Preparation method and application of a phosphoric acid group modified beta-cyclodextrin based polymer thin film microextraction coating material

Abstract

The application discloses a kind of phosphoric acid group modified β-cyclodextrin-based polymer film microextraction coating material and its application.First, a kind of phosphoric acid group β-CD porous crosslinked polymer (DBP-β-BNCD) and its preparation method are provided.The DBP-β-BNCD has the advantages of large specific surface area, narrow pore size distribution, large pore volume, good thermal stability, etc., which is beneficial to the accessibility of adsorption sites.When adsorbing hydrophilic pollutants antibiotics, various adsorption mechanisms such as polarity interaction, hydrogen bond interaction and π-π interaction are introduced.Further, by using DBP-β-BNCD as a thin film solid phase microextraction coating material, a method combining TFME with high performance liquid chromatography-tandem mass spectrometry (HPLC-QqQ-MS) is established, and the results show that the coating material has great potential for the extraction of hydrophilic organic pollutants in the environment.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of analytical chemistry and environmental analysis, in particular to a preparation method of a phosphoric acid group modified β-cyclodextrin-based polymer thin film microextraction coating material and its application. BACKGROUND

[0002] Antibiotics refer to a class of secondary metabolites produced by microorganisms (including bacteria, fungi, actinomycetes) or higher plants and animals in the process of life, which have anti-pathogen or other activities, and can inhibit the growth or cause death of various harmful microorganisms such as bacteria, fungi, viruses, protozoa and microalgae. According to the differences in chemical structure or reaction mechanism of antibiotics, the existing antibiotics can be divided into different categories, including aminoglycosides, β-lactams, macrolides, tetracyclines, nitroimidazoles, streptomyces, quinolones, lincosamides and polypeptides. Since antibiotics can be produced by natural, semi-synthetic and synthetic routes, they are widely distributed in environmental media. For the living environment related to human beings, antibiotics are usually used in aquaculture, livestock disease prevention and medical and health industries.

[0003] Although the half-life of most antibiotics is relatively short, they have been recognized as chronic environmental pollutants due to long-term use and accumulation. After antibiotics are discharged into the environment, on the one hand, antibiotics will interfere with normal human metabolism, change the human microbiota, and directly threaten human safety. On the other hand, antibiotic resistance genes will lead to drug-resistant bacteria and cause long-term harm to ecological health. Accurate and rapid determination is the premise of effective monitoring and control of antibiotic pollution, in addition, due to the low hydrophilicity of antibiotics, their occurrence concentration in environmental water samples is extremely low (nanograms per liter), which is difficult to detect directly. Therefore, it is necessary to develop a rapid and efficient detection and analysis method for antibiotics in environmental water samples.

[0004] Currently, common methods for detecting antibiotics in environmental water samples include microbiological / immunoassay, spectroscopic / electrochemical sensing, and chromatographic / mass spectrometry. Microbiological / immunoassay methods have the advantages of low cost, easy operation, and intuitive analysis. However, these methods also have the disadvantages of low sensitivity, low selectivity, long detection time, and strict storage conditions. Therefore, other methods such as optical / electrochemical methods and chromatographic / mass spectrometry have been further proposed. Compared with microbiological / immunoassay methods, optical sensing methods generally have the advantages of easy visual observation (even naked eye analysis), simple operation, and low cost, which are suitable for on-site analysis and rapid detection. However, the throughput is limited, and the number of compounds that can be detected at one time is limited. Electrochemical sensing methods mainly refer to electrochemical or field effect transistor (FET) sensors used for the determination of antibiotics in water samples. Electrochemical sensing methods have the advantages of simple operation, high sensitivity, strong selectivity, and fast response. However, there are problems of poor reproducibility and stability. Chromatographic / mass spectrometry is usually used as a standard method for antibiotic detection in government standards, which has high sensitivity, strong anti-interference ability, and high detection accuracy, and becomes the most popular and common antibiotic analysis method at present. However, due to the fact that antibiotics are trace organic pollutants in actual water environments, the concentration is relatively low, therefore, chromatographic / mass spectrometry usually relies on high-efficiency sample pretreatment technology. Solid-phase microextraction (SPME) is a green and efficient sample pretreatment technology that integrates sampling, extraction, concentration, and purification. In particular, thin-film microextraction (TFME) is a variant of traditional SPME technology. The coating volume of thin-film microextraction is 20-100 times that of the traditional probe form, which will greatly increase the effective surface area of the extraction phase in contact with the sample, and the analysis sensitivity will be greatly improved. Among them, the extraction coating is the key to SPME technology, which is related to the enrichment efficiency between the coating and the target analyte, and then determines the sensitivity of the analysis method. However, the currently developed coatings such as carbon materials and aerogels are relatively hydrophobic materials, which are suitable for the extraction of non-polar or weakly polar substances, and are not suitable for the extraction of antibiotics which are relatively hydrophilic substances.

