A solid phase extraction membrane based on defective MOF and a preparation method and application thereof

Abstract

The present application belongs to the technical field of solid phase extraction, and particularly relates to a solid phase extraction membrane based on a defective MOF as well as a preparation method and application thereof. The solid phase extraction membrane based on the defective MOF comprises a carrier and a coating layer loaded on the surface of the carrier; the composition of the coating layer comprises a defective amino MOF material; the defective amino MOF material is prepared by taking a metal as a center, taking 3,5-dibromo-4-hydroxybenzaldehyde as a template molecule, and reacting with an amino organic ligand. By adopting a specific template molecule, the defective MOF structure has pores that are matched with the shape and size of the template molecule, has strong adsorption capacity for structural analogues of the template molecule, has strong selectivity for target analytes, can highly selectively enrich chlorophenol, and makes the solid phase extraction membrane have excellent adsorption effect on chlorophenol, high enrichment multiple and good reproducibility.

Description

Technical Field

[0001] This invention belongs to the field of solid-phase extraction technology, and specifically relates to a solid-phase extraction membrane based on defective MOFs, its preparation method, and its application. Background Technology

[0002] Chlorination disinfection is the most common treatment process for aquaculture water to eliminate pathogens. However, chlorine disinfectants can react with natural organic matter (chlorophenols, phenols, lignin, and humic acid, etc.) and antibiotics to form disinfection byproducts (DBPs). Chlorophenols are common DBPs and have been detected in aquaculture water, wastewater, and tap water at levels in the ng / L range. Chlorophenols are toxic to aquatic organisms, have high permeability and the potential to cause tissue damage, and have mutagenic and carcinogenic effects, posing a significant threat to the aquatic environment. Therefore, accurate detection of chlorophenol DBPs in aquaculture water and aquatic products is of great significance for food and biosafety monitoring.

[0003] Metal-organic frameworks (MOFs) possess advantages such as large specific surface area, abundant active sites, easy functionalization, and easily tunable porosity, leading to their widespread application in sample pretreatment. However, most MOFs are microporous materials, which not only results in a homogeneous pore environment but also slows the diffusion of target molecules and prevents macromolecules from entering their inner surfaces. Therefore, when used as enrichment media for the analysis and detection of DBPs, MOFs still suffer from poor enrichment efficiency and poor reproducibility.

[0004] Besides enrichment media, such as metal framework materials, the development of advanced sample pretreatment techniques is also crucial. Currently, the most efficient pretreatment method for chlorophenols in drinking water is solid phase extraction (SPE). SPE utilizes solid adsorbents to adsorb and separate the target analyte from the sample matrix, followed by removal of the analyte with an eluent, thus achieving separation and enrichment. However, SPE often suffers from column clogging and stationary phase loss due to channeling. Membrane solid phase extraction (M-SPE) is a miniaturized form of SPE. Currently, research on MOFs in the field of membrane solid phase extraction is limited, and there is no development of membrane solid phase extraction technology specifically for chlorophenols.

[0005] Therefore, it is of great significance to provide a solid-phase extraction membrane that has excellent adsorption effect on p-chlorophenol, high enrichment factor and good reproducibility. Summary of the Invention

[0006] The present invention aims to solve one or more technical problems existing in the prior art, and at least provide a beneficial alternative or create conditions. Specifically, the present invention provides a solid-phase extraction membrane based on a defective MOF, which has excellent adsorption effect on chlorophenol, with high enrichment factor and good reproducibility.

[0007] The inventive concept of this invention is as follows: The solid-phase extraction membrane of this invention comprises a carrier and a coating loaded on the surface of the carrier; the coating comprises a defective amino MOF material; the defective amino MOF material is prepared by reacting an amino organic ligand with a metal as the core and 3,5-dibromo-4-hydroxybenzaldehyde as the template molecule. The defective amino MOF material of this invention possesses mesoporous and microporous structures, resulting in a larger specific surface area and porosity, and faster diffusion rates of solute and target molecules, thereby enhancing the accessibility of adsorption sites. This invention, by employing a specific template molecule, creates channels in the defective MOF structure that are adapted to the shape and size of the template molecule, exhibiting strong adsorption capacity for structural analogues of the template molecule. The coating exhibits strong selectivity for the target analyte, resulting in excellent adsorption performance of the solid-phase extraction membrane for chlorophenol, with high enrichment factor and good reproducibility.

