Covalent organic framework materials, solid phase microextraction probes, and methods of making and using the same

Abstract

The application discloses a covalent organic framework material, a solid-phase microextraction probe and a preparation method and application thereof, and relates to the technical field of material preparation and component detection. The application adopts 3,3'-dihydroxydiphenylamine and 1,3,6,8-tetra(4-formaldehyde phenyl) perylene as synthetic monomers, and synthesizes Py-DHBD-COF through a solvothermal method. The synthetic material is coated on the surface of an acid-etched stainless steel wire through polyacrylonitrile glue, and a solid-phase microextraction probe modified with a Py-DHBD-COF coating is prepared. The Py-DHBD-COF coating forms hydrogen bonds, pi-pi stacking and hydrophobic interaction with psychotropic drugs through its pi conjugated system, imine bonds and hydroxyl groups, so that efficient and selective adsorption of various psychotropic drugs is realized. In combination with HPLC-MS / MS technology, the probe shows high sensitivity, a wide linear range and good precision in the detection of three kinds of psychotropic drugs.

Description

Technical Field

[0001] This invention relates to the field of materials preparation and component detection technology, specifically to a covalent organic framework material, a solid-phase microextraction probe, its preparation method, and its application. Background Technology

[0002] With the widespread use of psychotropic drugs in medicine and society, residues resulting from their abuse and improper disposal have entered the aquatic environment through various pathways and may migrate and accumulate along the food chain, posing a persistent and insidious threat to ecosystems and public health. Therefore, establishing efficient and sensitive detection technologies for trace psychotropic drugs in water and food is of great significance for environmental monitoring, food safety supervision, and public health risk assessment. Directly detecting ultra-low concentrations of psychotropic drugs in complex matrices (such as wastewater and food extracts) presents significant challenges; therefore, efficient sample pretreatment techniques are a crucial step in the entire analytical process.

[0003] Solid-phase microextraction (SPME) technology has been widely used in this field due to its integration of sampling, extraction, enrichment, and injection, as well as its advantages of simple operation and low solvent consumption. The core performance of this technology largely depends on the physicochemical properties of the extraction coating material. Currently, commercially available SPME coatings (such as polydimethylsiloxane and polyacrylate) often suffer from insufficient selectivity, limited adsorption capacity, and poor chemical / thermal stability when dealing with complex psychotropic drugs with diverse structures and polarities. Furthermore, traditional coatings are prone to peeling or performance degradation during long-term use or when facing complex real-world samples, affecting the reproducibility and reliability of the method. Therefore, developing a high-performance coating material is an urgent need to improve the capabilities of SPME technology and ultimately achieve accurate detection.

[0004] Covalent organic frameworks (COFs) are a class of crystalline porous polymers formed by reversibly covalently linked lightweight elements (such as C, H, O, and N). Due to their high specific surface area, well-defined and tunable pore structure, excellent thermal / chemical stability, and ease of functionalization, they exhibit great potential in the field of adsorption separation. However, existing COF materials are limited in their ability to achieve high selectivity and sensitivity for target analytes in complex matrices due to issues such as limited functional groups and steric hindrance. Therefore, developing a COF extraction coating material with functionalized groups and high selective adsorption performance for target analytes is of great significance for promoting the practical application of SPME technology. Summary of the Invention

[0005] The purpose of this invention is to at least solve one of the technical problems existing in the prior art, and to provide a covalent organic framework material, a solid-phase microextraction probe, a preparation method thereof, and an application thereof. Specifically, the first objective of this invention is to provide a covalent organic framework material (Py-DHBD-COF), the second objective is to provide an extraction coating material, the third objective is to provide a solid-phase microextraction probe (SPME probe), and the fourth objective is to provide an application of the above-mentioned covalent organic framework material, the above-mentioned extraction coating material, and the above-mentioned SPME probe in the detection of psychotropic drugs.

[0006] This invention utilizes a covalent organic framework material to modify a probe, forming a Py-DHBD-COF-modified SPME probe. The Py-DHBD-COF coating on the SPME probe forms hydrogen bonds, π-π stacking, and hydrophobic interactions with psychotropic drugs through its π-conjugated system, imine bonds, and hydroxyl groups, thereby achieving highly efficient and selective adsorption of various psychotropic drugs. Combined with HPLC-MS / MS technology, this probe exhibits high sensitivity, a wide linear range, and good precision in the detection of three psychotropic drugs. Furthermore, its extraction coating possesses high stability and excellent reusability, making it suitable for the rapid analysis and detection of trace psychotropic drugs in environmental water samples and food (milk).

