Sodium alginate hydrogel for extracting pesticide and veterinary drug COFs and application of sodium alginate hydrogel

Abstract

The invention discloses sodium alginate hydrogel for extracting pesticide and veterinary drug COFs and application of the sodium alginate hydrogel, and belongs to the field of detection. According to the invention, seven COFs are designed and synthesized, including grafting of different functional groups, different charged properties and different conjugated structures, and then corresponding seven COFs-sodium alginate hydrogel (CACPs) are prepared, and the COFs-sodium alginate hydrogel (CACPs) is used as an extraction material of dSPE to be applied to detection of common pesticide and veterinary drugs. The adsorption capacity of the CACPs on pesticide and veterinary drugs is coordinated and determined by the porous structure properties (specific surface area and pore size) of the CACPs and the inherent structure (conjugate structure size and grafting group) of the loaded COFs. The CACPs prepared from the COFs with large conjugated structures and grafted hydroxyl groups are most beneficial to adsorption of carbamate pesticides; for triazole and triazine pesticides and sulfonamide antibiotics, the CACPs with large specific surface area and medium pore diameter has the best extraction effect; for beta-receptor agonists, the CACPs with a large specific surface area have the best extraction effect.

Description

Technical Field

[0001] The invention relates to a sodium alginate hydrogel for extracting COFs of agricultural and veterinary drugs and application thereof, belonging to the detection field. Background Art

[0002] Pesticides and veterinary drugs are indispensable for increasing food production and improving animal and aquaculture. The current problem of multi-media residues caused by the extensive use and abuse of pesticides and veterinary drugs is becoming increasingly serious. It has been reported that the relevant literature surveyed in the past two decades shows that the pesticide residues with the highest concentrations in fruits and vegetables are fungicides, insecticides and herbicides. Triazole, carbamate and triazine pesticides are widely used as representatives of insecticides, fungicides and herbicides, respectively. Sulfonamides and β-agonists are often widely used or abused in animal husbandry to treat diseases or for commercial purposes. β-agonists, as an illegal feed additive used to increase the lean meat rate of animals, have attracted great attention due to frequent poisoning incidents; sulfonamides are one of the most widely used antibiotics for the treatment of bacterial infections. They are difficult to degrade and not easily metabolized by the human body. Since pesticide and veterinary drug residues can accumulate through the food chain and produce a biomagnification effect, they pose a threat to human health and ecological balance. Therefore, it is very necessary to develop convenient, efficient and accurate residue detection methods to monitor food safety and ensure public health. Summary of the invention

[0003] In view of the existing problems, the present invention provides a COFs sodium alginate hydrogel for extracting agricultural and veterinary drugs. The preparation method of the COFs sodium alginate hydrogel is as follows: COFs are added to a sodium alginate solution, and ultrasonic dispersion is performed to uniformly obtain a COFs sodium alginate mixed solution; anhydrous CaCl2 is dissolved in polyacrylic acid to prepare a solidification receiving solution; the COFs-sodium alginate mixed solution is added dropwise to the solidification receiving solution, fully solidified, collected after shaping, washed, and dried to obtain the COFs sodium alginate hydrogel, namely CACPs;

[0004] Among them, COFs are TpPa-1, TpPa-2, TpPa-(COOH)2, TpPa-SO3H, TFP-DG Cl , Dt-TAPB or TAPB-DMTA.

[0005] In one embodiment, the preparation method of COFs sodium alginate hydrogel is as follows: 25 mg COFs is added to 1 mL 20 mg / mL sodium alginate solution, and ultrasonic dispersion is performed to uniformly obtain a COFs sodium alginate mixed solution; 60 mg anhydrous CaCl2 is dissolved in 10 mL 0.01 mol / L polyacrylic acid to prepare a solidification receiving solution; the COFs sodium alginate mixed solution is added dropwise to the solidification receiving solution, and magnetic stirring is performed for 5 minutes to fully solidify it. After the mixed beads are set, they are collected, washed with ultrapure water, and freeze-dried for later use.

[0006] In one embodiment, the preparation method of TpPa-1 is as follows: 0.30mmolTp and 0.45mmolPa-1 are dispersed in a mixed solution of 3mL trimethylbenzene and 3mL 1,4-dioxane, and after ultrasonication for 10 minutes, 0.45mL3mmol acetic acid aqueous solution is added dropwise, and the mixture is placed in a vacuum oven at 120°C for 72 hours for reaction, and then washed with acetone and dried at 70°C.

[0007] In one embodiment, the preparation method of TpPa-2 is as follows: 0.30mmolTp and 0.45mmolPa-2 are dispersed in a mixed solution of 3mL of trimethylbenzene and 3mL of 1,4-dioxane, and after ultrasonication for 10 minutes, 0.45mL of 3mmol acetic acid aqueous solution is added dropwise, and the mixture is placed in a vacuum oven at 120°C for 72 hours for reaction, and then washed with acetone and dried at 70°C.