[0005] β-cyclodextrin (β-CD) is derived from starch, with a unique hydrophobic cavity and hydrophilic shell, which can adsorb organic pollutants through host-guest mechanism. β-CD molecules have high reactivity, and due to the presence of a large number of hydroxyl groups on both sides, they can be easily modified to form macromolecular networks. Among various methods, cross-linking reaction is of great concern due to its simple operation, high efficiency and high content of β-CD units in the corresponding product. Due to the high content of β-CD units and the introduction of various cross-linking units, the cross-linked β-CD-based polymers can adsorb various organic pollutants with different properties. In addition, they have the advantages of low cost and good regeneration performance. However, most of the β-CD-based polymers used at present are non-porous, with very low surface area (1-10 m 2 g -1 ). In order to solve this problem, the research uses chemical cross-linking reaction of β-CD-based polymers with epichlorohydrin to improve their chemical and physical properties, and thus improves the adsorption capacity of various pollutants. In addition, the β-CD-based polymer prepared by Huang et al. has a rich benzene ring, and the introduction of π-π interaction can improve the affinity for aromatic pollutants such as bisphenols (Huang, Q.; Chai, K.; Zhou, L.; Ji, H. A Phenyl-Rich β-Cyclodextrin Porous Crosslinked Polymer for Efficient Removal of Aromatic Pollutants: Insight into Adsorption Performance and Mechanism. Chem. Eng. J. 2020, 387, 124020. https: / / doi.org / 10.1016 / j.cej.2020.124020.). However, the β-CD-based polymer with small size linker has almost no framework nanopore in addition to the inherent β-CD cavity, which limits the entry of adsorbate molecules, thus limiting the adsorption capacity and efficiency. Therefore, it is of great significance to further increase the specific surface area and pore volume of β-CD-based polymers and introduce appropriate functional groups to improve their adsorption capacity. SUMMARY

[0006] The purpose of the present application is to overcome the above-mentioned defects and shortcomings in the prior art, and to provide a preparation method and application of a phosphonic group modified β-cyclodextrin-based polymer thin film microextraction coating material.

[0007] The above-mentioned purpose of the present application is realized by the following technical solutions:

[0008] This invention first provides a method for preparing a phosphate-modified β-cyclodextrin porous crosslinked polymer (DBP-β-BNCD), wherein the phosphate-modified β-cyclodextrin porous crosslinked polymer is obtained by crosslinking benzylated β-cyclodextrin (β-BNCD) with dibenzyl phosphate (DBP) via a Friedel-Crafts alkylation reaction.

[0009] Furthermore, the preparation method includes mixing dibenzyl phosphate, benzylated β-cyclodextrin, and alkoxylated compounds that can form CH2. 2+ Ether compounds and metal catalysts are added to anhydrous 1,2-dichloroethane, mixed evenly, stirred and prepolymerized under a nitrogen atmosphere, heated to 80-85℃ for reaction, the crosslinking reaction is quenched after the reaction is completed, and then cooled to room temperature to obtain the product.

[0010] This invention prepares a porous crosslinked polymer (DBP-β-BNCD) rich in polar functional groups, namely β-CD, by crosslinking benzylated β-CD (β-BNCD) with dibenzyl phosphate (DBP) via Friedel-Crafts alkylation. In the Friedel-Crafts alkylation reaction, alkoxy groups are used to form CH2. 2+ Ether compounds are used as electrophilic substitution agents, which are then subjected to the removal of the -OCH3 functional group by a metal catalyst to form CH2. 2+ Positive ions then attack the electron-rich benzene rings in β-BNCD and DBP, ultimately generating electrophilic substitution products. The prepared DBP-β-BNCD has advantages such as large specific surface area, narrow pore size distribution, large pore volume, and good thermal stability, which is beneficial to the accessibility of adsorption sites. Because a large number of polar functional groups, phosphate groups, are introduced into the DBP-β-BNCD prepared in this invention, it introduces multiple adsorption mechanisms, such as polar interactions, hydrogen bonding interactions, and π-π interactions, when adsorbing organic pollutants, especially hydrophilic pollutants such as antibiotics.