[0007] The technical solution of the present invention is as follows: In a first aspect, the present invention provides a covalent organic framework material having the following structural formula: .

[0008] To address the shortcomings of existing extraction coating materials, such as low adsorption efficiency and poor selectivity for psychotropic drugs, this invention uses 1,3,6,8-tetra(4-carboxyphenyl)perylene and 3,3'-dihydroxybenzidine as reactants to prepare a mesoporous COF material, Py-DHBD-COF, with high-density hydroxyl functional groups via a solvothermal synthesis strategy. Its hydroxyl functional groups can bind the hydroxyl and nitrogen atoms of psychotropic drugs through hydrogen bonding and electrostatic interactions. Combined with a suitable pore size structure and BET surface area, it achieves highly efficient and selective adsorption of the target analytes.

[0009] Secondly, the present invention provides a method for preparing the covalent organic framework material, the method comprising: The covalent organic framework material was prepared by a solvothermal method using 1,3,6,8-tetra(4-carboxyphenyl)perylene and 3,3'-dihydroxybenzidine in the presence of a catalyst.

[0010] In one specific embodiment of the present invention, the molar ratio of 1,3,6,8-tetratetra(4-formaldehyde-phenyl)perylene and 3,3'-dihydroxybenzidine is 1:1.5~2.5; preferably, the molar ratio of 1,3,6,8-tetratetra(4-formaldehyde-phenyl)perylene and 3,3'-dihydroxybenzidine is 1:2.

[0011] In one specific embodiment of the present invention, the solvent in the solvothermal method is a mixed solvent of o-dichlorobenzene and n-butanol, or a mixed solvent of 1,4-dioxane and mesitylene, or a mixed solvent of mesitylene and 1,2-dichloroethane. The volume ratio of o-dichlorobenzene to n-butanol, or the volume ratio of 1,4-dioxane to mesitylene, or the volume ratio of mesitylene to 1,2-dichloroethane is 1:0.5~1.5. Preferably, the solvent is o-dichlorobenzene and n-butanol in a volume ratio of 1:1.

[0012] In one specific embodiment of the present invention, the reaction temperature of the solvothermal method is 100℃~150℃; preferably, the reaction temperature is 120℃.

[0013] In one specific embodiment of the present invention, the catalyst comprises glacial acetic acid, which mainly acts as a Brønsted acid catalyst in such reactions; the concentration of the glacial acetic acid is 6 mol / L to 12 mol / L; preferably, the concentration of the glacial acetic acid is 6 mol / L.

[0014] In one specific embodiment of the present invention, the preparation method includes: dispersing 1,3,6,8-tetra(4-formaldehyde-phenyl)perylene and 3,3'-dihydroxybenzidine in a mixed solution of o-dichlorobenzene / n-butanol or 1,4-dioxane / trimethylbenzene or trimethylbenzene / 1,2-dichloroethane, adding a catalyst, heating the reaction, collecting the product, washing it with ethanol 3 to 5 times, and drying it under vacuum at 80 °C for 8 to 12 h to obtain Py-DHBD-COF.

[0015] In one specific embodiment of the present invention, the reaction involves rapid freezing in liquid nitrogen, followed by degassing via a freeze pump-thaw cycle, then sealing the reaction chamber, washing, and drying to obtain the product. Preferably, the reaction involves sonicating the mixture, then rapidly freezing it in a liquid nitrogen bath at -196 °C, and degassing it via three freeze pump-thaw cycles. Subsequently, a vacuum-sealed reaction is carried out at 120 °C for 72 h. The resulting solid product is washed and centrifuged repeatedly with tetrahydrofuran and ethanol, and finally dried under vacuum to obtain Py-DHBD-COF.

[0016] Thirdly, the present invention provides an extraction coating material comprising polyacrylonitrile adhesive and the covalent organic framework material.

[0017] This invention selects PAN adhesive and Py-DHBD-COF as raw materials for coating materials, and prepares extraction coating materials with multiple active sites and rapid mass transfer kinetics by adjusting the appropriate amount of materials added to the coating raw materials.

