A silver-zinc bimetallic organic framework functionalized monolithic column, its preparation method, and its application.

Abstract

This invention discloses the preparation of a silver-zinc bimetallic organic framework functionalized monolithic column (AgZnMOF monolithic column) and its application in selective solid-phase microextraction (SPE), belonging to the field of monolithic column preparation technology. First, a matrix monolithic column with epoxy functional groups on its surface is prepared. Then, 1-(3-aminopropyl)imidazolium is used as a bifunctional reagent to graft imidazolium groups onto the surface of the monolithic column, providing coordination anchors for metal ions. Finally, a bimetallic ion solution and an organic ligand solution are mixed and injected into the monolithic column, and the AgZnMOF monolithic column is obtained through in-situ bimetallic-controlled self-assembly reaction. This invention organically combines a bimetallic organic framework with a monolithic column. The prepared monolithic column can be used as a stationary phase for SPE, achieving selective enrichment and highly sensitive analysis of trace amounts of unsaturated fatty acid methyl esters in complex samples. This invention is convenient to operate, ingenious in method, requires no special instrument assistance, and the prepared monolithic column has a strong unsaturated selective enrichment and extraction capability.

Description

Technical Field

[0001] This invention belongs to the field of monolithic column preparation technology, specifically relating to the preparation of a bimetallic organic framework monolithic column and its application in selective solid-phase microextraction. Background Technology

[0002] Monolithic columns, also known as continuous beds, are continuous column beds with a porous structure prepared by in-situ polymerization within a tube. Due to their unique network spatial structure, monolithic columns offer numerous advantages, including good permeability, fast mass transfer, strong mechanical stability, ease of chemical modification, and good biocompatibility, leading to their widespread application in chromatographic separation and sample pretreatment.

[0003] Metal-organic frameworks (MOFs) have become ideal adsorbent materials in sample pretreatment due to their tunable structure and diverse functions. Among them, silver-based MOFs (AgMOFs) utilize Ag... + The specific charge transfer interaction between Ag and C=C double bonds shows unique application potential in the enrichment and extraction of unsaturated compounds. In AgMOFs, active Ag... + The sites are embedded and protected within a stable framework structure, which not only helps to improve the durability of active sites and extend the service life of materials, but also maintains their high selectivity, and is expected to further improve the performance of silver ion functionalized materials in selective enrichment and extraction.

[0004] However, directly synthesized AgMOFs are usually in nanoparticle form, which presents problems such as easy particle aggregation, inconvenience in handling and recovery, and difficulty in direct application to dynamic extraction processes. They must be supported by porous substrates such as monolithic columns. Existing AgMOF materials also suffer from excessively rapid and difficult-to-control crystallization kinetics, which not only affects the uniformity of the framework structure but may also cause Ag... + Site loss leads to decreased long-term stability and makes it difficult to apply to functionalization in monolithic columns. Introducing a second metal ion (such as Zn) into the framework... 2+ ) Regulates coordination kinetics, enhances structural stability, and stabilizes active Ag + Locating sites is a feasible strategy to solve the above problems.

[0005] Based on this, the present invention proposes an in-situ bimetallic controlled self-assembly strategy, which constructs a silver-zinc bimetallic organic framework (AgZnMOF) in situ within a monolithic column, prepares a silver-zinc bimetallic organic framework functionalized monolithic column (AgZnMOF monolithic column), and uses it for selective solid-phase microextraction of trace amounts of unsaturated fatty acid methyl esters (UFAMEs) in complex samples. Summary of the Invention

[0006] The purpose of this invention is to provide a silver-zinc bimetallic organic framework functionalized monolithic column, which can be used as a stationary phase for selective solid-phase microextraction (SPE) to achieve selective SPE and highly sensitive analysis of trace amounts of unsaturated fatty acid methyl esters in complex samples.

