A solid phase extraction membrane, a preparation method and application thereof

Abstract

The application discloses a kind of solid phase extraction membranes, the solid phase extraction membrane includes carrier and enrichment medium coating layer loaded on the surface of carrier;The material of the enrichment medium coating layer is MOF@COF material;The MOF@COF material includes the amino-functionalized metal organic framework material in core and the covalent organic framework material in outer layer;The amino-functionalized metal organic framework material is MIL-101 (Cr)-NH2;The covalent organic framework material is prepared by 1,4-dialdehyde-2,5-divinylbenzene and 1,3,5-tri (4-aminophenyl) benzene condensation reaction;The carrier is organic filter membrane.This material has the advantages of large adsorption capacity, good chemical stability and the like;The solid phase membrane coating prepared from the material has good water resistance, high enrichment multiple, and good reproducibility, and has excellent adsorption effect on halogenated benzoic acid and halogenated benzaldehyde DBPs.

Description

Technical Field

[0001] The present invention relates to the technical field of solid phase extraction, and in particular to a solid phase extraction membrane and a preparation method and application thereof. Background Art

[0002] Disinfection by-products (DBPs) are compounds produced by the reaction of natural organic matter, inorganic ions (such as bromide and iodide), algal biomass, and anthropogenic contaminants (such as pesticides, pharmaceuticals, and detergents) with disinfectants in water. Their widespread presence in drinking water supplies and environmental waters has raised concerns about human health and aquatic life. Epidemiological studies have linked the consumption of disinfected drinking water with the incidence of bladder cancer, colorectal cancer, and other diseases. Furthermore, their widespread distribution in the natural environment can adversely impact marine ecosystems. With increasing concern about DBPs, countries are gradually refining their drinking water DBP limit standards. Aromatic DBPs, as an emerging class of DBPs, have much lower concentrations than aliphatic DBPs, but their contribution to overall toxicity cannot be ignored. Because most aromatic DBPs exist at trace levels and in complex water matrices, their efficient separation, enrichment, and accurate quantification remain challenging.

[0003] Currently, the main method for efficiently enriching aromatic DBPs in drinking water is liquid-liquid extraction (LLE). This method utilizes the differential partition coefficients of the analytes between two immiscible solvents to extract and concentrate aromatic DBPs, enabling trace detection of these substances. The concentration of aromatic DBPs in raw water samples is typically in the ng / L range, below the detection limit of analytical instruments. Accurately quantifying trace aromatic DBPs using this method requires increased sample volume and large amounts of organic solvent to elute the target compounds, resulting in significant experimental costs. Membrane solid phase extraction (M-SPE) offers strong matrix cleanup capabilities, high separation capacity, and the ability to perform concentration and purification in a single step. This significantly simplifies sample preparation and improves extraction efficiency, making it ideal for the efficient separation and enrichment of trace aromatic DBPs in complex samples. The performance of M-SPE is closely related to the enrichment medium immobilized on the membrane. The key to improving M-SPE efficiency lies in the development of highly efficient separation and enrichment media.

[0004] Metal-organic frameworks (MOFs) are crystalline porous inorganic-organic hybrid materials with periodic network structure composed of organic linkers and transition metal ions as secondary building units through self-assembly. In addition, covalent organic frameworks (COFs) are a class of porous materials connected by light elements and organic monomers through strong covalent bonds. With the development of MOFs and COFs synthesis technology in recent years, MOF@COF composite materials prepared by cross-functioning of MOFs and COFs have become a new class of materials, which can maximize the inherent properties and additional functions through synergistic effect, and have made preliminary progress in sample pretreatment, and are expected to be applied to solid phase extraction. However, there are still few studies on this kind of composite material in the field of membrane solid phase extraction, especially the research and development of membrane solid phase extraction technology for aromatic DBPs has not been reported. SUMMARY

[0005] In order to overcome the problems existing in the prior art, one of the purposes of the present application is to provide a solid phase extraction membrane. The second purpose of the present application is to provide a preparation method of the solid phase extraction membrane. The third purpose of the present application is to provide an application of the solid phase extraction membrane in detecting disinfection by-products. The solid phase extraction membrane has high selectivity for aromatic DBPs, is suitable for detection of aromatic DBPs in a wide concentration range, and can realize trace detection of aromatic DBPs in beverage samples.