[0018] In one specific embodiment of the present invention, the polyacrylonitrile adhesive is prepared by dissolving polyacrylonitrile in N,N-dimethylformamide, wherein the concentration of polyacrylonitrile is 80 mg / mL to 120 mg / mL, the dissolution temperature is 80℃ to 100℃, and the dissolution time is 0.5 h to 2 h; preferably, the concentration of polyacrylonitrile is 100 mg / mL, the dissolution temperature is 90℃, and the dissolution time is 1 h.

[0019] In one specific embodiment of the present invention, the mass of the covalent organic framework material added to each milliliter of polyacrylonitrile adhesive is 80 mg to 100 mg, that is, the mixing ratio of Py-DHBD-COF and PAN adhesive is 80 mg to 120 mg: 1 mL. When the amount of COF added is too low, the adsorption efficiency of the coating decreases, mainly due to the reduction of effective adsorption sites. Conversely, excessive addition of COF will lead to hindered mass transfer diffusion and significantly reduce the effective specific surface area of ​​the coating surface. Therefore, rationally selecting the amount of COF added is crucial for forming more efficient adsorption sites on the coating surface. Preferably, the mixing ratio of Py-DHBD-COF and PAN adhesive is 100 mg: 1 mL.

[0020] Fourthly, the present invention provides a solid-phase microextraction probe, the solid-phase microextraction probe comprising a probe and a coating modified on the surface of the probe, the coating being formed of the extraction coating material.

[0021] This invention also provides an SPME probe, which is obtained by etching the probe with concentrated hydrochloric acid, then applying the aforementioned surface coating material to the probe surface, followed by curing. Further, the probe is a stainless steel wire with a diameter of 700 µm. Preferably, the thickness of the Py-DHBD-COF coating is 30 µm, and the length of the Py-DHBD-COF coating is 1 cm.

[0022] Fifthly, the present invention provides a method for preparing the aforementioned solid-phase microextraction probe, comprising the following steps: A covalent organic framework material is dispersed in polyacrylonitrile adhesive and mixed evenly to obtain an extraction coating material; The probe, after being acid-etched, is immersed in the extraction coating material, and then the probe is removed to obtain a probe coated with a covalent organic framework material. The probe coated with the covalent organic framework material was dried to obtain a solid-phase microextraction probe.

[0023] In one specific embodiment of the present invention, Py-DHBD-COF is dispersed in PAN adhesive and stirred for 24 h to obtain a uniformly dispersed solution. Next, an acid-etched probe is immersed in the mixed solution and then extracted to form a Py-DHBD-COF coating on the probe surface. Finally, the Py-DHBD-COF-coated probe is dried in an oven at 90 °C for 30 min to obtain a Py-DHBD-COF-modified SPME probe.

[0024] In a sixth aspect, the present invention provides the application of the covalent organic framework material, the extraction coating material, or the solid-phase microextraction probe in the enrichment, extraction, or detection of trace psychotropic drugs.

[0025] In one specific embodiment of the present invention, the present invention provides the application of a Py-DHBD-COF modified SPME probe in the detection of three psychotropic drugs in aquatic environments or milk, wherein the three psychotropic drugs are clozapine, olanzapine and quetiapine.

[0026] In one specific embodiment of the present invention, the enrichment extraction method includes: placing the sample to be tested in an EP tube, and placing the solid-phase microextraction probe in the EP tube for shaking extraction; wherein the extraction time is 5 min to 40 min, the extraction volume is 100 µL to 500 µL, and the pH is 4.0 to 9.0; more preferably, the extraction time is 30 min; the extraction solution volume is 400 µL; and more preferably, the extraction pH is 7.

[0027] In one specific embodiment of the present invention, the detection method includes: removing the solid-phase microextraction probe after shaking extraction, eluting the solid-phase microextraction probe with an elution solvent to obtain an eluent; and detecting the eluent using HPLC-MS / MS; wherein the elution solvent is at least one selected from methanol, acetonitrile, ethanol, methanol containing 0.1% (v / v) formic acid, and acetonitrile containing 0.1% (v / v) formic acid, and the volume of the elution solvent is 50 µL to 250 µL. More preferably, the elution time is 15 min, the elution solvent is methanol, and the volume of the elution solvent is 150 µL.

