Application of a ratio type metal organic framework material in thiuram detection

Abstract

The application provides application of a ratio type metal organic framework material in detection of thiram. The application develops a ratio type fluorescent sensing platform for detecting thiram with the assistance of copper ions, which is excellent in selectivity and low in cost. The method is the first fluorescent method for detecting thiram based on a luminescent metal organic framework material, and the phenomenon has good repeatability. The method provided by the application is simple, sensitive, fast in detection speed, high in selectivity, low in cost, and can realize high-selectivity and high-sensitivity analysis and detection of thiram in food.

Description

Technical Field

[0001] This invention relates to the technical field of pharmaceutical analysis, specifically to the application of a ratiometric metal-organic framework material in the detection of thiram. Background Technology

[0002] Thiram (Tr) is a fungicide widely used in modern agriculture to protect crops, vegetables, and fruits from pests and increase yields. However, excessive use of thiram in agriculture can lead to environmental imbalance and pose a significant challenge to food safety. Currently, thiram residues in food are typically detected using conventional analytical methods such as high-performance liquid chromatography (HPLC), liquid chromatography-mass spectrometry (LC-MS), and gas chromatography-mass spectrometry (GC-MS). While these methods offer good sensitivity, they often require expensive and sophisticated equipment, time-consuming and labor-intensive sample extraction procedures, and skilled operators. Therefore, developing a simple, rapid, and practical method for detecting thiram is of great significance for food safety and environmental monitoring.

[0003] In recent years, fluorescence technology has become a cost-effective and highly promising detection method due to its advantages such as high sensitivity, easy visualization, simple operation, and fast sensing response. Among the various known fluorescence sensors reported to date, luminescent metal-organic frameworks (LMOFs) have attracted considerable attention. Luminescent metal-organic framework materials are porous crystalline materials with luminescent properties, composed of conjugated organic ligands and metal ions. Besides retaining the ultra-high porosity, diverse functions, varied structures, large specific surface area and pore volume, and uniform pore size of metal-organic frameworks, they also offer advantages such as good water stability, good thermal stability, high emission intensity, and low cost. Recent studies have found that fluorescence methods based on luminescent metal-organic frameworks have significant advantages such as high sensitivity, high selectivity, rapid response, and real-time monitoring. However, current dual-fluorescence detection methods based on luminescent metal-organic frameworks generally suffer from poor specificity, weak anti-interference ability, and high cost. Ratiometric fluorescence sensing is considered an effective strategy for specifically identifying target analytes and achieving anti-interference detection. Ratiometric fluorescence sensing can be regarded as a self-calibrating system that can overcome environmental interference or instrument errors.

[0004] CN110194950A discloses a method for preparing a single-particle dual-emission ratiometric fluorescent probe and its application. The method involves first preparing carboxylated silicon dioxide embedded with red CdTe quantum dots using a specific method, and then covalently coupling aminated blue carbon dots to the surface to construct the dual-emission ratiometric fluorescent probe. This invention combines a ratiometric fluorescent probe with a fluorescence quenching system constructed from gold nanoparticles, which can be used for fluorescence-enhanced detection of the pesticide thiram. Based on the fluorescence resonance energy transfer between the gold nanoparticles and the carbon dots, the blue fluorescence is quenched. The red fluorescent silicon dioxide serves as an internal standard. Upon the addition of thiram, the strong bonding between the gold nanoparticles and sulfur atoms causes aggregation, restoring the blue fluorescence. This process of turning the blue fluorescence off and back on achieves the detection of thiram.

[0005] CN104927862A discloses an upconversion luminescent nanoprobe for determining the fungicide thiram, its preparation method, and its application. The method includes the preparation of blue luminescent upconversion nanoparticles and their surface carboxylation modification, further adsorbing Cu on the nanoparticle surface through positive and negative electrostatic attraction. 2+ This allows for the acquisition of upconversion luminescent nanoprobes; the concentration of the bactericide thiram can be quantitatively detected by measuring the change in luminescence intensity before and after the addition of an aqueous solution of the upconversion luminescent nanoprobe to the test solution.

[0006] CN109813686A discloses a method for detecting organonitrogen and sulfur pesticides. This method first uses a chemical reduction method to prepare a fluorescent copper nanosheet material. The method involves mixing hexadecyltrimethylammonium bromide and copper chloride dihydrate in water, followed by a reduction reaction to prepare the copper nanosheet material. The method is based on a constructed fluorescent colorimetric sensor for detecting organonitrogen and sulfur pesticides, specifically including: ferric sulfate, zinc sulfate, zineb, methyl zineb, mancozeb, sodium zineb, mancozeb, mancozeb, dazomet, thiram, or thiamethoxam.

[0007] Therefore, developing a fluorescence detection method for a probe that is highly sensitive, selective, and cost-effective for thiamethoxam is a key research focus in this field. Summary of the Invention

[0008] To address the shortcomings of existing technologies, the present invention aims to provide an application of a ratiometric metal-organic framework material in the detection of thiram. The ratiometric metal-organic framework material is a fluorescent probe with high sensitivity and selectivity for recognizing thiram.

[0009] To achieve this objective, the present invention adopts the following technical solution:

[0010] In a first aspect, the present invention provides an application of a ratiometric metal-organic framework material in the detection of thiamethoxam.

[0011] In this invention, the ratiometric metal-organic framework material is a fluorescent probe with high sensitivity and high selectivity for the recognition of thiram, thereby solving the problem that existing methods for detecting thiram involve expensive instruments, complex preparation steps, or time costs.

[0012] Preferably, the ratiometric metal-organic framework material is an aluminum metal-organic framework material modified with fluorescent dye monomers.

[0013] Preferably, the raw materials for preparing the ratiometric metal-organic framework material include: aluminum compounds, iron compounds, organic ligands, and fluorescent dye monomers.

[0014] Preferably, the aluminum compound is a hydrate of an aluminum salt, and more preferably aluminum chloride hexahydrate.

[0015] Preferably, the iron compound is a hydrate of an iron salt, and more preferably ferric chloride hexahydrate.

[0016] Preferably, the organic ligand is an amino-substituted benzoic acid compound.