[0007] To achieve the above objectives, the present invention adopts the following technical solution: A silver-zinc bimetallic organic framework functionalized monolithic column is prepared by using glycidyl methacrylate (GMA) and ethylene glycol dimethacrylate (EDMA) as matrix monomers, and preparing a poly(GMA-co-EDMA) matrix monolithic column in a vinyl-functionalized polyethylene-tetrafluoroethylene (ETFE) tube via a two-step photo-initiated-thermal-initiated polymerization method. Then, using 1-(3-aminopropyl)imidazolium (APIm) as a bifunctional reagent, imidazolium groups are grafted onto the surface of the monolithic column through a ring-opening reaction between its amino groups and the epoxy groups on the surface of the matrix monolithic column, resulting in an APIm functionalized monolithic column with imidazolium coordination anchors on its surface. Finally, a mixed metal ion solution containing silver and zinc ions is mixed with an equal volume of deprotonated 2-methylimidazolium ligand solution and injected into the APIm functionalized monolithic column. Through in-situ bimetallic controlled self-assembly reaction, a silver-zinc bimetallic organic framework (AgZnMOF) is formed in situ within the monolithic column, thus obtaining the silver-zinc bimetallic organic framework functionalized monolithic column (AgZnMOF monolithic column).

[0008] The APIm functionalization grafting is performed using a 0.5–2.0 mol / L APIm methanol solution; the silver ions are derived from AgNO3; the concentration of silver ions in the metal ion mixed solution is controlled at 25–55 mmol / L; the zinc ions are derived from Zn(NO3)2·6H2O; and the concentration of zinc ions in the metal ion mixed solution is Ag... + 1.3 to 3.0 times the concentration.

[0009] The preparation method of the above-mentioned AgZnMOF monolithic column includes the following steps: 1) Vinyl functionalization of ETFE tubes: The ETFE tubes were rinsed sequentially with acetone and methanol, and dried with nitrogen. A 5% (w / w) benzophenone-methanol solution was injected, sealed, and placed in an ultraviolet crosslinker. The tubes were uniformly irradiated with 254 nm ultraviolet light for 40 min. The tubes were rinsed with methanol and dried with nitrogen. A 15% (v / v) EDMA-methanol solution was then injected and uniformly irradiated for 40 min. The tubes were rinsed with methanol and dried with nitrogen to obtain vinyl functionalized ETFE tubes.

[0010] 2) Preparation of monolithic matrix column: 280 mg GMA, 90 mg EDMA, 340 mg N,N-dimethylformamide (DMF), 1.0 g butanediol (BDO) and 1.2 mg azobisisobutyronitrile (AIBN) were mixed, vortexed for 30 s, bubbled with nitrogen for 20 min, and degassed by sonication for 20 min to obtain a polymer mixture; the mixture was injected into a vinyl-functionalized ETFE tube, sealed, and reacted with UV light at a wavelength of 254 nm for 3-30 min in a UV crosslinker, and then thermally initiated in an 80℃ water bath for 12-24 h; after the reaction was completed, the monolithic column was rinsed with methanol to remove porogens and oligomers to obtain a poly(GMA-co-EDMA) monolithic matrix column that is fully bonded to the ETFE tube.

[0011] 3) Construction of coordination anchors on the surface of the matrix monolithic column: The matrix monolithic column was filled with 0.5~2.0 mol / L APIm methanol solution using a micro-injection pump, both ends were sealed, and the reaction was carried out in a 60℃ water bath for 3 h; after the reaction was completed, it was washed with methanol to obtain a monolithic column with imidazole coordination anchors (poly(GMA-co-EDMA)@APIm monolithic column).

[0012] 4) Preparation of AgZnMOF monolithic column: Prepare a 200 mmol / L 2-methylimidazolium methanol solution, add a trace amount of triethylamine to deprotonate it; separately prepare a mixed metal ion solution: Ag + The concentration was controlled within the range of 25~55 mmol / L, Zn 2+ The concentration should be controlled at 1.3 to 3.0 times that of Ag. + To determine the concentration, equal volumes of the two solutions were mixed and immediately injected into a poly(GMA-co-EDMA)@APIm monolithic column using a micro-injection pump. Both ends were sealed, and the column was reacted in a 60°C water bath for 30 min. After the reaction, the monolithic column was rinsed with methanol to obtain an AgZnMOF monolithic column.

