Rare earth metal-organic framework material, method for fluorescence detection of biogenic amine in water body and fluorescence test paper

Abstract

The invention provides a rare earth metal-organic framework material, a method for fluorescence detection of biogenic amines in a water body and fluorescent test paper, and belongs to the technical field of fluorescence sensing. The material is prepared by the following steps: dissolving a strong alkali compound in H2O to obtain a strong alkali solution; adding an organic ligand into the strong alkali solution, stirring and dissolving to obtain an organic ligand salt solution; stirring and dissolving rare earth metal salt in H2O to obtain a rare earth metal salt solution; and finally, mixing the organic ligand salt solution with the rare earth metal salt solution to obtain the Ln-MOFs material. According to the invention, the Ln-MOFs fluorescent test paper is also prepared by using a spray coating mode. The synthesis method of the Ln-MOFs material provided by the invention has the advantages of simplicity in operation, room temperature and normal pressure, environment friendliness, large-scale preparation and the like. The Ln-MOFs fluorescent test paper provided by the invention is convenient to carry, clear in color development, high in sensitivity and low in detection limit, and can meet on-site visual detection requirements of BAs in a water body.

Description

Technical Field

[0001] The present invention belongs to the technical field of fluorescence sensing, and particularly relates to a rare earth metal-organic framework material, a method for fluorescence detection of biogenic amines in water, and a fluorescence test strip. Background Art

[0002] Biogenic amines (BAs) are a class of nitrogen-containing small molecules with biological activity, which are widely present in edible substances such as meat, seafood, wine, fermented foods, etc., as well as biological samples such as blood, urine, and cerebrospinal fluid. However, excessive accumulation of BAs in the human body and organisms can cause symptoms such as headache, dizziness, vomiting, and respiratory disorders, and even damage the kidneys and reproductive systems, leading to cell carcinogenesis. Therefore, in many fields such as water environment, food quality control, and medical diagnosis, the establishment of appropriate BA detection and analysis methods has received extensive attention. Currently, methods for BA detection include high-performance liquid chromatography, fluorescence analysis, gas chromatography combined with mass spectrometry, etc. Although the above methods have high sensitivity, they have strict requirements for equipment and reagents, are expensive, and have complex operations, making it difficult to conduct on-site detection and analysis. Therefore, there is an urgent need to develop more convenient and economical methods for rapid and intuitive on-site detection of BAs. Patent ZL202211579181.9 discloses a method for on-site detection of BAs using a test strip loaded with TP-A. Among them, the preparation method of the fluorescent probe TP-A includes the following steps: (1) Under an inert gas, a mixture of 4-dimethylamino-2-nitrobenzaldehyde, 1,3-cyclopentanedione, iron powder, and acetic acid is heated and stirred. After the reaction is complete, the solvent is removed by rotary evaporation, and the product is extracted and purified to obtain compound N1; (2) Compound N1, malononitrile, ammonium acetate, glacial acetic acid, and toluene are mixed and refluxed with stirring. After the reaction is complete, the solvent is removed by rotary evaporation, and the product is extracted and purified to obtain compound N2; (3) Compound N2 and DMF-DMA are heated and stirred. After the reaction is complete, the solvent is removed by rotary evaporation, and the product is extracted and purified to obtain compound TP-A. The process for preparing TP-A in this patent is not only complex but also involves the use of inert gases and toxic organic solvents. In addition, the time for detecting BAs using a test strip loaded with TP-A is relatively long (12 h), and only the detection of 3 kinds of BAs (spermine, putrescine, and cadaverine) is involved. Patent 202310294280.0 discloses an AgNPs@PCN-224 paper-based fluorescence sensing material and its application in BA detection. The MOF nanomaterial PCN-224 prepared by this method also involves the use of the organic reagent DMF and heating means (90 °C), and the research scope is limited to the detection of diamine biogenic amines (histamine, cadaverine, and putrescine).