[0006] In order to achieve the above purposes, the technical scheme adopted by the present application is as follows:

[0007] The first aspect of the present application provides a solid phase extraction membrane, which comprises a carrier and an enrichment medium coating layer loaded on the surface of the carrier.

[0008] The material of the enrichment medium coating layer is MOF@COF material; the MOF@COF material comprises an amino-functionalized metal-organic framework material at the core and a covalent organic framework material at the outer layer; the amino-functionalized metal-organic framework material is MIL-101(Cr)-NH2; and the covalent organic framework material COF-V is prepared by condensation reaction of 1,4-dialdehyde-2,5-divinylbenzene and 1,3,5-tris(4-aminophenyl)benzene.

[0009] The carrier is an organic filter membrane.

[0010] Preferably, the carrier is a nylon-66 membrane.

[0011] Preferably, the preparation method of the MIL-101(Cr)-NH2 comprises the following steps: first, uniformly mixing chromium nitrate hydrate and 2-amino terephthalic acid in water, and then keeping the mixed solution at 100-150℃ for 12-48h to prepare the MIL-101(Cr)-NH2.

[0012] More preferably, the chromium nitrate hydrate is chromium nitrate nonahydrate.

[0013] More preferably, the mass ratio of the chromium nitrate hydrate to 2-aminoterephthalic acid is (1.5-3):1.

[0014] More preferably, the preparation method further comprises separation, washing, purification and drying; further preferably, the separation and washing step comprises: after cooling, separating the crude product and washing it with N,N-dimethylformamide and pure water; further preferably, the purification step comprises: treating it with ethanol at 90-120° C. in a high-pressure reactor for 8-12 hours; further preferably, the drying step comprises: drying it in an oven at 70-90° C. for 20-28 hours.

[0015] Preferably, the preparation method of the MOF@COF material comprises the following steps:

[0016] S1, MIL-101(Cr)-NH2 and 1,4-dialdehyde-2,5-divinylbenzene reacted to obtain the intermediate product MIL-101(Cr)-NH2@DVA;

[0017] S2. The MIL-101(Cr)-NH2@DVA reacts with 1,4-dialdehyde-2,5-divinylbenzene and 1,3,5-tris(4-aminophenyl)benzene to prepare MOF@COF material.

[0018] More preferably, the reaction temperature in step S1 is 100-150°C; further preferably, the reaction temperature is 110-130°C.

[0019] More preferably, the reaction temperature in step S2 is 15-40°C; further preferably, the reaction temperature is 20-30°C.

[0020] More preferably, in step S1, the mass ratio of the MIL-101(Cr)-NH2 to 1,4-dialdehyde-2,5-divinylbenzene is (3-5):1.

[0021] More preferably, in step S1, the reaction is carried out in 1,4-dioxane solvent.

[0022] More preferably, in step S1, the reaction time is 0.5 to 2 hours.

[0023] More preferably, in step S1, the reaction uses glacial acetic acid as a catalyst;.

[0024] More preferably, in step S2, the mass ratio of MIL-101(Cr)-NH2@DVA, 1,4-dialdehyde-2,5-divinylbenzene and 1,3,5-tri(4-aminophenyl) is (2-4):1:(1-1.5).

[0025] More preferably, in step S2, the reaction is carried out in acetonitrile solvent.

[0026] More preferably, in step S2, the reaction time is 70-74h.

[0027] More preferably, in step S2, the reaction uses glacial acetic acid as a catalyst.