[0011] Furthermore, the DBP, β-BNCD, and alkoxy-containing compounds can form CH2. 2+ The feed equivalent ratio (eq) of the ether compounds and metal catalysts is 21:(1~4):63:63.

[0012] Preferably, the DBP, β-BNCD, and alkoxy-containing compounds can form CH2. 2+ The feed equivalent ratio (eq) of the ether compounds and metal catalysts is 21:(1~2):63:63.

[0013] Preferably, the DBP, β-BNCD, and alkoxy-containing compounds can form CH2. 2+an ether compound, and a metal catalyst.

[0014] Further, the ether compound containing an alkoxy group is capable of forming CH2 2+ The ether compound containing an alkoxy group is capable of forming CH2

[0015] Further, the ether compound containing an alkoxy group is capable of forming CH2 2+ The ether compound containing an alkoxy group is capable of forming CH2

[0016] Further, the metal catalyst includes aluminum chloride, iron chloride.

[0017] Preferably, the metal catalyst is iron chloride.

[0018] Further, the volume / mass ratio of the anhydrous 1,2-dichloroethane to DBP is 100:0.71.

[0019] Further, the stirring pre-polymerization temperature is 45℃, and the pre-polymerization time is 3h.

[0020] Further, the temperature is raised to 80℃, and the reaction time is 18h.

[0021] Further, the quenching cross-linking reaction is quenching by adding methanol.

[0022] Further, the prepared porous cross-linked polymer of phosphoric acid group modified β-cyclodextrin is further purified, and the purification step is that the porous cross-linked polymer of phosphoric acid group modified β-cyclodextrin is first washed with methanol to remove unreacted organic substances, then washed with distilled water for multiple times to remove the metal catalyst, and the washed product is collected by centrifugation. The above obtained product is Soxhlet extracted in methanol for 24h, and finally the Soxhlet extracted product is vacuum dried at 130℃ for 12h.

[0023] Further, the preparation method of the β-BNCD is that the β-cyclodextrin is dissolved in an organic solvent, the solution is cooled and NaH is added in batches, after stirring, benzyl bromide is added, mixed, heated to room temperature, stirred for 6-12h, the reaction is quenched, and then extracted, dried and concentrated to obtain; the organic solvent is any one of pyridine, dimethylformamide, dimethyl sulfoxide and ethylene glycol.

[0024] Preferably, the organic solvent is dimethylformamide.

[0025] Preferably, the feeding equivalent (eq) ratio of the β-cyclodextrin, NaH and benzyl bromide is 1:42:42.

[0026] Preferably, the cooling is cooled to 0℃.

[0027] Preferably, the stirring is for 15 minutes.

[0028] Preferably, the extraction is with dichloromethane.

[0029] Preferably, the drying is drying of the obtained organic layer with anhydrous sodium sulfate.

[0030] Preferably, the concentration is rotary evaporation.

[0031] Preferably, the obtained β-BNCD can be further purified by silica gel chromatography (hexane: ethyl acetate = 8:1) to obtain colorless oil of β-BNCD.

[0032] The present application provides the porous cross-linked polymer of phosphoric acid group modified β-cyclodextrin (DBP-β-BNCD) prepared by the preparation method described above.

[0033] The present application provides the use of the DBP-β-BNCD described above in the preparation of solid phase microextraction coating material.

[0034] The present application provides the use of the DBP-β-BNCD described above in the preparation of solid phase microextraction film or solid phase microextraction extraction head.

[0035] The present application also provides a solid phase microextraction film, which is a mixture of the porous cross-linked polymer of phosphoric acid group modified β-cyclodextrin and PDMS coated on the surface of a hydrophilic modified carbon cloth as a carrier.

[0036] Further, the preparation method of the hydrophilic modified carbon cloth is to clean the carbon cloth by ultrasonic treatment in a solution, and then put it in a mixed solution of concentrated sulfuric acid and nitric acid, and hydrothermally react for 3-4 hours, and then rinse to obtain the hydrophilic modified carbon cloth.

[0037] Preferably, the ultrasonic cleaning is to clean the surface of the carbon cloth by ultrasonic treatment in acetone, ethanol and deionized water for 30 minutes each.

[0038] Preferably, the hydrothermal reaction is to react in a mixed solution of concentrated sulfuric acid and nitric acid (v:v = 1:1) at 95℃ for 3 hours.