[0003] Rare earth metal-organic framework materials (Ln-MOFs) have attracted great interest in the field of fluorescence sensing due to their tunable luminescence properties and rich energy transfer processes. Through rare earth metal ion centers (Eu3+ , La 3+ , Tb 3+ ), or the interaction between an organic ligand and a specific guest, the emission of Ln-MOFs can be modulated, and the change in luminescence color is obvious, which can be visually detected with the naked eye under ultraviolet light. In recent years, researchers have successfully developed fluorescence sensors based on Ln-MOFs materials using different preparation methods. For example, Cui et al. synthesized a series of Ln-MOF materials doped with different Eu 3+ / Tb 3+ molar ratios. That is, Eu(NO3)3·6H2O and Tb(NO3)3·6H2O were used as metal sources, 2-hydroxyterephthalic acid was used as a ligand, DMF was used as a solvent, and acetic acid was added as a reaction regulator. The reaction was carried out at 85 °C for 72 h to obtain the target material Eu x Tb 1-x -BDC-OH, and it was applied to the detection of Th 4+ (Angew. Chem. Int. Ed. 2024, e202410453). However, the disadvantages of this method are: long reaction time (72 h), consumption of a large amount of organic solvents (at least 20 - 100 mL of DMF is required for every 1 g of MOF prepared), and the need for heating (85 °C), high cost and energy consumption, and difficulty in large-scale production. Gong et al. converted waste PET into MOF materials by a two-step ball milling method for PET, that is, first ball milling and degrading PET to obtain disodium terephthalate and ethylene glycol, and then adding Eu(NO3)3·6H2O and ball milling again to promote the coordination of terephthalic acid ions with Eu 3+ to form La-MOF, and it was applied to the detection of Fe in water 3+ (Rare Met., 2024, 3(8): 3833 - 3843). The disadvantage of this method is that the product contains insoluble impurities (undegraded PET powder), these impurities are likely to damage the crystal structure of MOF, and the ball milling process is likely to block the MOF pores, which is not conducive to expanding the practical application of MOF materials. More importantly, currently, there is no report on the research of using Ln-MOFs to detect BAs in water. Summary of the Invention

[0004] The object of the present invention is to provide a rare earth metal-organic framework material, a method for fluorescence detection of biogenic amines in water and a fluorescence test strip. The preparation method of the Ln-MOFs material provided by the present invention is simple (stirring in a normal temperature aqueous solution), with a high yield (92% - 99%) and strong water stability; the above Ln-MOFs material has the advantages of a rich variety of detectable BAs (7 kinds) and qualitative detection in the detection of BAs; the fluorescence test strip based on the above Ln-MOFs material has a high sensitivity (BAs detection limit: 1.5 μg / L), far lower than the safety concentration of biogenic amines in water quality specified by the national standard (GB / T - 21970 - 2008) (<2 mg / L), and can meet the requirements of rapid (2 - 10 min) and intuitive on-site visual semi-quantitative detection of BAs.

[0005] To achieve the above object, the present invention adopts the following technical solutions:

[0006] The present invention provides a rare earth metal-organic framework material, and its preparation method includes the following steps:

[0007] (1) Dissolve a strong base compound in H2O to obtain a strong base solution;

[0008] (2) Add an organic ligand to the above strong base solution, stir and dissolve to obtain an organic ligand salt solution;

[0009] (3) Stir and dissolve a rare earth metal salt in H2O to obtain a rare earth metal salt solution;

[0010] (4) Mix the organic ligand salt solution and the rare earth metal salt solution, stir, and wash and dry the solid product to obtain the Ln-MOFs material.

[0011] Preferably, the strong base compound in step (1) is LiOH, NaOH or KOH;

[0012] The organic ligand in step (2) is terephthalic acid, trimellitic acid or pyromellitic acid.

[0013] Preferably, the molar ratio of the strong base compound to the organic ligand is 2:1 - 4:1.

[0014] Preferably, the rare earth metal salt in step (3) is a rare earth nitrate salt, a rare earth sulfate salt or a rare earth chloride salt; the rare earth metal ions include Eu 3+ 、La 3+ or Tb 3+ .

[0015] Preferably, the molar ratio of the organic ligand salt to the rare earth metal salt in step (4) is 1:2 - 1:1.

[0016] Preferably, the stirring temperature in step (4) is room temperature, and the stirring time is 10 - 36 h.

[0017] The present invention also provides a method for fluorescence detection of biogenic amines in water based on rare earth metal-organic framework materials, including:

[0018] Adding the above Ln-MOFs materials into the BAs solution for reaction, measuring the fluorescence intensity of the suspension, and determining the detection performance of the Ln-MOFs materials for biogenic amines by recording the change in fluorescence intensity.

[0019] Preferably, the types of BAs include His, Cad, Put, Spd, Spm, Tyr, and Try.

[0020] Preferably, the reaction temperature is 10 - 30 °C, and the reaction time is 10 - 120 min.

[0021] The present invention also provides Ln-MOFs fluorescence test strips for detecting BAs, including the above Ln-MOFs materials.