[0028] The second aspect of the present application provides a preparation method of the solid-phase extraction membrane of the first aspect, comprising the following steps:

[0029] 1) dispersing the MOF@COF material in a solvent to prepare a suspension with a certain concentration;

[0030] 2) filtering the suspension by using an organic filter membrane, and loading the MOF@COF material on the organic filter membrane to obtain a solid-phase extraction membrane.

[0031] Preferably, in step 2), the filtering mode uses a needle cylinder filter.

[0032] More preferably, the step of needle cylinder filter is as follows: a certain amount of suspension is injected into a syringe, a nylon-66 membrane filter head is connected to the outlet of the syringe, and the syringe is pushed so that the MOF@COF material passes through the membrane together with the solvent, wherein the organic solvent flows out through the micropores of the membrane, and the MOF@COF is deposited on the membrane, and then dried to obtain a solid-phase extraction membrane.

[0033] Preferably, the solvent is methanol.

[0034] Preferably, the concentration of the suspension is 0.1-10mg / mL.

[0035] Preferably, the organic filter membrane is a nylon-66 membrane; more preferably, the diameter of the nylon-66 membrane is 13mm, and the pore size is less than 1μm.

[0036] The third aspect of the present application provides the application of the solid-phase extraction membrane of the first aspect in detecting disinfection by-products.

[0037] Preferably, the disinfection by-products are halogenated benzoic acid or halogenated benzaldehyde. More preferably, the disinfection by-products are 3,5-dichlorosalicylic acid, 3,5-dibromo-4-hydroxybenzoic acid, 3,5-dibromo-4-hydroxybenzaldehyde, 3,5-dichloro-4-hydroxybenzaldehyde, 3-bromo-5-chloro-4-hydroxybenzaldehyde.

[0038] Preferably, the extraction conditions of the solid phase extraction membrane for detecting disinfection by-products are as follows: the amount of enrichment medium is 0.8-4.0 mg, the extraction flow rate is 0.5-2.5 mL / min, the desorption solvent is methanol, the desorption solvent volume is 0.5-2.5 mL, the desorption flow rate is 0.1-0.4 mL / min, and the extraction pH is 1.0-5.0. More preferably, the extraction conditions of the solid phase extraction membrane for detecting disinfection by-products are as follows: the amount of enrichment medium is 2.0-4.0 mg, the extraction flow rate is 1.0-2.0 mL / min, the desorption solvent is methanol, the desorption solvent volume is 1.0-2.0 mL, the desorption flow rate is 0.2-0.4 mL / min, and the extraction pH is 1.0-2.0.

[0039] Preferably, the solid phase extraction membrane is used in detecting disinfection by-products in beverage samples.

[0040] The beneficial effects of the present invention are:

[0041] The present invention provides a solid-phase extraction membrane. The adsorbent used in the solid-phase extraction membrane coating is a MOF@COF composite material. The material has the advantages of large adsorption capacity and good chemical stability. The solid-phase membrane coating prepared with the MOF@COF composite material as the raw material has good water resistance, high enrichment multiple, and good reproducibility, and has an excellent adsorption effect on halogenated benzoic acid and halogenated benzaldehyde DBPs.

[0042] Specifically, compared with the prior art, the present invention has the following advantages:

[0043] 1) The present invention provides a solid-phase extraction membrane. The adsorbent used in the solid-phase extraction membrane coating is a MOF@COF composite material. The MOF structure is rich in benzene rings and amino groups, and has a strong adsorption effect on halogenated benzoic acids and halogenated benzaldehydes. The rich planar π structure and oxygen-containing functional groups in the COF material structure synthesized with 1,3,5-tris(4-aminophenyl)benzene and 1,4-dialdehyde-2,5-divinylbenzene as monomers can further improve the medium's enrichment ability for halogenated benzoic acids and halogenated benzaldehyde disinfection by-products. The MOF@COF composite material synthesized by combining MIL-101(Cr)-NH2 and COF-V through a Schiff base reaction can be used as an enrichment medium to efficiently enrich halogenated benzoic acids and halogenated benzaldehyde disinfection by-products. Moreover, the solid-phase extraction membrane coating made of the MOF@COF composite material can highly selectively enrich aromatic DBPs, is simple to prepare, and has good chemical stability.

