A magnetic solid phase extraction material, a preparation method and application thereof

Abstract

The application provides a preparation method of a magnetic solid-phase extraction material, comprising the following steps: A) bonding a silane containing a double bond to the surface of silica-coated Fe3O4 nano magnetic particles to obtain double-bond functionalized magnetic nanoparticles; B) synthesizing polymer-coated magnetic microspheres by suspension polymerization of a material containing divinylbenzene and the double-bond functionalized magnetic nanoparticles; C) grafting carboxyl groups on the surface of the polymer-coated magnetic microspheres through a Friedel-Crafts reaction; and D) coupling a compound containing an amino group on the surface of the magnetic microspheres grafted with the carboxyl groups through a carboxyl activation method to obtain the magnetic solid-phase extraction material. The preparation method has controllability and flexibility, and is suitable for stable production on a large scale. The dispersion structure magnetic solid-phase extraction material formed has not only adjustable selectivity, but also good dispersity, a large specific surface area and high adsorption capacity. The application further provides a magnetic solid-phase extraction material and application thereof.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of solid phase extraction, and particularly relates to a magnetic solid phase extraction material, a preparation method and application thereof. BACKGROUND

[0002] Magnetic solid phase extraction (MSPE) was first developed by Heden et al. in 1972, who first demonstrated the ability of magnetic solid phase extraction materials to separate biologically active proteins (Biotechnol. Bioeng. Symp., 1972, pp. 173-174.). In 1973, Robinson et al. used magnetic solid phase extraction materials to effectively extract two enzymes produced in a stirred reactor (Biotechnology and Bioengineering, 15 (1973) 603-606). In 1996, Towler et al. used manganese dioxide-loaded magnetite to concentrate and effectively separate metal elements such as radium, lead and polonium in seawater (Analytica chimica acta, 328 (1996) 53-59). However, the true sense of magnetic solid phase extraction was not developed until 1999 by M. Safarikova and I. Safarik et al., and was applied to the extraction and separation of copper phthalocyanine dyes (Journal of Magnetism and Magnetic Materials, 194 (1999) 108-112).

[0003] MSPE technology uses magnetic adsorbents to extract analytes. Under the action of an external magnetic field, the target analyte can be rapidly separated from the sample matrix along with the adsorbent. Finally, the analyte is eluted from the adsorbent by a suitable eluent, thereby achieving the purpose of separation and enrichment. Compared with traditional solid phase extraction, magnetic solid phase extraction using magnetic particles as carriers has many advantages, (1) MSPE directly disperses magnetic adsorbents into sample solutions, increasing the contact area and improving the extraction efficiency, and solving the problem of column resistance; (2) The analyte does not need to be centrifuged or filtered, and the operation is simpler; (3) Easy to wash and elute, avoiding the use of large amounts of organic reagents; (4) Lower interference, because most sample impurities are non-magnetic; (5) The operating conditions of MSPE are controllable, and the entire process is easy to automate; (6) Most magnetic adsorbents can be easily recycled and reused, greatly saving costs and protecting the environment. Therefore, MSPE has great application prospects in the fields of food and drug analysis, environmental detection, customs quarantine, biomedicine, etc.