[0022] Advantages of the present invention

[0023] (1) Compared with the traditional solvothermal method or ball milling method, the present invention uses the room temperature aqueous solution stirring method to synthesize Ln-MOFs materials. This method is simple to operate, has mild conditions, is green and environmentally friendly, has strong water stability of the materials, and can be produced on a large scale. Specifically, in the presence of strong base compounds, the organic ligand reacts with it to form the corresponding carboxylate salt. The carboxylate salt has good water solubility, and the aqueous solution can provide a good reaction environment. At the same time, the carboxylate group in the form of ions is more likely to coordinate with metal ions in the rare earth metal salt solution to form a complex, thereby constructing Ln-MOFs materials. Ln-MOFs have a rigid skeleton and metal sites that are difficult to access. H2O molecules are difficult to approach the metal ions, or the coordinated water has almost no effect on its emission. Therefore, Ln-MOFs have stable luminescence properties in water.

[0024] (2) Ln-MOFs materials can selectively recognize and distinguish specific BAs. The specific reasons are as follows: The amino groups in BAs are good electron donors. When the rare earth metal ions (electron acceptors) in Ln-MOFs bind to BAs, the charge transfer from the electron donor to the electron acceptor increases or decreases, thereby causing fluorescence changes; Different Ln-MOFs materials have different pore structures and surface properties, so that aliphatic or aromatic BAs show different hydrogen bond interactions with the active sites in different Ln-MOF pores; Affected by geometric factors, different N-containing groups in BA molecules will produce different steric hindrances when adsorbed on the active sites. The above factors enable Ln-MOFs to present different detection mechanisms for different types of BA molecules, and can meet the qualitative and quantitative detection and analysis requirements for specific BA molecules.

[0025] (3) Compared with the existing chromatographic methods for detecting BAs, in this invention, the Ln-MOF fluorescence probe is loaded on the cellulose filter paper by spray coating. The Ln-MOF fluorescence test paper for BA detection has the characteristics of "convenient to carry, clear color development, and rapid detection", can meet the on-site visualization detection requirements, and makes up for the deficiencies of the existing detection technologies. In addition, this method is simple to operate, and the testers do not need to have a complex professional background. Description of the Drawings

[0026] Figure 1 X-ray powder diffraction patterns of the Eu-BDC and La-BDC materials prepared for Examples 1 and 2 and the fluorescence intensity change diagrams of the characteristic peaks in the presence of different concentrations of BAs.

[0027] Figure 2 X-ray powder diffraction pattern, scanning electron microscope image of the Tb-BDC material prepared for Example 3 and the fluorescence intensity change diagrams of the characteristic peaks in the presence of different concentrations of BAs.

[0028] Figure 3 X-ray powder diffraction pattern of the Eu-BTC material prepared for Example 4 and the fluorescence intensity change diagrams of the characteristic peaks in the presence of different concentrations of BAs.

[0029] Figure 4 X-ray powder diffraction pattern of the La-BTC material prepared for Example 5 and the fluorescence intensity change diagrams of the characteristic peaks in the presence of different concentrations of BAs.

[0030] Figure 5 X-ray powder diffraction pattern of the Tb-BTC material prepared for Example 6 and the fluorescence intensity change diagrams of the characteristic peaks in the presence of different concentrations of BAs.

[0031] Figure 6X-ray powder diffraction pattern of the Eu-BTEC material prepared in Example 7 and the change diagram of the fluorescence intensity of characteristic peaks in the presence of different concentrations of BAs.

[0032] Figure 7 X-ray powder diffraction pattern of the La-BTEC material prepared in Example 8 and the change diagram of the fluorescence intensity of characteristic peaks in the presence of different concentrations of BAs.

[0033] Figure 8 X-ray powder diffraction pattern of the Tb-BTEC material prepared in Example 9 and the change diagram of the fluorescence intensity of characteristic peaks in the presence of different concentrations of BAs.

[0034] Figure 9 (a) Fluorescence change diagram (under ultraviolet lamp irradiation, λ = 254 nm) of the Ln-MOF fluorescent test paper prepared in Example 10 immersed in BAs solution (1.5 μg / L) or deionized water and taken out after 10 min. (b) Product photos of Ln-MOF fluorescent test papers based on different spraying concentrations.

[0035] Figure 10 X-ray powder diffraction pattern of the La-MOF material prepared in Comparative Example 1 and the change diagram of the fluorescence intensity of characteristic peaks in the presence of different concentrations of His.