[0044] 2) The present invention prepares the MOF@COF solid-phase extraction membrane coating by direct deposition. The preparation steps are simple and do not require complex equipment. The solid-phase extraction membrane coating prepared by the method has good chemical stability, excellent adsorption effect on aromatic compounds, high enrichment multiples and good reproducibility.

[0045] 3) The prepared solid phase extraction membrane coating of the application is used for determining halobenzoic acid and halobenzaldehyde DBPs in beverage samples, and has good linear range, low detection limit, high recovery rate and the like. The analysis method enriches halobenzoic acid and halobenzaldehyde DBPs in beverage samples through the MOF@COF composite material, can be combined with LC-MS / MS for detection of halobenzoic acid and halobenzaldehyde DBPs, and the signal strength generated by halobenzoic acid and halobenzaldehyde DBPs has a good linear relationship with the content, so that trace detection of halobenzoic acid and halobenzaldehyde DBPs in beverage samples can be realized. Compared with the prior art, the operation is more simple and the detection capacity is greatly improved, and has practical application value. BRIEF DESCRIPTION OF DRAWINGS

[0046] Figure 1 It is a scanning electron microscope graph of MIL-101(Cr)-NH2@COF-V composite material;

[0047] Figure 2 It is a preparation process schematic diagram of MIL-101(Cr)-NH2@COF-V solid phase extraction membrane;

[0048] Figure 3 It is MIL-101(Cr)-NH2@COF-V solid phase extraction membrane coating filler amount optimization;

[0049] Figure 4 It is MIL-101(Cr)-NH2@COF-V solid phase extraction membrane extraction flow rate optimization;

[0050] Figure 5 It is MIL-101(Cr)-NH2@COF-V solid phase extraction membrane desorption solvent optimization;

[0051] Figure 6 It is MIL-101(Cr)-NH2@COF-V solid phase extraction membrane desorption solvent volume optimization;

[0052] Figure 7 It is MIL-101(Cr)-NH2@COF-V solid phase extraction membrane desorption flow rate optimization;

[0053] Figure 8 It is MIL-101(Cr)-NH2@COF-V solid phase extraction membrane extraction pH optimization;

[0054] Figure 9 It is the linear range of MIL-101(Cr)-NH2@COF-V solid phase extraction membrane for halobenzoic acid and halobenzaldehyde compound detection;

[0055] Figure 10 Chromatograms of coconut water sample and spiked sample using MIL-101(Cr)-NH2@COF-V solid phase extraction membrane;

[0056] Figure 11 Chromatograms of orange juice sample and spiked sample subjected to MIL-101(Cr)-NH2@COF-V solid phase extraction membrane. DETAILED DESCRIPTION

[0057] The present invention is further described in detail below through specific examples. Unless otherwise specified, the raw materials used in the following examples can be obtained from conventional commercial sources or prepared and isolated by simple synthesis; unless otherwise specified, the processes used are conventional processes in the art.

[0058] Example 1 Preparation of solid phase extraction membrane

[0059] 1. Preparation of MOF materials

[0060] Chromium nitrate nonahydrate (2.00 g) and 2-aminoterephthalic acid (0.90 g) were dissolved in 28 ml of ultrapure water and transferred to a Teflon-lined autoclave. The autoclave was heated in an oven at 130°C for 24 hours. After cooling, the crude product was isolated and washed with N,N-dimethylformamide and ultrapure water. The product was then treated in an autoclave with 70 mL of ethanol at 100°C for 10 hours. The purified green crystals were filtered, washed with ultrapure water, and dried in an oven at 80°C for 24 hours to produce the MOF material, designated MIL-101(Cr)-NH2.