[0017] Preferably, the benzoic acid compound includes any one or a combination of at least two of terephthalic acid, phthalic acid, pyromellitic acid, pyromellitic tetracarboxylic acid, or biphenyl acid.

[0018] Preferably, the organic ligand is 2-aminoterephthalic acid.

[0019] Preferably, the fluorescent dye monomer includes any one or a combination of at least two of Rhodamine 6G, Rhodamine B, or Rhodamine, with Rhodamine B being the most preferred.

[0020] Preferably, the molar ratio of the aluminum compound, iron compound, organic ligand, and fluorescent dye monomer is (0.0001-3):(0.0001-3):3:(0.0001-1);

[0021] The first "0.0001-3" can be, for example, 0.0001, 0.75, 1.5, 2.25, 3, etc.

[0022] The second "0.0001-3" can be, for example, 0.0001, 0.75, 1.5, 2.25, 3, etc.

[0023] Among them, "0.0001-1" can be, for example, 0.0001, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1, etc.

[0024] Preferably, the ratiometric metal-organic framework material is prepared by the following method:

[0025] (a) The organic ligands were dissolved and mixed with aluminum and iron compounds, ultrasonically treated, and reacted in a high-pressure reactor to obtain a preliminarily synthesized metal-organic framework material. After washing, stirring, centrifugation, and drying, the metal-organic framework material was obtained.

[0026] (b) The metal-organic framework material obtained in step (a) is modified with a fluorescent dye monomer, and then washed, centrifuged and dried in sequence to obtain the ratiometric metal-organic framework material.

[0027] Preferably, in step (a), the solvent used for dissolution is ultrapure water.

[0028] Preferably, in step (a), the power of the ultrasonic treatment is 120-300W, for example, it can be 120W, 140W, 160W, 180W, 200W, 220W, 240W, 260W, 280W, 300W, etc., and the time of the ultrasonic treatment is 20-40min, for example, it can be 20min, 25min, 30min, 35min, 40min, etc.

[0029] Preferably, in step (a), the reaction temperature is 120-180℃, for example, it can be 120℃, 130℃, 140℃, 150℃, 160℃, 170℃, 180℃, etc., and the reaction time is 4-8h, for example, it can be 4h, 5h, 6h, 7h, 8h, etc.

[0030] Preferably, in step (a), the washing process uses deionized water and / or dimethylformamide, and the washing is performed more than three times, for example, three, four, five, six, etc.

[0031] Preferably, in step (a), the stirring operation is as follows: the preliminarily synthesized metal-organic framework material after washing is dispersed in anhydrous methanol and stirred.

[0032] Preferably, in step (a), the stirring speed is 100-300 rpm, for example, 100 rpm, 150 rpm, 200 rpm, 250 rpm, 300 rpm, etc., the stirring temperature is 20-30℃, for example, 20℃, 22℃, 24℃, 26℃, 28℃, 30℃, etc., and the stirring time is 20-30h, for example, 20h, 22h, 24h, 26h, 28h, 30h, etc.

[0033] Preferably, in step (a), the centrifugation speed is 2000-6000 rpm, for example, 2000 rpm, 3000 rpm, 4000 rpm, 5000 rpm, 6000 rpm, etc., and the centrifugation time is 4-8 min, for example, 4 min, 5 min, 6 min, 7 min, 8 min, etc.

[0034] Preferably, in step (a), the drying is vacuum drying, the temperature of the vacuum drying is 60-80℃, for example, 60℃, 65℃, 70℃, 75℃, 80℃, etc., and the time of the vacuum drying is 6-18h, for example, 6h, 9h, 12h, 15h, 18h, etc.

[0035] Preferably, in step (b), the modification is performed by mixing the metal-organic framework material, the fluorescent dye monomer, the crosslinking agent, and the solvent, followed by stirring.

[0036] Preferably, in step (b), the mass ratio of the metal-organic framework material, fluorescent dye monomer, crosslinking agent and solvent in the modification is (30-70):(10-50):(10-100):(40-70);

[0037] The first "30-70" can be, for example, 30, 40, 50, 60, 70, etc.

[0038] The second "10-50" can be, for example, 10, 20, 30, 40, 50, etc.

[0039] The third "10-100" can be, for example, 10, 30, 50, 70, etc.

[0040] Among them, "40-70" can be, for example, 40, 50, 55, 60, 70, etc.

[0041] Preferably, the crosslinking agent comprises 1-ethyl-(3-dimethylaminopropyl)carbodiimide and / or N-hydroxythiosuccinimide, more preferably 1-ethyl-(3-dimethylaminopropyl)carbodiimide and N-hydroxythiosuccinimide.

[0042] Preferably, the mass ratio of 1-ethyl-(3-dimethylaminopropyl)carbodiimide to N-hydroxythiosuccinimide is (10-70):(10-30);

[0043] The first "10-70" can be, for example, 10, 30, 50, 70, etc.

[0044] The second "10-30" can be, for example, 10, 15, 20, 25, 30, etc.

[0045] Preferably, the solvent is water.

[0046] Preferably, the stirring is an oil bath mechanical stirring, the temperature of the oil bath mechanical stirring is 30-50℃, for example, 30℃, 35℃, 40℃, 45℃, 50℃, etc., and the time of the oil bath mechanical stirring is 12-36h, for example, 12h, 20h, 28h, 36h, etc.

[0047] Preferably, in step (b), the washing process uses deionized water, and the washing is performed more than three times, for example, three, four, five, or six times.

[0048] Preferably, in step (b), the centrifugation speed is 6000-10000 rpm, for example, 6000 rpm, 7000 rpm, 8000 rpm, 9000 rpm, 10000 rpm, etc., and the centrifugation time is 4-6 min, for example, 4 min, 5 min, 6 min, etc.

[0049] Preferably, in step (b), the drying is vacuum drying, the temperature of the vacuum drying is 60-80℃, for example, 60℃, 65℃, 70℃, 75℃, 80℃, etc., and the time of the vacuum drying is 6-18h, for example, 6h, 9h, 12h, 15h, 18h, etc.

[0050] Secondly, the present invention also provides a method for detecting thiram using the above-mentioned ratio-type metal-organic framework material, the detection method specifically including the following steps:

[0051] (1) The ratio-type metal-organic framework material was dispersed in ultrapure water to obtain a suspension of the ratio-type metal-organic framework material, and the fluorescence signal intensity was detected.