[0036] Figure 11 X-ray powder diffraction pattern of the Eu-MOF material prepared in Comparative Example 2 and the change diagram of the fluorescence intensity of characteristic peaks in the presence of different concentrations of Spd. Detailed implementation manners

[0037] In order to make the objectives, technical solutions and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0038] The present invention first provides a rare earth metal-organic framework material, and its preparation method includes the following steps:

[0039] (1) Dissolve a strong base compound in H2O to obtain a strong base solution; the strong base compound is preferably LiOH, NaOH or KOH; the concentration of the strong base solution is preferably 15-70 g / L;

[0040] (2) Add an organic ligand to the above strong base solution, stir and dissolve to obtain an organic ligand salt solution; the organic ligand is preferably terephthalic acid, trimesic acid or pyromellitic acid; the molar ratio of the strong base compound to the organic ligand is 2:1 to 4:1;

[0041] (3) Stir and dissolve the rare earth metal salt in H2O to obtain a rare earth metal salt solution; the rare earth metal salt is preferably one of rare earth nitrate salts, rare earth sulfate salts or rare earth chloride salts, more preferably a rare earth nitrate salt; the rare earth metal ions preferably include Eu 3+ , La 3+ , Tb 3+ ; the concentration of the rare earth metal salt solution is preferably 170 - 450 g / L;

[0042] (4) Mix the organic ligand salt solution with the rare earth metal salt solution, preferably stir at room temperature for 10 - 36 h, and the solid product is washed and dried to obtain the Ln-MOFs material; the molar ratio of the organic ligand salt to the rare earth metal salt is preferably 1:2 - 1:1.

[0043] The present invention also provides a method for fluorescently detecting water body biogenic amines using the above Ln-MOFs material, including the following steps: adding the above Ln-MOFs material to the BAs sample solution to be measured for reaction, the reaction temperature is preferably 10 - 30 °C, the reaction time is preferably 10 - 120 min, and the fluorescence of the reaction solution is detected. The detection performance of the Ln-MOFs material for BAs is determined by recording the fluorescence intensity changes of the characteristic peaks of the Ln-MOFs material in different samples to be measured. Among them, the types of BAs include histamine (His), cadaverine (Cad), putrescine (Put), spermidine (Spd), spermine (Spm), tyramine (Tyr) and tryptamine (Try). The concentration range of Ln-MOFs in the suspension is preferably 0.25 - 2 mg / mL, and the concentration range of BAs is preferably 0 - 100 mg / L.

[0044] The present invention also provides a Ln-MOFs fluorescent test paper for detecting BAs, including the above Ln-MOFs material.

[0045] The following further elaborates on the present invention in conjunction with specific embodiments. All raw materials involved in the embodiments are obtained through commercial purchase.

[0046] Example 1

[0047] (1) Take 26.708 g of KOH and dissolve it in 400 mL of H2O; take 39.528 g of terephthalic acid and add it to the above KOH solution to dissolve and make up the volume to 500 mL to obtain an organic ligand salt solution, denoted as solution A.

[0048] (2) Take 4.246 g of Eu(NO3)3·6H2O and dissolve it in 10 mL of H2O, denoted as solution B. Mix 20 mL of solution A and solution B, and stir at room temperature for 10 h. The product is washed and dried to obtain the Eu-BDC material, and the yield is 99%.

[0049] (3) Add the above Eu-BDC material to Put solutions with different concentrations for reaction, and conduct fluorescence detection on the Eu-BDC+Put test solution after the reaction. Determine the detection performance of the Eu-BDC material for Put by recording the changes in the fluorescence intensity of the characteristic peaks of the Eu-BDC material in different test solutions. In the test solution, the concentration of Eu-BDC is 0.25 mg / mL, and the concentration range of Put is 0 - 100 mg / L.

[0050] Example 2

[0051] Change the metal salt in step (2) of Example 1 to La(NO3)3·6H2O, with an addition amount of 4.122 g, and keep other steps and conditions unchanged to obtain the La-BDC material with a yield of 96%; change Put in step (3) to Spd to obtain the La-BDC+Spd test solution. In the test solution, the concentration of La-BDC is 0.5 mg / mL, and the concentration range of Spd is 0 - 100 mg / L.

[0052] Figure 1 In a and b are the X-ray powder diffraction patterns of the Eu-BDC and La-BDC materials respectively. It can be seen from the X-ray powder diffraction patterns that the above two materials both have characteristic diffraction peaks at 5° - 10°, and are consistent with the corresponding simulated diffraction peaks or the diffraction peaks of the PDF cards, indicating the successful synthesis of the Eu-BDC and La-BDC materials. c and d are the fluorescence emission spectra of the Eu-BDC and La-BDC materials for detecting BAs respectively. It can be seen from c and d that when the concentration of Put or Spd increases from 2.5 mg / L to 100 mg / L, the fluorescence intensity of the emission peaks of Eu-BDC and La-BDC gradually decays and quenches. This shows that the Eu-BDC and La-BDC materials can effectively identify and detect Put and Spd respectively.