[0039] Further, the solid phase microextraction film preparation method comprises ultrasonic dispersion of DBP-beta-BNCD in cyclohexane, addition of high-viscosity polydimethylsiloxane, re-ultrasonic dispersion, removal of cyclohexane by nitrogen blowing, addition of polydimethylsiloxane curing agent (peroxide-based catalyst), mixing to obtain an adsorbent mixture. The adsorbent mixture is extruded to the top of the carbon cloth by a syringe, the gap between the coating rod and the carbon cloth is adjusted to 100 mu m, and then the adsorbent mixture is slowly coated on the surface of the carbon cloth by hand. Finally, curing is performed at 90 DEG C for 4 hours in a nitrogen atmosphere; since the carbon cloth is double-sided, the preparation of the solid phase microextraction film needs to be completed by a second coating.

[0040] The application further provides application of the solid phase microextraction film in detection of trace antibiotics in environmental water bodies.

[0041] The application provides a pretreatment method for detecting trace antibiotics in water based on a thin-film solid phase microextraction (TFME) technology, wherein the solid phase microextraction film is placed in a water sample to be detected, extraction is performed at 30-80 DEG C for 40-70 min, the solid phase microextraction film is placed in a desorption solution, and elution is performed by oscillation to obtain an eluent, and the sample to be detected is obtained after filtration; the desorption solution is methanol, and the volume ratio of the desorption solution to the water sample to be detected is (0.5-2):40.

[0042] Further, the extraction temperature is 50-80 DEG C.

[0043] Preferably, the extraction temperature is 60 DEG C.

[0044] Further, the extraction time is 70-80 min.

[0045] Preferably, the extraction time is 70 min.

[0046] Further, the volume ratio of the water sample to be detected to the desorption solution is 40:(0.5-1.5).

[0047] Further, the volume ratio of the water sample to be detected to the desorption solution is 40:1.

[0048] Further, the above pretreatment method is combined with a liquid chromatography-mass spectrometry method to establish a method combining the thin-film solid phase microextraction technology and liquid chromatography-tandem mass spectrometry (HPLC-QqQ-MS) for evaluating the performance of the novel coating material DBP-beta-BNCD in detection of multiple antibiotics in environmental water samples. The results show that the method shows excellent enrichment performance in determination of 20 antibiotics in water samples, the method has a wide linear range, a low detection limit and good reproducibility, and is simple and convenient to operate, short in time consumption, and overcomes the shortcomings of existing sample pretreatment methods.

[0049] Compared with the prior art, the present application has the following beneficial effects:

[0050] The present application provides a phosphoric acid group modified beta-cyclodextrin based polymer film microextraction coating material, a beta-CD porous cross-linked polymer (DBP-beta-BNCD) rich in polar functional groups of phosphoric acid groups is prepared by cross-linking benzylated beta-CD with dibenzyl phosphate (DBP) through Friedel-Crafts alkylation, the DBP-beta-BNCD has the advantages of large specific surface area, narrow pore size distribution, large pore volume, good thermal stability and the like, which is conducive to the accessibility of adsorption sites, when adsorbing hydrophilic pollutants of antibiotics, a plurality of adsorption mechanisms such as polar interaction, hydrogen bond interaction and pi-pi interaction are introduced. Further, the DBP-beta-BNCD is used as a film solid phase microextraction coating material, a method of TFME combined with liquid chromatography-tandem mass spectrometry (HPLC-QqQ-MS) is established, and the results show that the prepared coating material has great potential for the extraction of hydrophilic organic pollutants in the environment. BRIEF DESCRIPTION OF DRAWINGS

[0051] Figure 1 It is a scanning electron micrograph of DBP-beta-BNCD.

[0052] Figure 2 It is an infrared spectrum of DBP, BNCD and DBP-beta-BNCD.

[0053] Figure 3 It is a solid-state carbon nuclear magnetic resonance spectrum of DBP-beta-BNCD.

[0054] Figure 4 It is a photoelectron spectrum of carbon, oxygen and phosphorus of DBP-beta-BNCD.

[0055] Figure 5 It is a thermogravimetric analysis curve of DBP-beta-BNCD.

[0056] Figure 6 It is a nitrogen isothermal adsorption-desorption curve of DBP-beta-BNCD.

[0057] Figure 7 It is a mesopore pore size distribution of DBP-beta-BNCD.

[0058] Figure 8 It is a micropore pore size distribution of DBP-beta-BNCD.

[0059] Figure 9 It is a preparation and application flowchart of the phosphoric acid group modified beta-cyclodextrin polymer coating material of the present application. DETAILED DESCRIPTION

[0060] The present application is further described in conjunction with the accompanying drawings and specific examples, which are intended to illustrate but not limit the present application. Unless otherwise specified, the reagents, methods and apparatus employed in the following examples are of a type as is commonly employed by those in the art.