[0028] In one specific embodiment of the present invention, the specific parameters of the high-performance liquid chromatography and triple quadrupole mass spectrometer (HPLC-MS / MS) are as follows: The liquid chromatography conditions included: an ACQUITY UPLC BEH C18 column with parameters of 50 mm × 3 mm and 2.6 µm; a column temperature of 40 ℃; mobile phase A being a 0.1% (v / v) aqueous solution of formic acid, and mobile phase B being acetonitrile, using gradient elution. The elution gradient was set as follows: 0 min–0.5 min, mobile phase B 5%–10%; 0.5 min–1.0 min, mobile phase B 10%–90%; 1.0 min–3.0 min, mobile phase B maintained at 90%; 3.0 min–5.0 min, mobile phase B 90%–5%; 5.0 min–5.5 min, mobile phase B maintained at 5%; the flow rate was 0.3 mL / min, and the injection volume was 2 µL. The mass spectrometry detection conditions included: electrospray ionization (ESI), ionization mode was positive ion mode, monitoring mode was multiple reaction monitoring (MRM), ion source temperature was 300 °C, curtain gas was 20 psi, collision gas was 9 psi, ion spray voltage was 4500 V, and ion source gas was 20 psi.

[0029] This invention has at least one of the following beneficial effects: This invention provides a covalent organic framework material Py-DHBD-COF, an extraction coating material based on Py-DHBD-COF, a solid-phase microextraction (SPME) probe, and their preparation methods and applications. The SPME probe is prepared by modifying the surface of a stainless steel wire with an extraction coating material followed by curing. Py-DHBD-COF is synthesized from 1,3,6,8-tetra(4-carboxyphenyl)perylene and 3,3'-dihydroxybenzidine via a solvothermal method. The π-conjugated system, imine bonds, and hydroxyl groups of Py-DHBD-COF form hydrogen bonds, π-π stacking, and hydrophobic interactions with psychotropic drugs. Combined with its suitable pore size structure and high BET surface area, it achieves highly efficient and selective adsorption of target analytes. Therefore, the Py-DHBD-COF-modified SPME probe prepared in this invention exhibits excellent extraction performance for psychotropic drugs, enabling high-throughput adsorption and enrichment of trace amounts of various psychotropic drugs in complex aquatic environments and milk matrices, thereby achieving high-sensitivity detection. Attached Figure Description

[0030] Figure 1 This is a schematic diagram illustrating the synthesis of Py-DHBD-COF according to the present invention.

[0031] Figure 2 The image shows the infrared spectrum characterization of the Py-DHBD-COF described in this invention.

[0032] Figure 3 This is an X-ray diffraction characterization pattern of the Py-DHBD-COF described in this invention.

[0033] Figure 4 This is a scanning electron microscope (SEM) characterization image of the Py-DHBD-COF described in this invention.

[0034] Figure 5 This is an X-ray photoelectron spectroscopy characterization diagram of the Py-DHBD-COF described in this invention.

[0035] Figure 6 The nitrogen adsorption-desorption characterization of the Py-DHBD-COF described in this invention is shown in Figure (a), which represents the nitrogen adsorption-desorption isotherm, and Figure (b) shows the pore size distribution.

[0036] Figure 7 The images show scanning electron microscopy (SEM) characterizations of the Py-DHBD-COF-modified SPME probe described in this invention. In the images, (a) shows the unmodified probe after acid etching, and (b) shows the Py-DHBD-COF-modified probe.

[0037] Figure 8 The effect of elution conditions on the extraction efficiency of Py-DHBD-COF modified SPME probes is shown in the figure. In the figure, (a) represents extraction time, (b) represents extraction solution volume, (c) represents extraction solution pH, (d) represents elution solvent type, (e) represents elution time, and (f) represents elution solvent volume.

[0038] Figure 9 This is a repeatability graph of the Py-DHBD-COF modified SPME probe described in this invention.

[0039] Figure 10 This invention compares the extraction performance of the Py-DHBD-COF modified SPME probe with that of commercial probes polydimethylsiloxane (PDMS) and polyacrylonitrile (PAN) for extracting three psychotropic drugs. Detailed Implementation

[0040] To make the technical problems solved, the technical solutions, and the beneficial effects of this invention clearer, the 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 merely illustrative and are not intended to limit the invention.

