Preparation method of conjugated microporous polymer solid-phase extraction membrane material and application of conjugated microporous polymer solid-phase extraction membrane material in detection of benzoylurea insecticides

Abstract

The invention discloses a preparation method of a conjugated microporous polymer solid-phase extraction membrane material and application of the conjugated microporous polymer solid-phase extraction membrane material in detection of benzoylurea insecticides, and belongs to the technical field of pesticide detection and analysis. And a membrane solid phase extraction-liquid chromatography-tandem mass spectrometry detection method is established, and the method has the advantages of less adsorbent dosage, short adsorption time, low desorption solvent dosage, simple and convenient operation process, wide linear range, high sensitivity, good repeatability, high recovery rate and low detection limit, and can realize ultra-trace detection of the benzoylurea insecticides in matrixes such as fruit juice and tea leaves.

Description

Technical Field

[0001] The invention belongs to the technical field of pesticide detection and analysis, and specifically is a method for preparing a conjugated microporous polymer solid phase extraction membrane material and an application thereof in the detection of benzoylurea insecticides. Background Art

[0002] Benzoylurea pesticides are widely used in crop pest prevention, especially in crops such as tea, fruits, grains and vegetables, due to their broad-spectrum insecticidal effects, high efficiency and high environmental compatibility. However, benzoylurea pesticides have potential hazards to the ecological environment and human health. The US EPA defines phenoxyurea pesticides as Class III and IV hazardous substances. Japan and my country also stipulate limit standards for phenoxyurea pesticides. Therefore, it is urgent to establish a detection method for benzoylurea pesticides to achieve rapid, accurate and efficient detection.

[0003] For the detection of benzoylurea pesticides in food and environmental samples, the sample types are diverse and complex, which is prone to matrix effects, thereby reducing the sensitivity, accuracy and precision of the method; at the same time, the residual level of benzoylurea pesticides is trace or ultra-trace, which not only requires the detection method to be highly sensitive, but also requires the use of sample pretreatment methods to selectively enrich it, thereby achieving the dual effects of enrichment and purification. At present, rapid extraction technologies mainly include dispersed solid phase extraction, magnetic solid phase extraction, membrane solid phase extraction, etc. Among them, membrane solid phase extraction technology can immobilize the adsorbent, greatly reducing the loss of the adsorbent during the extraction process, and does not require processes such as centrifugation and magnetic adsorption, and has the characteristics of a simpler operation process. Therefore, the development of new membrane solid phase extraction materials is of great significance for achieving efficient adsorption of benzoylurea pesticides, thereby ultra-trace detection of benzoylurea pesticides in matrices such as juice and tea. Summary of the invention

[0004] To solve the above problems, the purpose of the present invention is to provide a method for preparing a conjugated microporous polymer solid phase extraction membrane material and its application in the detection of benzoylurea pesticides.

[0005] In order to achieve the above object, the present invention is implemented through the following technical solutions: A method for preparing a conjugated microporous polymer solid phase extraction membrane material is to prepare the material by interfacial polymerization of 3,5-dihydroxy-2,4,6-triiodobenzoic acid and 2,4,6-tris(4-ethynylphenyl)-1,3,5-triazine to produce a Sonogashira-Hagihara coupling reaction; The structural formula of the conjugated microporous polymer solid phase extraction membrane material is: ; The specific steps include: 1) Preparation of aqueous phase: 3,5-dihydroxy-2,4,6-triiodobenzoic acid is added to water, and then ethanol is added thereto. After ultrasonic dispersion is performed, alkali, tetrahydrofuran and cuprous iodide are added to obtain an aqueous phase; 2) Preparation of an organic phase: adding 2,4,6-tris(4-ethynylphenyl)-1,3,5-triazine to a non-polar organic solvent, and then adding bistriphenylphosphine palladium dichloride thereto, stirring and dispersing the mixture evenly to obtain an organic phase; 3) The aqueous phase prepared in step 1) is added to the reactor, and then the organic phase prepared in step 2) is added thereto. After slowly stirring and reacting for 12 hours at 25° C. under vacuum, the thin film formed at the interface is taken out, washed with water, methanol and acetonitrile for 3 to 5 times respectively, and dried to obtain a conjugated microporous polymer solid phase extraction membrane material.

[0006] The base in step 1) is triethylamine or diisopropylethylamine.