[0061] 2. Preparation of MOF@COF composite materials

[0062] The synthesized MOF material MIL-101(Cr)-NH2 (70.0 mg) and 1,4-dialdehyde-2,5-divinylbenzene (2,5-Divinylterephthalaldehyde, DVA, 22.3 mg) were dissolved in 20 mL of 1,4-dioxane solution, followed by the addition of 300 μL of glacial acetic acid. After stirring for 1 minute, the mixed solution was transferred to a 50 mL Teflon-lined autoclave and heated at 120°C for 1 hour. After cooling to room temperature, the product was isolated and washed with N,N-dimethylformamide, 1,4-dioxane, and methanol, and then dried under vacuum at 60°C to obtain the intermediate product MIL-101(Cr)-NH2@DVA, which was used in the next step to synthesize the composite material.

[0063] MIL-101(Cr)-NH2@DVA (50.0 mg) was dispersed in acetonitrile (10 mL). 1,3,5-Tris(4-aminophenyl)benzene (TAPB, 28.0 mg) and DVA (22.3 mg) were then added and stirred for 30 min. Glacial acetic acid (1 mL) was then added and the reaction solution was allowed to stand at room temperature for 72 h after stirring, forming orange core-shell MIL-101(Cr)-NH2@COF-V microspheres. The microspheres were then washed several times with tetrahydrofuran and ethanol, centrifuged, and dried in vacuum at 60°C overnight to obtain the MOF@COF composite, designated MIL-101(Cr)-NH2@COF-V.

[0064] The powder of the MIL-101(Cr)-NH2@COF-V material obtained by the synthesis method is used to prepare the solid phase extraction membrane coating in the solid phase extraction membrane of the present invention.

[0065] The micromorphology of the prepared MIL-101(Cr)-NH2@COF-V material was characterized by scanning electron microscopy. Figure 1 The scanning electron microscope image shown shows that the material has good dispersion and the particle size is about 450nm.

[0066] 3. Preparation of solid phase extraction membrane containing MIL-101(Cr)-NH2@COF-V coating

[0067] The preparation process of solid phase extraction membrane is as follows Figure 2 As shown, the specific preparation method is carried out according to the following steps:

[0068] (1) MIL-101(Cr)-NH2@COF-V powder was stirred and dispersed in methanol to prepare a suspension with a concentration of 1 mg / mL. 3 mL of the suspension was injected into a needle syringe, and a nylon-66 membrane filter (13 mm in diameter and 0.22 μm in pore size) was connected to the syringe outlet. The syringe was manually pushed to allow MIL-101(Cr)-NH2@COF-V to pass through the membrane along with methanol. Methanol flowed out through the micropores of the membrane, and MIL-101(Cr)-NH2@COF-V was deposited on the membrane to form a uniform coating. The membrane was then dried at room temperature to obtain a solid phase extraction membrane containing a MIL-101(Cr)-NH2@COF-V coating.

[0069] (2) Activation of the solid phase extraction membrane coating: 3.0 mL of methanol and 3.0 mL of ultrapure water were respectively injected into a needle syringe, and the syringe was manually pushed to allow the methanol and water to pass through the solid phase extraction membrane obtained in step (1) for later use.

[0070] Example 2 Optimization of solid phase extraction membrane coating operating conditions

[0071] In this example, the operating conditions of the solid phase extraction membrane coating made of MIL-101(Cr)-NH2@COF-V material when used in membrane solid phase extraction were optimized through experiments.

[0072] 1. Chromatographic conditions

[0073] During the experiment, liquid chromatography-mass spectrometry (LC-MS / MS) was used to characterize the properties of the MIL-101(Cr)-NH2@COF-V coating prepared in Example 1.