[0053] Example 3

[0054] Change the metal salt in step (2) of Example 1 to Tb(NO3)3·6H2O, with an addition amount of 4.313 g, and keep other steps and conditions unchanged to obtain the Tb-BDC material with a yield of 92%. Change Put in step (3) of Example 1 to Tyr or Spd to obtain the Tb-BDC+Tyr / Spd test solutions respectively. In the test solutions, the concentration of Tb-BDC is 0.25 mg / mL, and the concentration ranges of Tyr and Spd are both 0 - 100 mg / L.

[0055] Figure 2In a, b are respectively the X-ray powder diffraction pattern and scanning electron microscope image of the Tb-BDC material. From a, it can be seen that Tb-BDC has characteristic diffraction peaks at 5° - 10°, and they coincide with the corresponding simulated diffraction peaks, indicating the successful synthesis of the Tb-BDC material. From b, it can be seen that the morphology of Tb-BDC presents a uniform nanorod-like structure. c, d are respectively the fluorescence emission spectra of Tb-BDC for detecting BAs. From c, d, it can be known that when the concentration of Tyr or Spd increases from 2.5 mg / L to 100 mg / L, the fluorescence intensity of the emission peak of Tb-BDC gradually decays and quenches. It shows that the Tb-BDC material can effectively identify and detect Tyr and Spd.

[0056] Example 4

[0057] (1) Dissolve 15.964 g of NaOH in 400 mL of H2O; add 27.956 g of trimesic acid to the above NaOH solution to dissolve and make up the volume to 500 mL to obtain an organic ligand salt solution, denoted as solution A.

[0058] (2) Dissolve 1.781 g of Eu(NO3)3·6H2O in 10 mL of H2O, denoted as solution B. Mix 15 mL of solution A and solution B, stir at room temperature for 24 h, and the product is washed and dried to obtain the Eu-BTC material, with a yield of 95%.

[0059] (3) Add the above Eu-BTC material to solutions of different concentrations of Cad, Tyr or Spm for reaction, and perform fluorescence detection on the Eu-BTC + BAs test solution after the reaction. Determine the detection performance of the Eu-BTC material for BAs by recording the changes in the fluorescence intensity of the characteristic peaks of the Eu-BTC material in different test solutions. In the test solution, the concentration of Eu-BTC is 0.25 mg / mL, and the concentration range of BAs is 0 - 100 mg / L.

[0060] Figure 3 In a is the X-ray powder diffraction pattern of the Eu-BTC material. From a, it can be seen that Eu-BTC has characteristic diffraction peaks at 5° - 10°, and they coincide with the corresponding simulated diffraction peaks, indicating the successful synthesis of the Eu-BTC material. b - d are respectively the fluorescence emission spectra of Eu-BTC for detecting different BAs. From b - d, it can be known that when the concentration of Cad or Spm increases from 2.5 mg / L to 100 mg / L, the fluorescence intensity of the emission peak of Eu-BTC gradually decays and quenches. And with the increase in the concentration of Tyr, the intensity of the emission peak of Eu-BTC has no obvious change, indicating that the Eu-BTC material can selectively identify and detect Cad and Spm.

[0061] Example 5

[0062] In Example 4, change the metal salt in step (2) to La(NO3)3·6H2O, change the addition amount to 1.728 g, and change the stirring time to 12 h. Keep other steps and conditions unchanged to obtain the La-BTC material with a yield of 98%. In step (3) of Example 4, change BAs to Cad, Spd, or Put to obtain the La-BTC + Cad / Spd / Put test solution. In the test solution, the concentration of La-BTC is 0.5 mg / mL, and the concentration range of Cad / Spd / Put is 0 - 100 mg / L.

[0063] Figure 4 In a, it is the X-ray powder diffraction pattern of the La-BTC material. It can be seen from a that La-BTC has characteristic diffraction peaks at 5° - 10°, which coincide with the diffraction peaks of the corresponding PDF card, indicating the successful synthesis of the La-BTC material. b - d are the fluorescence emission spectra of La-BTC for detecting different BAs respectively. It can be seen from b - d that when the concentration of Cad, Spd, or Put increases from 2.5 mg / L to 100 mg / L, the fluorescence intensity of the emission peak of La-BTC gradually decays and quenches, indicating that the La-BTC material can effectively identify and detect Cad, Spd, or Put.