[0007] The mass ratio of 3,5-dihydroxy-2,4,6-triiodobenzoic acid, water, ethanol, alkali, tetrahydrofuran and cuprous iodide in step 1) is 1:70-100:8-10:15-20:20-25:0.2-0.3.

[0008] The non-polar organic solvent in step 2) is toluene, n-hexane or cyclohexane.

[0009] The mass ratio of 2,4,6-tris(4-ethynylphenyl)-1,3,5-triazine, non-polar organic solvent and bistriphenylphosphine palladium dichloride in step 2) is 1:80-100:0.4-0.6.

[0010] The mass ratio of 2,4,6-tris(4-ethynylphenyl)-1,3,5-triazine in step 2) to 3,5-dihydroxy-2,4,6-triiodobenzoic acid in step 1) is 1:0.8~1.

[0011] The present invention also includes the application of the conjugated microporous polymer solid phase extraction membrane material in the detection of benzoylurea pesticides.

[0012] The method for detecting benzoylurea pesticides comprises: using the conjugated microporous polymer solid phase extraction membrane material as a membrane extraction adsorbent to perform membrane solid phase extraction on a sample to be tested to obtain a test liquid, and then using liquid chromatography-tandem mass spectrometry for detection and analysis.

[0013] The membrane solid phase extraction process is as follows: a conjugated microporous polymer solid phase extraction membrane material is applied to a stainless steel wire, and then immersed in a glass bottle containing a sample solution, mixed for 1 minute, and then placed in a rotary mixer at a speed of 200 rpm for oscillation extraction for 2 to 30 minutes. After the extraction is completed, the conjugated microporous polymer solid phase extraction membrane material is taken out, and an analytical solvent is used to oscillate and analyze in an air bath oscillator for 5 to 20 minutes. The collected eluate is blown dry with nitrogen, and then the analytical solvent 2 is added for redissolution, vortexed for 1 minute, and filtered with a 0.45 μm organic filter membrane to obtain a test solution for detection.

[0014] The analytical solvent is the same as analytical solvent 2, which is methanol, acetonitrile, acetone or n-hexane.

[0015] The pH of the sample solution is 2.0-10.0.

[0016] The mass volume ratio of the conjugated microporous polymer solid phase extraction membrane material, the sample solution, the analytical solvent and the analytical solvent 2 is 3-12 mg: 50 mL: 1-5 mL: 0.5 mL.

[0017] Preferably, the pH of the sample solution is 6.0; the analytical solvent is methanol; the extraction time is 5 min; the analytical time is 5 min; the mass volume ratio of the conjugated microporous polymer solid phase extraction membrane material, the sample solution, the analytical solvent and the analytical solvent 2 is 9 mg: 50 mL: 3 mL: 0.5 mL.

[0018] The liquid chromatography conditions are as follows: C18 chromatographic column: 100mm × 2.1mm × 2.6μm; mobile phase: phase A is acetonitrile, phase B is 5mM formic acid water, gradient elution conditions are: 0~5min, phase A 45%~20%; 5.1~7.0min, phase A 45%~45%; 7.1~9.0 min, phase A 75%; flow rate: 0.3mL / min; column temperature: 25°C; injection volume: 10μL.

[0019] Since benzoylurea pesticides all contain fluorine atoms, the abundant hydroxyl groups provide abundant adsorption sites for fluorine ions, which is beneficial to the adsorption of the target by the conjugated microporous polymer solid phase extraction membrane material. To verify the adsorption mechanism, the adsorption mechanism between benzoylurea pesticides and conjugated microporous polymer solid phase extraction membrane materials (OH-CMPs) was verified at the molecular level by density functional theory (DFT). Based on the visualization results of Visual Molecular Dynamics (VMD) (such as Figure 1As shown in the figure, using Triflumuron as a model molecule, two different adsorption model configurations of benzoylurea insecticides on the surface of functionalized conjugated microporous polymer solid phase extraction membrane materials were determined: (i) Triflumuron tends to be arranged parallel to the benzene rings on the nanostructured surface of the conjugated microporous polymer solid phase extraction membrane material, forming an offset face-to-face (OFF) π-π stacking configuration; (ii) the F group in Triflumuron has a strong electronegativity ( Figure 1 (A)), and the highly polar -OH groups in the unreacted functionalized -OH groups on the conjugated microporous polymer solid phase extraction membrane material ( Figure 1 (B)) interact with each other to form -F···OH hydrogen bonds, thereby enabling rapid enrichment of benzoylurea insecticides.