[0074] In LC-MS / MS, a Hypersil GOLD C18 column (2.1 mm × 100 mm × 5 μm) was used; mobile phase A consisted of 0.001% acetic acid solution; mobile phase B was pure methanol; the injection volume was 10 μL, the flow rate was 0.4 mL / min, and the column temperature was 40°C. A liquid chromatography gradient elution program was used: 0-0.5 min, 20%-30% B; 0.5-5.0 min, 30%-95% B; 5.0-6.5 min, 95% B; 6.5-9.0 min, 20% B.

[0075] The disinfection by-products extracted were 3,5-dichlorosalicylic acid, 3,5-dibromo-4-hydroxybenzoic acid, 3,5-dibromo-4-hydroxybenzaldehyde, 3,5-dichloro-4-hydroxybenzaldehyde, and 3-bromo-5-chloro-4-hydroxybenzaldehyde.

[0076] 2. Optimization of optimal extraction conditions

[0077] The concentration of analytes in samples measured using solid-phase membrane extraction technology is affected by factors such as the amount of enrichment medium, extraction flow rate, desorption solvent type, desorption solvent volume, desorption flow rate, and sample pH. Before using the MIL-101(Cr)-NH2@COF-V coating prepared in Example 2, it is necessary to optimize the optimal extraction conditions for the coating. Experiments have shown that the optimal extraction conditions for the five DBPs vary. The optimal extraction conditions for most DBPs were determined as follows: the amount of enrichment medium was 3.0 mg ( Figure 3 ), the extraction flow rate was 1.0 mL / min ( Figure 4 ), the desorption solvent is methanol ( Figure 5 ), the desorption solvent volume is 1.5mL( Figure 6 ), the desorption flow rate was 0.3 mL / min ( Figure 7 ), extraction pH was 1.0( Figure 8 ).

[0078] Example 3 Performance Characterization of Membrane Solid Phase Extraction Coating

[0079] The performance of the membrane solid phase extraction coating prepared from MIL-101(Cr)-NH2@COF-V material is characterized in this embodiment.

[0080] 1. Preparation of solution

[0081] (1) Preparation of stock solution of halogenated benzoic acid and halogenated benzaldehyde compounds: first, dissolve 3,5-dichlorosalicylic acid, 3,5-dibromo-4-hydroxybenzoic acid, 3,5-dibromo-4-hydroxybenzaldehyde, 3,5-dichloro-4-hydroxybenzaldehyde and 3-bromo-5-chloro-4-hydroxybenzaldehyde in chromatographically pure methanol respectively to prepare initial standard solutions. Then, take a certain amount of the initial standard solutions of the above-mentioned five aromatic compounds, add them to 20 mL brown volumetric flasks containing a small amount of chromatographically pure methanol, dilute with methanol to prepare stock solutions with a concentration of 1000 mg / L, and then store them at 4°C for later use.

[0082] (2) Preparation of working solution: prepare a certain amount of stock solution in a 20 mL sample bottle, shake well and use. The working solution is prepared and used immediately.

[0083] 2. Under the optimal extraction conditions, a series of freshly prepared working solutions with concentrations of 1.5 ng / L, 2.0 ng / L, 5.0 ng / L, 10.0 ng / L, 20.0 ng / L, 50.0 ng / L, 100.0 ng / L, 200.0 ng / L, 400.0 ng / L, 500.0 ng / L, 1000.0 ng / L and 2000.0 ng / L are extracted by the MIL-101(Cr)-NH2@COF-V membrane respectively, 3 groups are tested in parallel for each test condition, and LC-MS / MS analysis is performed to obtain a series of peak areas corresponding to the concentrations. The linear range of the MIL-101(Cr)-NH2@COF-V membrane test is obtained by plotting the peak area as the vertical coordinate (such as Figure 9 ).

[0084] The specific results are shown in Table 1. The linear detection of the MIL-101(Cr)-NH2@COF-V coating on aromatic compounds is good (R 2 between 0.9919 and 0.9970), and the detection limit is 0.5-3.0 ng / L.