[0008] In one embodiment, the preparation method of TpPa-(COOH)2 is to disperse 0.30mmol Tp and 0.9mmolPa-(COOH)2 in 3mL 1,4-dioxane, ultrasonicate at room temperature for 5min, then add 0.5mL, 6.0mol / L acetic acid aqueous solution, ultrasonicate at room temperature for 5min, mix well, quickly freeze the reaction mixture in a 77K liquid N2 bath, and degas through three freeze-pump-thaw cycles, seal the reaction tube, heat at 120°C for 72h, and after the reaction is completed, wash with THF, DMF, ultrapure water and acetone in sequence until a colorless filtrate is observed, and dry the obtained solid at 90°C under high vacuum for 12h to obtain TpPa-(COOH)2.

[0009] In one embodiment, the preparation method of the iCOF TpPa-SO3H is to disperse 0.3mmol Tp and 0.45mmol Pa-SO3H in 20mL 1,4-dioxane, add 2mL, 3mol / L acetic acid aqueous solution after ultrasonic mixing, transfer the mixture to a high-pressure reactor after ultrasonic treatment for 15min, react at 120°C for 72h, wash the obtained red solid with ethanol, water and ethanol respectively, and then vacuum dry at 60°C for 12h.

[0010] In one embodiment, the iCOF TFP-Dg Cl The preparation method is to mix 0.75mmol TFP and 1mmol Dg Cl 20 mL of a 3:11,4-dioxane-pure water solvent system was added, and the blend was then ultrasonically treated for 30 min to ensure that the material in the tube was monodisperse. The mixture was then transferred to a high-pressure reactor and reacted at 120 °C for 24 h. The yellow precipitate was centrifuged and washed with methanol, water and acetone in sequence, and dried in vacuo at 60 °C for 12 h.

[0011] In one embodiment, the preparation method of Dt-TAPB is as follows: 0.6mmolDt and 0.4mmolTAPB are dissolved in 30mL anhydrous ethanol and 60mL anhydrous ethanol respectively, and after dissolution, they are mixed in a 250mL beaker, and after mixing evenly, 1.33mL, 6.0mol / L acetic acid aqueous solution is added as a catalyst to initiate the condensation reaction, and magnetic stirring is used to assist the reaction at room temperature for 72h, and then washed with anhydrous ethanol 3 times, and vacuum dried at 60°C overnight to obtain a yellow powder.

[0012] In one embodiment, the preparation method of TAPB-DMTA is to dissolve 0.6mmolDt and 0.4mmolTAPB in 30mL anhydrous ethanol and 60mL anhydrous ethanol respectively, mix them in a 250mL beaker after dissolution, add 1.33mL, 6.0mol / L acetic acid aqueous solution as a catalyst to initiate the condensation reaction after mixing evenly, and magnetic stirring is used to assist the reaction at room temperature for 72h, and then wash with anhydrous ethanol for 3 times, and vacuum dry at 60°C overnight to obtain a yellow powder; the preparation method of TAPB-DMTA is to dissolve 1,3,5-tris(4-aminophenyl)benzene and 2,5-dimethoxyterephthalaldehyde in a mixed solution of mesitylene and 1,4-dioxane, add acetic acid aqueous solution, stir at room temperature, separate and collect the precipitate after the reaction is completed, wash and dry to obtain a yellow powder.

[0013] The second object of the present invention is to provide the use of any of the above-mentioned COFs sodium alginate hydrogels in the extraction of agricultural and veterinary drugs.

[0014] In one embodiment, the veterinary pesticide comprises a carbamate pesticide, a triazole pesticide, a triazine pesticide, a sulfonamide antibiotic or a β-receptor agonist.

[0015] In one embodiment, 2 to 20 CACPs are added to a solution to be tested, and ultrasonic-assisted extraction is performed. The residual solution on the surface is treated with absorbent paper, and the extracted CACPs are ultrasonically eluted by adding methanol, and the eluate is collected, filtered, and then quantitatively analyzed.

[0016] In one embodiment, COFsDt-TAPB sodium alginate hydrogel is used to adsorb carbamate pesticides;

[0017] COFsTAPB-DMTA sodium alginate hydrogel was used to adsorb triazole, triazine pesticides and sulfonamide antibiotics;

[0018] COFsTpPa-2 sodium alginate hydrogel was used to adsorb β-receptor agonists.

[0019] Beneficial Effects

[0020] The present invention designs and synthesizes 7 kinds of COFs from three perspectives, including COFs with different grafted functional groups (TpPa-1, TpPa-2, TpPa-(COOH)2, TpPa-SO3H), COFs with different charged properties (cationic COF TFP-DgCl, anionic COF TpPa-SO3H, etc.) and COFs with different conjugated structures (Dt-TAPB, TAPB-DMTA and TpPa-1, etc.). The corresponding 7 kinds of COFs-sodium alginate hydrogels are prepared and used as extraction materials for dSPE. The CACPs-dSPE method is established and applied to three types of commonly used pesticides (carbamates, triazoles, triazines) and two types of commonly used veterinary drugs (β-receptor agonists, sulfonamides). The adsorption capacity of CACPs for pesticides and veterinary drugs is coordinated and determined by the properties of its porous structure (specific surface area, pore size) and the inherent structure of the loaded COFs (conjugated structure size, grafted groups). CACPs prepared from COFs with large conjugated structures and grafted hydroxyl groups are most favorable for the adsorption of carbamate pesticides; for triazole, triazine pesticides and sulfonamide antibiotics, CACPs with large specific surface area and medium pore size have the best extraction effect; for β-receptor agonists, CACPs with large specific surface area are preferred. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 The synthesis process of TpPa-1, TpPa-2, TpPa-(COOH)2, and TpPa-SO3H;