[0020] Compared with the prior art, the present invention has the following advantages: The conjugated microporous polymer solid phase extraction membrane material prepared by the present invention has a large specific surface area, abundant adsorption sites, strong hydrophobicity, and halogen bonds and hydrogen bonds with strong interactive forces, and can quickly achieve the enrichment of benzoylurea insecticides; the adsorbent can be immobilized by using membrane solid phase extraction technology, which greatly reduces the loss of the adsorbent during the extraction process, reduces the adsorption time, and has a simple post-treatment process, so that trace detection of benzoylurea insecticides can be achieved.

[0021] The present invention adopts a membrane solid phase extraction method to separate the membrane material from the sample to be tested by extracting the membrane material from the sample to be tested. There is no need for operations such as centrifugation and magnetic adsorption. The process is convenient, the pre-treatment steps are further simplified, and the loss of recovery rate caused by centrifugation and magnetic adsorption operations is reduced.

[0022] The present invention uses a conjugated microporous polymer solid phase extraction membrane material to detect benzoylurea pesticides, and establishes a membrane solid phase extraction-liquid chromatography-tandem mass spectrometry detection method. The method has the advantages of small adsorbent dosage, short adsorption time, low analytical solvent dosage, simple operation process, wide linear range, high sensitivity, good repeatability, high recovery rate, low detection limit, and can realize ultra-trace detection of benzoylurea pesticides in matrices such as fruit juice and tea. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 The diagram is an adsorption mechanism diagram between benzoylurea pesticides and conjugated microporous polymer solid phase extraction membrane materials; (A) is a model molecular diagram of thiocarbamide; (B) is a model molecular diagram of conjugated microporous polymer solid phase extraction membrane materials; (C) is a diagram of the action mechanism of thiocarbamide and conjugated microporous polymer solid phase extraction membrane materials; (D) is an isosurface color band of the reference standard and the force diagram it represents; Figure 2This is the infrared spectrum of the conjugated microporous polymer solid phase extraction membrane material prepared in Example 3 of the present invention; Figure 3 This is a scanning electron microscope image of the conjugated microporous polymer solid phase extraction membrane material prepared in Example 3 of the present invention; Figure 4 This is a contact angle test diagram of the conjugated microporous polymer solid phase extraction membrane material prepared in Example 3 of the present invention; Figure 5 This is a graph showing the N2 adsorption-desorption experiment of the conjugated microporous polymer solid phase extraction membrane material prepared in Example 3 of the present invention; Figure 6 It is a membrane solid phase extraction flow chart of the conjugated microporous polymer solid phase extraction membrane material of the present invention; Figure 7 The diagram is a graph of factors affecting solid phase extraction of the conjugated microporous polymer solid phase extraction membrane material of the present invention, wherein (A) is a pH influence diagram; (B) is a conjugated microporous polymer solid phase extraction membrane material dosage influence diagram; (C) is an extraction time influence diagram; (D) is an analysis solvent type influence diagram; (E) is an analysis time influence diagram; and (F) is an analysis solvent dosage influence diagram. DETAILED DESCRIPTION

[0024] In order to better understand the technical solution of the present invention, the above content of the present invention is further described in detail below through specific implementation methods in the form of embodiments, but this should not be understood as the scope of the above subject matter of the present invention being limited to the following examples. All technologies realized based on the above content of the present invention belong to the scope of the present invention.

[0025] Example 1 Preparation of conjugated microporous polymer solid phase extraction membrane material 1) Preparation of aqueous phase: 0.25 g of 3,5-dihydroxy-2,4,6-triiodobenzoic acid was added to 17.5 g of water, and 2 g of ethanol was added thereto. After ultrasonic dispersion, 3.75 g of triethylamine, 5 g of tetrahydrofuran and 0.05 g of cuprous iodide were added to obtain an aqueous phase; 2) Preparation of organic phase: add 0.2 g of 2,4,6-tris(4-ethynylphenyl)-1,3,5-triazine to 16 g of n-hexane, then add 0.08 g of bistriphenylphosphine palladium dichloride, stir and disperse evenly to obtain an organic phase; 3) The aqueous phase prepared in step 1) is added into the reactor, and then the organic phase prepared in step 2) is added thereto. After slowly stirring the reaction at 25° C. for 12 h under vacuum, the thin film formed at the interface is taken out, washed three times with water, methanol and acetonitrile respectively, and dried to obtain a conjugated microporous polymer solid phase extraction membrane material.