[0052] (2) Add Cu to the suspension of the ratiometric metal-organic framework material obtained in step (1). 2+ The fluorescence signal intensity was detected after incubation with standard solutions of thiram at different concentrations.

[0053] (3) Based on the fluorescence signal intensity fitting curve of the concentration of thiram and the ratio of the metal-organic framework material, the thiram in the sample is qualitatively and / or quantitatively detected according to the fluorescence signal and working curve.

[0054] In the process of detecting thiram, step (2) uses a Cu-containing... 2+Based on the synergistic effect between thiram and copper ions, a high-selectivity, low-cost, and rapid method for the detection of thiram in food was established using standard solutions of thiram at different concentrations. This method utilizes a ratiometric metal-organic framework material to achieve highly selective and sensitive analysis and detection of thiram in food. This is because thiram reacts with Cu... 2+ The ratio of the complex to Cu 2+ It possesses a stronger quenching effect and, compared to thiram, can produce a larger fluorescence resonance energy transfer, thereby achieving a highly sensitive and selective detection method for thiram and a fluorescent detection method for probes.

[0055] Preferably, in step (1), the dispersion is ultrasonic dispersion, the power of the ultrasonic dispersion is 120-300W, for example, it can be 120W, 140W, 160W, 180W, 200W, 220W, 240W, 260W, 280W, 300W, etc., and the ultrasonic dispersion time is 1-10min, for example, it can be 1min, 3min, 5min, 8min, 10min, etc.

[0056] Preferably, in step (1), the concentration of the suspension of the ratiometric metal-organic framework material is 10-100 μg / mL, for example, it can be 10 μg / mL, 20 μg / mL, 50 μg / mL, 80 μg / mL, 100 μg / mL, etc.

[0057] Preferably, in step (1), the detection measures the emission spectrum of 360-660nm (e.g., 360nm, 380nm, 400nm, 420nm, 440nm, 480nm, 500nm, 520nm, 540nm, 560nm, 580nm, 600nm, 620nm, 640nm, 660nm, etc.) at an excitation wavelength of 320-360nm (e.g., 320nm, 330nm, 340nm, 350nm, 360nm, etc.).

[0058] Preferably, in step (2), the Cu-containing 2+ In standard solutions of thiram at different concentrations, Cu 2+ The concentration of the solution is 0-80 μM, for example, 0 μM, 10 μM, 40 μM, 80 μM, etc., and the concentration of the thiram solution is 0.5-8 μg / mL, for example, 0.5 μg / mL, 1 μg / mL, 2 μg / mL, 4 μg / mL, 6 μg / mL, 8 μg / mL, etc.

[0059] Preferably, the Cu 2+ The sources include any one or a combination of at least two of copper sulfate pentahydrate, copper chloride dihydrate, or copper nitrate trihydrate.

[0060] Preferably, the Cu-containing 2+ The standard solutions of thiram at different concentrations were obtained by adding copper salt after preparing a series of thiram standard solutions.

[0061] Preferably, the standard solution of thiram comprises thiram, acetonitrile, and ultrapure water.

[0062] Preferably, the mass ratio of thiram, acetonitrile, and ultrapure water is (2.5-50):(2.5-50):(4900-4995);

[0063] The first "2.5-50" can be, for example, 2.5, 5, 10, 20, 30, 40, 50, etc.

[0064] The second "2.5-50" can be, for example, 2.5, 5, 10, 20, 30, 40, 50, etc.

[0065] Among them, "4900-4995" can be, for example, 4900, 4920, 4940, 4960, 4980, 4990, 4995, etc.

[0066] Preferably, step (2) specifically involves: adding Cu... 2+ Standard solutions of thiram at different concentrations were mixed with suspensions of ratiometric metal-organic framework materials to obtain solutions of the same volume but different thiram concentrations. After incubation, the fluorescence signal intensity was then detected.

[0067] Preferably, in step (2), the incubation temperature is 20-30℃, for example, it can be 20℃, 22℃, 24℃, 26℃, 28℃, 30℃, etc., and the incubation time is 0.01-40min, for example, it can be 0.01min, 0.05min, 0.1min, 0.5min, 1min, 2min, 4min, 6min, 8min, 10min, 20min, 30min, 40min, etc.

[0068] Preferably, in step (2), the detection measures the emission spectrum of 360-660nm (e.g., 360nm, 380nm, 400nm, 420nm, 440nm, 480nm, 500nm, 520nm, 540nm, 560nm, 580nm, 600nm, 620nm, 640nm, 660nm, etc.) under an excitation wavelength of 320-360nm (e.g., 320nm, 330nm, 340nm, 350nm, 360nm, etc.), and more preferably, measures the emission spectrum of 360-660nm under an excitation wavelength of 340nm.

[0069] Preferably, in step (3), the fitting curve is plotted using the ratio of fluorescence intensity at emission wavelengths of 430-440nm (e.g., 430nm, 432nm, 434nm, 435nm, 436nm, 438nm, 440nm, etc.) to 585-595nm (e.g., 585nm, 587nm, 589nm, 590nm, 591nm, 593nm, 595nm, etc.), and more preferably using the ratio of fluorescence intensity at emission wavelengths of 435nm and 590nm.

[0070] For example, the ratio of fluorescence intensity at 435 nm and 590 nm (defined as P = I) 435 / I 590 Fitted curve;

[0071] Among them, I 435 This represents the addition of a certain concentration of Cu 2+ The fluorescence signal intensity of the ratiometric metal-organic framework material at 435 nm after the standard solution of thiram was obtained. 590 This represents the addition of a certain concentration of Cu 2+ The fluorescence signal intensity of the ratiometric metal-organic framework material at 590 nm after the standard solution of thiram.

[0072] The working curve is as follows: Using the concentration of the thiram standard solution as the x-axis and P as the y-axis, curve fitting is performed, and I is found to be... 435 / I 590 It showed a good linear relationship with the concentration of thiram.

[0073] Preferably, the ratiometric metal-organic framework material is used for the detection of thiram in food.

[0074] Preferably, the food includes any one of fruits, vegetables, or mushrooms.