[0022] Figure 2 TFP-Dg Cl The synthesis process;

[0023] Figure 3 The synthesis process of Dt-TAPB;

[0024] Figure 4 The synthesis process of TAPB-DMTA;

[0025] Figure 5 Dispersive solid phase extraction flow chart;

[0026] Figure 6 SEM images of a series of COFs: (A) TpPa-1, (B) TpPa-2, (C) TpPa-(COOH)2, (D) TpPa-SO3H, (E) TFP-Dg Cl , (F) Dt-TAPB;

[0027] Figure 7 FT-IR spectra of a series of COFs: (A) TpPa-1, (B) TpPa-2, (C) TpPa-(COOH)2, (D) TpPa-SO3H, (E) TFP-Dg Cl , (F) Dt-TAPB;

[0028] Figure 8 XRD patterns of a series of COFs: (A) TpPa-1, (B) TpPa-2, (C) TpPa-(COOH)2, (D) TpPa-SO3H, (E) TFP-Dg Cl , (F) Dt-TAPB;

[0029] Fig. 9 (A)TpPa-1, (B)TpPa-2, (C)TpPa-(COOH)2, (D)TpPa-SO3H, (E)TFP-Dg Cl and (F) SEM images of CACPs prepared by Dt-TAPB;

[0030] Fig.10 Nitrogen adsorption-desorption curves of ACPs;

[0031] Fig.11 (A)TpPa-1, (B)TpPa-2, (C)TpPa-(COOH)2, (D)TpPa-SO3H, (E)TFP-Dg Cl , (F) Nitrogen adsorption-desorption curves of CACPs prepared by Dt-TAPB;

[0032] Fig.12 (A) Molecular structure and size of carbamate pesticides and (B) comparison of their extraction effects by CACPs;

[0033] Fig.13 (A) Molecular structure and size of triazole pesticides and (B) comparison of their extraction effects by CACPs;

[0034] Fig.14 (A) Molecular structure and size of triazine pesticides and (B) comparison of their extraction effects by CACPs;

[0035] Fig.15(A) Molecular structure and size of β-receptor agonists and (B) Comparison of their extraction effects by CACPs

[0036] Fig.16 (A) Molecular structure and size of sulfonamide antibiotics and (B) Comparison of their extraction effects by CACPs DETAILED DESCRIPTION

[0037] Example 1: Synthesis of TpPa-1

[0038] Tp (63 mg, 0.30 mmol) and Pa-1 (48 mg, 0.45 mmol) were dispersed in a mixed solution of 3 mL trimethylbenzene and 3 mL 1,4-dioxane, and then ultrasonicated for 10 min and then acetic acid aqueous solution (3 mmol, 0.45 mL) was added dropwise, and placed in a vacuum oven at 120 ° C for 72 h for reaction. Then it was washed with acetone and dried at 70 ° C. The synthesis process is as follows Figure 1 shown.

[0039] Example 2: Synthesis of TpPa-2

[0040] The synthesis of TpPa-2 was based on Example 1, with Pa-2 (63 mg, 0.45 mmol) replacing Pa-1, and other conditions were the same. Figure 1 shown.

[0041] Example 3: Synthesis of carboxyl functionalized COFTpPa-(COOH)2

[0042] Tp (63 mg, 0.30 mmol) and Pa-(COOH)2 (191.8 mg, 0.9 mmol) were dispersed in 3 mL of 1,4-dioxane, ultrasonicated at room temperature for 5 min, and then an aqueous acetic acid solution (0.5 mL, 6.0 mol / L) was added, and ultrasonicated at room temperature for 5 min. After mixing evenly, the reaction mixture was quickly frozen at 77 K (liquid N2 bath) and degassed through three freeze-pump-thaw cycles. The reaction tube was sealed and heated at 120 ° C for 72 h. After the reaction was completed, it was washed with THF, DMF, ultrapure water and acetone in sequence until a colorless filtrate was observed. The obtained solid was dried at 90 ° C under high vacuum for 12 h to obtain TpPa-(COOH)2 as a dark red powder. The synthesis process is as follows Figure 1 shown.

[0043] Example 4: Synthesis of sulfonic acid functionalized, anionic iCOFTpPa-SO3H

[0044] Tp (63 mg, 0.3 mmol) and Pa-SO3H (85 mg, 0.45 mmol) were dispersed in 20 mL of 1,4-dioxane, and then ultrasonically mixed and then added with acetic acid aqueous solution (2 mL, 3 mol / L). After ultrasonic treatment for 15 min, the mixture was transferred to a high-pressure reactor and reacted at 120 ° C for 72 h. The obtained red solid was washed with ethanol, water and ethanol respectively, and then vacuum dried at 60 ° C for 12 h. The synthesis process is as follows Figure 1 shown.