[0061] Unless otherwise specified, the reagents and materials used in the following examples are commercially available.

[0062] Example 1

[0063] The preparation conditions of the phosphonic group modified β-cyclodextrin polymer were optimized, and it was first used as a coating material for thin film microextraction combined with liquid chromatography-tandem mass spectrometry for the detection of trace antibiotics in water. The preparation of the phosphonic group modified β-cyclodextrin polymer coating material for thin film microextraction is as follows:

[0064] 1. Preparation of β-BNCD monomer. 1.16 g of β-cyclodextrin (1 eq) was dissolved in dry DMF. The solution was cooled to 0°C, and 1.01 g of NaH (42 eq) was added to it in batches. After stirring for 15 minutes, 7.18 g of benzyl bromide (42 eq) was slowly added, and the mixture was heated to room temperature. After stirring overnight, methanol was added to quench the reaction. The resulting residue was mixed with water, and extracted with dichloromethane. The combined organic layers were dried over anhydrous sodium sulfate and concentrated by rotary evaporation. The crude product was purified by silica gel chromatography (hexane: ethyl acetate = 8:1) to obtain benzyl-modified β-CD (named β-BNCD) monomer as a colorless oil.

[0065] 2. Preparation of DBP-β-BNCD material. 0.71 g of dibenzyl phosphate (DBP) (21 eq), an appropriate amount of benzyl-modified β-CD (β-BNCD), 0.93 g of dimethoxymethane (63 eq), and 1.99 g of dry FeCl3 (63 eq) were added to a round-bottom flask containing 100 mL of anhydrous 1,2-dichloroethane, and the mixture was stirred until homogeneous. The above-mentioned round-bottom flask was connected to a condensing device, and the temperature was controlled at 45°C under a nitrogen atmosphere. The mixture was stirred for 3 h, then the temperature was raised to 80°C and reacted for 18 h. Finally, methanol was added to quench the crosslinking reaction, and the mixture was cooled to room temperature for subsequent treatment. The amount of β-BNCD was 1 eq (0.58 g), 2 eq (1.16 g), or 4 eq (2.32 g). The crude product obtained in the previous step was first washed with 150 mL of methanol to remove unreacted organic compounds, then washed with distilled water several times to remove the metal catalyst, and the washed product was collected by centrifugation. The above-mentioned product was Soxhlet extracted in methanol for 24 hours, and finally the Soxhlet extracted product was vacuum dried at 130°C for 12 hours to obtain the product, which was named as DBP-β-BNCD.

[0066] 3. Pretreatment of carbon cloth: Commercially available carbon cloth was cut into desired size and cleaned by ultrasonication in acetone, ethanol and deionized water for 30 min each to clean the surface of carbon cloth. Subsequently, the cleaned carbon cloth was treated by hydrothermal reaction with a mixture of concentrated sulfuric acid and nitric acid (v:v = 1:1) at 95 °C for 3 h to improve the surface hydrophilicity and affinity to adsorbents. After treatment, the obtained modified carbon cloth was rinsed with deionized water.

[0067] 4. Preparation of solid phase microextraction film. 500 mg of the above self-made material particles were ultrasonically dispersed in 10 mL of cyclohexane, and then 2 g of high-viscosity polydimethylsiloxane was added to the above dispersed particles in cyclohexane and ultrasonically dispersed again. Then most of the cyclohexane was volatilized from the mixture by nitrogen blowing, and the nitrogen blowing was stopped when there was almost no flow when the mixture was inverted in a vial. Finally, 200 mg of polydimethylsiloxane curing agent (peroxide-based catalyst) was added and mixed evenly by hand. Then the pretreated carbon cloth was laid flat on the horizontal table top, and the above adsorbent mixture was extruded onto the top of the carbon cloth with a syringe. Then the gap between the coating rod and the carbon cloth was adjusted to 100 μm, and then the adsorbent mixture was slowly coated on the surface of the carbon cloth by hand. Finally, in a nitrogen atmosphere, it was cured at 90 °C for 4 h. Since the carbon cloth is double-sided, the entire process needs to be repeated twice to complete the preparation of the solid phase microextraction film. After the film was prepared, the whole film was manually cut into the required size (4 x 50 mm) for subsequent sampling analysis.