[0004] MSPE materials are usually composed of magnetic materials and functional surface coatings, both of which need to have certain excellent properties. Among them, the magnetic components are usually represented by metal oxides such as iron, cobalt, nickel and their composites, which usually have good superparamagnetic or ferromagnetic properties. Magnetite (Fe3O4) nanoparticles are often used in magnetic solid phase extraction due to their simple preparation process, low cost, large specific surface area, good biocompatibility and other advantages. According to the structural characteristics of the material, the existing MSPE materials can be divided into inorganic coating type and organic coating type. Among them, the common inorganic coating type magnetic solid phase extraction agent types are: alumina coated type, silica coated type, carbon material coated type, etc. The surface of this type of MSPE material is wrapped by a porous or dense inorganic material layer, which gives it good physical and chemical stability. The porous structure can increase the specific surface area of the MSPE material and improve the adsorption effect. The surface of Fe3O4 magnetic nanoparticles contains a large number of hydroxyl functional groups, which can combine with a variety of organic molecules or polymers. The surface of Fe3O4 magnetic nanoparticles can even be directly coated with agarose, proteins and general organic polymers to form a polymer coating. The outermost organic polymer coating layers of the above different strategies are different, which can be polystyrene, polymethyl methacrylate, polyvinylpyrrolidone, etc. It can also be a high molecular weight copolymer, it can also be a molecularly imprinted type, and it can even be a metal organic framework material (Metal Organic Frameworks, MOF), the purpose is to provide better extraction selectivity (Journal of Chromatography A, 2012, 1245, 8-16, Journal of Chromatography A, 2020, 1630, 461531, Analyst, 2012, 137, 3445, J. Sep. Sci. 2017, 40: 909-918, CN105233799A). Therefore, the external modification of Fe3O4 magnetic nanoparticles with different organic or inorganic materials can achieve effective adsorption of different types of target molecules and ions and improve the solid phase extraction efficiency.

[0005] In recent years, polymer materials have been widely studied and applied due to their high structural stability and easily controlled physicochemical properties in a wide range of acid-base. And the copolymerization of monomers with different properties can form polymers with different functions. In the 1990s, the American company Waters co-polymerized hydrophilic N-vinyl pyrrolidone (NVP) and hydrophobic divinylbenzene (DVB) to prepare a hydrophilic-lipophilic balanced water-infiltrable reversed-phase adsorbent (Oasis HLB). Due to the hydrogen bond acceptor and dipole polarity of pyrrolidone, combined with the π-π interaction of divinylbenzene and the mesoporous structure of the copolymer, the Oasis HLB extraction column has good enrichment and extraction effect on many substances such as antibiotics, endocrine disruptors, pesticides and drugs in the environment. However, this reversed-phase adsorbent needs to be used by the traditional solid-phase extraction method of column separation, which is easily affected by the complex matrix of the sample, causing column plugging, affecting the separation effect, and the extraction time of large volume samples is long, which greatly limits the industrial application of SPE. Chinese invention patent application (202010174037.1) coated the hydrophilic-lipophilic balanced water-infiltrable polymer on the surface of magnetic particles to prepare MSPE materials. This kind of magnetic solid phase extraction material not only retains the advantages of polymer extractant, but also has magnetic properties. By treating the sample by MSPE, the column plugging phenomenon is avoided, and the operation is simple, the extraction efficiency is high (Analytical chemistry, 2018, 90: 14072-14080). However, the above hydrophilic-lipophilic balanced polymer system with magnetic material is not easy to control, and the dispersion and uniformity are poor, and some small particles are easy to fall off. Especially when preparing mixed weak cation exchange-reversed phase adsorbent, it is difficult to form microspheres in the mixed copolymerization system of divinylbenzene, p-vinylbenzoic acid and magnetic nanoparticles. SUMMARY

[0006] The purpose of the present application is to provide a kind of magnetic solid phase extraction material, its preparation method and application, the composite magnetic solid phase extraction material prepared by the method in the present application has good uniformity, stability, controllability and flexibility, is suitable for scale stable production;This solid phase extraction material not only has adjustable selectivity, but also has high adsorption capacity and good uniformity. In the sample analysis of chemical industry, food, environment and biology, these magnetic solid phase extraction materials can be used for effective separation, purification and enrichment of samples, and the analysis sensitivity can be improved.

[0007] The present application provides a kind of preparation method of magnetic solid phase extraction material, comprising the following steps:

[0008] A) bonding double bond-containing silane on the surface of silica-coated Fe3O4 nano-magnetic particles to obtain double bond-functionalized magnetic nanoparticles;

[0009] B) synthesizing polymer-coated magnetic microspheres by suspension polymerization of the material containing divinylbenzene and the double bond functionalized magnetic nanoparticles;

[0010] C) grafting carboxyl groups on the surface of the polymer-coated magnetic microspheres through a Friedel-Crafts reaction;

[0011] D) coupling a compound containing an amino group on the surface of the magnetic microspheres grafted with carboxyl groups through a carboxyl activation method to obtain a magnetic solid-phase extraction material.

