is added, and the mixture is vortexed at room temperature for 5 min and ultrasonically degassed for 10 min to form a uniform pre-polymerization solution;

[0034] 2) The pre-polymerization solution obtained in step 1) is injected into a γ-methacryloyloxypropyltrimethylsilane (γ-MAPS) treated quartz capillary, both ends are sealed with silicone rubber plugs, and placed in a 85-95 ℃ water bath for reaction for 5-15 min, and then washed with methanol to remove the ionic liquid pore-forming agent system and unreacted monomers, to obtain a polymer monolithic column matrix rich in metal oxide nanoparticles on the surface;

[0035] 3) 10-20 mL of solvent is added to 40-400 mg of organic linker, and the mixture is ultrasonically dissolved at room temperature for 5-15 min to form a uniform transparent solution;

[0036] 4) The organic linker solution obtained in step 3) is pumped into the polymer monolithic column obtained in step 2) and the ends of the column are sealed after 0.5-2 h;

[0037] 5) The monolithic column obtained in step 4) is placed in a 60-70 ℃ water bath for 16-24 h, and then washed with methanol for 1 h to remove the unreacted solution, to obtain a polymer microextraction column with in-situ growth of MOF.

[0038] The nano-metal oxide is any one of MOF phase metal oxides such as nano-zinc oxide (ZnO), nano-aluminum oxide (Al2O3), nano-copper oxide (CuO), and nano-iron oxide (Fe2O3).

[0039] The multi-functional monomer is composed of one of dodecafluoroheptyl methacrylate, trifluoromethyl methacrylate, 3-(perfluoro-3-methylbutyl) 2-hydroxypropyl acrylate, and one or two of methacrylic acid, methyl acrylate, butyl methacrylate, hydroxyethyl methacrylate, ethylene glycol dimethacrylate, trimethylolpropane trimethacrylate, lauryl methacrylate.

[0040] The ionic liquid porogen system is a mixture of 1-hexyl-3-methylimidazolium tetrafluoroborate, 1-butyl-3-methylimidazolium tetrafluoroborate or 1-octyl-3-methylimidazolium tetrafluoroborate and n-propanol; the mass ratio of n-propanol in the mixture is 23-48%.

[0041] The organic linking agent is any one of 2-methylimidazole, trimesic acid, terephthalic acid, and 2,3-diaminoterephthalic acid.

[0042] The solvent is one of water, N,N-dimethylformamide and water, ethanol and water, or nitric acid, hydrogen fluoride and water.

[0043] In order to make the content of the application more convenient to understand, the technical solutions of the application will be further described below in combination with specific embodiments, but the application is not limited to this.

[0044] Example 1

[0045] (1) Alkenyl treatment of the inner wall of the capillary column

[0046] The quartz capillary was washed with 0.1 mol / L hydrochloric acid solution for 1 h, then washed with deionized water for 30 min to neutral, then washed with 0.1 mol / L sodium hydroxide solution for 5 h, then washed with deionized water for 30 min to neutral, then washed with methanol for 30 min, and finally dried at 0.4 MPa under nitrogen at 70 ℃ for 30 min; the mixed solution of 3-(methacryloyloxy) propyl trimethoxysilane and methanol in a volume ratio of 1:1 was injected into the above treated quartz capillary, the two ends were sealed with silicone rubber plugs, and after reaction in a 60 ℃ water bath for 24 h, the capillary was washed with methanol for 30 min, and finally dried at 70 ℃ under nitrogen for 3 h to obtain an alkenylated quartz capillary column.

[0047] (2) Preparation of ZnO NPs hybrid polymer monolithic column matrix

[0048] Dodecafluoroheptyl methacrylate (DFA, 10 mg) was added into a centrifuge tube followed by methacrylic acid (MAA, 10 mg), ethylene glycol dimethacrylate (EDMA, 24 mg), ZnO NPs (0-9 mg), 1-hexyl-3-methylimidazolium tetrafluoroborate ([HMIM][BF4], 110 mg), n-propanol (46 mg), and azobisisobutyronitrile (1 mg) initiator. The mixture was vortexed for 5 min at room temperature and degassed by ultrasonication for 10 min to form a homogeneous prepolymerization solution. The prepolymerization solution was injected into the alkenylated quartz capillary from step (1), which was sealed with silicone rubber plugs at both ends and placed in a 90 °C water bath for 15 min. After the reaction, the capillary monolithic column was removed and rinsed with methanol to remove the porogen and unreacted monomers, resulting in a ZnO NPs hybrid polymer monolithic column (ZnO@poly(EDMA-co-DFA-co-MAA)).