[0064] Example 6

[0065] In Example 4, change the metal salt in step (2) to Tb(NO3)3·6H2O, change the addition amount to 1.808 g, and change the stirring time to 12 h. Keep other steps and conditions unchanged to obtain the Tb-BTC material with a yield of 99%. In step (3) of Example 4, change BAs to Try, Spm, or Cad to obtain the Tb-BTC + Try / Spm / Cad test solution respectively. In the test solution, the concentration of Tb-BTC is 0.25 mg / mL, and the concentration range of Try / Spm / Cad is 0 - 100 mg / L.

[0066] Figure 5 In a, it is the X-ray powder diffraction pattern of the Tb-BTC material. It can be seen from a that Tb-BTC has characteristic diffraction peaks at 5° - 10°, which coincide with the corresponding simulated diffraction peaks, indicating the successful synthesis of the Tb-BTC material. b - d are the fluorescence emission spectra of Tb-BTC for detecting different BAs respectively. It can be seen from b - d that when the concentration of Try, Spm, or Cad increases from 2.5 mg / L to 100 mg / L, the fluorescence intensity of the emission peak of Tb-BTC gradually decays and quenches, indicating that the Tb-BTC material can effectively identify and detect Try, Spm, or Cad.

[0067] Example 7

[0068] (1) Dissolve 6.993 g of LiOH in 400 mL of H2O; take 18.572 g of pyromellitic acid and add it to the above LiOH solution to dissolve and make up the volume to 500 mL to obtain an organic ligand salt solution, denoted as solution A.

[0069] (2) Dissolve 1.956 g of Eu(NO3)3·6H2O in 10 mL of H2O, denoted as solution B. Mix 15 mL of solution A and solution B and stir at room temperature for 18 h. The product is washed and dried to obtain Eu-BTEC material, and the yield is 97%.

[0070] (3) Add the above Eu-BTEC material to Spd, Put or Try solutions with different concentrations for reaction, and perform fluorescence detection on the Eu-BTEC + BAs test solution after the reaction. Determine the detection performance of the Eu-BTEC material for BAs by recording the changes in the fluorescence intensity of the characteristic peaks of the Eu-BTEC material in different test solutions. In the test solution, the concentration of Eu-BTEC is 0.25 mg / mL, and the concentration range of BAs is 0 - 100 mg / L.

[0071] Figure 6 In a, it is the X-ray powder diffraction pattern of the Eu-BTEC material. It can be seen from a that Eu-BTEC has characteristic diffraction peaks at 5° - 10°, and they coincide with the corresponding simulated diffraction peaks, indicating the successful synthesis of the Eu-BTEC material. b - d are the fluorescence emission spectra of Eu-BTEC detecting different BAs respectively. It can be seen from b - d that when the concentration of Spd, Put or Try increases from 2.5 mg / L to 100 mg / L, the fluorescence intensity of the emission peak of Eu-BTEC gradually decays and quenches, indicating that the Eu-BTEC material can effectively recognize and detect Spd, Put or Try.

[0072] Example 8

[0073] Change the metal salt in step (2) of Example 6 to La(NO3)3·6H2O, the addition amount to 1.899 g, and the stirring time to 36 h, with other steps and conditions unchanged, to obtain La-BTEC material, and the yield is 94%. Change BAs in step (3) of Example 6 to His, Spm or Spd respectively to obtain La-BTEC + His / Spm / Spd test solutions. In the test solution, the concentration of La-BTEC is 0.5 mg / mL, and the concentration range of His / Spm / Spd is 0 - 100 mg / L.

[0074] Figure 7In a, it is the X-ray powder diffraction pattern of the La-BTEC material. It can be seen from a that La-BTEC has characteristic diffraction peaks at 5° to 10°, and they coincide with the corresponding simulated diffraction peaks, indicating the successful synthesis of the La-BTEC material. b-d are respectively the fluorescence emission spectra of La-BTEC for detecting different BAs. It can be seen from b-d that when the concentration of Spm or Spd increases from 2.5 mg / L to 100 mg / L, the fluorescence intensity of the emission peak of La-BTEC gradually decays and quenches. And with the increase in the concentration of His, the intensity of the emission peak of La-BTEC shows no obvious change, indicating that the La-BTEC material can only effectively recognize and detect Spm and Spd.

[0075] Example 9

[0076] Change the metal salt in step (2) of Example 7 to Tb(NO3)3·6H2O, change the addition amount to 1.987 g, and change the stirring time to 24 h. Keep other steps and conditions unchanged to obtain the Tb-BTEC material with a yield of 99%. Change the BAs in step (3) of Example 7 to Cad, Tyr or Try to obtain the Tb-BTEC+Cad / Tyr / Try test solutions respectively. In the test solutions, the concentration of Tb-BTEC is 0.25 mg / mL, and the concentration range of Cad / Tyr / Try is 0 to 100 mg / L.