[0012] Preferably, the Fe3O4 nano-magnetic particles are prepared by a solvothermal method.

[0013] Preferably, the double bond-containing silane is one or more of 3-(trimethoxysilyl) methyl propyl methacrylate, vinyltrimethoxysilane, vinyltriethoxysilane and vinyltris(2-methoxyethoxy)silane.

[0014] Preferably, in step B), the double bond functionalized magnetic nanoparticles are coated with one or more organic monomers;

[0015] The organic monomers include divinylbenzene and optionally other monomers; the other monomers include one or more of styrene, methyl acrylate, N-vinyl pyrrolidone, N-methyl acrylamide, acrylonitrile, acrylic acid, etc.

[0016] Preferably, in step C), a compound containing a benzoic acid group is modified on the surface of the polymer-coated magnetic microspheres through a Friedel-Crafts reaction.

[0017] Preferably, the catalyst for the Friedel-Crafts reaction is anhydrous tin tetrachloride, and the compound containing a benzoic acid group is p-chloromethyl benzoic acid.

[0018] Preferably, in step D), EDC / NHS is used as the carboxyl activation reagent;

[0019] The compound containing an amino group includes one or more of ethanolamine, amino polyethylene glycol, taurine, N, N-diethyl ethylenediamine and (2-aminoethyl) trimethylammonium chloride hydrochloride.

[0020] The present application provides a magnetic solid-phase extraction material prepared by the preparation method as described above; the magnetic solid-phase extraction material is a microsphere with a dispersion structure, the inside of the microsphere is a cross-network formed by magnetic nanoparticles and a polymer containing divinylbenzene, and the surface of the microsphere is grafted with a functional group containing an amino group through a carboxyl group, which is used to provide different adsorption mechanisms.

[0021] The present application provides the use of the magnetic solid-phase extraction material as described above in solid-phase extraction.

[0022] The application provides a preparation method of a magnetic solid-phase extraction material, comprising the following steps: A) bonding a silane containing a double bond to the surface of a silica-coated Fe3O4 nano magnetic particle to obtain a double bond functionalized magnetic nanoparticle; B) synthesizing a polymer coated magnetic microsphere by suspension polymerization of a material containing divinylbenzene and the double bond functionalized magnetic nanoparticle; C) grafting a carboxyl group to the surface of the divinylbenzene polymer coated magnetic microsphere through a Friedel-Crafts reaction; and D) coupling a compound containing an amino group to the surface of the magnetic microsphere grafted with the carboxyl group through a carboxyl activation method to obtain the magnetic solid-phase extraction material. The application precisely and rationally designs a two-step preparation scheme of a magnetic solid-phase extraction material with a dispersion structure. First, the magnetic nanoparticle is coated with silica, and a double bond coating is formed on the surface thereof through silanization, so that the problem of poor dispersibility is solved; meanwhile, the double bond on the surface can be copolymerized with a monomer such as divinylbenzene to form a dispersion type magnetic microsphere, so that the problem of failure to form a microsphere is solved; in addition, the coupling of an amine compound is realized through further chemical modification of the formed magnetic microsphere, such as a Friedel-Crafts reaction and EDC / NHS activation, so that the goals of improving extraction selectivity, recovery rate and repeatability are achieved. The preparation method of the application has controllability and flexibility, and is suitable for stable production on a large scale; the dispersion structure magnetic solid-phase extraction material formed has adjustable selectivity, good dispersibility, large specific surface area and high adsorption capacity. The magnetic solid-phase extraction material can be used for the pretreatment of complex samples in the fields of chemical industry, food, environmental analysis and biological detection, so that the purposes of effective separation, purification and enrichment are achieved. BRIEF DESCRIPTION OF DRAWINGS

[0023] In order to more clearly illustrate the technical solutions in the embodiments of the application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or the prior art description. Obviously, the drawings in the following description only constitute the embodiments of the application, and for those skilled in the art, other drawings can also be obtained without creative labor on the basis of the provided drawings.