[0085] Table 1 Linear range, detection limit, limit of quantification and reproducibility of MIL-101(Cr)-NH2@COF-V membrane

[0086]

[0087] Example 4 Membrane solid phase extraction coating for determination of benzoic acid and benzaldehyde disinfection byproducts in beverages.

[0088] In this embodiment, the solid-phase extraction membrane prepared from MIL-101(Cr)-NH2@COF-V material is used to determine benzoic acid and benzaldehyde disinfection byproducts in beverages, namely 3,5-dichlorosalicylic acid, 3,5-dibromo-4-hydroxybenzoic acid, 3,5-dibromo-4-hydroxybenzaldehyde, 3,5-dichloro-4-hydroxybenzaldehyde and 3-bromo-5-chloro-4-hydroxybenzaldehyde.

[0089] The experiment purchased coconut water beverage and orange juice beverage samples from a conventional commercial channel to detect the content of benzoic acid and benzaldehyde compounds. The benzoic acid and benzaldehyde compounds in the beverage sample treated by the MIL-101(Cr)-NH2@COF-V membrane prepared in Example 2 were extracted, and the peak area obtained was substituted into the linear equation to obtain the content of the five kinds of benzoic acid and benzaldehyde compounds.

[0090] Sample treatment: The beverage sample was ultrasonically treated for 10 min, centrifuged to remove the precipitate, and the supernatant was filtered with a 0.22 μm water-based filter membrane. 20.0 mL of the sample was taken, the pH was adjusted to 1.0, and it was placed in a 20 mL needle syringe. The syringe was connected to the MIL-101(Cr)-NH2@COF-V extraction membrane prepared in Example 2, which was fixed on a ten-channel syringe pump, and enrichment was carried out at a flow rate of 1.0 mL / min. After enrichment, 1.5 mL of methanol was used to elute the solid-phase extraction membrane, and the eluate was concentrated to near dryness by nitrogen blowing, dissolved in 0.2 mL of methanol, and 10 μL of the liquid sample was injected for analysis.

[0091] By adding a certain concentration of the mixed standard solution to the beverage sample, the chromatograms of the original coconut water sample and the coconut water spiked sample are as shown in Figure 10 The chromatograms of the orange juice sample and the orange juice spiked sample are as shown in Figure 11 The specific detection amount and the standard addition recovery rate of the sample are shown in Tables 2 and 3, and the recovery rate of the five kinds of benzoic acid and benzaldehyde compounds is between 85.9% and 125%, indicating that this method meets the requirements of trace analysis.

[0092] Table 2 Detection results of MIL-101(Cr)-NH2@COF-V extraction membrane for benzoic acid and benzaldehyde DBPs in coconut water

[0093]

[0094] Table 3 Detection results of MIL-101(Cr)-NH2@COF-V extraction membrane for benzoic acid and benzaldehyde DBPs in orange juice

[0095]

[0096] Example 5 Comparison of the analysis method with the LLE-LC-MS / MS method.

[0097] In this embodiment, the LLE-LC-MS / MS method reported in the literature (Water Research, 2020, 170, 115283; DOI: 10.1016 / j.watres.2019.115283) was used to detect halogenated benzoic acids and halogenated benzaldehydes disinfection by-products in coconut water and orange juice samples.

[0098] Treatment of samples: The beverage sample was ultrasonicated for 10 min, centrifuged to remove the precipitate, and the supernatant was filtered with a 0.22 μm water-based filter membrane. 100.0 mL of the sample was taken, the pH was adjusted to 0.5 with sulfuric acid, and then 10.0 g of Na2SO4 was added. The acidified sample was extracted with 10 mL of methyl tert-butyl ether. After extraction, the organic layer was transferred to a centrifuge tube, the extract was concentrated to 0.5 mL by nitrogen blowing, 1 mL of acetonitrile was added to the concentrate, and then it was blown to near dryness with nitrogen, dissolved with 0.1 mL of methanol, and 10 μL of the liquid sample was injected for analysis. The detection results are shown in Table 4.