[0077] Figure 8 In a, it is the X-ray powder diffraction pattern of the Tb-BTEC material. It can be seen from a that Tb-BTEC has characteristic diffraction peaks at 5° to 10°, and they coincide with the corresponding simulated diffraction peaks, indicating the successful synthesis of the Tb-BTEC material. b-d are respectively the fluorescence emission spectra of Tb-BTEC for detecting different BAs. It can be seen from b-d that when the concentration of Cad, Tyr or Try increases from 2.5 mg / L to 100 mg / L, the fluorescence intensity of the emission peak of Tb-BTEC gradually decays and quenches, indicating that the Tb-BTEC material can effectively recognize and detect Cad, Tyr and Try.

[0078] Example 10

[0079] To further study the practical applications of Ln-MOFs materials, one of the above Ln-MOFs materials (Tb-BDC) was loaded onto the surface of cellulose filter paper by spray coating to prepare an Ln-MOFs fluorescent test strip for detecting BAs. The specific steps are as follows: Weigh 60 mg of Tb-BDC and 10 mL of EtOH into a 40 mL sample bottle, and ultrasonicate for 10 min to obtain a 6 mg / mL Tb-BDC-EtOH stock suspension, denoted as solution A; Dissolve 0.1 g of gelatin in 10 mL of H2O by stirring at 90 °C to obtain a 10 mg / mL gelatin solution, denoted as solution B; Use a pipette to transfer 60 μL of solution B into solution A (gelatin is ~1 wt% relative to MOF), and ultrasonicate for 10 min, denoted as solution C; Transfer 9 mL of solution C into a 500 mL beaker, and make up the volume to 500 mL with EtOH to obtain a 106 μg / mL Tb-BDC-gelatin-EtOH suspension, denoted as solution D. Transfer 45 mL of solution D diluted with a certain volume of EtOH into a spray bottle (50 mL), and spray the cellulose filter paper (15 cm × 15 cm) in small amounts multiple times. After each spraying, dry it at 70 °C for 5 min, and then carry out the next spraying. This process is repeated 5 - 7 times.

[0080] Figure 9 a is a comparison chart of the fluorescence changes of the fluorescent test strip after being immersed in BAs solution (1.5 μg / L) and deionized water respectively. Figure 9 b is a product photo of Tb-BDC fluorescent test strips based on two different models. Among them, for the 1001 model test strips (the 3 strips on the left), the spraying concentration of Tb-BDC per unit area is the same, which are 1.272, 1.484, 1.696, 1.908, 2.12 μg / cm 2 . For the 1002 model test strips (the 3 strips on the right), the spraying concentration of Tb-BDC per unit area is the same, which are 2.332, 2.544, 2.756, 2.968, 3.392 μg / cm 2 . As can be seen from a, when the test strip immersed in the BAs solution is taken out and the color change is observed under an ultraviolet lamp (λ = 254 nm), an obvious fluorescence quenching phenomenon occurs on the surface of the reaction area of the test strip, indicating that the fluorescent test strip based on Ln-MOFs materials has good detection sensitivity and can achieve on-site visual detection. In addition, the test strip immersed in deionized water does not show fluorescence attenuation under the ultraviolet lamp, indicating that the attachment of Ln-MOFs on the test strip is good and will not fall off easily.

[0081] Comparative Example 1

[0082] This comparative example has the same crystal structure as the La-BDC material prepared in Example 2, and the types and methods of detecting biogenic amines are the same. The differences lie in the raw materials and preparation methods. The specific differences are as follows: Polyethylene terephthalate (PET) is used instead of terephthalic acid in Example 1, and the two-step ball milling method is used instead of the normal temperature aqueous solution stirring method in Example 1. The synthesis steps include:

[0083] (1) Add 12 g of waste PET and 5 g of KOH to the ball milling tank, set the ball milling speed at 600 r / min, and ball mill for 4 h to obtain a white organic ligand salt product.

[0084] (2) Weigh 27.1 g of La(NO3)3·6H2O and add it to the white product in (1), and continue ball milling for 4 h.

[0085] (3) Collect, wash, and dry the above ball milled product to obtain the La-MOF material, and the yield is 93%.