[0008] Therefore, a first aspect of the present invention provides a solid-phase extraction membrane based on a defective MOF.

[0009] Specifically, the solid-phase extraction membrane based on defective MOFs includes a support and a coating loaded on the surface of the support.

[0010] The coating is composed of defective amino MOF materials;

[0011] The defective amino MOF material is prepared by reacting an amino organic ligand with a metal as the center and 3,5-dibromo-4-hydroxybenzaldehyde as the template molecule.

[0012] Preferably, the carrier is an organic filter membrane.

[0013] Preferably, the carrier includes any one of nylon filter membrane, polyvinylidene fluoride filter membrane, and polytetrafluoroethylene filter membrane.

[0014] More preferably, the carrier is a nylon-66 membrane.

[0015] Preferably, the particle size of the defective amino MOF material is 0.45-1.7 μm; more preferably, the particle size of the defective amino MOF material is 0.5-1.5 μm.

[0016] Preferably, the defective amino MOF material includes mesoporous and microporous structures.

[0017] Preferably, the pore size of the mesopore is 2-50 nm; more preferably, the pore size of the mesopore is 2-3 nm.

[0018] Preferably, the pore size of the micropore is less than 2 nm; more preferably, the pore size of the micropore is greater than or equal to 0.5 and less than 2 nm.

[0019] Preferably, the metal includes any one of Fe, Zr, and Cr.

[0020] Preferably, the defective amino MOF is prepared by mixing a metal salt, a template molecule, an amino organic ligand, and an organic solvent, and reacting them to obtain the defective amino MOF.

[0021] Preferably, the metal salt includes any one of iron salt, zirconium salt, and chromium salt.

[0022] Preferably, the iron salt includes at least one of ferric chloride and ferric oxychloride.

[0023] Preferably, the zirconium salt includes at least one of zirconium chloride and zirconium oxychloride.

[0024] Preferably, the chromium salt includes at least one of chromium chloride and chromium oxychloride.

[0025] Preferably, the template molecule comprises 3,5-dibromo-4-hydroxybenzaldehyde.

[0026] Preferably, the amino organic ligand comprises 2-aminoterephthalic acid.

[0027] Preferably, the organic solvent includes N,N-dimethylformamide solution (DMF solution).

[0028] Preferably, the molar ratio of the metal salt to the template molecule is 1:(0.45-1.1); more preferably, the molar ratio of the metal salt to the template molecule is 1:(0.5-1.0).

[0029] Preferably, the molar ratio of the metal salt to the amino organic ligand is 1:(0.27-1.1); more preferably, the molar ratio of the metal salt to the amino organic ligand is 1:(0.3-1).

[0030] Preferably, the reaction temperature is 100-150℃ and the reaction time is 12-48h; more preferably, the reaction temperature is 110-130℃ and the reaction time is 12-36h.

[0031] Preferably, the reaction further includes separation, elution, and drying processes.

[0032] Preferably, the elution specifically involves washing with a methanol solution.

[0033] Preferably, the washing time is 9-14 hours; more preferably, the washing time is 10-13 hours.

[0034] Preferably, the washing temperature is 20-30°C; more preferably, the washing temperature is 22-27°C; and even more preferably, the washing temperature is 25°C.

[0035] A second aspect of the present invention provides a method for preparing a solid-phase extraction membrane based on a defective MOF as described in the first aspect of the present invention.

[0036] Specifically, the method for preparing the solid-phase extraction membrane based on defective MOFs includes the following steps:

[0037] (1) The defective amino MOF material and solvent are mixed to obtain a suspension;

[0038] (2) The suspension obtained in step (1) is filtered using the carrier, and the defective amino MOF material is loaded on the carrier to obtain the solid phase extraction membrane.