[0024] Figure 1 It is a preparation flowchart of the magnetic solid-phase extraction material of the application;

[0025] Figure 2 It is a TEM photo of Fe3O4@SiO2 prepared in Example 1 of the application;

[0026] Figure 3 It is a SEM photo of Fe3O4@SiO2 prepared in Example 1 of the application;

[0027] Figure 4SEM image of amphiphilic magnetic solid phase extraction material (HLB-1) prepared in Example 2 of the present application;

[0028] Figure 5 SEM image of weak cation exchange magnetic solid phase extraction material (WCX) prepared in Example 1 of the present application;

[0029] Figure 6 Infrared spectrum of hydrophobic magnetic polymer microspheres (HPM), weak cation exchange magnetic solid phase extraction material (WCX), hydrophilic-lipophilic balance water-wettable magnetic solid phase extraction material (HLB-2) prepared in Example 1 of the present application and amphiphilic magnetic solid phase extraction material (HLB-1) prepared in Example 2 of the present application. DETAILED DESCRIPTION

[0030] The present application provides a preparation method of a magnetic solid phase extraction material, comprising the following steps:

[0031] A) bonding a silane containing a double bond to the surface of a silica-coated Fe3O4nanomagnetic particle to obtain a double bond functionalized magnetic nanoparticle;

[0032] B) synthesizing a polymer-coated magnetic microsphere by suspension polymerization of a material containing divinylbenzene and the double bond functionalized magnetic nanoparticle;

[0033] C) grafting a carboxyl group to the surface of the polymer-coated magnetic microsphere by a Friedel-Crafts reaction;

[0034] D) coupling a compound containing an amino group to the surface of the magnetic microsphere grafted with the carboxyl group by a carboxyl activation method to obtain a magnetic solid phase extraction material.

[0035] Figure 1For the preparation process of the magnetic solid phase material in one embodiment of the present application, firstly, a dense layer of silicon dioxide is coated on the surface of the magnetic nano Fe3O4 particles synthesized by the solvothermal method, which not only effectively protects the stability of the magnetic core, but also lays a foundation for subsequent modification. Then, silane containing double bonds is bonded on the surface, so as to copolymerize with organic monomers. Then, by the method of suspension polymerization, the magnetic core is copolymerized with divinylbenzene and other monomers, to preliminarily form magnetic microspheres with cross-linked network and magnetic particles inside. A large number of aromatic skeletons exist on the surface of the microspheres, which can further undergo a Friedel-Crafts reaction with compounds containing specific groups, such as p-chloromethylbenzoic acid, to obtain magnetic microspheres (WCX) containing carboxyl groups and having weak cation exchange performance. Finally, the carboxyl groups on the surface of the WCX can further react with other groups, such as the coupling of amine compounds by activating the surface carboxyl groups through EDC / NHS, and the reaction with compounds with different properties and containing amino groups, so as to obtain magnetic solid phase extraction materials with multiple adsorption mechanisms. The magnetic microspheres synthesized in this way are not only easy to control, but also can realize the regulation of extraction performance through different molecular structure design and combination.

[0036] In the present application, the Fe3O4 nano magnetic particles are preferably prepared by the solvothermal method, which is well known to those skilled in the art, and the present application does not make special limitations here. Specifically, in one embodiment of the present application, iron salt can be used to prepare Fe3O4 nano magnetic particles in an ethylene glycol / anhydrous sodium acetate / sodium citrate system. In the present application, the particle size of the Fe3O4 nano magnetic particles is preferably 200-500 nm, and more preferably 300-400 nm.