[0026] Example 2 Preparation of conjugated microporous polymer solid phase extraction membrane material 1) Preparation of aqueous phase: 0.25 g of 3,5-dihydroxy-2,4,6-triiodobenzoic acid was added to 25 g of water, and 2.5 g of ethanol was added thereto. After ultrasonic dispersion, 5 g of diisopropylethylamine, 6.25 g of tetrahydrofuran and 0.075 g of cuprous iodide were added to obtain an aqueous phase; 2) Preparation of organic phase: Add 0.25 g of 2,4,6-tris(4-ethynylphenyl)-1,3,5-triazine to 25 g of cyclohexane, then add 0.15 g of bistriphenylphosphine palladium dichloride, stir and disperse evenly to obtain an organic phase; 3) The aqueous phase prepared in step 1) is added to the reactor, and then the organic phase prepared in step 2) is added thereto. After slowly stirring the reaction at 25° C. for 12 hours under vacuum, the thin film formed at the interface is taken out, washed with water, methanol and acetonitrile for 4 times respectively, and dried to obtain a conjugated microporous polymer solid phase extraction membrane material.

[0027] Example 3 Preparation of conjugated microporous polymer solid phase extraction membrane material 1) Preparation of aqueous phase: 0.25 g of 3,5-dihydroxy-2,4,6-triiodobenzoic acid was added to 20 g of water, and 2.3 g of ethanol was added thereto. After ultrasonic dispersion, 4 g of triethylamine, 5.5 g of tetrahydrofuran and 0.06 g of cuprous iodide were added to obtain an aqueous phase; 2) Preparation of an organic phase: Add 0.22 g of 2,4,6-tris(4-ethynylphenyl)-1,3,5-triazine to 19.8 g of toluene, and then add 0.11 g of bistriphenylphosphine palladium dichloride thereto, stir and disperse evenly to obtain an organic phase; 3) The aqueous phase prepared in step 1) is added to the reactor, and then the organic phase prepared in step 2) is added thereto. After slowly stirring the reaction at 25° C. under vacuum for 12 hours, the thin film formed at the interface is taken out, washed with water, methanol and acetonitrile for 5 times respectively, and dried to obtain a conjugated microporous polymer solid phase extraction membrane material.

[0028] The conjugated microporous polymer solid phase extraction membrane material prepared in Example 3 was characterized by FTIR, and its detection spectrum was as follows: Figure 2 As shown by Figure 2 It can be seen that the characteristic signal peak of -C≡CH in the raw material 2,4,6-tris(4-ethynylphenyl)-1,3,5-triazine (TEPT) (3290 cm -1 ) and the -CI stretching vibration peak (564 cm -1 ) basically disappeared, indicating that the two raw materials underwent a Sonogashira reaction. At the same time, a new characteristic peak -C≡C- (2205 cm -1), confirming that a polymer was generated between the two monomers through a Sonogashira reaction.

[0029] The conjugated microporous polymer solid phase extraction membrane material prepared in Example 3 was subjected to scanning electron microscope detection and contact angle test. The detection results are as follows: Figure 3 and Figure 4 As shown by Figure 3 It can be seen that the surface of the conjugated microporous polymer solid phase extraction membrane material is a rod-shaped morphology, indicating that the prepared conjugated microporous polymer solid phase extraction membrane material has a large specific surface area and good stability, and the internal channel of the rod-shaped structure is conducive to molecular diffusion, thereby improving the adsorption rate. Figure 4 It can be seen that the contact angle of the conjugated microporous polymer solid phase extraction membrane material is 148°, indicating that the material has strong hydrophobicity and can effectively adsorb the target.

[0030] The conjugated microporous polymer solid phase extraction membrane material prepared in Example 3 was subjected to N2 adsorption-desorption experiment, and the test results are as follows: Figure 5 As shown by Figure 5 It can be seen that the specific surface area of ​​the conjugated microporous polymer solid phase extraction membrane material is 427.0 m 2 / g, indicating that the prepared membrane material has a good specific surface area.