[0068] The specific surface area and pore size structure are important indicators for evaluating the adsorption capacity of materials. Therefore, before selecting the coating material for antibiotic analysis, the specific surface area and pore size structure of the prepared materials with different feeding equivalents were characterized by nitrogen isothermal adsorption-desorption experiments. The surface area and pore size distribution were obtained by BET method and density functional theory (NLDFT), respectively. The results are shown in Table 1. The BET surface area of the material obtained by β-BNCD with a feeding equivalent of 2 eq is 1537.3 m 2 ·g -1 , which is significantly higher than the specific surface area of the other two materials. In addition, the pore volume of the material obtained by β-BNCD with a feeding equivalent of 2 eq is 1.509 cm 3 ·g -1 , which is also much higher than the pore volume of the other two materials. The BET surface area and pore volume of the material obtained by β-BNCD with a feeding equivalent of 1 eq are also large. Therefore, in the subsequent examples, the material obtained by β-BNCD with a feeding equivalent of 2 eq will be selected as the coating material for SPME for subsequent quantitative analysis of antibiotics.

[0069] Table 1. Specific surface area and pore size structure of different materials

[0070]

[0071] The coating material prepared by selecting the β-BNCD feeding equivalent of 2 eq was selected for performance characterization, and the specific characterization was as follows:

[0072] 1. Morphology analysis: scanning electron microscope images were obtained by using SU8010 field emission scanning electron microscope (Japan, Hitachi). From the scanning electron microscope images, Figure 1 ), the DBP-β-BNCD material was an irregular block structure, and the material was distributed on the surface of the thin film. Compared with the traditional solid-phase microextraction fiber, the solid-phase microextraction thin film prepared in the application has a larger volume, good adsorption performance, higher sensitivity, and is suitable for the detection and analysis of trace antibiotics in real water samples.

[0073] 2. Fourier infrared spectrum analysis: infrared spectra were analyzed by using PerkinElmer Frontier thermogravimetric spectrometer (USA, PerkinElmer). In the infrared spectrum, Figure 2 the main functional groups, skeletons and the like in the structural formula of the DBP-β-BNCD were consistent, proving the successful synthesis of the material.

[0074] 3. Solid-state carbon nuclear magnetic resonance spectrum analysis: solid-state nuclear magnetic experiment was carried out on an AVANCE-III600 Bruker Biospin spectrometer (Germany, Bruker) using a 1.6mm MAS probe. Figure 3 From the nuclear magnetic carbon spectrum, the C peak of C-O on the aliphatic chain was at 40ppm, and the C peak on the benzene ring was at 125-150ppm, which was consistent with the main functional groups, skeletons and the like in the structural formula of the DBP-β-BNCD.

[0075] 4. Photoelectron spectrum analysis: X-ray photoelectron spectroscopy (XPS) spectrum was obtained by using Thermo-VG Scientific spectrometer (USA, ESCALAB 250). The structure of the material was characterized by using photoelectron spectrum, Figure 4 From the carbon spectrum in the photoelectron spectrum, the main bond energy of the material at 285eV corresponded to the C atom on the benzene ring, the C atom of C-O on the aliphatic chain was at 286eV, and the π-π satellite peak of C between benzene rings was at 290-293eV, which was consistent with the types of C in the structure of the material. From the oxygen spectrum, there was a peak at 530-536eV, which was the peak of the ether bond, which could prove the successful benzylation of β-cyclodextrin. From the phosphorus spectrum, there was a peak at 132-137eV, which was the characteristic peak of the phosphoric acid functional group, which could prove the existence of the phosphoric acid group in the material. In summary, the spectra of the carbon spectrum, the phosphorus spectrum and the oxygen spectrum were consistent with the structural formula of the material, which verified the successful synthesis of the material.

[0076] 5. Thermogravimetric test: Thermogravimetric analysis was performed on a TG 209F3 Tarsus thermogravimetric analyzer (Netzsch, Germany). For SPME coating materials, high temperature resistance is also an important factor affecting its performance and service life. From the thermogravimetric curve in FIG. 6, it can be seen that before 300°C, the material has no obvious weight loss phenomenon, and its mass is 97% of the original mass, which proves that the material is relatively stable at 300°C, has good thermal stability, and can be extracted at a higher temperature. Figure 5

[0077] 6. Nitrogen isothermal adsorption-desorption curve and pore size distribution: The nitrogen adsorption-desorption isotherm at 77K was measured by using a gas automatic adsorption analyzer Autosorb-IQ3 (Quantachrome Instruments, USA), and the pore structure and specific surface area of the material were further studied by using the nitrogen adsorption-desorption isotherm. From the isothermal adsorption-desorption graph, it can be seen that the adsorption-desorption curve of the material is nearly coincided under low pressure conditions, which proves that the material has good adsorption-desorption capacity. In addition, the hysteresis loop existing under medium-high pressure conditions indicates that there are a large number of mesoporous structures in the material. Based on the DFT theory calculation, it is further obtained that the mesopore pore size distribution of the material is concentrated near 4.0 nm. Figure 6 Figure 7 Figure 8 The results show that the BET specific surface area of the material is 1537.3 m 2 / g, the pore volume is 1.51 cm 3 / g, and the adsorption capacity can be greatly improved, which lays a solid foundation for subsequent excellent adsorption efficiency.