[0013] In the third step of preparing the AgZnMOF monolithic column, 1-(3-aminopropyl)imidazole (APIm) is used as a bifunctional reagent, which acts as both an epoxy ring-opening agent and a metal ion immobilizer. Specifically, the amino functional group of APIm undergoes a ring-opening reaction with the epoxy groups on the surface of the poly(GMA-co-EDMA) matrix monolithic column, covalently grafting the imidazole group onto the surface of the monolithic column to achieve imidazole functionalization of the monolithic column.

[0014] In the fourth step of the AgZnMOF monolithic column preparation, an in-situ bimetallic controlled self-assembly strategy was employed to construct a silver-zinc bimetallic imidazole organic framework (AgZnMOF) within the monolithic column; specifically, Ag... + With Zn 2+After the mixed solution and the deprotonated 2-methylimidazolium ligand solution were mixed in equal volumes and injected into the APIm functionalized monolithic column, Ag... + Rapid coordination with imidazole groups forms AgMOF microcrystals; while Zn 2+ The introduction of [a specific substance] effectively regulates coordination kinetics, slows down the reaction rate, and guides Ag [reaction]. + Zn 2+ The imidazole ligand further synergistically assembles with the AgMOF microcrystals on the surface to form a structurally stable Ag... + The site is effectively protected by a bimetallic organic framework; the imidazole groups grafted onto the surface of the monolithic column further participate in coordination anchoring, ensuring the firm fixation of AgZnMOF within the monolithic column.

[0015] This invention further provides the application of the above-mentioned AgZnMOF monolithic column in the selective solid-phase microextraction and online coupling analysis of trace unsaturated fatty acid methyl esters in complex food samples. Due to the Ag on the surface of the AgZnMOF monolithic column... + There is a specific charge transfer interaction between the site and the unsaturated carbon-carbon double bond. Therefore, unsaturated fatty acid methyl esters with unsaturated carbon-carbon double bonds can be selectively enriched and extracted on the AgZnMOF monolithic column. When combined with relevant analytical methods, highly selective enrichment and sensitive analysis of trace amounts of unsaturated fatty acids in complex real samples can be achieved.

[0016] The significant advantages of this invention are: 1) The monolithic column preparation scheme of this invention is ingenious and concise. APIm is used as a bifunctional reagent to achieve surface imidazole functionalization, providing abundant coordination anchoring sites for subsequent in-situ self-assembly of metal-organic frameworks.

[0017] 2) This invention is the first to propose a self-assembly strategy regulated by in-situ bimetals to solve the technical problem of AgMOF crystallization being too rapid and difficult to uniformly construct within a monolithic column. This is achieved by using Ag... + Introducing Zn into the solution 2+ This effectively regulates the crystallization kinetics of AgMOF, significantly improving the controllability and success rate of the preparation process.

[0018] 3) In the AgZnMOF monolithic column prepared in this invention, the active Ag... + The sites are embedded and stabilized within AgZnMOF, effectively inhibiting the loss of active sites, significantly improving the durability and service life of the material, while maintaining excellent selective extraction performance.

[0019] 4) This invention provides a new approach to combining bimetallic organic frameworks with monolithic columns, which is convenient to operate, ingenious in method, requires no special instrument assistance, and is easy to promote. Attached Figure Description

[0020] Figure 1 These are XRD patterns of materials prepared with different silver-zinc ratios. Where 'a' represents materials prepared using Zn alone. 2+ The synthesized ZIF-8; b is a silver-zinc bimetallic organic framework material with an Ag:Zn molar ratio of 30:85; c is a silver-zinc bimetallic organic framework material with an Ag:Zn molar ratio of 40:80; d is a silver-zinc bimetallic organic framework material with an Ag:Zn molar ratio of 50:75; e is an AgMOF prepared using silver ions alone.

[0021] Figure 2 These are energy-dispersive X-ray spectra (EDS) for two monolithic column materials. Here, a represents the poly(GMA-co-EDMA)@APIm monolithic column material; and b represents the AgZnMOF monolithic column material.

[0022] Figure 3 These are the full X-ray photoelectron spectroscopy (XPS) spectra of two monolithic column materials. Wherein, a is the AgZnMOF monolithic column material; b is the poly(GMA-co-EDMA)@APIm monolithic column material.