[0039] Preferably, in step (1), the solvent includes methanol.

[0040] Preferably, in step (1), the concentration of the suspension is 0.09-11 mg / mL; more preferably, in step (1), the concentration of the suspension is 0.1-10 mg / mL.

[0041] Preferably, in step (2), the filtration method is to use a syringe-type filter membrane.

[0042] Preferably, the syringe-type filter membrane filtration steps are as follows: inject the suspension into the syringe, connect the filter head of the carrier (organic filter membrane) to the syringe outlet, push the syringe so that the defective amino MOF material passes through the filter membrane along with the solvent, the solvent flows out through the micropores of the filter membrane, the defective amino MOF is deposited on the filter membrane, and dried to obtain a solid phase extraction membrane.

[0043] Preferably, the preparation method further includes a process of activating the solid-phase extraction membrane.

[0044] Preferably, the specific process for activating the solid-phase extraction membrane is as follows: methanol and water are injected into a syringe, and the syringe is manually pushed to allow the methanol and water to pass through the solid-phase extraction membrane for later use.

[0045] A third aspect of the present invention provides an application of the solid-phase extraction membrane based on defective MOF described in the first aspect of the present invention in the detection of disinfection byproducts.

[0046] Preferably, the disinfection byproduct includes chlorophenol; more preferably, the disinfection byproduct includes at least one of 2-chlorophenol (2-CP), 2,4-dichlorophenol (2,4-DCP), 2,4,6-trichlorophenol (2,4,6-TCP), and 2,4,5-trichlorophenol (2,4,5-TCP).

[0047] Preferably, the extraction conditions for detecting disinfection byproducts using the solid-phase extraction membrane based on defective MOFs are as follows: the amount of defective amino MOF material is 0.5-4.0 mg, the extraction flow rate is 0.5-2.5 mL / min, the desorption solvent includes methanol, the volume of the desorption solvent is 0.1-1.0 mL, the desorption flow rate is 0.02-0.05 mL / min, and the extraction pH is 2.0-10.0.

[0048] More preferably, the extraction conditions for detecting disinfection byproducts using the solid-phase extraction membrane based on defective MOFs are as follows: the amount of defective amino MOF material is 0.5-2.0 mg, the extraction flow rate is 1.0-2.0 mL / min, the desorption solvent includes methanol, the volume of the desorption solvent is 0.1-0.4 mL, the desorption flow rate is 0.03-0.05 mL / min, and the extraction pH is 2.0-6.0.

[0049] Preferably, when using the solid-phase extraction membrane based on defective MOF to detect disinfection byproducts in aquatic product samples, the aquatic product samples need to be pretreated.

[0050] Preferably, the pretreatment process specifically includes: crushing and homogenizing the aquatic products; placing the homogenized meat sample in a centrifuge tube; adding anhydrous magnesium sulfate and extraction solvent sequentially; vortexing to obtain a mixture; then ultrasonically extracting the mixture; centrifuging; collecting the acetonitrile phase in the supernatant as the extract; repeating the above extraction process once; combining the two collected extracts in a centrifuge tube; filtering with a 0.22 μm filter membrane; then purging with nitrogen to dryness; finally redissolving the extract; performing membrane solid-phase extraction (M-SPE); and detecting the target analyte content in the obtained eluent using high performance liquid chromatography-ultraviolet-visible spectroscopy (HPLC-UV).

[0051] Specifically, the role of anhydrous magnesium sulfate is to remove moisture from the sample. The extraction conditions during membrane solid-phase extraction are the same as those for the above-mentioned solid-phase extraction membrane based on defective MOF when detecting disinfection byproducts.

[0052] Preferably, the ratio of the amount of meat sample, anhydrous magnesium sulfate, and solvent is 5g:(1.5-2.5)g:(10-20)mL; more preferably, the ratio of the amount of meat sample, anhydrous magnesium sulfate, and solvent is 5g:(1.8-2.2)g:(13-17)mL; even more preferably, the ratio of the amount of meat sample, anhydrous magnesium sulfate, and solvent is 5g:2g:15mL.