[0075] Compared with the prior art, the present invention has the following beneficial effects:

[0076] This invention develops a ratiometric fluorescence sensing platform for the detection of thiram with copper ions, exhibiting high selectivity and low cost. This method is the first fluorescence method for detecting thiram based on luminescent metal-organic framework materials, and this phenomenon demonstrates good reproducibility. The method provided by this invention is simple, sensitive, fast, highly selective, and low-cost, enabling highly selective and sensitive analysis and detection of thiram in food. The metal-organic framework material of this invention demonstrates excellent sensing capability for thiram. Attached Figure Description

[0077] Figure 1 The emission spectrum of the ratiometric fluorescence sensing platform provided in Example 1.

[0078] Figure 2 The emission spectra of the ratiometric fluorescence sensing platform at different thiram dual concentrations provided in Example 1 are shown.

[0079] Figure 3 The fitting curve provided for Example 1.

[0080] Figure 4 The response of the ratiometric fluorescence sensing platform to the same concentration of thiram under different Al and Fe ratios provided in Example 2.

[0081] Figure 5 The response of the fluorescence sensing platform to thiram at different reaction times is shown.

[0082] Figure 6 For different Cu 2+ The response of the fluorescence sensing platform to thiram at different concentrations.

[0083] Figure 7 The response of different metal-organic framework materials as sensing materials to the same concentration of thiram.

[0084] Figure 8 The effect of metal ions on the fluorescence intensity of the material.

[0085] Figure 9 The effect of metal ions on the fluorescence intensity of ratiometric metal-organic framework materials in the presence of thiamethoxam.

[0086] Figure 10 The selectivity of the fluorescence sensing platform for thiram in the presence of potential interfering substances. Detailed Implementation

[0087] The technical solution of the present invention will be further described below with reference to the accompanying drawings and specific embodiments. Those skilled in the art should understand that the specific embodiments described are merely illustrative of the present invention and should not be considered as specific limitations thereof.

[0088] Preparation Example 1

[0089] This preparation example provides a ratiometric metal-organic framework material, which is prepared by the following method:

[0090] (a) Dissolve 0.543 g of 2-aminoterephthalic acid (3 mmol) in 30 mL of ultrapure water, sonicate at 300 W for 30 min, then add 0.543 g of aluminum chloride hexahydrate (2.25 mmol) and 0.203 g of ferric chloride hexahydrate (0.75 mmol) to the above solution, sonicate at 300 W for 30 min, then transfer the mixed solution to a polytetrafluoroethylene-lined high-pressure reactor and keep it at 150 °C for 6 h, then cool it naturally to room temperature to obtain the preliminarily synthesized metal-organic framework material; wash the preliminarily synthesized metal-organic framework material three times with deionized water and DMF respectively, then disperse it in 40 mL of anhydrous methanol, stir at room temperature for 24 h, centrifuge at 4000 rpm for 6 min, collect the precipitate, vacuum dry at 70 °C for 12 h to obtain the metal-organic framework material, grind it for later use.

[0091] (b) 30 mg Rhodamine B (0.063 mmol) was dispersed in 40 mL of ultrapure water and sonicated at 300 W for 5 min. Then, 50 mg of 1-ethyl-(3-dimethylaminopropyl)carbodiimide and 20 mg of N-hydroxythiosuccinimide were added and stirred for 15 min. 50 mg of metal-organic framework material dispersed in 15 mL of water was added and mechanically stirred in an oil bath at 30 °C for 24 h. The mixture was then washed three times with deionized water, centrifuged at 8000 rpm for 4 min, and the precipitate was collected. The precipitate was then vacuum dried at 70 °C for 12 h to obtain a ratiometric metal-organic framework material, which was then ground for later use.

[0092] Preparation Example 2

[0093] This preparation example provides a ratiometric metal-organic framework material, which is prepared by the following method:

[0094] (a) 0.543 g of 2-aminoterephthalic acid (3 mmol) was dissolved in 30 mL of ultrapure water and sonicated at 300 W for 30 min. Then, 0.181 g of aluminum chloride hexahydrate (0.75 mmol) and 0.609 g of ferric chloride hexahydrate (2.25 mmol) were added to the above solution and sonicated at 300 W for 30 min. The mixed solution was then transferred to a polytetrafluoroethylene-lined high-pressure reactor and kept at 150 °C for 6 h. After that, it was naturally cooled to room temperature to obtain the preliminarily synthesized metal-organic framework material. The preliminarily synthesized metal-organic framework material was washed three times with deionized water and DMF, and then dispersed in 40 mL of anhydrous methanol. After stirring at room temperature for 24 h, it was centrifuged at 4000 rpm for 6 min, the precipitate was collected, and vacuum dried at 70 °C for 12 h to obtain the metal-organic framework material, which was then ground for later use.

[0095] (b) 30 mg Rhodamine B (0.063 mmol) was dispersed in 40 mL of ultrapure water and sonicated at 300 W for 5 min. 50 mg 1-ethyl-(3-dimethylaminopropyl)carbodiimide and 20 mg N-hydroxythiosuccinimide were added and stirred for 15 min. 50 mg of metal-organic framework material dispersed in 15 mL of water was added and mechanically stirred in an oil bath at 30 °C for 24 h. The mixture was then washed three times with deionized water, centrifuged at 8000 rpm for 4 min, and the precipitate was collected. The precipitate was vacuum dried at 70 °C for 12 h to obtain a ratiometric metal-organic framework material, which was then ground for later use.

[0096] Preparation Example 3

[0097] This preparation example provides a ratiometric metal-organic framework material, which is prepared by the following method:

[0098] (a) Dissolve 0.543 g of 2-aminoterephthalic acid (3 mmol) in 30 mL of ultrapure water, sonicate at 300 W for 30 min, then add 0.362 g of aluminum chloride hexahydrate (1.50 mmol) and 0.406 g of ferric chloride hexahydrate (1.50 mmol) to the above solution, sonicate at 300 W for 30 min, then transfer the mixed solution to a polytetrafluoroethylene-lined high-pressure reactor and keep it at 150 °C for 6 h, then cool naturally to room temperature to obtain the preliminarily synthesized metal-organic framework material; wash the preliminarily synthesized metal-organic framework material three times with deionized water and DMF respectively, then disperse it in 40 mL of anhydrous methanol, stir at room temperature for 24 h, centrifuge at 4000 rpm for 6 min, collect the precipitate, vacuum dry at 70 °C for 12 h to obtain the metal-organic framework material, grind it for later use.