[0037] After obtaining the Fe3O4 nano magnetic particles, the present application coats them with silicon dioxide. In the present application, the Fe3O4 nano magnetic particles are coated with silicon dioxide in an alcohol solution using tetraethoxysilane (TEOS) as a silicon source under the catalytic action of ammonia water, to obtain magnetic nanoparticles Fe3O4@SiO2 coated with SiO2. This technology is a well-known coating technology for silicon dioxide for those skilled in the art, and the present application does not repeat it here. In the present application, the particle size of the magnetic nanoparticles Fe3O4@SiO2 coated with SiO2 is preferably 250-550 nm, and more preferably 350-450 nm.

[0038] After obtaining Fe3O4@SiO2, the present application carries out double bond modification on it, and the present application preferably uses silane containing double bond to modify it. In the present application, the silane containing double bond is preferably one or more of 3-(trimethoxysilyl) methyl propyl methacrylate (MPS), vinyl trimethoxysilane (VTMS), vinyl triethoxysilane and vinyl tri(2-methoxyethoxy)silane; the molar ratio of the silane containing double bond to Fe3O4@SiO2 is preferably 1:(1-5), more preferably 1:(2-4), such as 1:1, 1:2, 1:3, 1:4, 1:5, preferably a range value with any of the above values as the upper limit or lower limit.

[0039] In the present application, the particle size of the double bond functionalized magnetic nanoparticles is preferably 300-600 nm, more preferably 350-550 nm, and most preferably 400-500 nm.

[0040] After completing the double bond modification, the present application carries out copolymerization of the double bond functionalized magnetic nanoparticles and organic monomers in a suspension polymerization manner to form a magnetic microsphere with an internal crosslinked network structure and coated with magnetic nanoparticles.

[0041] In the present application, the organic monomer includes divinylbenzene and can also include one or more of other monomers such as styrene, methyl acrylate, N-vinyl pyrrolidone, N-methyl acrylamide, acrylonitrile, acrylic acid, etc. In an embodiment of the present application, it can be a combination of divinylbenzene (DVB) and N-vinyl pyrrolidone (NVP).

[0042] In the present application, a hydroxypropyl methyl cellulose solution is preferably used as the water phase, and an organic monomer, double bond functionalized magnetic nanoparticles and azobisisobutyronitrile (AIBN) are used as the oil phase, the oil phase is added to the water phase, stirred and dispersed, suspension polymerization is carried out, and a magnetic microsphere is obtained after drying.

[0043] In the present application, the molar ratio of divinylbenzene to other monomers is preferably (2-5):1, more preferably (3-4):1, such as 2:1, 3:1, 4:1, 5:1, preferably a range value with any of the above values as the upper limit or lower limit; and the molar ratio of divinylbenzene to double bond functionalized magnetic nanoparticles is preferably (10-20):1, more preferably (12-18):1, such as 10:1, 11:1, 12:1, 13:1, 14:1, 15:1, 16:1, 17:1, 18:1, 19:1, 20:1, preferably a range value with any of the above values as the upper limit or lower limit.

[0044] In the present application, the concentration of the water phase is preferably 1-10 mg / mL, more preferably 3-8 mg / mL, and most preferably 5-6 mg / mL.

[0045] In the present application, the temperature of the suspension polymerization is preferably 70-85℃, more preferably 75-80℃, and the time of the suspension polymerization is preferably 18-24 hours, more preferably 20-22 hours.

[0046] In the present application, the particle size of the obtained magnetic microspheres is preferably 15-50μm, more preferably 20-40μm.

[0047] After obtaining the magnetic microspheres, the present application grafts carboxyl groups on the surface of the magnetic microspheres through a Friedel-Crafts reaction, and in an embodiment of the present application, the carboxyl groups are preferably groups containing benzoic acid.

[0048] In the present application, the Friedel-Crafts reaction preferably uses anhydrous tin tetrachloride as a catalyst and a compound containing a benzoic acid group, such as p-chloromethyl benzoic acid, as an alkylating agent.

[0049] After grafting the carboxyl groups, the present application uses EDC / NHS as an activating agent to activate the carboxyl groups on the surface of the magnetic microspheres in a 2-morpholinoethanesulfonic acid (MES) buffer solution, and further couples with a compound containing an amino group.