[0053] Preferably, the solvent includes acetonitrile and n-hexane.

[0054] Preferably, the volume ratio of acetonitrile to n-hexane is 1:(0.8-1.2); more preferably, the volume ratio of acetonitrile to n-hexane is 1:(0.9-1.1); and even more preferably, the volume ratio of acetonitrile to n-hexane is 1:1.

[0055] Preferably, the vortex oscillation time is 4-6 minutes; more preferably, the vortex oscillation time is 4.5-5.5 minutes; even more preferably, the vortex oscillation time is 5 minutes.

[0056] Preferably, the ultrasonic extraction time is 15-25 min; more preferably, the ultrasonic extraction time is 18-22 min; and even more preferably, the ultrasonic extraction time is 20 min.

[0057] Preferably, in the application, the method for detecting disinfection byproducts specifically includes:

[0058] (1) Use solid phase extraction membrane to extract working solutions of different concentrations and use HPLC-UV to detect them. Obtain the peak area corresponding to different concentrations. Plot the peak area as the ordinate to obtain the linear range of solid phase extraction membrane test.

[0059] (2) The test solution was extracted using a solid phase extraction membrane and analyzed by HPLC-UV. The obtained peak area was substituted into the linear equation to determine the content of chlorophenol in the test solution.

[0060] Preferably, the concentration of the working solution is 0.09-55 μg / L; more preferably, the concentration of the working solution is 0.1-50 μg / L.

[0061] Preferably, the working solution is a mixed standard solution of chlorophenol.

[0062] Specifically, in step (1), three groups of samples are extracted for each concentration condition.

[0063] Compared with the prior art, the beneficial effects of the technical solution provided by the present invention are as follows:

[0064] (1) The defective amino MOF material of this invention is prepared by reacting an amino organic ligand with a metal as the center and 3,5-dibromo-4-hydroxybenzaldehyde as the template molecule. By using a specific template molecule, this invention enables the defective MOF structure to have channels that are adapted to the shape and size of the template molecule, which has a strong adsorption capacity for structural analogs of the template molecule. The coating has a strong selectivity for the target analyte and can selectively enrich chlorophenol, so that the solid phase extraction membrane has excellent adsorption effect on chlorophenol, with high enrichment factor and good reproducibility.

[0065] (2) The present invention prepares a solid-phase extraction membrane of defective MOF by direct deposition. The preparation steps are simple and do not require complicated equipment. The solid-phase extraction membrane prepared by the method has good chemical stability, excellent adsorption effect on chlorophenol, high enrichment factor and good reproducibility.

[0066] (3) The solid-phase extraction membrane prepared in this invention is used to determine chlorophenols in aquatic product samples, and has the advantages of good linear range, low detection limit, and high recovery rate. This analytical method enriches chlorophenols in aquatic product samples using defective MOF materials, and can also be coupled with HPLC-UV for the detection of chlorophenols. The signal intensity generated by chlorophenols shows a good linear relationship with their content, enabling trace detection of chlorophenol DBPs in aquatic product samples. Compared with existing technologies, it is simpler to operate and has greatly improved sensitivity, making it valuable for practical applications. Attached Figure Description

[0067] Figure 1 This is a scanning electron microscope image of the defective MOF prepared in Example 1 of the present invention;

[0068] Figure 2 This is a schematic diagram of the preparation process of the solid-phase extraction membrane in Example 1 of the present invention;

[0069] Figure 3 This is a graph showing the optimized results of the amount of defective MOF in the solid-phase extraction membrane prepared in Example 1 of the present invention;

[0070] Figure 4 This is a graph showing the optimization results of the extraction flow rate of the solid-phase extraction membrane prepared in Example 1 of the present invention;

[0071] Figure 5 This is a graph showing the optimization results of the desorption solvent for the solid-phase extraction membrane prepared in Example 1 of this invention;

[0072] Figure 6 This is a graph showing the optimization results of the desorption solvent volume of the solid-phase extraction membrane prepared in Example 1 of the present invention;

[0073] Figure 7 This is a graph showing the optimization results of the desorption flow rate of the solid-phase extraction membrane prepared in Example 1 of the present invention;

[0074] Figure 8 This is a graph showing the pH optimization results of the solid-phase extraction membrane prepared in Example 1 of the present invention;

[0075] Figure 9 The linear range diagram shows the solid-phase extraction membrane prepared in Example 1 of this invention for the detection of four chlorophenols.