[0023] Figure 4 This is a high-performance liquid chromatography (HPLC) chromatogram. 'a' shows an in-tube SPME-Ag microextraction system using an AgZnMOF monolithic column as the stationary phase. + - HPLC method was used to detect the chromatograms of four unsaturated fatty acid methyl ester standard solutions; b. The same in-tube-SPME-Ag method was used. + -Chromatogram of blank milk tea sample detected by HPLC method; c is the chromatogram of the sample detected by the same in-tube-SPME-Ag method. + -Chromatogram of spiked milk tea sample detected by HPLC method; d represents the chromatogram of the sample spiked with Ag. + - HPLC method was used to detect the chromatogram of spiked milk tea samples. The analyte spike concentration was 0.5 μg / mL; peak assignments were: (1) methyl trans-9-octadecenoate (9t-C18:1); (2) methyl trans-linoleate (9t,12t-C18:2); (3) methyl cis-9-octadecenoate (9c-C18:1); (4) methyl cis-linoleate (9c,12c-C18:2). Detailed Implementation

[0024] To make the content of this invention easier to understand, the technical solution of this invention will be further described below with reference to specific embodiments, but this invention is not limited thereto.

[0025] The method for vinyl functionalization of the inner wall of ETFE tubes involved in the following embodiments is as follows: Vinyl functionalization of the inner wall of ETFE tubes: ETFE tubes (inner diameter 750 μm) were sequentially rinsed with methanol and acetone, and dried with nitrogen; a 5% (w / w) benzophenone methanol solution was injected, sealed, and placed in an ultraviolet crosslinker, and uniformly irradiated with ultraviolet light at a wavelength of 254 nm for 40 min; after rinsing with methanol and drying with nitrogen; a 15% (v / v) EDMA methanol solution was injected, and uniformly irradiated for 40 min; after rinsing with methanol and drying with nitrogen, vinyl functionalized ETFE tubes were obtained.

[0026] Example 1: This example provides the preparation and characterization of AgZnMOF monolithic columns, wherein Ag... + With Zn 2+ The molar ratio is 30:85, and the specific steps include: 1) Preparation of monolithic matrix column: 280 mg GMA, 90 mg EDMA, 340 mg DMF, 1.0 g BDO and 1.2 mg AIBN were mixed, vortexed for 30 s, bubbled with nitrogen for 20 min, and degassed by sonication for 20 min to obtain a polymer mixture; the mixture was injected into a vinyl-functionalized ETFE tube, sealed and reacted with ultraviolet light at a wavelength of 254 nm for 15 min in an ultraviolet crosslinker, and then thermally initiated in an 80℃ water bath for 12 h; after the reaction was completed, the monolithic column was washed with methanol to remove porogens and oligomers, and a poly(GMA-co-EDMA) matrix monolithic column fully bonded to the ETFE tube was obtained.

[0027] 2) Construction of coordination anchors on the surface of the matrix monolithic column: The matrix monolithic column was filled with 1.5 mol / L APIm methanol solution using a micro-injection pump, both ends were sealed, and the reaction was carried out in a 60℃ water bath for 3 h; after the reaction was completed, it was washed with methanol to obtain a monolithic column with imidazole coordination anchors (poly(GMA-co-EDMA)@APIm monolithic column).

[0028] 3) Preparation of AgZnMOF monolithic column: Prepare a 200 mmol / L 2-methylimidazolium methanol solution and add a trace amount of triethylamine to deprotonate it; prepare a metal ion mixed solution with AgNO3 concentration of 30 mmol / L and Zn(NO3)2 concentration of 85 mmol / L; mix the two solutions in equal volumes and immediately inject them into the APIm functionalized monolithic column using a micro-injection pump, seal both ends, and react in a 60℃ water bath for 30 min; after the reaction is completed, wash the monolithic column with methanol to obtain the AgZnMOF monolithic column.