[0045] Example 6: Cationic iCOF TFP-Dg Cl Synthesis

[0046] TFP (125.0 mg, 0.75 mmol) and Dg Cl (125.5 mg, 1 mmol) was added to 20 mL of 1,4-dioxane-pure water (3:1, v:v) solvent system. The blend was then ultrasonicated for 30 min to ensure that the material in the tube was monodisperse, and the mixture was transferred to an autoclave and reacted at 120 °C for 24 h. Subsequently, the yellow precipitate was centrifuged and washed with methanol, water and acetone in sequence. Finally, the obtained TFP-Dg Cl The powder was dried under vacuum at 60 °C for 12 h. Figure 2 shown.

[0047] Example 7: Synthesis of Dt-TAPB

[0048] Dt (0.1 g, 0.6 mmol) and TAPB (0.14 g, 0.4 mmol) were dissolved in 30 mL of anhydrous ethanol and 60 mL of anhydrous ethanol respectively, and then mixed in a 250 mL beaker. After mixing evenly, acetic acid aqueous solution (1.33 mL, 6.0 mol / L) was added as a catalyst to initiate the condensation reaction, and the reaction was assisted by magnetic stirring at room temperature for 72 h. Then, it was washed with anhydrous ethanol three times and vacuum dried at 60 ° C overnight to obtain a yellow powder. The synthesis process is as follows Figure 3 shown.

[0049] Example 8: Synthesis of TAPB-DMTA

[0050] 1,3,5-tris(4-aminophenyl)benzene and 2,5-dimethoxyterephthalaldehyde are dissolved in a mixed solution of mesitylene and 1,4-dioxane, and then an acetic acid aqueous solution is added and stirred at room temperature. After the reaction is completed, the precipitate is separated and collected, washed, and dried to obtain a yellow TAPB-DMTA powder.

[0051] The synthesis process is as follows Figure 4 shown.

[0052] Example 9: Preparation of CACPs

[0053] A series of COFs-doped CACPs were prepared. 25 mg COFs (TpPa-1, TpPa-2, TpPa-(COOH)2, TpPa-SO3H, TFP-DG Cl , Dt-TAPB, TAPB-DMTA) were added to 1mL 20mg / mL sodium alginate solution, and ultrasonically dispersed uniformly; at the same time, 60mg anhydrous CaCl2 was dissolved in 10mL 0.01mol / L polyacrylic acid to prepare solidification receiving solutions. The COFs-sodium alginate mixed solution was added dropwise to the solidification receiving solution with a 1mL pipette, and magnetic stirring was performed for 5min to fully solidify it. After the mixed beads were fixed, they were collected, washed with ultrapure water, and freeze-dried for 24h for use.

[0054] Example 10: dSPE Procedure

[0055] dSPE process and conditions are as follows Figure 5 As shown. Five freeze-dried CACPs were added to 10 mL of standard solution (pH = 6) and ultrasonic-assisted extraction was performed for 30 min. After extraction, the residual solution on the surface was treated with absorbent paper. The extracted CACPs were placed in a 5 mL centrifuge tube, 0.5 mL of methanol was added for ultrasonic elution for 15 min, and the eluate was collected and quantitatively analyzed after passing through a 0.22 μm nylon filter.

[0056] The quantification of carbamate pesticides (isoprocarb, carbaryl, and mefenamic acid) was carried out by HPLC, and the detection procedure was as follows: the mobile phase was acetonitrile and water (25:75, v:v), the flow rate was 1 mL / min, the detection temperature was 25 °C, the time was 7 min, and the detection wavelength was 220 nm.

[0057] The quantification of β-receptor agonists (clenbuterol, ractopamine) was carried out by HPLC, and the detection procedure was as follows: the mobile phase was methanol and 0.1% formic acid-water solution, the gradient elution procedure was as shown in Table 3-1, the flow rate was 1 mL / min, the detection temperature was 30°C, the time was 11 min, and the detection wavelengths were 244 nm (clenbuterol) and 276 nm (ractopamine).

[0058] The sulfonamide antibiotics (sulfamethoxazole, sulfathiazole, sulfadiazine) were quantified using the HPLC method, and the detection procedure was as follows: the mobile phase was acetonitrile and 0.1% formic acid-water solution, gradient elution was used (Table 3-2), the flow rate was 1 mL / min, the detection temperature was 30°C, the time was 9 min, and the detection wavelength was 270 nm.

[0059] The quantification of triazole pesticides (hexaconazole, flusilazole, tebuconazole) and triazine pesticides (atrazine, simazine, cyanazine) was carried out by ultraviolet absorption spectroscopy, and their absorbance was measured at 220nm.

[0060] Table 3-1 β-receptor agonist liquid chromatography gradient elution table

[0061]

[0062]

[0063] Table 3-2 Liquid chromatography gradient elution table of sulfonamide antibiotics

[0064]

[0065] Example 11: Characterization of the morphology, structure and properties of a series of COFs

[0066] The morphology of the series of COFs was characterized by SEM, such as Figure 6 As shown in A, TpPa-1 presents a flower-like morphology, which can be seen as an aggregation of strip-like structures with a length in the micrometer range (1-3 μm); Figure 3-6 B It can be observed that TpPa-2 has a typical reticular porous structure, and its pore structure provides random channels and a large specific surface area for the adsorption of the target; SEM image of TpPa-(COOH)2 ( Figure 6 C) shows that it presents a flower cluster morphology composed of 1-2 μm strip structures; Figure 6 D shows that TpPa-SO3H presents a uniform fibrous structure; TFP-Dg Cl ( Figure 6 E) presents a distinct leaf-like morphology, a smooth surface, a length of about 1 μm, and contains abundant flocculent material; Figure 6 F shows that COF Dt-TAPB presents a spherical structure with a diameter of about 0.5 μm. The above morphological characterization is similar to that reported in the literature, which preliminarily indicates the successful synthesis of COFs.