[0076] Figure 10 The chromatograms of grass carp samples and spiked samples obtained by the solid-phase extraction membrane prepared in Example 1 of this invention are shown.

[0077] Figure 11 The chromatograms of crucian carp samples and spiked samples prepared by the solid-phase extraction membrane in Example 1 of this invention are shown.

[0078] Figure 12 The chromatograms are of shrimp meat samples and spiked samples prepared by solid-phase extraction membrane in Example 1 of this invention.

[0079] Figure 13 The enrichment efficiency diagrams are for the solid-phase extraction membranes prepared in Example 1 and Comparative Example 1 of this invention. Detailed Implementation

[0080] To enable those skilled in the art to more clearly understand the technical solutions described in this invention, the following embodiments are provided for illustration. It should be noted that the following embodiments do not constitute a limitation on the scope of protection claimed by this invention.

[0081] Unless otherwise specified, the raw materials, reagents or devices used in the following examples are available from conventional commercial sources or can be obtained by existing known methods.

[0082] Example 1

[0083] A method for preparing a solid-phase extraction membrane based on a defective MOF includes the following steps.

[0084] (1) Preparation of defective MOF: 675 mg ferric chloride hexahydrate (2.497 mmol) and 524 mg 3,5-dibromo-4-hydroxybenzaldehyde (1.873 mmol) were placed together in a beaker; then 30 mL DMF was added as a solvent, and the reactants were stirred and sonicated to promote complete dissolution of the reactants and formation of the metal-template precursor. After the solution was thoroughly mixed, 225 mg of 2-aminoterephthalic acid (1.242 mmol) was added, and ultrasonic stirring was continued until completely dissolved to obtain a mixture. The mixture was then transferred to a 100 mL stainless steel reactor lined with polytetrafluoroethylene. The reactor was placed in an oven and the reaction was maintained at 120 °C for 24 h. After the reaction was completed, the reactor was allowed to cool naturally to room temperature. The solid product was centrifuged and washed three times with DMF. The solid product was then transferred to 30 mL of methanol, stirred for 12 h, and centrifuged to elute the template molecules. This elution step was repeated once. The solid product was then vacuum dried at 60 °C for 12 h to obtain the defective MOF, denoted as defective MIL-101(Fe)-NH2.

[0085] (2) Preparation of solid-phase extraction membrane based on defective MOF: The powdered defective MOF obtained in step (1) was stirred and dispersed in methanol to prepare a suspension with a concentration of 1 mg / mL; 1 mL of the suspension was injected into a syringe, and a nylon-66 membrane filter head (diameter of 13 mm and pore size of 0.22 μm) was connected to the syringe outlet. The syringe was manually pushed so that the defective MOF passed through the nylon-66 membrane along with the methanol. The methanol flowed out through the micropores of the nylon-66 membrane, and the defective MOF was deposited on the membrane to form a uniform membrane. The membrane was dried at room temperature to form a coating and obtain a solid-phase extraction membrane; then 3.0 mL of methanol and 3.0 mL of ultrapure water were injected into the syringe, and the syringe was manually pushed so that the methanol and water passed through the solid-phase extraction membrane for later use.

[0086] The scanning electron microscope image of the defective MOF prepared in Example 1 is shown below. Figure 1 As shown, by Figure 1 The material can be seen to have an octahedral morphology, a rough surface, and a particle size of approximately 0.8 μm.

[0087] Example 1: Schematic diagram of solid-phase extraction membrane preparation process as shown below Figure 2As shown in the figure. Here, Fe-O cluster represents the template molecule, self-sssembly represents self-assembly, complex represents coordination synthesis, NH2-BDC represents 2-aminoterephthalic acid, solvent other method represents solvent method, activation represents activation, filtration represents filtration, membrane represents solid-phase extraction membrane, enrichment represents enrichment, membrane solid-phase extraction represents membrane solid-phase extraction, and analysis represents analysis.