[0031] Example 4 (1) Liquid chromatography-tandem mass spectrometry conditions Instrument model: Liquid chromatography-triple quadrupole mass spectrometer (6470 LC / TQ, Agilent Technologies, USA).

[0032] Liquid chromatography column conditions: Thermo Fisher C18 column (100mm × 2.1mm × 2.6μm); mobile phase: phase A is acetonitrile, phase B is 5mM formic acid water, gradient elution conditions are: 0~5min, phase A 45%~20%; 5.1~7.0min, phase A 45%~45%; 7.1~9.0 min, phase A 75%; flow rate: 0.3mL / min; column temperature: 25℃; injection volume: 10μL.

[0033] Mass spectrometry parameters: In this application, an electrospray ionization source (ESI) was used, and the selected multiple reaction monitoring (MRM) mode was used for quantification; drying gas temperature: 300°C, dryer flow: 5L / min, nebulizer voltage: 35psi, capillary voltage: 4000V, sheath gas flow rate: 11L / min, sheath gas temperature: 300°C. The optimized MRM parameters include the qualitative ion, quantitative ion, and its declustering voltage and collision energy as shown in Table 1, where * indicates the quantitative ion.

[0034] Table 1 Optimized parameters

[0035] (2) Membrane solid phase extraction (the flow chart is as follows Figure 6 (shown) The conjugated microporous polymer solid phase extraction membrane material prepared in Example 3 of the present invention was stained on a stainless steel wire, and then immersed in a glass bottle containing 50 mL of an aqueous solution, wherein the spiked concentration of 6 benzoylurea insecticides (thiocarb, flubendiamide, flufenoxuron, flufenoxuron, fluflufenuron, and flupyraliduron) in the aqueous solution was 500 ng / L. After mixing for 1 min, the mixture was placed in a rotary mixer at a speed of 200 rpm for oscillation extraction for 2 to 30 min. After the extraction was completed, the conjugated microporous polymer solid phase extraction membrane material was taken out, and an analytical solvent was used to oscillate and analyze in an air bath oscillator for 5 to 20 min. The collected eluate was blown dry with nitrogen, and then the analytical solvent 2 was added for redissolution, vortexed for 1 min, and filtered with a 0.45 μm organic filter membrane to obtain a test solution for detection. Each group of experiments was conducted in parallel three times.

[0036] This experiment investigated the effect of sample solution pH (2.0-10.0) on the extraction of benzoylurea pesticides. Figure 7 As shown in (A). When the pH is 6.0, the recovery rate of the six benzoylurea insecticides is the highest, about 95%. At other pH values, the recovery rates of the six benzoylurea insecticides are slightly reduced, about 85%. Therefore, the pH value of the sample solution is determined to be 6.

[0037] This experiment investigated the effect of the amount of conjugated microporous polymer solid phase extraction membrane material (3mg, 6mg, 9mg, 12mg) on ​​the extraction of benzoylurea pesticides. The detection spectrum is as follows: Figure 7 (B) As shown in the experimental results, as the amount of conjugated microporous polymer solid phase extraction membrane material increases, the extraction efficiency gradually increases. When the amount of conjugated microporous polymer solid phase extraction membrane material is 9 mg, the recovery rate of the target reaches more than 90%, indicating that 9 mg of conjugated microporous polymer solid phase extraction membrane material is sufficient to achieve the enrichment of 6 benzoylurea pesticides. Therefore, the amount of conjugated microporous polymer solid phase extraction membrane material is determined to be 9 mg.

[0038] This experiment investigated the effect of extraction time (2-30 min) on the extraction of benzoylurea insecticides. Figure 7 (C) As shown in the experimental results, at 2 minutes, the extraction efficiency of the six benzoylurea insecticides all reached more than 60%, but with a certain discrete type. As the extraction time increases, the extraction efficiency gradually increases. When the extraction time is 5 minutes, the recovery rate of the six benzoylurea insecticides is as high as 90%. Therefore, the extraction time is determined to be 5 minutes.

[0039] This experiment investigated the effects of analytical solvents (methanol, acetonitrile, acetone and n-hexane) on the extraction of benzoylurea pesticides. Figure 7 (D) As shown. The experimental results show that methanol, acetone and acetonitrile have high analytical capabilities for the six benzoylurea pesticides, while n-hexane has the lowest analytical capability. However, considering that the influence of pigments should be minimized during the actual sample tea beverage detection process, acetone solvents tend to dissolve more pigments. Secondly, from an economic perspective, the elution cost of acetonitrile is higher. Therefore, methanol was determined to be the analytical solvent.