[0041] Example 1: Preparation of the covalent organic framework material Py-DHBD-COF according to the present invention I. Preparation method: Figure 1 The diagram shows the synthetic route of the covalent organic framework material Py-DHBD-COF in Example 1, including the following steps: Step 1: Place 13.9 mg of 1,3,6,8-tetra(4-formaldehyde phenyl)perylene and 9.72 mg of 3,3'-dihydroxybenzidine in a heat-resistant glass tube, add 1 mL of a mixed solution of o-dichlorobenzene and n-butanol (v / v=1:1), and sonicate for 30 min at room temperature.

[0042] Step 2: Add 100 µL of glacial acetic acid (6 mol / L) to the mixed solution from Step 1, then place the heat-resistant glass tube containing the sample in a liquid nitrogen bath at 77 K for rapid freezing. Repeat this freezing process three times. Air extraction After thawing and cycling, the sample was vacuum sealed and then heated at 120 °C for 72 h.

[0043] Step 3: After cooling the mixture, transfer the sample to a centrifuge tube, centrifuge for 10 min to collect the solid precipitate, wash with tetrahydrofuran to remove impurities or unreacted ligands, wash repeatedly until the supernatant is clear after centrifugation, then wash the product with ethanol solution for solution displacement, repeat the displacement process three times, and vacuum dry at 80 °C for 12 h to obtain Py-DHBD-COF.

[0044] II. Characterization of Py-DHBD-COF 1. FT of Py-DHBD-COF and its synthetic monomers IR spectrum such as Figure 2 As shown. By Figure 2 It can be seen that 1,3,6,8-tetra(4-carboxyphenyl)perylene (Py) contains 1695 cm⁻¹ -1 The characteristic C=O peak at this point weakens, as does the peak at 3355 cm⁻¹ in 3,3'-dihydroxybenzidine (DHBD). -1 and 3280 cm -1 The NH characteristic peak weakens at this point, and a C=N characteristic peak (1666 cm⁻¹) appears in Py-DHBD-COF. -1 This indicates that Py-DHBD-COF was successfully synthesized via the Schiff base reaction.

[0045] 2. X-ray diffraction results of Py-DHBD-COF are shown in [reference needed]. Figure 3 The main characteristic peaks of Py-DHBD-COF are located at 3.20°, 4.71°, 6.46°, 7.54° and 9.72°, which belong to the (100), (110), (200), (120) and (220) crystal planes, respectively, indicating the successful preparation of the crystal material.

[0046] 3. The scanning electron microscopy results of Py-DHBD-COF are shown in [the table below]. Figure 4This COF material exhibits typical micron-sized porous aggregates formed by the close packing and aggregation of nanoscale primary particles. These aggregates have irregular contours and rough surface morphology, with an overall loose structure and obvious three-dimensional characteristics.

[0047] 4. The X-ray photoelectron spectroscopy results of Py-DHBD-COF are shown in [reference needed]. Figure 5 XPS analysis confirmed the presence of C1s, N1s, and O1s in the COF framework. Quantitative XPS analysis showed that the elemental contents of COF were C (81.29%), O (13.52%), and N (5.19%).

[0048] 5. The results of nitrogen adsorption and desorption experiments of Py-DHBD-COF are shown in [the table below]. Figure 6 . Figure 6 In (a), the BET surface area of ​​Py-DHBD-COF is found to be 507.3 m². 2 / g; pore size distribution as follows Figure 6 As shown in (b), the pore volume is 0.38 m³. 3 / g, with an average pore size of 2.9nm.

[0049] In summary, the successful preparation of Py-DHBD-COF lays the foundation for its adsorption and enrichment of psychotropic drugs.

[0050] Example 2: Preparation of the Py-DHBD-COF modified SPME probe of the present invention The preparation method of the solid-phase microextraction probe (Py-DHBD-COF modified SPME probe) includes the following steps: I. Preparation method: Step 1: Dissolve 100 mg PAN in 1 mL of N,N-dimethylformamide (DMF), vortex for 5 min until PAN is evenly dispersed, and then heat in an oven at 90 °C for 1 h until PAN is completely dissolved to obtain PAN adhesive.