[0088] Example 2

[0089] Example 2 is an optimization of the operating conditions when using the solid-phase extraction membrane prepared in Example 1 for extraction.

[0090] (1) Chromatographic conditions

[0091] During the experiment, HPLC-UV was used to characterize the performance of the solid-phase extraction membrane based on defective MOF prepared in Example 1.

[0092] In HPLC-UV, the chromatographic column was a Diamonsil Plus C18-A column (4.6 mm × 250 mm × 5 μm); mobile phase A was 0.1% acetic acid solution, mobile phase B was pure acetonitrile, isocratic elution (A / B = 52 / 48), the detection wavelength was 218 nm, the injection volume was 20 μL, the flow rate was 1.0 mL / min, and the column temperature was 25 °C.

[0093] The extracted disinfection byproducts were 2-chlorophenol (2-CP), 2,4-dichlorophenol (2,4-DCP), 2,4,6-trichlorophenol (2,4,6-TCP) and 2,4,5-trichlorophenol (2,4,5-TCP).

[0094] (2) Optimization of optimal extraction conditions

[0095] Solid-phase extraction (SPE) technology is affected by factors such as the amount of defective MOF used, extraction flow rate, type and volume of desorption solvent, desorption flow rate, and sample pH when measuring analyte concentration in a sample. Before using the SPE membrane prepared in Example 1, the optimal extraction conditions need to be optimized. The optimization results for the amount of defective MOF are shown below. Figure 3 As shown; the experimental results of solid-phase extraction membrane extraction flow rate optimization are as follows. Figure 4 As shown; the experimental results of solvent optimization for solid-phase extraction membrane desorption are as follows. Figure 5 As shown; the experimental results of optimizing the desorption solvent volume of the solid-phase extraction membrane are as follows. Figure 6As shown; the experimental results of optimizing the desorption flow rate of the solid-phase extraction membrane are as follows. Figure 7 As shown; the results of the pH optimization experiment for solid-phase extraction membrane extraction are as follows. Figure 8 As shown; Figure 3-8 In the middle, the vertical axis represents the peak area (×10). 5 () All of these represent peak area.

[0096] Depend on Figure 3-8 It can be seen that the optimal extraction conditions for the four DBPs are different. The extraction conditions at which most DBPs achieve the best extraction efficiency are taken as the final optimized conditions, namely, the amount of defective MOF in the enrichment medium is 1.0 mg, the extraction flow rate is 1.5 mL / min, the desorption solvent is methanol, the desorption solvent volume is 0.2 mL, the desorption flow rate is 0.03 mL / min, and the extraction pH is 4.0.

[0097] Comparative Example 1

[0098] The only difference between Comparative Example 1 and Example 1 is that Comparative Example 1 did not add the template molecule 3,5-dibromo-4-hydroxybenzaldehyde when preparing the defective MOF; otherwise, it was the same as Example 1.

[0099] Performance testing

[0100] 1. Determination of linear range, limit of detection (LOD), limit of quantitation (LOQ), and reproducibility (RSD) of solid-phase extraction membranes based on defective MOFs.

[0101] Under the optimal extraction conditions described above (i.e., 1.0 mg of defective MOF enrichment medium, 1.5 mL / min extraction flow rate, methanol as desorption solvent, 0.2 mL desorption solvent volume, 0.03 mL / min desorption flow rate, and extraction pH 4.0), a series of freshly prepared mixed standard solutions of the target analyte (chlorophenol) at different concentrations (0.1-50 μg / L) were extracted using this solid-phase extraction membrane. Three parallel tests were conducted for each concentration condition, and HPLC-UV analysis was used to obtain the peak areas corresponding to each concentration. A graph with peak area as the ordinate was plotted to obtain the linear range of the solid-phase extraction membrane based on the defective MOF. Specifically, the mixed standard solutions of the target analyte were prepared as follows: a 1 mg / mL standard solution of the analyte was purchased as a standard stock solution. A certain amount of the stock solution was then pipetted into a 100 mL volumetric flask and diluted to volume with ultrapure water to prepare working solutions of different concentrations.