[0040] This experiment investigated the effects of the analytical time (5-20 min) and the amount of analytical solvent (1-5 mL) on the extraction of benzoylurea pesticides. Figure 7 (E) and Figure 7 (F). The experimental results show that when the analysis time is 5 minutes, the recovery rate of the six benzoylurea insecticides is as high as 90%. When the analysis time is extended, the analysis efficiency remains unchanged. Therefore, the analysis time is determined to be 5 minutes. When the amount of methanol used as the analysis solvent is in the range of 1~3mL, the analysis efficiency increases with the increase of the analysis volume, and the analysis rate is 80%. When the volume of methanol continues to increase, the analysis rate hardly changes. Therefore, from the perspective of protecting the environment and saving nitrogen blowing time, the amount of analysis solvent is determined to be 3mL.

[0041] The optimal membrane solid phase extraction parameters were finally determined as: sample solution pH 6.0; analytical solvent methanol; extraction time 5 min; analytical time 5 min; the mass volume ratio of conjugated microporous polymer solid phase extraction membrane material, sample solution, analytical solvent and analytical solvent 2 was 9 mg: 50 mL: 3 mL: 0.5 mL.

[0042] Example 5 (1) Preparation of mixed standard solution of benzoylurea insecticides: Accurately weigh 100.0 mg of high-purity reagents of fluazifop, chloranil, flubenzuron, fluacrylonitrile, flufenoxuron and flufluanidone, dissolve them in methanol and transfer them to a 10 mL volumetric flask, add methanol to the mark, shake well, and obtain a single standard stock solution with a mass concentration of 10 mg / mL. Accurately measure 1.00 mL of single standard stock solutions of fluazifop, chloranil, flubenzuron, fluacrylonitrile, flufenoxuron and flufluanidone, place them in a 100 mL brown volumetric flask, add methanol to the mark, shake well, and obtain a mixed standard solution of benzoylurea insecticides with a mass concentration of 100 μg / mL. The mixed standard solution is stored in a refrigerated storage at -4°C and is valid for one year.

[0043] (2) Preparation of standard working solutions of benzoylurea insecticides: dilute the 100 μg / mL mixed standard solution of benzoylurea insecticides into standard working solutions of benzoylurea insecticides with concentrations of 0.5, 1, 2.5, 5, 10, 25, 40, 50 and 100 μg / L respectively; (3) The benzoylurea insecticide standard working solution prepared in step (2) was subjected to liquid chromatography-tandem mass spectrometry for detection, and a standard curve was established based on the correspondence between the chromatographic peak area and the mass concentration of the benzoylurea insecticide standard working solution; the detection results are shown in Table 2.

[0044] Table 2 Standard curve determination results

[0045] From the results in Table 2, it can be seen that the six benzoylurea insecticides showed a good linear relationship in the concentration range of 0.5~100 ng / L, and the linear correlation coefficient was higher than 0.999. The detection limits (LODs) (S / N=3) of the method were 0.08~0.60 ng / L, and the quantification limits (LOQs) (S / N=10) of the method were 0.29~2.00 ng / L. The experimental results showed that the method for determining benzoylurea insecticides by membrane solid phase extraction-liquid chromatography-tandem mass spectrometry had high sensitivity, good repeatability, low detection limits and quantification limits, and could achieve trace detection of benzoylurea insecticides.

[0046] Example 6 Determination of samples (1) Preparation of sample solution Groundwater and surface water were selected as actual water samples for analysis. The environmental water samples were filtered through a water filter membrane with a pore size of 0.45 µm, adjusted to pH = 6, and stored in a clean brown glass bottle at 4°C for future use.

[0047] Green tea and black tea samples were ground into fine powder by a grinder. 0.50 g of tea powder was accurately weighed and placed in a 50 mL centrifuge tube, and 2.5 mL of acidified acetonitrile (1% formic acid) was added. The mixture was vortexed for 5 min. After the extraction was completed, the mixture was centrifuged at 8000 rpm for 5 min to separate the supernatant. The same extraction operation was repeated, and the supernatants were combined twice. Finally, the supernatant was transferred to a clean 50 mL flat-bottomed glass tube with a cover, and the supernatant was diluted to 50 mL with ultrapure water. The pH of the sample solution was adjusted to 6.0 for later use.