[0099] (b) 30 mg Rhodamine B (0.063 mmol) was dispersed in 40 mL of ultrapure water and sonicated at 300 W for 5 min. 50 mg 1-ethyl-(3-dimethylaminopropyl)carbodiimide and 20 mg N-hydroxythiosuccinimide were added and stirred for 15 min. 50 mg of metal-organic framework material dispersed in 15 mL of water was added and mechanically stirred in an oil bath at 30 °C for 24 h. The mixture was then washed three times with deionized water, centrifuged at 8000 rpm for 4 min, and the precipitate was collected. The precipitate was vacuum dried at 70 °C for 12 h to obtain a ratiometric metal-organic framework material, which was then ground for later use.

[0100] Preparation Example 4

[0101] This preparation example provides a ratiometric metal-organic framework material, which is prepared by the following method:

[0102] (a) 0.543 g of 2-aminoterephthalic acid (3 mmol) was dissolved in 30 mL of ultrapure water and sonicated at 300 W for 30 min. Then, 0.812 g of ferric chloride hexahydrate (3.00 mmol) was added to the solution and sonicated at 300 W for 30 min. The mixture was then transferred to a polytetrafluoroethylene-lined high-pressure reactor and kept at 150 °C for 6 h. After natural cooling to room temperature, the preliminarily synthesized metal-organic framework material was obtained. The preliminarily synthesized metal-organic framework material was washed three times with deionized water and DMF, respectively, and then dispersed in 40 mL of anhydrous methanol. After stirring at room temperature for 24 h, the mixture was centrifuged at 4000 rpm for 6 min, the precipitate was collected, and vacuum dried at 70 °C for 12 h to obtain the metal-organic framework material, which was then ground for later use.

[0103] (b) 30 mg Rhodamine B (0.063 mmol) was dispersed in 40 mL of ultrapure water and sonicated at 300 W for 5 min. 50 mg 1-ethyl-(3-dimethylaminopropyl)carbodiimide and 20 mg N-hydroxythiosuccinimide were added and stirred for 15 min. 50 mg of metal-organic framework material dispersed in 15 mL of water was added and mechanically stirred in an oil bath at 30 °C for 24 h. The mixture was then washed three times with deionized water, centrifuged at 8000 rpm for 4 min, and the precipitate was collected. The precipitate was vacuum dried at 70 °C for 12 h to obtain a ratiometric metal-organic framework material, which was then ground for later use.

[0104] Preparation Example 5

[0105] This preparation example provides a ratiometric metal-organic framework material, which is prepared by the following method:

[0106] (a) Dissolve 0.543 g of 2-aminoterephthalic acid (3 mmol) in 30 mL of ultrapure water, sonicate at 300 W for 30 min, add 0.724 g of aluminum chloride hexahydrate (3.00 mmol) to the above solution, sonicate at 300 W for 30 min, transfer the mixed solution to a polytetrafluoroethylene-lined high-pressure reactor and keep it at 150 °C for 6 h, then cool naturally to room temperature to obtain the preliminarily synthesized metal-organic framework material; wash the preliminarily synthesized metal-organic framework material three times with deionized water and DMF respectively, then disperse it in 40 mL of anhydrous methanol, stir at room temperature for 24 h, centrifuge at 4000 rpm for 6 min, collect the precipitate, vacuum dry at 70 °C for 12 h to obtain the metal-organic framework material, grind it for later use.

[0107] (b) 30 mg Rhodamine B (0.063 mmol) was dispersed in 40 mL of ultrapure water and sonicated at 300 W for 5 min. 50 mg 1-ethyl-(3-dimethylaminopropyl)carbodiimide and 20 mg N-hydroxythiosuccinimide were added and stirred for 15 min. 50 mg of metal-organic framework material dispersed in 15 mL of water was added and mechanically stirred in an oil bath at 30 °C for 24 h. The mixture was then washed three times with deionized water, centrifuged at 8000 rpm for 4 min, and the precipitate was collected. The precipitate was vacuum dried at 70 °C for 12 h to obtain a ratiometric metal-organic framework material, which was then ground for later use.

[0108] Comparative Preparation Example 1

[0109] This comparative preparation example provides a zirconium metal-organic framework material, which is prepared by the following method: A mixed solution of 300 mg zirconium tetrachloride, 75 μL deionized water, and 20 mL dimethylformamide is stirred for 15 min. Then, 235 mg 2-aminoterephthalic acid, 4.88 g benzoic acid, 347 μL hydrochloric acid, and 10 mL dimethylformamide are added. After thorough stirring, the mixture is transferred to a 100 mL high-pressure reactor and reacted at 120 °C for 24 h. After the reaction, the mixture is cooled to room temperature. The sample is washed three times with dimethylformamide and then three times with water. The sample is then vacuum dried overnight at 50 °C. A pale yellow Uio-66-NH2 material is obtained.

[0110] Comparative Preparation Example 2

[0111] This comparative preparation example provides a europium metal-organic framework material, which is prepared by the following method: 44.6 mg Eu(NO3)3·6H2O (0.1 mmol) and 21 mg H3BTC (0.1 mmol) were dissolved in 10 mL of deionized water and 10 mL of ethanol, respectively, under stirring. The two solutions were then mixed and stirred vigorously at room temperature until a large amount of white precipitate formed. After stirring for 1 h, the synthesized white solid was collected by centrifugation. Finally, it was washed 6 times with ethanol and water and dried under vacuum at 50 °C overnight to obtain a white Eu-MOF material.

[0112] Comparative preparation example 3

[0113] This comparative preparation example exemplarily provides a non-LMOF type ratiometric fluorescent probe, which is synthesized according to Example 1 of CN110194950A.