[0067] FT-IR is used to characterize the chemical bonds and functional groups of a series of COFs. The FT-IR spectrum of TpPa-1 is shown in Figure 7 As shown in A, the N–H stretching band of Pa-1 (3199~3374cm -1 ) and the C=O stretching band of Tp (1640cm -1 ) disappeared, proving the complete consumption of the monomer; no characteristic stretching bands of –O–H and C=N were observed, but at 1578cm -1 and 1255cm -1Strong peaks appeared at , corresponding to C=C and C–N stretching, respectively, verifying the conversion of the enol structure of TpPa-1 into a keto structure, indicating the successful synthesis of the material. Compared with TpPa-1, the FT-IR spectrum of TpPa-2 ( Figure 7 B) at 2910cm -1 An additional peak is shown at , which is derived from the C–H stretching of the methyl group of Pa-2. Figure 7 C) In the FT-IR spectrum, 1590 and 1250 cm -1 The strong peak at 1710 cm-1 can be attributed to the stretching vibrations of C=C and C–N in the keto structure, indicating the formation of a β-keto-enamine connection. -1 The peak at 1192 cm corresponds to the C=O band in the carboxyl group. -1 )、C=O(1640cm -1 ) and C–H bonds (2892 cm -1 ) and the disappearance of the N–H stretching bands corresponding to the amino groups in Pa-(COOH)2 (3458 and 3350 cm -1 ), demonstrating the consumption of the monomer. Figure 7 D can be seen that Tp is at 2892cm -1 、1640cm -1 and 1192cm -1 Characteristic peaks appeared at 1020 cm-1, corresponding to C–H, C=O and C–O stretching vibrations; Pa-SO3H -1 and 3336~3429cm -1 The characteristic peaks appeared at 2892 cm -1 、1640cm -1 、1192cm -1 and 3336~3429cm -1 The characteristic peak at 1020cm -1 The characteristic peak at 1582 cm -1 and 1239cm -1 New stretching vibration peaks appeared at , corresponding to C=C and C–N, respectively, proving the successful synthesis of TpPa-SO3H. Cl It is the aldehyde group in TFP and Dg Cl The amino groups in the TFP-Dg Cl FTIR spectrum of ( Figure 7 E) corresponds to the position of monomer TFP at 1688 cm -1 The C=O characteristic peak of DgCl The N–H related -1 and 3315cm -1 The stretching vibration peak at 1625cm -1 A new peak appeared at , corresponding to the C=N stretching vibration band, indicating that TFP-Dg Cl The successful synthesis of Figure 7 As shown in F, in the FT-IR spectrum of COF Dt-TAPB, 1614 cm -1 The -C=N stretching characteristic vibration peak at 1670 cm corresponds to the condensation of aldehyde and amine to form a Schiff base, accompanied by the C=O characteristic stretching band of monomer Dt (1670 cm -1 ) and the characteristic N–H stretching bands of TAPB (3205–3461 cm -1 ) disappears. In addition, the Dt-TAPB spectrum shows a -1 The broad peak at 40° belongs to the unreacted –OH. The above results indicate that Dt-TAPB was successfully prepared.

[0068] The crystal structure of COFs was further characterized by XRD. Figure 8 A) and TpPa-2( Figure 8 B) The XRD pattern has three different reflection peaks at 4.72°, 8.28°, 27.14° and 4.7°, 8.0°, 26.6°, corresponding to the (100), (110) and (001) planes, respectively, which are consistent with those reported in the literature. Figure 8 C shows the diffraction peak of TpPa-(COOH)2 at 2θ=27.38°, corresponding to the (001) plane. XRD pattern of TpPa-SO3H ( Figure 8 D) shows a main characteristic diffraction peak at 2θ = 26.68°, corresponding to the (001) plane. Figure 8 As shown in E, a broad peak (20.0°~40.0°) appears at 27.00°, which matches the (001) reflection of the flake material. This may be due to the Cl The π-π stacking in is poor. Figure 8 F shows the XRD pattern of Dt-TAPB, and a broad peak appears at 28.30°, which also corresponds to the (001) crystal plane.

[0069] Example 12: Characterization of the morphology, structure and properties of a series of CACPs.

[0070] The morphology and structure of the CACPs were characterized by SEM. Fig. 9As shown, the series of CACPs all present a layered structure with porous cavities, and the corresponding morphology of COFs can be observed in their layered structure, indicating the successful loading of COFs, proving the successful preparation of the series of CACPs, and verifying the universality of the CACPs composite strategy.