[0048] Grape juice and apple juice were filtered through a water filter membrane with a pore size of 0.45 µm, adjusted to pH = 6, and stored in clean brown glass bottles at 4 °C for later use.

[0049] (2) Membrane solid phase extraction 9 mg of the conjugated microporous polymer solid phase extraction membrane material prepared in Example 3 of the present invention was applied to a stainless steel wire and immersed in a glass bottle containing 50 mL of the sample solution prepared in step (1). After mixing for 1 min, the mixture was placed in a rotary mixer at a speed of 200 rpm and subjected to oscillation extraction for 5 min. After the extraction was completed, the conjugated microporous polymer solid phase extraction membrane material was taken out and oscillated in an air bath oscillator with 3 mL of methanol for 5 min. The collected eluate was dried with nitrogen, and then 0.5 mL of methanol was added for redissolution. The mixture was vortexed for 1 min and filtered with a 0.45 μm organic filter membrane to obtain a test solution.

[0050] (3) Setting up liquid chromatography-tandem mass spectrometry conditions Instrument model: Liquid chromatography-triple quadrupole mass spectrometer (6470 LC / TQ, Agilent Technologies, USA).

[0051] Liquid chromatography column conditions: Thermo Fisher C18 column (100mm × 2.1mm × 2.6μm); mobile phase: phase A is acetonitrile, phase B is 5mM formic acid water, gradient elution conditions are: 0~5min, phase A 45%~20%; 5.1~7.0min, phase A 45%~45%; 7.1~9.0 min, phase A 75%; flow rate: 0.3mL / min; column temperature: 25℃; injection volume: 10μL.

[0052] Mass spectrometry parameters: In this application, an electrospray ionization source (ESI) was used, and the selected multiple reaction monitoring (MRM) mode was adopted for quantification; drying gas temperature: 300°C, dryer flow: 5L / min, nebulizer voltage: 35psi, capillary voltage: 4000V, sheath gas flow rate: 11L / min, sheath gas temperature: 300°C.

[0053] (4) The test solutions prepared in step (2) were respectively subjected to liquid chromatography-tandem mass spectrometry. The six samples were spiked with 20 ng / L and 500 ng / L for low and high concentration spike recovery experiments, and each group of samples was measured in parallel 3 times. The test results are shown in Table 3.

[0054] Table 3 Sample determination and spike recovery results

[0055] From the results in Table 3, it can be seen that the concentration of fluuron in grape juice is 0.66ng / L, the concentration of fluuron in apple juice is 0.68ng / L, and no residues of benzoylurea insecticides were detected in other samples. The six samples were subjected to low (20ng / L) and high concentration (500ng / L) spike recovery experiments, and the results showed that the recovery rates of the six benzoylurea insecticides were between 72% and 120%, and the measured recovery rates all met the measurement method requirements of the SANTE / 11945 / 2015 guideline.

[0056] Although the above describes the specific implementation methods of the present invention, it does not limit the scope of protection of the present invention. Based on the technical solution of the present invention, various modifications or variations that can be made by those skilled in the art without creative work are still within the scope of protection of the present invention.

Claims

1. A method for preparing a conjugated microporous polymer solid phase extraction membrane material, characterized in that: It is prepared by Sonogashira-Hagihara coupling reaction of 3,5-dihydroxy-2,4,6-triiodobenzoic acid and 2,4,6-tris(4-ethynylphenyl)-1,3,5-triazine through interfacial polymerization; The structural formula of the conjugated microporous polymer solid phase extraction membrane material is: ； The specific steps include: 1) Preparation of aqueous phase: 3,5-dihydroxy-2,4,6-triiodobenzoic acid is added to water, and then ethanol is added thereto. After ultrasonic dispersion, alkali, tetrahydrofuran and cuprous iodide are added to obtain an aqueous phase; 2) Preparation of an organic phase: adding 2,4,6-tris(4-ethynylphenyl)-1,3,5-triazine to a non-polar organic solvent, and then adding bistriphenylphosphine palladium dichloride thereto, stirring and dispersing the mixture evenly to obtain an organic phase; 3) The aqueous phase prepared in step 1) is added to the reactor, and then the organic phase prepared in step 2) is added thereto. After slowly stirring and reacting for 12 hours at 25° C. under vacuum, the thin film formed at the interface is taken out, washed with water, methanol and acetonitrile for 3 to 5 times respectively, and dried to obtain a conjugated microporous polymer solid phase extraction membrane material.