[0049] (3) Preparation of a polymer microextraction column with in-situ grown ZIF-8

[0050] A 2-methylimidazole solution was prepared by dissolving 49.2-246 mg of 2-methylimidazole in 10 mL of a N,N-dimethylformamide / water solution (DMF / H2O = 1:1, v / v). The ZnO NPs hybrid polymer monolithic column prepared in step (2) was activated with methanol for half an hour. Then, the resulting 2-methylimidazole solution was passed through the ZnO NPs hybrid polymer monolithic column at a flow rate of 0.02 mL / min for 2 h. The column was sealed with silicone rubber plugs at both ends and placed in a 70 °C water bath for 20 h. After that, the monolithic column was removed and rinsed with methanol for 1 h to remove the unreacted solution, resulting in a polymer microextraction column with in-situ grown ZIF-8 (ZIF@poly(EDMA-co-DFA-co-MAA)).

[0051] Table 1

[0052]

[0053] Since the ZnO-NPs immobilized in the ZnO NPs hybrid polymer monolithic column can be used as a metal source and anchor seed for the in-situ growth of ZIF-8 crystals, the content of ZnO-NPs in the prepolymerization solution not only affects the permeability of the ZnO NPs hybrid polymer monolithic column, but also has a great influence on the growth of ZIF-8 crystals. As shown in Table 1, when the content of ZnO-NPs is 0 mg, the prepolymerization solution cannot form a column. With the increase of the amount of ZnO-NPs in the prepolymerization solution, the permeability K decreases from 10.4 x 10 -14 m 2 to 3.3 x 10 -14 m 2ZnO-NPs are embedded into the polymer monolith through electrostatic interaction. Figure 1 As can be seen in the figure, the structure of the monolith becomes denser with increasing ZnO-NPs content in the prepolymerization solution. However, when the ZnO-NPs content increases to 9 mg, separation between the column body and the column wall occurs (d). Furthermore, more microspheres can be seen aggregated within the porous network of the ZnO NPs hybrid polymer monolith. This is because the ZnO-NPs in the prepolymerization solution act as seeds for polymer nucleation, limiting the further growth of polymer microspheres and resulting in a denser porous structure within the ZnO NPs hybrid polymer monolith. The ZnO NPs hybrid polymer monolith prepared with 7 mg of ZnO-NPs exhibits numerous large pores and uniform microsphere clusters, providing suitable permeability for PFPAs and thus exhibiting superior extraction efficiency. Therefore, 7 mg of ZnO-NPs represents the optimal nanometal oxide addition amount for the preparation of ZnONPs hybrid polymer monoliths.

[0054] The chemical transformation of ZnO-NPs to ZIF-8 nanocrystals is based on the ZnO-NPs dissolution-precipitation equilibrium and involves two key steps: 2+ The release rate and Zn 2+ The coordination rate of 2-methylimidazole and 2-methylimidazole is related to the dosage of 2-methylimidazole. Therefore, the dosage of 2-methylimidazole is an important factor to be considered. Figure 2 The N2 adsorption-desorption isotherms of ZIF-8 polymer microextraction columns prepared with different 2-methylimidazole dosages are shown in Figure 2. Figure 2 It can be seen that when the amount of 2-methylimidazole increases from 49.2 mg to 147.6 mg, the N2 adsorption-desorption isotherm of the ZIF-8 polymer microextraction column changes from Type II to Type IV, that is, the nitrogen adsorption amount increases significantly when the relative pressure P / P0 is less than 0.1, and the specific surface area also increases from 40.37 m 2 g -1 Increased to 71.61 m 2 g -1 , indicating that the hybrid monolithic column had increased micropores, successfully transforming ZnO-NPs into ZIF-8 nanocrystals. Further increasing the amount of 2-methylimidazole did not significantly change the specific surface area and average pore size of the ZIF-8 polymer microextraction column, indicating that the chemical conversion of ZnO-NPs into ZIF-8 nanocrystals was essentially complete. Therefore, 147.6 mg of 2-methylimidazole is the optimal amount for constructing a polymer microextraction column for in situ ZIF-8 growth.

[0055] The ZnO NPs hybrid polymer monolithic column prepared under the selected optimal conditions and the polymer microextraction column with in situ grown ZIF-8 were further compared.