[0078] Examples 2-15

[0079] The material obtained by taking β-BNCD as raw material at an equivalent of 2 eq was used as the coating material of SPME as the coating material of thin film microextraction. The solid phase microextraction technology combined with liquid chromatography-tandem mass spectrometry was applied to the detection of trace antibiotics in water. First, the extraction parameters were optimized. The method is as follows:

[0080] 1. Solid phase microextraction technology process (pretreatment):

[0081] ​​​The cut SPME film with coating material was placed in a sample vial containing 40 mL of sample, and the vial was placed on a heated stirrer for extraction at different extraction temperatures at a rotation speed of 500 rpm. The extracted film was removed, and the surface of the film was then wiped with a lint-free paper and immediately immersed in a sample injection vial containing chromatographic grade methanol (i.e., desorption solution), and the vial was placed on a shaker for elution at a rotation speed of 500 rpm for 30 min to obtain an eluate. The eluate was filtered through a 0.22 pm nylon membrane to remove insoluble impurities and stored in a -20 °C refrigerator for subsequent instrumental analysis. The used film was washed with methanol three times to remove residual impurities, and then dried in air for standby. The extraction temperature, time, and desorption solution volume parameters are shown in Table 2.

[0082] 2. HPLC-QqQ-MS quantitative analysis:

[0083] In the present application, high performance liquid chromatography (HPLC, Agilent 1290 Infiniti II) and tandem mass spectrometry (QqQ-MS, Agilent 6475 LC / TQ) were used for separation and quantitative analysis of antibiotics. Chromatographic separation was performed using an Agilent Zorbax Eclipse Plus C18 column (3 mm x 150 mm, 1.8 pm) at a constant column temperature of 30 °C. The mobile phase for liquid chromatography consisted of phase A (0.1% formic acid in water) and phase B (0.1% formic acid in methanol), and the gradient elution program is shown in Table 2, with an injection volume and flow rate of 5 pL and 0.3 mL / min, respectively. Quantitative analysis of substances was performed using an electrospray tandem mass spectrometry (ESI-MS / MS) system, operating in multiple reaction monitoring (MRM) mode. The mass spectrometry source temperature was set to 300 °C, with nitrogen as the collision gas, and the capillary voltage and nozzle voltage were set to 4400 and 1500 V under positive ion, and -3500 and -1000 V under negative ion, respectively. According to the optimized chromatographic and mass spectrometric parameters, the antibiotics were analyzed to obtain the optimal mass spectrometric conditions for each antibiotic substance, as shown in Table 3.

[0084] Table 2 Chromatographic reference solvent gradient

[0085]

[0086]

[0087] Table 3 Mass spectrometric conditions for quantitative substances

[0088]

[0089]

[0090] The number of detected antibiotics and the average peak area are shown in Table 4. When the extraction parameters are extraction temperature of 30-80℃, extraction time of 40-70min, and desorption solution volume of 0.5-2mL, the number of 20 kinds of antibiotics can be detected, wherein the average peak area of the obtained antibiotics is the largest when the extraction temperature is 60℃, the extraction time is 70min, and the desorption solution volume is 1mL.

[0091] Table 4: Specific embodiment for detecting antibiotics in water samples by SPME technology

[0092]

[0093] Test example

[0094] In order to illustrate the solid phase microextraction coating material of the phosphoric acid group modified β-cyclodextrin polymer for the detection and analysis of antibiotics in environmental water samples. The following example 15 is selected for specific characterization and application. The preparation and application flow chart of example 15 is shown in Figure 9 The steps of the developed method include material preparation, sample pretreatment, and sample analysis.

[0095] The present application develops a SPME-LC-MS / MS method for antibiotics based on DBP-β-BNCD solid phase microextraction film. The analysis parameters of the method are referred to example 2. The detection level parameters obtained by detecting antibiotic standard by the method are shown in Table 5. The coating material has good extraction performance for antibiotics, and can simultaneously adsorb 20 kinds of antibiotics. The Kow value of the antibiotic spans 5 orders of magnitude, which proves that the coating material has good broad spectrum. In addition, the results show that the method has a wide linear range, low detection limit and high enrichment multiple for antibiotics.