[0029] Example 2: This example provides the preparation of a monolithic AgZnMOF column and its application in selective solid-phase microextraction, wherein Ag... + With Zn 2+The molar ratio is 40:80, and the specific steps include: 1) Preparation of monolithic matrix column: 280 mg GMA, 90 mg EDMA, 340 mg DMF, 1.0 g BDO and 1.2 mg AIBN were mixed, vortexed for 30 s, bubbled with nitrogen for 20 min, and degassed by sonication for 20 min to obtain a polymer mixture; the mixture was injected into a vinyl-functionalized ETFE tube, sealed and reacted with ultraviolet light at a wavelength of 254 nm for 5 min in an ultraviolet crosslinker, and then thermally initiated in an 80℃ water bath for 24 h; after the reaction was completed, the monolithic column was washed with methanol to remove porogens and oligomers to obtain a poly(GMA-co-EDMA) monolithic matrix column that is fully bonded to the ETFE tube.

[0030] 2) Construction of coordination anchors on the surface of the matrix monolithic column: The matrix monolithic column was filled with 1.0 mol / L APIm methanol solution using a micro-injection pump, both ends were sealed, and the reaction was carried out in a 60℃ water bath for 3 h; after the reaction was completed, it was washed with methanol to obtain a monolithic column with imidazole coordination anchors (poly(GMA-co-EDMA)@APIm monolithic column).

[0031] 3) Preparation of AgZnMOF monolithic column: Prepare a 200 mmol / L 2-methylimidazolium methanol solution and add a trace amount of triethylamine to deprotonate it; prepare a metal ion mixed solution with AgNO3 concentration of 40 mmol / L and Zn(NO3)2 concentration of 80 mmol / L; mix the two solutions in equal volumes and immediately inject them into the APIm functionalized monolithic column using a micro-injection pump, seal both ends, and react in a 60℃ water bath for 30 min; after the reaction is completed, wash the monolithic column with methanol to obtain the AgZnMOF monolithic column.

[0032] Example 3: This example provides the preparation of a monolithic AgZnMOF column and its application in selective solid-phase microextraction, wherein Ag... + With Zn 2+ The molar ratio is 50:75, and the specific steps include: 1) Preparation of monolithic matrix column: 280 mg GMA, 90 mg EDMA, 340 mg DMF, 1.0 g BDO and 1.2 mg AIBN were mixed, vortexed for 30 s, bubbled with nitrogen for 20 min, and degassed by sonication for 20 min to obtain a polymer mixture; the mixture was injected into a vinyl-functionalized ETFE tube, sealed and reacted with ultraviolet light at a wavelength of 254 nm for 5 min in an ultraviolet crosslinker, and then thermally initiated in an 80℃ water bath for 24 h; after the reaction was completed, the monolithic column was washed with methanol to remove porogens and oligomers to obtain a poly(GMA-co-EDMA) monolithic matrix column that is fully bonded to the ETFE tube.

[0033] 2) Construction of coordination anchors on the surface of the matrix monolithic column: The matrix monolithic column was filled with 1.0 mol / L APIm methanol solution using a micro-injection pump, both ends were sealed, and the reaction was carried out in a 60℃ water bath for 3 h; after the reaction was completed, it was washed with methanol to obtain a monolithic column with imidazole coordination anchors (poly(GMA-co-EDMA)@APIm monolithic column).

[0034] 3) Preparation of AgZnMOF monolithic column: Prepare a 200 mmol / L 2-methylimidazolium methanol solution and add a trace amount of triethylamine to deprotonate it; prepare a metal ion mixed solution with AgNO3 concentration of 50 mmol / L and Zn(NO3)2 concentration of 75 mmol / L; mix the two solutions in equal volumes and immediately inject them into the APIm functionalized monolithic column using a micro-injection pump, seal both ends, and react in a 60℃ water bath for 30 min; after the reaction is completed, wash the monolithic column with methanol to obtain the AgZnMOF monolithic column.

[0035] Figure 1 By analyzing the XRD patterns of AgZnMOF materials prepared with different silver-zinc ratios, the results show that compared with using Zn alone... 2+ Synthetic ZIF-8 ( Figure 1 a) Compared to all AgZnMOF samples ( Figure 1 The characteristic diffraction peaks of ZIF-8 in (bd) completely disappeared, while the main diffraction peaks of AgMOF ( Figure 1 e) Remains intact. Furthermore, several new diffraction peaks appeared in the range of 2θ > 45°. Therefore, it is inferred that the formation mechanism of AgZnMOF is: Ag... + First, it reacts rapidly with deprotonated 2-methylimidazole to generate AgMOF microcrystals, which serve as a "template"; then Ag... + Zn 2+ The imidazole ligand further coordinates and assembles on the template surface to form an AgZnMOF structure, which retains the characteristic peaks of AgMOF but lacks the characteristic peaks of ZIF-8, while also showing new signal peaks.