[0051] Step 2: Add the synthesized Py-DHBD-COF (100 mg) to 1 mL of PAN glue, and stir magnetically for 24 h at room temperature to obtain a uniformly dispersed mixture, which is the extraction coating material.

[0052] Step 3: Cut several stainless steel wires with a length of 5 cm and a diameter of 700 µm, clean them with ultrapure water and ethanol in sequence, and then dry them. Then, etch the front end of the wire (1 cm in length) with concentrated hydrochloric acid (12 M), clean it with ultrapure water, and dry it for later use.

[0053] Step 4: Immerse the acid-etched stainless steel wire tip into the extraction coating material obtained in Step 2 at a uniform speed, and slowly pull it up at a uniform speed. The resulting coated probe is cured in an oven at 90 ℃ for 30 min to prepare the Py-DHBD-COF modified SPME probe.

[0054] II. Characterization of Py-DHBD-COF modified SPME probes: The scanning electron microscopy results of the Py-DHBD-COF modified SPME probe are shown in [the figure]. Figure 7 .Depend on Figure 7 It can be seen that, with Figure 7 Compared to (a) untreated stainless steel wire, Figure 7 In the scanning electron microscope image of the SPME probe modified with Py-DHBD-COF (b), it can be seen that Py-DHBD-COF is uniformly coated on the surface of the stainless steel wire. The probe diameter is about 720 µm and the coating thickness is about 30 µm.

[0055] Example 3: Validation of the extraction performance of Py-DHBD-COF modified SPME probe I. This invention constructs a method for detecting psychotropic drugs based on Py-DHBD-COF modified SPME probes and HPLC-MS / MS technology. The specific experimental method is as follows.

[0056] 1. Extraction method: A 400 µL aqueous solution containing a certain concentration of psychotropic drugs was placed in a 1.5 mL EP tube. The Py-DHBD-COF modified SPME probe prepared in Example 2 was then placed inside, and the tube was shaken and extracted at 250 rpm for 30 min. The probe was then removed and placed in a lined HPLC vial containing 150 µL of methanol solution, and desorbed at 250 rpm for 15 min to obtain the eluent for subsequent detection.

[0057] 2. Detection method: The detection of psychotropic drugs was performed using a combination of high-performance liquid chromatography (HPLC) and triple quadrupole mass spectrometry (HPLC-MS / MS), specifically, the eluent was detected using HPLC-MS / MS. The HPLC conditions were as follows: an ACQUITY UPLC BEHC18 column was used with parameters of 50 mm × 3 mm and 2.6 µm; the column temperature was 40 ℃; mobile phase A was a 0.1% (v / v) aqueous solution of formic acid, and mobile phase B was acetonitrile. Gradient elution was used, with the elution gradient set as follows: 0 min–0.5 min, mobile phase B 5–10%; 0.5 min–1.0 min, mobile phase B 10–90%; 1.0 min–3.0 min, mobile phase B maintained at 90%; 3.0 min–5.0 min, mobile phase B 90–5%; 5.0 min–5.5 min, mobile phase B maintained at 5%. The flow rate was 0.3 mL / min, and the injection volume was 2 µL. The mass spectrometry detection conditions were: electrospray ionization (ESI), positive ion mode, multiple reaction monitoring (MRM), ion source temperature of 300 °C, curtain gas of 20 psi, collision gas of 9 psi, ion spray voltage of 4500 V, and ion source gas of 20 psi.

[0058] The SPME process was investigated methodologically, and the effects of extraction liquid volume (100 µL–500 µL), extraction time (5 min–40 min), extraction liquid pH (4.0–9.0), elution solvent type (methanol, acetonitrile, ethanol, methanol containing 0.1% formic acid, acetonitrile containing 0.1% formic acid), elution solvent volume (50 µL–250 µL), and elution time (5 min–25 min) on the extraction results were examined.

[0059] II. Experimental Results Experimental results are as follows Figure 8 As shown. Based on the experimental results, the extraction time was ultimately selected as 30 min, the extraction liquid volume as 400 µL, the extraction liquid pH value as 7, the elution solvent as methanol, the elution time as 15 min, and the elution solvent volume as 150 µL.