[0071] The porous structure and properties of the prepared hydrogel CACPs were investigated by N2 adsorption-desorption experiments at 77K. Fig.10 , Fig.11 As shown in Table 3, according to the IUPAC classification, the N2 adsorption-desorption isotherms of ACPs and CACPs series all show type IV and correspond to the H4 type hysteresis loop, which verifies the mesoporous and lamellar pore structures of ACPs and CACPs.

[0072] From Table 3-3, we can see that the specific surface areas are TpPa-2, TAPB-DMTA, TpPa-1, TpPa-SO3H, TFP-Dg from high to low. Cl , TpPa-(COOH)2, and Dt-TAPB prepared CACPs and ACPs, the total pore volume from high to low is TpPa-2, TpPa-SO3H, TAPB-DMTA, TpPa-1, TFP-Dg Cl , TpPa-(COOH)2, and Dt-TAPB prepared CACPs and ACPs. It can be seen that doping COFs can increase the specific surface area and total pore volume of sodium alginate hydrogel (ACPs) to varying degrees. Among them, the specific surface area of ​​CACPs doped with TpPa-(COOH)2 and Dt-TAPB is not significantly increased. The main reason is that TpPa-(COOH)2, TFP-Dg Cl The specific surface areas of Dt-TAPB and Dt-TAPB are much lower than those of other COFs (the reference values ​​are 87.6 m 2 / g, 12.7m 2 / g and 33.29m 2 / g), thus making little contribution to increasing the specific surface area of ​​ACPs. In addition, by comparing the pore volume data of COFs, it was found that the pore volume of COFs can be increased to a certain extent by doping COFs with CACPs. The reason may be that the layered porous structure of ACPs provides more adsorption sites.

[0073] Table 3 Pore structure parameters of ACPs and series CACPs

[0074]

[0075] Example 13: Extraction effect of CACPs on carbamate pesticides

[0076] Carbamate pesticides are a class of substances developed from formate precursor compounds. Their structural characteristics are that they contain an N-methyl group in the molecule. Representative substances include carbaryl, isoprocarb, and mefenamic acid. They are highly water-soluble (logKow = 1.6 to 3.4) and have a molecular size range of ( Fig.12 A), which is smaller than the most probable pore size of the prepared CACPs (2.967-4.177 nm). The extraction effect of the prepared CACPs on isoprocarb, carbaryl and cypermethrin was investigated by dSPE-HPLC. Fig.12 B shows that ACPs has the worst extraction effect on isoprocarb and mefenamic acid. Its poor extraction performance can be attributed to its low specific surface area and relatively simple internal structure, with only the hydroxyl groups contained in the sodium alginate-PAA chain providing hydrogen bonding sites. Cl -CACPs showed a poorer extraction effect than ACPs, which may be due to the relatively poor polarity of carbaryl, which made the contact with hydrophilic CACPs incomplete during the adsorption process, and thus relied more on the pore size effect for adsorption. Cl -CACPs and ACPs have similar specific surface areas, but the pore sizes of the two CACPs are larger (4.173nm and 4.177nm, respectively). ACPs provide a more moderate pore size (2.967nm), which is closer to the molecular size of the target, thus showing a better extraction effect. On the contrary, TpPa-2-CACPs and TAPB-DMTA-CACPs with larger specific surface areas also show good adsorption performance. Combined analysis proves that a large specific surface area is conducive to the adsorption of carbamate pesticides by CACPs.

[0077] CACPs prepared by Dt-TAPB showed the best extraction effect for the three carbamate pesticides. Compared with other COFs except TAPB-DMTA, Dt-TAPB has a larger conjugated structure, so it can be considered that π-π conjugation plays a key role in the extraction of carbamate pesticides. The conjugated structure of Dt-TAPB and TAPB-DMTA is the same size, but the reason why Dt-TAPB has a better extraction effect may be that its structure is rich in hydroxyl groups, and it may have better adsorption capacity for oxygen- and nitrogen-containing carbamates due to hydrogen bonding.

[0078] Example 14: Comparison of the extraction effects of CACPs on triazole pesticides

[0079] Triazole fungicides are a class of organic nitrogen-containing heterocyclic compounds, mainly containing 1,2,3-triazole rings, hydroxyl (keto) groups, and substituted benzyl groups. This study selected three commonly used triazole pesticides (hexaconazole, flusilazole, and tebuconazole) as analytes, with logKow values ​​of 3.58 to 3.84, which are moderately lipophilic. The molecular size of triazole pesticides obtained by simulation is between Within the range ( Fig.13 A), which is smaller than the pore size of ACPs and CACPs, indicating that the prepared hydrogel has the potential to effectively adsorb them through the pore size effect. On this basis, the extraction effects of a series of CACPs on hexaconazole, flusilazole and tebuconazole were compared by dSPE-UV-Vis method. Fig.13 As shown in B, TAPB-DMTA-CACPs showed the best extraction effect, while ACPs had the worst extraction effect. Cl The extraction effect of the prepared CACPs was slightly better than that of ACPs, which proved that the doping of the two COFs did not significantly improve the extraction performance of ACPs. Combined with the analysis of nitrogen adsorption results, it was found that ACPs, TpPa-(COOH)2-CACPs and TFP-Dg Cl -CACPs extraction performance may be poor because of its relatively smaller specific surface area, specifically, 66.9% to 95.5% smaller than other materials except Dt-TAPB-CACPs. Although Dt-TAPB-CACPs has a smaller specific surface area, it is speculated that the large conjugated system of Dt-TAPB plays an important role in the extraction process. In addition, TAPB-DMTA-CACPs has the best extraction effect because of its larger specific surface area and moderate pore size (2.968nm), which can better adsorb analytes and reduce the probability of molecular escape.