[0036] Figure 2 Poly(GMA-co-EDMA)@APIm monolithic column materials and AgZnMOF monolithic column materials were analyzed by energy-dispersive X-ray spectroscopy (EDS). Figure 2It can be seen that, in addition to containing C and O elements, the poly(GMA-co-EDMA)@APIm monolithic column also contains N element, which is not present in the matrix monolithic column, indicating the successful functionalization of the monolithic column surface by APIm. Compared with the poly(GMA-co-EDMA)@APIm monolithic column, the AgZnMOF monolithic column also shows newly added Zn and Ag element signals, which is attributed to the self-assembly of AgZnMOF on the monolithic column surface.

[0037] Figure 3 X-ray photoelectron spectroscopy (XPS) was used to characterize the poly(GMA-co-EDMA)@APIm monolithic pillar material and the AgZnMOF monolithic pillar material. C 1s, O 1s, and N 1s peaks were clearly observed in the full XPS spectra of both materials. Furthermore, Ag 3d and Zn 2p peaks were also observed in the full spectrum of the AgZnMOF monolithic pillar material, indicating the successful fabrication of the AgZnMOF monolithic pillar.

[0038] The AgZnMOF monolithic column prepared in Example 2 was used as the stationary phase for solid-phase microextraction (SPME), combined with in-tube SPME-Ag... + The system, coupled with direct silver ion high-performance liquid chromatography (HPLC), achieved selective enrichment and efficient analysis of trace amounts of unsaturated fatty acid methyl esters in actual milk tea samples, and was further enhanced by direct silver ion high-performance liquid chromatography (HPLC). + The results of the combined HPLC method were compared. The optimal detection conditions for this method are as follows: sample solution: n-hexane; sample flow rate: 0.06 mL / min; eluent: acetonitrile / n-hexane = 1.2% / 98.8% (v / v); elution flow rate: 0.06 mL / min; acquisition time range: 1.67~5.00 min; injection volume: 500 μL; elution volume: 200 μL; separation mobile phase: n-hexane / acetonitrile = 99.7% / 0.3% (v / v); mobile phase flow rate: 1.0 mL / min; column oven temperature: 40 ℃; detection wavelength: 203 nm.

[0039] Figure 4 Typical chromatograms of target unsaturated fatty acid methyl esters are shown under different detection modes. Direct detection of spiked milk tea samples using Ag⁺-HPLC is also demonstrated. Figure 4 d) Due to severe interference from the complex sample matrix, all spiked unsaturated fatty acid methyl esters could not be effectively detected. However, the in-tube SPME-Ag synthesized in this work... + When using an HPLC-coupled system for detection ( Figure 4 b) The sample matrix interference was significantly reduced, and there were no obvious interference peaks near the target unsaturated fatty acid methyl ester; when detecting spiked milk tea samples ( Figure 4 c) Several unsaturated fatty acid methyl esters spiked at 0.5 μg / mL were clearly detected with good peak shapes, indicating that the AgZnMOF monolithic column prepared in this example has excellent selective enrichment and extraction capabilities and matrix purification effects for trace unsaturated fatty acid methyl esters in complex samples.

[0040] The results above demonstrate that the AgZnMOF monolithic column prepared in this work has excellent selective enrichment and extraction performance for target unsaturated fatty acid methyl esters, enabling efficient selective enrichment analysis and accurate identification of trace amounts of unsaturated fatty acid methyl esters in complex samples.

[0041] The above description is only a preferred embodiment of the present invention. All equivalent changes and modifications made within the scope of the claims of the present invention should be included in the scope of the present invention.