[0114] The quantum dots used in this patent are small in size and difficult to separate and purify, while the metal nanoclusters used have poor stability. Therefore, it is crucial to seek fluorescent materials with high stability, low cost, and excellent performance. Luminescent metal-organic frameworks (LMOFs) are porous crystalline materials with luminescent properties, composed of conjugated organic ligands and metal ions. Besides retaining the ultra-high porosity, diverse functions, varied structures, large specific surface area and pore volume, and uniform pore size of LMOFs, they also offer advantages such as good water stability, good thermal stability, high emission intensity, and low cost. Recent studies have found that fluorescence methods based on LMOFs have significant advantages such as high sensitivity, high selectivity, rapid response, and real-time monitoring of analytes. Therefore, it is essential to develop a ratiometric fluorescence sensing platform based on LMOFs for the detection of thiamethoxam.

[0115] Example 1

[0116] A ratiometric fluorescence sensing platform for the detection of thiamethoxam was built based on ratiometric metal-organic framework materials.

[0117] In this embodiment, the ratiometric metal-organic framework material prepared in Preparation Example 1 was used to detect thiram. The specific method is as follows:

[0118] (1) 5 mg of the ratio-type metal-organic framework material prepared in Example 1 was dispersed in 10 mL of pure water at room temperature and sonicated at 300 W for 5 min to obtain a suspension of the ratio-type metal-organic framework material (500 μg / mL). The fluorescence spectrum of the mixed solution in the range of 360 nm to 660 nm was recorded under 340 nm excitation.

[0119] (2) Next, take 0.5 mL of the suspension (500 μg / mL) and add it to different samples (as shown in Table 1 below), and make up to 5 mL. After incubating at room temperature for 10 minutes, record the fluorescence spectrum of the mixed solution in the range of 360 nm to 660 nm under 340 nm excitation. "-" indicates no addition.

[0120] Table 1

[0121]

[0122] in, Figure 1 For ratiometric fluorescence sensing platform (Cu 2+ Emission spectra of assisted LMOFs; such as Figure 1 As shown, the fluorescence spectrum of LMOFs is basically unaffected when thiram is added alone, but if it is added to Cu... 2+ With the assistance of [unclear], LMOFs have a high quenching efficiency against [unclear] methylphenidate.

[0123] in, Figure 2For ratiometric fluorescence sensing platforms (Cu) at different thiram dual concentrations 2+ Emission spectra of assisted LMOFs, such as Figure 2 As shown, the fluorescence intensity gradually decreases with increasing concentration of thiram.

[0124] (3) Based on the concentration and ratio-based fluorescence sensing platform (Cu) of thiamethoxam 2+ The ratio of fluorescence intensity at 435 nm and 590 nm of assisted LMOFs (defined as P = I) 435 / I 590 The fitted curve, based on the fluorescence signal and the working curve, allows for qualitative and quantitative detection of thiram in the sample;

[0125] Qualitative detection: LMOFs are pink solutions. LMOFs + Cu 2+ +Thiram is a gray solution;

[0126] Quantitative detection: Within the range of 0.5–8.0 μg / mL, I 435 / I 590 It showed a good linear relationship with the concentration of thiram (R 2 =0.9961). According to 3S b / K SV The detection limit for thiram was calculated to be 0.11 μg / mL, where S b The standard deviation of the blank signal (n=10).

[0127] Example 2

[0128] The detection of thiram based on ratiometric metal-organic frameworks prepared with different Al and Fe ratios.

[0129] In this embodiment, the response of metal-organic framework materials prepared with different Al and Fe ratios was tested using thiram. Except for using a certain concentration of thiram and changing the metal-organic framework material (as shown in Table 2), the other operation steps were the same as in Example 1.

[0130] Table 2

[0131]

[0132]

[0133] This work was optimized using luminescent metal-organic framework materials (materials provided in Preparation Examples 1-5), and the results were recorded after the addition of 40 μM concentrated Cu. 2+The ratio of fluorescence intensity of the initial system after adding (name: copper sulfate) is P0. After adding 6 ppm of thiamethoxam for 10 min, the ratio is P. ΔP = P0 - P; (P0 and P are calculated according to the ratio of fluorescence intensity at 435 nm and 590 nm of ratiometric metal-organic framework materials).

[0134] in, Figure 4 The response of a ratiometric fluorescence sensing platform to the same concentration of thiram under different Al and Fe ratios is shown, for example... Figure 3 As shown, the ratiomatic metal-organic framework material synthesized with x = 0.75 (i.e., preparation example 1) exhibits the best performance.

[0135] Example 3

[0136] Optimization of reaction conditions based on ratiometric metal-organic framework materials

[0137] In this embodiment, the response of the metal-organic framework material prepared in Preparation Example 1 was tested using thiram, except that the incubation time was changed (see Table 3 for details) or Cu was used. 2+ Except for adjusting the concentration (as shown in Table 4) and the concentration of thiram used, the other operating steps are the same as in Example 1; this work was optimized using ratiometric metal-organic framework materials, and the addition of Cu was recorded respectively. 2+ The ratio of the initial fluorescence intensity after adding thiram was P0, and the ratio after adding thiram was P.

[0138] Table 3

[0139]

[0140]

[0141] in, Figure 5 The response of the fluorescence sensing platform to thiram at different reaction times is shown, such as Figure 5 As shown, the reaction was basically completed in about 10 minutes, so all subsequent experiments were conducted after the reaction had been completed for 10 minutes.

[0142] Table 4

[0143]

[0144] in, Figure 6 For different Cu 2+ The response of the fluorescence sensing platform to thiram at different concentrations, such as Figure 6 As shown, Stern-Volmer curves were plotted to analyze Cu. 2+ The effect of concentration was studied. Based on the Stern-Volmer equation, the concentrations of Cu at 0 μM, 10 μM, 40 μM, and 80 μM were calculated. 2+ K at concentrationSV The values ​​are 4793, 11375, 13804, and 5750M respectively. -1 Therefore, the optimal Cu 2+ The concentration is 40 μM.

[0145] Example 4

[0146] Different metal-organic framework materials were used as sensing materials to detect thiram.

[0147] In this embodiment, the response of other metal-organic framework materials to thiram was tested using thiram, except that a certain concentration of thiram was used and Cu was not used. 2+ Except for the change of the metal-organic framework material, the other operation steps are the same as in Example 1; the reliability of this work is tested using the luminescent metal-organic framework material (the material provided in Comparative Preparation Examples 1-2). The fluorescence intensity of the initial system is recorded as P0, and the fluorescence intensity after adding the same concentration of thiram for 10 min is P. ΔP = P0 - P.