[0050] In some embodiments of the present application, the compound containing an amino group includes one or more of ethanolamine, amino polyethylene glycol, taurine, N,N-diethylethylenediamine, and (2-aminoethyl)trimethylammonium chloride hydrochloride, and different compounds containing an amino group are used to provide different adsorption mechanisms. Those skilled in the art can select different types or structures of compounds containing an amino group according to different application environments and requirements to achieve magnetic solid-phase extraction of different samples.

[0051] The present application also provides a magnetic solid-phase extraction material; the magnetic solid-phase extraction material is a microsphere with a dispersion structure, the inside of the microsphere is a cross-network formed by magnetic nanoparticles and a polydivinylbenzene-containing polymer, and the surface of the microsphere is grafted with a functional group containing an amino group through a carboxyl group, which is used to provide different adsorption mechanisms.

[0052] The particle size of the magnetic solid-phase extraction material is preferably 15-50μm, more preferably 20-40μm.

[0053] The present application also provides a use of the magnetic solid-phase extraction material described above in solid-phase extraction, which is preferably magnetic solid-phase extraction. By adjusting the physical structure, such as thickness and pore size, of the magnetic microspheres and selecting reactants with different chemical structures and properties, the present application can obtain a series of magnetic solid-phase extraction materials with controllable selectivity for different samples, which can be used for the pretreatment of complex samples in the fields of chemical industry, food, environmental analysis, and biological detection, so as to achieve the purpose of effective separation, purification, and enrichment.

[0054] The application provides a preparation method of a magnetic solid-phase extraction material, comprising the following steps: A) bonding a silane containing a double bond to the surface of silica-coated Fe3O4 nano magnetic particles to obtain double bond functionalized magnetic nanoparticles; B) synthesizing polymer-coated magnetic microspheres by suspension polymerization of a material containing divinylbenzene and the double bond functionalized magnetic nanoparticles; C) grafting carboxyl groups on the surface of the polymer-coated magnetic microspheres through a Friedel-Crafts reaction; and D) coupling an amino-containing compound to the surface of the magnetic microspheres grafted with carboxyl groups through a carboxyl activation method to obtain the magnetic solid-phase extraction material. The application precisely and rationally designs a two-step preparation scheme of a magnetic solid-phase extraction material with a dispersion structure. First, the magnetic nanoparticles are coated with silica, and a double bond coating is formed on the surface thereof through silanization, thus solving the problem of poor dispersibility. Meanwhile, the double bond on the surface can be copolymerized with monomers such as divinylbenzene to form dispersion-type magnetic microspheres, thus solving the problem of the inability to form microspheres. In addition, the formed magnetic microspheres are further chemically modified, such as the Friedel-Crafts reaction and EDC / NHS activation for amine coupling, to realize the goals of improving extraction selectivity, recovery rate and repeatability. The preparation method has controllability and flexibility, and is suitable for stable production on a large scale. The dispersion structure magnetic solid-phase extraction material formed has adjustable selectivity, good dispersibility, large specific surface area and high adsorption capacity. The magnetic solid-phase extraction material can be used for the pretreatment of complex samples in the fields of chemical industry, food, environmental analysis and biological detection, so as to achieve the purposes of effective separation, purification and enrichment.

[0055] In order to further illustrate the application, the application provides a magnetic solid-phase extraction material, a preparation method and application thereof are described in detail in the following examples, but it should not be understood as limiting the protection scope of the application.

[0056] Example 1

[0057] 1. Preparation of Fe3O4 nano magnetic particles

[0058] First, 16.2 grams of iron trichloride hexahydrate and 160 milliliters of ethylene glycol are ultrasonically dissolved to form a transparent brown-yellow solution, then 24 grams of anhydrous sodium acetate and 3 grams of sodium citrate are added and stirred to mix uniformly, and the mixture is placed in a high-pressure reaction kettle and reacted in a 200-degree oven for 12 hours, and then naturally cooled to room temperature. The product Fe3O4 nanoparticles are separated by a magnetic separator and washed with anhydrous ethanol and ultrapure water for three times, and each time needs to be cleaned with an ultrasonic cleaner. After washing, the product is dispersed with anhydrous ethanol.