[0099] Table 4 Summary of method comparison results

[0100]

[0101] The above embodiments are the preferred embodiments of the present application, but the embodiments of the present application are not limited to the above embodiments, and any changes, modifications, substitutions, combinations, simplifications made without departing from the spirit and principles of the present application should be equivalent replacement methods, and are all included in the protection scope of the present application.

Claims

1. A solid phase extraction membrane, characterized in that The solid phase extraction membrane includes a carrier and an enrichment medium coating loaded on the surface of the carrier; The material of the enriched medium coating is a MOF@COF material; the MOF@COF material includes an amino-functionalized metal organic framework material at the core and a covalent organic framework material at the outer layer; the amino-functionalized metal organic framework material is MIL-101(Cr)-NH2; the covalent organic framework material is prepared by a condensation reaction of 1,4-dialdehyde-2,5-divinylbenzene and 1,3,5-tris(4-aminophenyl)benzene; The carrier is an organic filter membrane; The preparation method of MIL-101(Cr)-NH2 comprises the following steps: firstly, uniformly mixing chromium nitrate hydrate and 2-aminoterephthalic acid in water, and then maintaining the mixed solution at 100-150° C. for 12-48 hours to obtain MIL-101(Cr)-NH2; The preparation method of the MOF@COF material comprises the following steps: S1, MIL-101(Cr)-NH2 reacts with 1,4-dialdehyde-2,5-divinylbenzene to obtain an intermediate product MIL-101(Cr)-NH2@DVA; in step S1, glacial acetic acid is used as a catalyst in the reaction; the reaction temperature is 100-150°C; S2. The MIL-101(Cr)-NH2@DVA reacts with 1,4-dialdehyde-2,5-divinylbenzene and 1,3,5-tris(4-aminophenyl)benzene to obtain MOF@COF material. In step S2, glacial acetic acid is used as a catalyst in the reaction. The reaction temperature is 15-40°C.

2. The solid phase extraction membrane according to claim 1, characterized in that The organic filter membrane is a nylon-66 membrane.

3. The solid phase extraction membrane according to claim 1, characterized in that The mass ratio of the chromium nitrate hydrate to 2-aminoterephthalic acid is (1.5-3):

1.

4. The solid phase extraction membrane according to claim 1, characterized in that The preparation conditions of the MOF@COF material are also selected from one or more of the following: A) In step S1, the mass ratio of MIL-101(Cr)-NH2 to 1,4-dialdehyde-2,5-divinylbenzene is (3-5):1; B) In step S1, the reaction is carried out in a 1,4-dioxane solvent; C) In step S1, the reaction time is 0.5 to 2 hours; D) In ​​step S2, the mass ratio of the MIL-101(Cr)-NH2@DVA to 1,4-dialdehyde-2,5-divinylbenzene and 1,3,5-tris(4-aminophenyl) is (2-4):1:(1-1.5); E) in step S2, the reaction is carried out in acetonitrile solvent; F) In step S2, the reaction time is 70-74 h.

5. The method for preparing a solid phase extraction membrane according to any one of claims 1 to 4, characterized in that: The steps include: 1) dispersing the MOF@COF material in a solvent to prepare a suspension; 2) The suspension is filtered through an organic filter membrane, and the MOF@COF material is loaded on the organic filter membrane to obtain a solid phase extraction membrane.

6. The method for preparing a solid phase extraction membrane according to claim 5, characterized in that: In step 2), the filtration method adopts syringe filter membrane filtration.

7. Use of the solid phase extraction membrane according to any one of claims 1 to 4 in detecting disinfection by-products.

8. Use of the solid phase extraction membrane according to claim 7 in detecting disinfection by-products, characterized in that: The disinfection by-product is a halogenated benzoic acid or a halogenated benzaldehyde.

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