[0056] Figure 3 Scanning electron microscope images of the ZnO NPs hybridized polymer monolithic column and the polymer microextraction column with in-situ grown ZIF-8. As can be seen from the images, the two column materials prepared are well combined with the inner wall of the capillary, without cracking and shrinkage. At the same time, compared with the ZnO NPs hybridized polymer monolithic column, the surface of the polymer microextraction column with in-situ grown ZIF-8 is formed by more small balls, and the whole is more compact, and the obtained particles are similar to the ZIF octahedral crystal form, indicating that the ZIF crystal with complete crystal form has been successfully in-situ grown in the ZnO NPs hybridized polymer monolithic column.

[0057] Figure 4 XRD diffractograms of the ZnO NPs hybridized polymer monolithic column and the polymer microextraction column with in-situ grown ZIF-8. As can be seen from the images, the ZnO NPs hybridized polymer monolithic column shows three weak diffraction peaks at 2θ of 30-40°, indicating the successful introduction of ZnO NPs. Compared with the ZnO NPs hybridized polymer monolithic column, the polymer microextraction column with in-situ grown ZIF-8 appears new diffraction peaks in the low diffraction angle range and is consistent with the simulated spectrum of ZIF-8, confirming the conversion of ZnO NPs to ZIF-8 crystal.

[0058] Figure 5 N2 adsorption-desorption isotherms of the ZnO NPs hybridized polymer monolithic column and the polymer microextraction column with in-situ grown ZIF-8. As can be seen from the images, the ZnO NPs hybridized polymer monolithic column is a typical Type II isotherm, mainly for large pore size, and the specific surface area is only 20.12 m 2 g -1 . While the polymer microextraction column with in-situ grown ZIF-8 shows a rapid rise in adsorption capacity at a lower relative pressure, showing a typical Type IV isotherm, which can be attributed to the ZIF-8 crystal layer in-situ grown on the surface of the microextraction column providing microporous properties to the material, making the specific surface area of the hybrid material increase to 71.61 m 2 g -1 .

[0059] Example 2

[0060] In order to verify the enrichment performance of the prepared polymer microextraction column with in-situ grown ZIF-8 for persistent organofluorine pollutants, three perfluoroalkyl phosphates (PFPAs) were extracted by the polymer microextraction column prepared under the best conditions in Example 1, and the detection of trace PFPAs in complex biological samples was carried out by combining LC-MS technology, and the specific extraction and detection conditions were as follows:

[0061] (1) Extraction: The capillary microextraction column (250 μm i.d. x 375 μm o.d. x 5 cm) was activated with methanol and sample loading solvent (pH 7 methanol solution) for half an hour, respectively. Then 1 mL sample was injected at a flow rate of 60 μL / min, and the surface unbound sample was removed by flushing with sample loading solvent. Finally, 50 μL of 3.5% formic acid / acetonitrile (1 / 9 v / v) was used for elution, and the elution tail was collected.

[0062] (2) LC-MS detection: The chromatographic conditions were as follows: C18 column (150 x 2.1 mm i.d., 5 μm), mobile phase A: 0.1% ammonia solution, mobile phase B: methanol, gradient elution mode, total flow rate: 0.3 mL / min; gradient elution program: 0.0-2.5 min = 30-70% (v / v) B, 2.5-4 min = 70% B, 4-6 min = 70%-30% B, 6-8 min = 30% B. The injection volume was 10 μL. The mass spectrometric conditions were as follows: MS tuning was performed in the negative ion electrospray ionization (ESI) mode by multiple reaction monitoring (MRM) mode, and the MS parameters of the three PFPAs were as follows: parent ions m / z PFHP = 399.1, m / z PFOP = 499.0, m / z PFDP = 598.9; the product ions of the three were all m / z = 79.0; the collision energy was PFHP: 44 eV, PFOP: 40 eV, PFDP: 42 eV.

[0063] Figure 6 The TIC chromatograms of perfluorohexylphosphonic acid (PFHP, 5 μg L -1 ), perfluorooctylphosphonic acid (PFOP, 0.5 μg L -1 ) and perfluorodecylphosphonic acid (PFDP, 5 μg L -1 ) were analyzed by using ZnO NPs hybrid polymer monolithic column and in-situ grown ZIF-8 polymer microextraction column, respectively. The spectra a and b in the figure are the ZnO NPs hybrid polymer monolithic column and the in-situ grown ZIF-8 polymer microextraction column, respectively. As can be seen from the figure, compared with the ZnO hybrid polymer monolithic column, the in-situ grown ZIF-8 polymer microextraction column shows more excellent extraction performance for the three target substances, indicating that the ZIF-8 crystal layer grown in-situ on the polymer matrix provides high specific surface area and rich active sites for the extraction column.