[0086] Figure 10 In which a is the X-ray powder diffraction pattern of the La-MOF material. It can be seen from a that La-MOF has characteristic diffraction peaks at 5° - 10°, and they are consistent with the corresponding simulated diffraction peaks, indicating the successful synthesis of the La-MOF material. b is the fluorescence emission spectrum of La-MOF for detecting His. It can be seen from b that as the concentration of His increases, the intensity of the emission peak of La-MOF does not change significantly, indicating that the ball milling process may block the pores of La-MOF, which is not conducive to exposing the reactive sites in the pores of the La-MOF material, resulting in no response signal when detecting His (the comparison of the result parameters of this comparative example and Example 2 is shown in Table 1).

[0087] Comparative Example 2

[0088] This comparative example is the same as the Eu-BTEC material prepared in Example 7. The differences lie in the raw materials and preparation methods. The specific differences are as follows: Polyimide (PI) is used instead of pyromellitic acid in Example 1, and the two-step solvothermal method is used instead of the normal temperature aqueous solution stirring method in Example 6. The synthesis steps include:

[0089] (1) Add 1 g of PI to 60 mL of LiOH (1 mol / L), transfer it to an autoclave, and react at 180 °C for 18 h to obtain an organic ligand salt solution, denoted as solution A.

[0090] (2) Weigh 0.46 g of EuCl3·6H2O and dissolve it in 10 mL of H2O, denoted as solution B.

[0091] (3) Mix 20 mL of solution A and solution B, stir at room temperature for 18 h, and the product is washed and dried to obtain the Eu-MOF material, and the yield is 66%.

[0092] Figure 11 In a, it is the X-ray powder diffraction pattern of the Eu-MOF material. It can be seen from a that the characteristic diffraction peaks of Eu-MOF partially coincide with those of Eu-BTEC, and there are impurity peaks, indicating that the crystal structure of Eu-MOF synthesized by the two-step solvothermal method is imperfect, the coordination of metal ions and organic ligands is incomplete, and there are other impurities, resulting in a low yield. b is the fluorescence emission spectrum of Eu-MOF for detecting Spd. It can be seen from b that the response signal of Eu-MOF to Spd is weak, indicating that the insoluble impurities (incompletely degraded PI powder) in the product easily damage the crystal structure of Eu-MOF, making it difficult to identify and detect Spd (the result parameters of this comparative example and Example 7 are compared in Table 1 as follows).

[0093] Table 1. Comparison of Results of Examples and Comparative Examples

[0094]

Claims

1. A rare earth metal-organic framework material, characterized in that, Its preparation method comprises the following steps: (1) Dissolve a strong base compound in H2O to obtain a strong base solution; (2) Add an organic ligand to the above strong base solution, stir and dissolve it to obtain an organic ligand salt solution; (3) Stir and dissolve a rare earth metal salt in H2O to obtain a rare earth metal salt solution; (4) Mix the organic ligand salt solution and the rare earth metal salt solution, stir, wash and dry the solid product to obtain the Ln-MOFs material.

2. The rare earth metal-organic framework material according to claim 1, wherein The strong base compound in step (1) is LiOH, NaOH or KOH; The organic ligand in step (2) is terephthalic acid, trimellitic acid or pyromellitic acid.

3. A rare earth metal-organic framework material according to claim 1, characterized in that, The molar ratio of the strong base compound to the organic ligand is 2:1 to 4:

1.

4. A rare earth metal-organic framework material according to claim 1, characterized in that, The rare earth metal salt in the step (3) is a rare earth nitrate salt, a rare earth sulfate salt or a rare earth chloride salt; the rare earth metal ions include Eu 3+ , La 3+ or Tb 3+ .

5. A rare earth metal-organic framework material according to claim 1, characterized in that, The molar ratio of the organic ligand salt to the rare earth metal salt in step (4) is 1:2 to 1:

1.

6. The rare earth metal-organic framework material according to claim 1, characterized in that, The stirring temperature in step (4) is room temperature, and the stirring time is 10 to 36 h.

7. A method for fluorescence detection of biogenic amines in water by using a rare earth metal-organic framework material according to claim 1, characterized in that, It includes: Add the above Ln-MOFs material into the BAs solution for reaction, measure the fluorescence intensity of the suspension, and determine the detection performance of the Ln-MOFs material for biogenic amines by recording the change of fluorescence intensity.

8. A method for fluorescence detection of biogenic amines in water by a rare earth metal-organic framework material according to claim 7, characterized in that The types of BAs include His, Cad, Put, Spd, Spm, Tyr and Try.

9. A method for fluorescence detection of biogenic amines in water by using a rare earth metal-organic framework material according to claim 7, characterized in that, The reaction temperature is 10 - 30 °C, and the reaction time is 10 - 120 min.

10. A Ln-MOFs fluorescent test strip for detecting BAs, characterized in that, It includes the rare earth metal-organic framework material described in claim 1.

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