[0102] The linear range of solid phase extraction membranes for the detection of chlorophenol is as follows: Figure 9 As shown, the horizontal axis C (μg / L) represents the concentration of the mixed standard solution of the target analyte; the vertical axis Peak area (×10) represents the concentration of the target analyte. 5 () indicates the peak area.

[0103] The linear range, LOD, LOQ, and RSD of solid-phase extraction membranes based on defective MOFs are shown in Table 1.

[0104] Table 1: The linear range, LOD, LOQ, and RSD of solid-phase extraction membranes based on defective MOFs are shown in Table 1.

[0105]

[0106]

[0107] From Table 1 and Figure 9 It can be seen that the solid-phase extraction membrane based on defective MOF prepared in this invention has good linearity for the detection of chlorophenol (R between 0.9985 and 0.9999), a detection limit of 0.03-0.15 μg / L, and good reproducibility.

[0108] 2. Detection of chlorophenol in aquatic products

[0109] The solid-phase extraction membrane prepared in Example 1 based on the defective MIL-101(Fe)-NH2 material was used to determine chlorophenols in aquatic products, namely 2-CP, 2,4-DCP, 2,4,6-TCP and 2,4,5-TCP.

[0110] Grass carp, crucian carp, and shrimp meat samples were purchased through conventional commercial channels for chlorophenol content detection. Under the optimized conditions of Example 2, the aquatic products were extracted and analyzed using the solid-phase extraction membrane prepared in Example 1. The obtained peak areas were substituted into the linear equation to obtain the content of the four chlorophenols.

[0111] Before testing, the aquatic product samples need to be processed. The sample processing procedure is as follows: the meat sample is crushed and homogenized using a meat grinder. 5.00g of the homogenized meat sample is accurately weighed and placed in a centrifuge tube. 2.00g of anhydrous magnesium sulfate is added, followed by 15mL of a mixed solvent of acetonitrile / n-hexane (1:1, V / V). The mixture is then vigorously vortexed for 5min. The mixture is then ultrasonically extracted for 20min, centrifuged, and the acetonitrile phase in the supernatant is collected. This extraction process is repeated once, and the extracts from both extractions are combined. The extract was filtered through a 0.22 μm filter membrane in a centrifuge tube and then purged with nitrogen until dry. The extract was then redissolved in 50 mL of ultrapure water, the pH was adjusted to 4.0, and the solution was placed in a 50 mL syringe. The syringe was connected to the solid-phase extraction membrane based on the defective MIL-101(Fe)-NH2 prepared in Example 1 and fixed on a ten-channel syringe pump. The solution was enriched at a flow rate of 1.5 mL / min. After enrichment, the solid-phase extraction membrane was eluted with 0.2 mL of methanol, and 20 μL of the eluent was injected for analysis.

[0112] Based on the actual content of the target analyte (chlorophenol) in the aquatic product samples, a certain amount of the target analyte was added to the samples, and then extraction and detection were performed using the established analytical method. Chromatograms of grass carp samples and spiked grass carp samples are shown below. Figure 10 As shown, the chromatograms of the crucian carp sample and the spiked crucian carp sample are as follows. Figure 11 As shown, the chromatograms of the shrimp meat sample and the spiked shrimp meat sample are as follows. Figure 12 As shown. Figure 10-12 In the graph, the horizontal axis Time (min) represents time (minutes), and the vertical axis Intensity (mV) represents the electrical signal strength (millivolts).

[0113] Depend on Figure 10-12 It can be seen that the retention times of the target analytes in the original sample chromatogram correspond one-to-one with the target peaks in the spiked sample chromatogram.

[0114] The detection results of chlorophenols in grass carp, crucian carp, and shrimp meat prepared by the solid-phase extraction membrane based on defective MIL-101(Fe)-NH2 in Example 1 are shown in Tables 2, 3, and 4, respectively.