[0080] Example 15: Extraction effect of CACPs on triazine pesticides

[0081] Triazine pesticides are based on a six-membered ring with three C and three N arranged in an orderly manner. According to their structure, triazine herbicides have a wide range of solubility in aqueous media and high mobility in soil. Atrazine, simazine and cyanazine are the most frequently detected triazine pesticides in food and environmental samples. Their molecular size is simulated as ( Fig.14 A), logKow value is 0.20~1.88, with strong polarity. Fig.14B shows the extraction of atrazine, simazine and cyanazine by a series of CACPs. Similar to triazole pesticides, TAPB-DMTA-CACPs achieved the best extraction effect for triazine pesticides due to its large specific surface area and medium pore size. Cl -CACPs have poor extraction performance due to their small specific surface area.

[0082] Example 16: Extraction effect of CACPs on β-receptor agonists

[0083] β-receptor agonists are a class of synthetic phenylethanolamine compounds with typical aromatic groups, β-hydroxyl groups and aliphatic nitrogen atoms. Clenbuterol and ractopamine are the most widely used and most valued β-receptor agonists, with logKow values ​​of 2.61 and 1.65, respectively. The molecular size of the β-receptor agonists obtained by simulation is ( Fig.15 A). Based on these structural characteristics, it can be preliminarily determined that ACPs and CACPs can effectively adsorb clenbuterol and ractopamine, and this speculation was verified by dSPE-HPLC experiments. Fig.15 As shown in B, the results show that TpPa-2-CACPs exhibited the best extraction effect, which was mainly attributed to the largest specific surface area of ​​TpPa-2-CACPs compared with other materials (1.7 to 22.4 times that of other materials). Cl -CACPs and Dt-TAPB-CACPs have better extraction effects. The reason may be that ACPs provide a moderate pore size (2.967 nm) while TFP-Dg Cl -CACPs and Dt-TAPB-CACPs have larger nanopore sizes (4.177 nm and 4.174 nm, respectively), which would increase the probability of escape of clenbuterol and ractopamine molecules during the adsorption process.

[0084] Example 17: Extraction effect of CACPs on sulfonamide antibiotics

[0085] Sulfonamide antibiotics refer to a class of drugs with a p-aminobenzenesulfonamide structure. The hydrogen on the sulfonamide group can be replaced by different heterocycles to form different sulfonamide drugs. Here, three commonly used sulfonamide antibiotics (sulfamethoxazole, sulfathiazole, and sulfadiazine) are selected as representative substances. They have high polarity (logKow = -0.12 to 0.89) and the simulated molecular size range is ( Fig.16 A). Based on this, we conducted further extraction research. Fig.16B shows that TAPB-DMTA-CACPs presents the best extraction effect, followed by TpPa-2-CACP. Combined with 3.3.4.2 and 3.3.4.3, it can be inferred that the large specific surface area of ​​the material plays a key role in its adsorption of pesticides and veterinary drugs. The large specific surface area provides more adsorption sites, thus showing a better extraction effect. It is worth noting that the specific surface area of ​​TAPB-DMTA-CACPs is smaller than that of TpPa-2-CACPs, and the specific surface area of ​​ACPs is smaller than that of TpPa-(COOH)2-CACPs and Dt-TAPB-CACPs, but their better extraction effect may still be attributed to their medium pore size.

[0086] Although the present invention has been disclosed as above in the form of a preferred embodiment, it is not intended to limit the present invention. Anyone familiar with this technology can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention should be based on the definition of the claims.

[0087] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the purpose and scope of the technical solution of the present invention, which should be included in the scope of the claims of the present invention.

Claims

1. A sodium alginate hydrogel for extracting COFs of agricultural and veterinary drugs, characterized in that: The preparation method of COFs sodium alginate hydrogel is as follows: COFs is added into a sodium alginate solution, and ultrasonic dispersion is performed to uniformly obtain a COFs sodium alginate mixed solution; anhydrous CaCl2 is dissolved in polyacrylic acid to prepare a solidified receiving solution; The COFs-sodium alginate mixed solution is added dropwise to the solidification receiving solution, fully solidified, collected after shaping, washed, and dried to obtain the COFs sodium alginate hydrogel, namely CACPs; Among them, COFs are TpPa-1, TpPa-2, TpPa-(COOH)2, TpPa-SO3H, TFP-DG Cl , Dt-TAPB or TAPB-DMTA.

2. The sodium alginate hydrogel for extracting COFs of agricultural and veterinary drugs according to claim 1, characterized in that: The preparation method of COFs sodium alginate hydrogel is as follows: 25 mg COFs is added into 1 mL 20 mg / mL sodium alginate solution, and the COFs sodium alginate mixed solution is uniformly obtained by ultrasonic dispersion; 60 mg anhydrous CaCl2 is dissolved in 10 mL 0.01 mol / L polyacrylic acid to prepare a solidification receiving solution; the COFs sodium alginate mixed solution is added dropwise into the solidification receiving solution, and magnetic stirring is performed for 5 minutes to fully solidify it. After the mixed beads are set, they are collected, washed with ultrapure water, and freeze-dried for later use.