[0148] in, Figure 7 The response of different metal-organic framework materials as sensing materials to the same concentration of thiram, such as Figure 7 As shown, the ratiometric metal-organic framework material synthesized in Preparation Example 1 exhibits the best performance, while other luminescent metal-organic framework materials (Uio-66-NH2, Eu-MOF) did not achieve a response superior to that of Preparation Example 1.

[0149] Example 5

[0150] Detecting potential interference based on ratiometric metal-organic framework materials as sensing materials.

[0151] This embodiment tested the response of the metal-organic framework material prepared in Preparation Example 1 using possible interfering substances. First, the response of the ratiometric metal-organic framework material to various metal ions was tested; second, the Cu in Example 1 was replaced... 2+ The effects of metal ions on ratiometric metal-organic framework materials in the presence of thiram were investigated, with other operating steps being the same as in Example 1. Finally, the selectivity of the proposed fluorescence sensing platform was tested by replacing thiram in Example 1 with other interfering substances, with other operating steps being the same as in Example 1.

[0152] in, Figure 8 The effect of metal ions (100 μM) on the fluorescence intensity of the material, such as Figure 8 As shown, Cu in metal ions 2+ It possesses the highest quenching efficiency. Other ions such as Na+... + K + Ca 2+ Ba 2+Zn 2+ Co 2+ Al 3+ Mn 2+ None of these will affect the fluorescence intensity of ratiometric metal-organic framework materials. Considering the effect of Fe... 3+ Compared to ratio-type metal-organic frameworks, which have a large response, NH4F can be added for masking during the measurement.

[0153] in, Figure 9 The effect of metal ions (40 μM) in the presence of thiram (8 μg / mL) on the fluorescence intensity of ratiometric metal-organic framework materials was investigated. Figure 9 As shown, the Cu of the sensing platform 2+ Replace with other ions at the same 40 μM (Na) + K + Ca 2+ Ba 2+ Zn 2+ Co 2+ Fe 3+ Al 3+ Mn 2+ The experiment tested the interference of different ions on the sensing platform. The results showed that Cu... 2+ It exhibits superior selectivity unlike other ions.

[0154] Among them, the determination of Fe 3+ To mask interference with the reaction, NH4F was added. It is worth noting that the addition of NH4F does not affect the Cu... 2+ Quenching of ratio-type metal-organic frameworks;

[0155] in, Figure 10 To assess the selectivity of the fluorescence sensing platform for thiram (8 μg / mL) in the presence of potential interfering substances (40 μg / mL), such as... Figure 10 As shown, the selectivity of the proposed method was tested by replacing thiram in the sensing platform with other analytes (sucrose, glucose, ascorbic acid, lactose, fructose, maltose, gallic acid, triazophos, chlorpyrifos, and zearalenone) at five times their concentration. The experiments revealed that even with an interfering concentration five times that of thiram, the sensor provided by this invention still exhibited satisfactory selectivity.

[0156] Example 6

[0157] Ratio-type metal-organic frameworks are used for the detection of thiram in real samples.

[0158] This embodiment provides a sensing application of metal-organic framework materials in the detection of thiram. A practical application example is as follows: Using fruit as a real sample, the performance of the sensor provided in Preparation Example 1 was evaluated. The sensing application specifically includes the following steps:

[0159] S1. First, cut the sample into small pieces and grind it into a homogenate using a mortar and pestle. Take 1g of the homogenate and mix it with 5mL of acetonitrile. Place the mixture in a water bath at 30℃ and 180rpm for 4 hours for extraction. Afterward, remove the solid suspension by centrifugation, then filter it through a 0.22μm needle-type aqueous filter membrane. Finally, dilute the filtrate 50 times with purified water.

[0160] S2. Sample extracts of different concentrations of thiram were prepared using the standard additive method. The samples were analyzed according to the procedure. 0.5 mL of tea sample or contaminated tea was added to 4.5 mL of the dispersion, and after incubation at room temperature for 10 min, the fluorescence spectrum of the mixed solution in the range of 360 nm to 660 nm was recorded under an excitation wavelength of 340 nm. For statistical purposes, all tested samples were in triplicate.

[0161] S3. Different concentrations of thiram were added to multiple food samples, such as apples and pears, and the recovery results were determined.

[0162] The results showed that the method recoveries ranged from 76.36% to 114.06% at spiking concentrations of 1 μg / mL, 4 μg / mL, and 7 μg / mL, with relative standard deviations ranging from 1.50% to 8.69%. These recovery experimental data demonstrate that this method can be used for the detection of thiram in food samples.

[0163] The applicant declares that this invention illustrates the application of the ratiometric metal-organic framework material described above in the detection of thiamethoxam through the above embodiments, but this invention is not limited to the above embodiments, that is, it does not mean that this invention must rely on the above embodiments to be implemented. Those skilled in the art should understand that any improvements to this invention, equivalent substitutions of the raw materials of this invention, additions of auxiliary components, and selection of specific methods, etc., all fall within the protection scope and disclosure scope of this invention.

Claims

1. Use of a ratiometric metal-organic framework material in the detection of thiram, characterized in that, The ratiometric metal-organic framework material is an aluminum metal-organic framework material modified with fluorescent dye monomers. The raw materials for preparing the ratiometric metal-organic framework material include: aluminum compounds, iron compounds, organic ligands and fluorescent dye monomers. The aluminum compound is aluminum chloride hexahydrate, the iron compound is ferric chloride hexahydrate, the organic ligand is 2-aminoterephthalic acid, and the fluorescent dye monomer is rhodamine B. The detection specifically includes the following steps: (1) The ratiometric metal-organic framework material was dispersed in ultrapure water to obtain a suspension of the ratiometric metal-organic framework material, and the fluorescence signal intensity was detected. (2) Adding standard solution containing different concentrations of thiram to the suspension of the ratio type metal organic framework material obtained in step (1), incubating, and then detecting the fluorescence signal intensity; 2+ ​ (3) Based on the fluorescence signal intensity fitting curve of the concentration of thiram and the ratio of the metal-organic framework material, the thiram in the sample is qualitatively and / or quantitatively detected according to the fluorescence signal and working curve.