[0060] Using the optimal extraction and desorption conditions described above, a standard mixed solution of 1 ng / mL to 500 ng / mL was extracted and analyzed by HPLC. MS / MS was used for detection, and probe working curves were prepared. Analytical methodological parameters such as the limit of detection (LODs, S / N=3), limit of quantitation (LOQs, S / N=10), linear range, linear correlation coefficient R, and precision are shown in Table 1. Quetiapine (QTP), clozapine (CLZ), and olanzapine (OLZ) showed good linearity in the range of 1 ng / mL to 500 ng / mL, with linear correlation coefficients R all higher than 0.999. The LODs of the three substances ranged from 0.010 ng / mL to 0.024 ng / mL, and the LOQs ranged from 0.033 ng / mL to 0.081 ng / mL. Inter-needle repeatability of individual extraction needles was good, with relative standard deviations (RSDs) within 5.38%.

[0061] Table 1. Methodological parameters for the analysis of three psychotropic drugs Example 4: Application of the Py-DHBD-COF modified SPME probe of the present invention in actual samples. Actual sample pretreatment: Two milk samples were purchased from a local supermarket. Before analysis, the milk sample (5 mL) and acetonitrile (5 mL) were transferred to glass centrifuge tubes and subjected to vortexing and high-speed centrifugation to separate fats and proteins. This process was repeated twice, and the supernatants were then combined. The supernatant was finally distilled to approximately 0.5 mL using a rotary evaporator at room temperature and then reconstituted with 50 mL of ultrapure water. The sample solution was filtered through a 0.22 µm syringe microfilter before use. Additionally, environmental water samples were collected from two local lakes. These water samples were filtered through a 0.22 µm syringe microfilter before analysis.

[0062] Using the optimal extraction and desorption conditions of Example 3, the extracts from actual environmental water samples and milk samples were tested. The actual concentration was calculated using the linear regression equation obtained in Example 3. The spiked concentrations were set to 10 ng / mL, 100 ng / mL, and 500 ng / mL. The results are shown in Table 2. The spiked recovery rate was in the range of 85.8% to 112.0%, and the RSDs were less than 6.34%, indicating that the method has good accuracy and precision and can be used for reliable detection of psychotropic drugs in aquatic environments and milk matrices.

[0063] Table 2. Detection results of psychotropic drugs in environmental water samples and milk. ND: Not detected.

[0064] Repeatability of the probe in this invention: This invention investigated the performance of the Py-DHBD-COF modified SPME probe in the repeated extraction of psychotropic drugs, with consistent extraction conditions for each extraction. After each extraction, the probe was washed with methanol and dried before being used for the next extraction. The experimental results of repeated use are as follows: Figure 9 As shown. From Figure 9 It can be seen that, under the same extraction conditions, the extraction efficiency of the Py-DHBD-COF modified SPME probe did not decrease significantly after 40 repeated uses, indicating that the extraction probe developed in this study has excellent reusability.

[0065] Commercial Value of the Py-DHBD-COF-Modified SPME Probe of this Invention: To evaluate the commercial potential of the Py-DHBD-COF-modified SPME probe, this invention compared it with commercially available PDMS (PDMS-modified probe) and PAN-coated probe (PAN-modified probe). Specifically, under the same extraction conditions, the SPME probe of this invention and the commercial coating were used to extract three psychotropic drugs, respectively. Figure 10 It can be seen that the extraction performance of the SPME probe modified by Py-DHBD-COF in this invention is significantly better than that of commercial PDMS and PAN, indicating that the Py-DHBD-COF extraction coating has better enrichment efficiency.

[0066] In summary, the method of using the Py-DHBD-COF modified SPME probe of this invention to detect trace amounts of psychotropic drugs in aquatic environments and milk samples not only exhibits a good linear range, but also has high sensitivity, high accuracy and good repeatability, and can be used for high-precision detection of psychotropic drugs in complex matrices.

[0067] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A covalent organic framework material, characterized in that, The covalent organic framework material has the following structural formula: 。 2. The method for preparing the covalent organic framework material according to claim 1, characterized in that, The preparation method includes: The covalent organic framework material was prepared by a solvothermal method using 1,3,6,8-tetra(4-carboxyphenyl)perylene and 3,3'-dihydroxybenzidine in the presence of a catalyst.