Claims

1. A method for preparing a silver-zinc bimetallic organic framework functionalized monolithic column, characterized in that: A poly(GMA-co-EDMA) matrix monolithic column was prepared in a vinyl-functionalized polyethylene-tetrafluoroethylene tube using glycidyl methacrylate and ethylene glycol dimethacrylate as matrix monomers via a two-step photo-initiated-thermal-initiated polymerization method. Then, using 1-(3-aminopropyl)imidazolium as a bifunctional reagent, imidazolium groups were grafted onto the surface of the monolithic column through a ring-opening reaction between its amino groups and the epoxy groups on the surface of the matrix monolithic column, thus obtaining an APIm-functionalized monolithic column. Finally, an equal volume mixture of a mixed metal ion solution containing silver and zinc ions and a deprotonated 2-methylimidazolium ligand solution was injected into the APIm-functionalized monolithic column. Through an in-situ bimetallic-controlled self-assembly reaction, a silver-zinc bimetallic organic framework (AgZnMOF) was formed, thus obtaining the silver-zinc bimetallic organic framework-functionalized monolithic column.

2. The method according to claim 1, characterized in that: Includes the following steps: 1) Vinyl functionalization of the inner surface of ETFE tubes: A 5% (w / w) benzophenone methanol solution was injected into a polyethylene-tetrafluoroethylene tube, sealed, and uniformly irradiated with ultraviolet light at a wavelength of 254 nm for 40 min; after rinsing with methanol, a 15% (v / w) ethylene glycol dimethacrylate methanol solution was injected, and uniformly irradiated with ultraviolet light at a wavelength of 254 nm for 40 min; after rinsing with methanol, a vinyl-functionalized polyethylene-tetrafluoroethylene tube was obtained. 2) Preparation of monolithic matrix column: 280 mg glycidyl methacrylate, 90 mg ethylene glycol dimethacrylate, 340 mg N,N-dimethylformamide, 1.0 g butanediol and 1.2 mg azobisisobutyronitrile were mixed, vortexed for 30 s, bubbled with nitrogen for 20 min, and sonicated for 20 min; the mixture was injected into a vinyl-functionalized polyethylene-tetrafluoroethylene tube, sealed, and uniformly irradiated with ultraviolet light at a wavelength of 254 nm for 3-30 min, and then thermally initiated in an 80℃ water bath for 12-24 h; after the reaction was completed, the monolithic column was washed with methanol to obtain a poly(GMA-co-EDMA) matrix monolithic column fully bonded to the polyethylene-tetrafluoroethylene tube; 3) Construction of coordination anchors on the surface of the monolithic matrix column: The monolithic matrix column was filled with 0.5~2.0 mol / L 1-(3-aminopropyl)imidazolium methanol solution, both ends were sealed, and the reaction was carried out in a 60℃ water bath for 3 h; after the reaction was completed, it was washed with methanol to obtain a poly(GMA-co-EDMA)@APIm monolithic column with imidazolium coordination anchors. 4) Preparation of silver-zinc bimetallic organic framework functionalized monolithic column: Prepare a 200 mmol / L 2-methylimidazolium methanol solution, add a trace amount of triethylamine to deprotonate it; separately prepare a mixed metal ion solution: Ag + The concentration was controlled within the range of 25~55 mmol / L, Zn 2+ The concentration should be controlled at 1.3 to 3.0 times that of Ag. + Concentration; Mix the two solutions in equal volumes and immediately inject them into the poly(GMA-co-EDMA)@APIm monolithic column, seal both ends, and react in a 60℃ water bath for 30 min; After the reaction is complete, rinse the monolithic column with methanol to obtain the silver-zinc bimetallic organic framework functionalized monolithic column.

3. The method according to claim 2, characterized in that: In a mixed solution of metal ions, silver ions originate from AgNO3, and zinc ions originate from Zn(NO3)2·6H2O.

4. A silver-zinc bimetallic organic framework functionalized monolithic column prepared by the method according to any one of claims 1-3.

5. An application of a silver-zinc bimetallic organic framework functionalized monolithic column prepared by the method according to any one of claims 1-3, characterized in that: The silver-zinc bimetallic organic framework functionalized monolithic column is used for selective solid-phase microextraction of trace amounts of unsaturated fatty acid methyl esters in complex samples.

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