[0115] Table 2: Detection results of chlorophenol in grass carp using the defective MIL-101(Fe)-NH2 solid-phase extraction membrane prepared in Example 1.

[0116]

[0117] In Table 2, ND indicates not detected.

[0118] Table 3: Detection results of chlorophenol in crucian carp using the defective MIL-101(Fe)-NH2 solid-phase extraction membrane prepared in Example 1.

[0119]

[0120] In Table 3, ND indicates not detected.

[0121] Table 4: Detection results of chlorophenols in shrimp meat using solid-phase extraction membrane of defective MIL-101(Fe)-NH2 prepared in Example 1.

[0122]

[0123] As can be seen from Tables 2, 3 and 4, the recoveries of the four chlorophenol compounds are between 82.0% and 110%, indicating that this method meets the requirements for trace analysis.

[0124] 3. Enrichment efficiency test

[0125] The enrichment efficiency of the solid-phase extraction membranes prepared in Example 1 and Comparative Example 1 was tested, and the specific testing methods were the same as the optimized extraction and chromatographic conditions finally used in Example 2.

[0126] The enrichment efficiency results of the solid-phase extraction membranes prepared in Example 1 and Comparative Example 1 are as follows: Figure 13 As shown, MIL-101(Fe)-NH2 represents the solid-phase extraction membrane prepared in Comparative Example 1, and the defective MIL-101(Fe)-NH2 represents the solid-phase extraction membrane prepared in Example 1. The vertical axis represents the peak area (×10). 5 () indicates the peak area.

[0127] Depend on Figure 13 It can be seen that the solid-phase extraction membrane based on defective MOF prepared in Example 1 has a better enrichment efficiency than the solid-phase extraction membrane based on parent MOF prepared in Comparative Example 1. This is because the addition and removal of template molecules in Example 1 can introduce additional imprinted cavities in the defective MOF that are adapted to the structure and shape of chlorophenol, thereby enhancing the affinity for chlorophenol and significantly improving the enrichment efficiency.

[0128] In summary, this invention employs specific template molecules to create pores in the defective MOF structure that are adapted to the shape and size of the template molecules. This results in strong adsorption capacity for structural analogs of the template molecules, and the coating exhibits strong selectivity for the target analyte. It can selectively enrich chlorophenol, thus enabling the solid-phase extraction membrane to have excellent adsorption effect on chlorophenol, with high enrichment factor and good reproducibility.

[0129] The above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. The application of a solid-phase extraction membrane in the detection of chlorophenol, characterized in that, The solid-phase extraction membrane includes a carrier and a coating loaded on the surface of the carrier; The carrier includes any one of nylon filter membrane, polyvinylidene fluoride filter membrane, and polytetrafluoroethylene filter membrane; The coating comprises a defective amino MOF material; the defective amino MOF material includes mesoporous and microporous components. The method for preparing the defective amino MOF material is as follows: mixing metal salt, template molecule, amino organic ligand and organic solvent, reacting, separating, eluting, and drying to obtain the defective amino MOF material; The metal salt includes any one of iron salt, zirconium salt, and chromium salt; the template molecule includes 3,5-dibromo-4-hydroxybenzaldehyde; and the amino organic ligand includes 2-aminoterephthalic acid. The molar ratio of the metal salt to the template molecule is 1:(0.45-1.1); the molar ratio of the metal salt to the amino organic ligand is 1:(0.27-1.1).

2. The application according to claim 1, characterized in that, The particle size of the defective amino MOF material is 0.45-1.7µm.

3. The application according to claim 1, characterized in that, The reaction temperature is 100-150℃; and / or the reaction time is 12-48h.

4. The application according to claim 1, characterized in that, The method for preparing the solid-phase extraction membrane includes the following steps: (1) The defective amino MOF material and solvent are mixed to obtain a suspension; (2) The suspension obtained in step (1) is filtered using the carrier, and the defective amino MOF material is loaded on the carrier to obtain the solid phase extraction membrane.

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