3. The preparation method according to claim 2, characterized in that, The molar ratio of 1,3,6,8-tetratetra(4-carboxyphenyl)perylene and 3,3'-dihydroxybenzidine is 1:1.5~2.5; The solvent in the solvothermal method is a mixture of o-dichlorobenzene and n-butanol, or a mixture of 1,4-dioxane and mesitylene, or a mixture of mesitylene and 1,2-dichloroethane. The volume ratio of o-dichlorobenzene to n-butanol, or the volume ratio of 1,4-dioxane to mesitylene, or the volume ratio of mesitylene to 1,2-dichloroethane is 1:0.5~1.

5. The reaction temperature of the solvothermal method is 100 ℃~150 ℃; The catalyst includes glacial acetic acid, and the concentration of the glacial acetic acid is 6 mol / L to 12 mol / L.

4. An extraction coating material, characterized in that, The extraction coating material includes polyacrylonitrile adhesive and the covalent organic framework material of claim 1.

5. The extraction coating material according to claim 4, characterized in that, The polyacrylonitrile adhesive is prepared by dissolving polyacrylonitrile in N,N-dimethylformamide, wherein the concentration of polyacrylonitrile is 80 mg / mL to 120 mg / mL, the dissolution temperature is 80℃ to 100℃, and the dissolution time is 0.5 h to 2 h. The mass of the covalent organic framework material added to each milliliter of polyacrylonitrile gel is 80 mg to 100 mg.

6. A solid-phase microextraction probe, characterized in that, The solid-phase microextraction probe includes a probe and a coating modified on the surface of the probe, the coating being formed from the extraction coating material of claim 4.

7. The method for preparing the solid-phase microextraction probe according to claim 6, characterized in that, Includes the following steps: A covalent organic framework material is dispersed in polyacrylonitrile adhesive and mixed evenly to obtain an extraction coating material; The probe, after being acid-etched, is immersed in the extraction coating material, and then the probe is removed to obtain a probe coated with a covalent organic framework material. The probe coated with the covalent organic framework material was dried to obtain a solid-phase microextraction probe.

8. The application of the covalent organic framework material of claim 1, the extraction coating material of claim 4, or the solid-phase microextraction probe of claim 6 in the enrichment, extraction, or detection of trace psychotropic drugs.

9. The application according to claim 8, characterized in that, The psychotropic drugs include at least one of clozapine, olanzapine, and quetiapine; The enrichment and extraction method includes: placing the sample to be tested in an EP tube, placing the solid-phase microextraction probe in the EP tube and performing shaking extraction; wherein the extraction time is 5 min to 40 min, the extraction volume is 100 µL to 500 µL, and the pH is 4.0 to 9.

0. The detection method includes: taking out the solid-phase microextraction probe after shaking extraction, eluting the solid-phase microextraction probe with an elution solvent to obtain an eluent; wherein the elution solvent is at least one of methanol, acetonitrile, ethanol, methanol containing 0.1% volume fraction of formic acid, and acetonitrile containing 0.1% volume fraction of formic acid, the elution time is 5 min to 25 min, and the volume of the elution solvent is 50 µL to 250 µL; The eluent was analyzed by HPLC-MS / MS.

10. The application according to claim 9, characterized in that, The parameters of the HPLC-MS / MS are as follows: The liquid chromatography conditions included: an ACQUITY UPLC BEH C18 column with parameters of 50 mm × 3 mm and 2.6 µm; a column temperature of 40 ℃; mobile phase A being a 0.1% (v / v) aqueous solution of formic acid, and mobile phase B being acetonitrile, using gradient elution. The elution gradient was set as follows: 0 min–0.5 min, mobile phase B 5%–10%; 0.5 min–1.0 min, mobile phase B 10%–90%; 1.0 min–3.0 min, mobile phase B maintained at 90%; 3.0 min–5.0 min, mobile phase B 90%–5%; 5.0 min–5.5 min, mobile phase B maintained at 5%; the flow rate was 0.3 mL / min, and the injection volume was 2 µL. The mass spectrometry detection conditions included: electrospray ionization (ESI), ionization mode was positive ion mode, monitoring mode was multiple reaction monitoring (MRM), ion source temperature was 300 °C, curtain gas was 20 psi, collision gas was 9 psi, ion spray voltage was 4500 V, and ion source gas was 20 psi.

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