2. Use according to claim 1, characterized in that, The molar ratio of the aluminum compound, iron compound, organic ligand and fluorescent dye monomer is (0.0001-3):(0.0001-3):3:(0.0001-1).

3. Use according to claim 1, characterized in that, The ratio-type metal-organic framework material is prepared by the following method: (a) The organic ligand is dissolved and mixed with aluminum and iron compounds, ultrasonically treated, and reacted in a high-pressure reactor to obtain a preliminary synthesized metal-organic framework material. After washing, stirring, centrifugation, and drying, the metal-organic framework material is obtained. (b) The metal-organic framework material obtained in step (a) is modified with a fluorescent dye monomer, and then washed, centrifuged and dried in sequence to obtain the ratio-type metal-organic framework material.

4. Use according to claim 3, characterized in that, In step (a), the solvent used for dissolution is ultrapure water.

5. Use according to claim 3, characterized in that, In step (a), the power of the ultrasonic treatment is 120-300 W, and the duration of the ultrasonic treatment is 20-40 min.

6. Use according to claim 3, characterized in that, In step (a), the reaction temperature is 120-180℃ and the reaction time is 4-8 h.

7. Use according to claim 3, characterized in that, In step (a), the washing process uses deionized water and / or dimethylformamide, and the washing is performed more than three times.

8. Use according to claim 3, characterized in that, In step (a), the specific operation of stirring is as follows: the preliminarily synthesized metal-organic framework material after washing is dispersed in anhydrous methanol and stirred.

9. Use according to claim 3, characterized in that, In step (a), the stirring speed is 100-300 rpm, the stirring temperature is 20-30℃, and the stirring time is 20-30 h.

10. Use according to claim 3, characterized in that, In step (a), the centrifugation speed is 2000-6000 rpm and the centrifugation time is 4-8 min.

11. Use according to claim 3, characterized in that, In step (a), the drying is vacuum drying, the temperature of the vacuum drying is 60-80℃, and the time of the vacuum drying is 6-18 h.

12. Use according to claim 3, characterized in that, In step (b), the modification is performed by mixing the metal-organic framework material, the fluorescent dye monomer, the crosslinking agent and the solvent, and then stirring.

13. Use according to claim 12, characterized in that, In step (b), the mass ratio of the metal-organic framework material, fluorescent dye monomer, crosslinking agent and solvent in the modification is (30-70):(10-50):(10-100):(40-70).

14. The use according to claim 12, characterized in that, The crosslinking agent comprises 1-ethyl-(3-dimethylaminopropyl) carbodiimide and / or N hydroxysuccinimide.

15. The use according to claim 12, characterized in that, The crosslinking agent is 1-ethyl-(3-dimethylaminopropyl)carbodiimide and N hydroxysuccinimide.

16. The use according to claim 15, characterized in that, said 1-ethyl-(3-dimethylaminopropyl)carbodiimide and N - the mass ratio of hydroxyl thiosuccinimide is (10-70):(10-30).

17. The use according to claim 12, characterized in that, The solvent is water.

18. The use according to claim 12, characterized in that, The stirring is performed by oil bath mechanical stirring, the temperature of which is 30-50℃ and the stirring time is 12-36 h.

19. The use according to claim 3, characterized in that, In step (b), deionized water is used for washing, and the washing is performed more than three times.

20. The use according to claim 3, characterized in that, In step (b), the centrifugation speed is 6000-10000 rpm and the centrifugation time is 4-6 min.

21. The use according to claim 3, characterized in that, In step (b), the drying is vacuum drying, the temperature of the vacuum drying is 60-80℃, and the time of the vacuum drying is 6-18 h.

22. The use according to claim 1, characterized in that, In step (1), the dispersion is ultrasonic dispersion, the ultrasonic dispersion power is 120-300 W, and the ultrasonic dispersion time is 1-10 min.

23. The use according to claim 1, characterized in that, In step (1), the concentration of the suspension of the ratiometric metal-organic framework material is 10-100 µg / mL.

24. The use according to claim 1, characterized in that, In step (1), the detection measures the emission spectrum of 360-660 nm at an excitation wavelength of 320-360 nm.

25. The use according to claim 1, characterized in that, In step (2), the Cu 2+ concentration in the standard solution containing Cu 2+ thiosemicarbazide of different concentrations is 0-80 µM, and the concentration of thiosemicarbazide solution is 0.5-8 µg / mL.

26. The use according to claim 1, characterized in that, The Cu 2+ Sources include any one or a combination of at least two of copper sulfate pentahydrate, copper chloride dihydrate, or copper nitrate trihydrate.

27. The use according to claim 1, characterized in that, The standard solutions containing Cu 2+ The standard solutions containing different concentrations of thiram were obtained by adding copper salts to a series of thiram standard solutions.

28. The use according to claim 27, characterized in that, The standard solution of thiram comprises thiram, acetonitrile, and ultrapure water.

29. The use according to claim 28, characterized in that, The mass ratio of thiram, acetonitrile, and ultrapure water is (2.5-50):(2.5-50):(4900-4995).

30. The use of claim 1, wherein, In step (2), the incubation temperature is 20-30℃ and the incubation time is 0.01-40 min.

31. The use of claim 1, wherein, In step (2), the detection measures the emission spectrum of 360-660 nm at an excitation wavelength of 320-360 nm.

32. The use of claim 1, wherein, In step (2), the detection measures the emission spectrum of 360-660 nm at an excitation wavelength of 340 nm.

33. The use of claim 1, wherein, In step (3), the fitting curve is plotted using the ratio of fluorescence intensity at emission wavelengths of 430-440 nm to 585-595 nm.

34. The use of claim 1, wherein, In step (3), the fitting curve is plotted using the ratio of fluorescence intensity at emission wavelengths of 435 nm and 590 nm.

35. The use of claim 1, wherein, The ratiometric metal-organic framework material is used for the detection of thiram in food.

36. The application according to claim 35, characterized in that, The food includes any one of fruits, vegetables, or mushrooms.

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