3. The sodium alginate hydrogel for extracting COFs of agricultural and veterinary drugs according to claim 1, characterized in that: The preparation method of TpPa-1 is as follows: 0.30mmolTp and 0.45mmolPa-1 are dispersed in a mixed solution of 3mL trimethylbenzene and 3mL 1,4-dioxane, 0.45mL 3mmol acetic acid aqueous solution is added dropwise after ultrasonication for 10min, and the mixture is placed in a vacuum oven at 120°C for 72h for reaction, then washed with acetone, and dried at 70°C; The preparation method of TpPa-2 is as follows: 0.30mmolTp and 0.45mmolPa-2 are dispersed in a mixed solution of 3mL trimethylbenzene and 3mL 1,4-dioxane, 0.45mL 3mmol acetic acid aqueous solution is added dropwise after ultrasonication for 10min, and the mixture is placed in a vacuum oven at 120°C for 72h for reaction, then washed with acetone, and dried at 70°C.

4. The sodium alginate hydrogel for extracting COFs of agricultural and veterinary drugs according to claim 1, characterized in that: The preparation method of TpPa-(COOH)2 is as follows: 0.30mmol Tp and 0.9mmol Pa-(COOH)2 are dispersed in 3mL 1,4-dioxane, ultrasonicated at room temperature for 5min, then 0.5mL, 6.0mol / L acetic acid aqueous solution is added, ultrasonicated at room temperature for 5min, and after uniform mixing, the reaction mixture is quickly frozen in a 77K liquid N2 bath, and degassed through three freeze-pump-thaw cycles, the reaction tube is sealed, and heated at 120°C for 72h. After the reaction is completed, the reaction tube is washed with THF, DMF, ultrapure water and acetone in sequence until a colorless filtrate is observed, and the obtained solid is dried at 90°C under high vacuum for 12h to obtain TpPa-(COOH)2; The preparation method of TpPa-SO3H is as follows: 0.3mmol Tp and 0.45mmol Pa-SO3H are dispersed in 20mL 1,4-dioxane, and 2mL, 3mol / L acetic acid aqueous solution is added after ultrasonic mixing. After ultrasonic treatment for 15min, the mixture is transferred to a high-pressure reactor, reacted at 120°C for 72h, and the obtained red solid is washed with ethanol, water and ethanol respectively, and then vacuum dried at 60°C for 12h.

5. The sodium alginate hydrogel for extracting COFs of agricultural and veterinary drugs according to claim 1, characterized in that: The iCOF TFP-Dg Cl The preparation method is to mix 0.75mmol TFP and 1mmol Dg Cl 20 mL of a 3:11,4-dioxane-pure water solvent system was added, and the blend was then ultrasonically treated for 30 min to ensure that the material in the tube was monodisperse. The mixture was then transferred to a high-pressure reactor and reacted at 120 °C for 24 h. The yellow precipitate was centrifuged and washed with methanol, water and acetone in sequence, and dried under vacuum at 60 °C for 12 h. The preparation method of Dt-TAPB is as follows: 0.6mmolDt and 0.4mmolTAPB are dissolved in 30mL anhydrous ethanol and 60mL anhydrous ethanol respectively, mixed in a 250mL beaker after dissolution, and added with 1.33mL, 6.0mol / L acetic acid aqueous solution as a catalyst to initiate condensation reaction after uniform mixing, and magnetic stirring is used to assist the reaction for 72h at room temperature, and then washed with anhydrous ethanol for 3 times, and vacuum dried at 60°C overnight to obtain a yellow powder; the preparation method of TAPB-DMTA is as follows: 1,3,5-tris(4-aminophenyl)benzene and 2,5-dimethoxyterephthalaldehyde are dissolved in a mixed solution of mesitylene and 1,4-dioxane, and acetic acid aqueous solution is added, stirred at room temperature, and after the reaction is completed, the precipitate is separated and collected, washed and dried to obtain a yellow powder.

6. Use of the COFs sodium alginate hydrogel according to any one of claims 1 to 5 in the extraction of agricultural and veterinary drugs.

7. The use according to claim 6, characterized in that: The veterinary pesticides include carbamate pesticides, triazole pesticides, triazine pesticides, sulfonamide antibiotics or beta-receptor agonists.

8. The use according to claim 6, characterized in that: The specific application method is to add 2 to 20 CACPs to the solution to be tested, perform ultrasound-assisted extraction, treat the residual solution on the surface with absorbent paper, add methanol to the extracted CACPs for ultrasonic elution, collect the eluate, filter the eluate and perform quantitative analysis.

9. The use according to claim 7, characterized in that: COFsDt-TAPB sodium alginate hydrogel was used to adsorb carbamate pesticides; COFsTAPB-DMTA sodium alginate hydrogel was used to adsorb triazole, triazine pesticides and sulfonamide antibiotics; COFsTpPa-2 sodium alginate hydrogel was used to adsorb β-receptor agonists.

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