[0096] Table 5: Detection level parameters of the antibiotic analysis method developed based on DBP-β-BNCD solid phase microextraction film

[0097]

[0098]

[0099] The developed analysis method is used for the analysis of real water samples, and the results are shown in Table 6. As shown in the above table, trace amounts of clarithromycin, sulfadoxine, sulfisoxazole, sulfathiazole, sulfamethazine, and sulfachloropyrazine can be detected in Xiaoguwei River. The recovery rate of the developed SPME-LC-MS / MS method is between 75% and 125%, which indicates that this method can accurately detect the content of antibiotics in water.

[0100] Table 6: Determination results of antibiotic content in real water samples

[0101]

[0102] ND: not detected, not detected

[0103] In summary, a kind of supercrosslinked polymer material derived from cyclodextrin is successfully prepared, which is applied to the detection of multiple antibiotics in environmental water samples.The material has good thermal stability, high specific surface area, narrow pore size distribution, large pore volume.Benefiting from the existence of polar interaction, π-π stacking effect and size matching effect between DBP-β-BNCD polymer and antibiotic molecules, the material has excellent extraction performance, and can be directly used for the detection of actual water samples.Finally, a method of thin-film microextraction (TFME) combined with liquid chromatography-tandem mass spectrometry (HPLC-QqQ-MS) is established, which is used to evaluate the analysis performance of new coating material DBP-β-BNCD for multiple antibiotics in environmental water samples.The results show that the method based on DBP-β-BNCD solid-phase microextraction film has wide linear range, low detection limit and good reproducibility.The method is simple and convenient, and the time consumption is short, which overcomes the shortcomings of existing sample pretreatment methods.The results show that the method shows excellent analysis performance in the determination of 20 antibiotics in water samples, which shows that the prepared new coating material has great potential for the extraction of hydrophilic organic pollutants in the environment.

Claims

1. A method for preparing a porous cross-linked polymer of a phosphoric acid group-modified β-cyclodextrin, characterized by, The benzylated β-cyclodextrin is prepared by dissolving β-cyclodextrin in an organic solvent, cooling the solution and adding NaH to the solution in batches, stirring, adding benzyl bromide, mixing, heating to room temperature, stirring for 6-12 hours, quenching the reaction, and then extracting, drying and concentrating to obtain the benzylated β-cyclodextrin; the organic solvent is any one of pyridine, dimethylformamide, dimethyl sulfoxide and ethylene glycol. 2+ The benzylated β-cyclodextrin is prepared by dissolving β-cyclodextrin in an organic solvent, cooling the solution and adding NaH to the solution in batches, stirring, adding benzyl bromide, mixing, heating to room temperature, stirring for 6-12 hours, quenching the reaction, and then extracting, drying and concentrating to obtain the benzylated β-cyclodextrin; the organic solvent is any one of pyridine, dimethylformamide, dimethyl sulfoxide and ethylene glycol.

2. The porous cross-linked polymer of phosphoric acid group modified β-cyclodextrin prepared by the preparation method of claim 1.

3. The use of the porous cross-linked polymer of phosphoric acid group modified β-cyclodextrin of claim 2 in the preparation of a solid phase microextraction film or a solid phase microextraction extraction head.

4. A solid phase microextraction film, characterized by The film is a hydrophilic modified carbon cloth carrier coated with a mixture of the porous cross-linked polymer of phosphoric acid group modified β-cyclodextrin of claim 2 and polydimethylsiloxane.

5. The solid phase microextraction film of claim 4, wherein the polymeric material is a polymeric material having a glass transition temperature of at least 50 °C. The preparation method of the hydrophilic modified carbon cloth is as follows: after cleaning the carbon cloth in a solution by ultrasonic treatment, the carbon cloth is placed in a mixed solution of concentrated sulfuric acid and nitric acid, and is subjected to hydrothermal reaction treatment for 3-4 hours, and then is rinsed to obtain the hydrophilic modified carbon cloth.

6. The use of the solid phase microextraction film of claim 4 in the detection of trace antibiotics in environmental water.

7. A pretreatment method for detecting trace antibiotics in water based on thin film solid phase microextraction technology, characterized in that, The solid phase microextraction film of claim 4 is placed in a water sample to be detected, and is extracted at 30-80℃ for 40-70 minutes, is placed in a desorption solution, is shaken and eluted to obtain an eluent, and after filtration, the water sample to be detected is obtained; the desorption solution is methanol; and the volume ratio of the desorption solution to the water sample to be detected is (0.5-2):40.

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