2. The method for preparing the conjugated microporous polymer solid phase extraction membrane material according to claim 1, characterized in that: The base in step 1) is triethylamine or diisopropylethylamine; the mass ratio of 3,5-dihydroxy-2,4,6-triiodobenzoic acid, water, ethanol, base, tetrahydrofuran and cuprous iodide in step 1) is 1:70-100:8-10:15-20:20-25:0.2-0.

3.

3. The method for preparing the conjugated microporous polymer solid phase extraction membrane material according to claim 1, characterized in that: The non-polar organic solvent in step 2) is toluene, n-hexane or cyclohexane; the mass ratio of 2,4,6-tris(4-ethynylphenyl)-1,3,5-triazine, the non-polar organic solvent and bistriphenylphosphine palladium dichloride in step 2) is 1:80~100:0.4~0.6; the mass ratio of 2,4,6-tris(4-ethynylphenyl)-1,3,5-triazine in step 2) to 3,5-dihydroxy-2,4,6-triiodobenzoic acid in step 1) is 1:0.8~1.

4. Application of the conjugated microporous polymer solid phase extraction membrane material obtained by the preparation method of claim 1 in the detection of benzoylurea pesticides.

5. The use of the conjugated microporous polymer solid phase extraction membrane material as claimed in claim 4 in the detection of benzoylurea pesticides, characterized in that: The method for detecting benzoylurea pesticides comprises: using the conjugated microporous polymer solid phase extraction membrane material as a membrane extraction adsorbent to perform membrane solid phase extraction on a sample to be tested to obtain a test liquid, and then using liquid chromatography-tandem mass spectrometry for detection and analysis.

6. The use of the conjugated microporous polymer solid phase extraction membrane material according to claim 5 in the detection of benzoylurea pesticides, characterized in that: The membrane solid phase extraction process is as follows: a conjugated microporous polymer solid phase extraction membrane material is applied to a stainless steel wire, and then immersed in a glass bottle containing a sample solution, mixed for 1 minute, and then placed in a rotary mixer at a speed of 200 rpm for oscillation extraction for 2 to 30 minutes. After the extraction is completed, the conjugated microporous polymer solid phase extraction membrane material is taken out, and an analytical solvent is used to oscillate and analyze in an air bath oscillator for 5 to 20 minutes. The collected eluate is blown dry with nitrogen, and then the analytical solvent 2 is added for redissolution, oscillated and vortexed for 1 minute, and filtered with a 0.45 μm organic filter membrane to obtain a test solution for detection.

7. The use of the conjugated microporous polymer solid phase extraction membrane material according to claim 6 in the detection of benzoylurea pesticides, characterized in that: The analytical solvent is the same as analytical solvent 2, which is methanol, acetonitrile, acetone or n-hexane; the pH of the sample solution is 2.0-10.0; the mass volume ratio of the conjugated microporous polymer solid phase extraction membrane material, sample solution, analytical solvent and analytical solvent 2 is 3-12 mg: 50 mL: 1-5 mL: 0.5 mL.

8. The use of the conjugated microporous polymer solid phase extraction membrane material according to claim 6 in the detection of benzoylurea pesticides, characterized in that: The pH of the sample solution is 6.0; the analytical solvent is methanol; the extraction time is 5 min; the analytical time is 5 min; The mass volume ratio of the conjugated microporous polymer solid phase extraction membrane material, the sample solution, the analytical solvent and the analytical solvent 2 is 9 mg: 50 mL: 3 mL: 0.5 mL.

9. The use of the conjugated microporous polymer solid phase extraction membrane material according to claim 5 in the detection of benzoylurea pesticides, characterized in that: The liquid chromatography conditions are as follows: C18 chromatographic column: 100 mm × 2.1 mm × 2.6 μm; mobile phase: phase A is acetonitrile, phase B is 5 mM formic acid water, gradient elution conditions are: 0-5 min, phase A 45%-20%; 5.1-7.0 min, phase A 45%-45%; 7.1-9.0 min, phase A 75%; flow rate: 0.3 mL / min; Column temperature: 25°C; injection volume: 10 μL.

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