[0064] Figure 7 The blank serum sample and the samples containing PFHP (5 μg L -1 ), PFOP (0.5 μg L -1), PFDP (5 μg L -1 The TIC chromatograms of the spiked serum samples of PFHP (a), PFOP (b), and PFDP (c) are shown in FIG. 3. The recoveries of the three target compounds in serum samples at three spiked concentrations were 70.0-91.2%, and the RSDs were 3.4-6.5%, which showed that the prepared in-situ grown ZIF-8 polymer microextraction column had good accuracy and reproducibility for enrichment.

[0065] The above merely describes preferred embodiments of the present application, and any equivalent changes and modifications made within the scope of the present application should be included in the scope of the present application.

Claims

1. A polymer microextraction column for in-situ growth of MOFs, characterized in that: The polymer micro-extraction column is formed by in-situ self-assembly of an organic linker and a metal oxide nanoparticle hybridized polymer monolithic column matrix in a solvent; wherein the metal oxide nanoparticle hybridized polymer monolithic column matrix is formed by thermal initiation of free radical polymerization of a plurality of functional monomers, nano metal oxide under the action of an initiator and an ionic liquid pore-forming agent system; and the preparation specifically comprises the following steps: 1) 3-9 mg of nano metal oxide, 30-60 mg of a plurality of functional monomers, and 1-3 mg of an initiator are mixed, and 140-170 mg of an ionic liquid pore-forming agent system is added, and vortexed at room temperature for 5 min, and ultrasonically degassed for 10 min to form a uniform pre-polymerization liquid; 2) The pre-polymerization liquid obtained in step 1) is injected into a quartz capillary, both ends are sealed with silicone rubber plugs, and placed in a 85-95℃ water bath for 5-15 min, then washed with methanol to remove the ionic liquid pore-forming agent system and unreacted monomers, and obtain a metal oxide nanoparticle hybridized polymer monolithic column matrix; 3) 10-20 mL of solvent is added to 40-400 mg of organic linker, and ultrasonically dissolved at room temperature for 5-15 min to form a uniform transparent solution; 4) The organic linker solution obtained in step 3) is pumped into the polymer monolithic column obtained in step 2), and the column is sealed after 0.5-2h; 5) The monolithic column obtained in step 4) is placed in a 60-70℃ water bath for 16-24h, and then washed with methanol for 1h to remove the unreacted solution, and obtain the polymer micro-extraction column.

2. The polymer microextraction column with MOF in situ growth according to claim 1, characterized in that: The organic linker is any one of 2-methylimidazole, trimesic acid, terephthalic acid, and 2,3-diaminoterephthalic acid.

3. The polymer microextraction column with MOF in situ growth according to claim 1, characterized in that: The solvent is one of water, N,N-dimethylformamide and water, ethanol and water, or nitric acid, hydrogen fluoride and water.

4. The polymer microextraction column with MOF in-situ growth according to claim 1, characterized in that: The plurality of functional monomers is composed of one fluorine-functionalized organic monomer containing a double bond and one or two organic monomers containing a double bond.

5. The polymer microextraction column with MOF in situ growth according to claim 1, characterized in that: The nano metal oxide is any one of nano zinc oxide, nano aluminum oxide, nano copper oxide, and nano iron oxide.

6. The polymer microextraction column with MOF in situ growth according to claim 1, characterized in that: The initiator is azobisisobutyronitrile.

7. The polymer microextraction column with MOF in situ growth according to claim 1, characterized in that: The ionic liquid pore-forming agent system is a mixture of 1-hexyl-3-methylimidazolium tetrafluoroborate, 1-butyl-3-methylimidazolium tetrafluoroborate, or 1-octyl-3-methylimidazolium tetrafluoroborate and n-propanol; the mass ratio of n-propanol in the mixture is 23-48%.

8. The application of the polymer micro-extraction column for in-situ growth of MOF in the enrichment analysis of persistent organic pollutants according to any one of claims 1-7.

9. Use according to claim 8, characterized in that: The persistent organic pollutants include perfluorinated compounds and fluorinated aromatic compounds.

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