[0059] 2. Silica coating of Fe3O4 nano magnetic particles (Fe3O4@SiO2)

[0060] The magnetic Fe3O4 nanospheres prepared in the previous step were dispersed in 300 mL of ethanol, 30 mL of deionized water was added, and the mixture was ultrasonically dispersed in an ultrasonic cleaner. Then the mixture was transferred to a 500 mL round-bottom flask, 5 mL of tetraethoxysilane (TEOS) and 2 mL of 28% ammonia water were added, and the mixture was stirred for 3 hours. The obtained product was washed twice with anhydrous ethanol and ultrapure water, and each time the ultrasonic cleaner was used. Finally, the product was dispersed in anhydrous ethanol.

[0061] ③ Double bond functional modification of Fe3O4 magnetic nanoparticles

[0062] The Fe3O4@SiO2 particles prepared in step ② were taken out and dispersed in 400 mL of ethanol / water mixture (v / v = 3:1). 8 mL of ammonia water was added to the mixture under a nitrogen atmosphere, and then 8 mL of 3-(trimethoxysilyl) methyl propyl methacrylate (MPS) was added under vigorous stirring. The uniform mixture was heated to 60 degrees and continued to be stirred vigorously for 12 hours. The product was separated by a magnetic separator and washed several times with ultrapure water and ethanol. The washed product was dispersed in anhydrous ethanol.

[0063] ④ Synthesis of hydrophobic magnetic polymer microspheres (HPM)

[0064] Magnetic microspheres were prepared by suspension polymerization. First, 750 mL of a 5 mg / mL hydroxypropyl methylcellulose solution was added to a 2 L round-bottom flask as the aqueous phase; 15 mL of magnetic nanoparticles prepared in step ③ was taken out, solvent replaced with toluene, then 75 mL of divinylbenzene and 0.75 g of azobisisobutyronitrile (AIBN) were added as the oil phase, and then added to the aqueous phase. The suspension was stirred at 700 rpm and gradually heated to 75 degrees. After 20 hours of reaction, the product was separated by a magnetic separator, and the magnetic microspheres were washed with cyclohexane and anhydrous ethanol, respectively, and finally dried at 60 degrees under vacuum to obtain a brown powder.

[0065] ⑤ Synthesis of weak cation exchange magnetic solid phase extraction material (WCX)

[0066] About 10 g of magnetic microspheres prepared in step ④ was taken out and dispersed in 500 mL of dimethylacetamide, poured into a 1000 mL three-necked flask, then 16.4 g of p-chloromethylbenzoic acid and 1.6 mL of anhydrous tin tetrachloride were added, and stirred at 70 degrees for 15 hours. After the reaction was completed, the product was separated by a magnetic separator and washed with 5% acetic acid solution, ultrapure water and anhydrous ethanol three times, respectively. After drying, the obtained magnetic microspheres were the magnetic solid phase extraction material with weak cation exchange function.

[0067] ⑥ Synthesis of hydrophilic-lipophilic balance water-wettable magnetic solid phase extraction material (HLB-2)

[0068] Take 10 grams of magnetic microspheres prepared in step 4, prepare a weak cation exchange function magnetic solid phase extraction material with the method of example 6, then disperse the material in a 2-morpholinoethanesulfonic acid (MES) buffer solution with a pH value of 6.0, add 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride (EDC, 4.65 g) and N-hydroxysuccinimide (NHS, 3.45 g), and stir at room temperature for 6 hours. Then add ethanolamine MEA (NH2CH2CH2OH, 5 ml) dissolved in MES (100 ml) dropwise into the activated magnetic microsphere suspension, and stir at room temperature for 24 hours. Finally, separate the product with a magnetic separator, and wash with ultrapure water several times to remove excess raw materials, and obtain a hydrophilic-lipophilic balance water-infiltrable polymer-coated magnetic solid phase extraction material after vacuum drying.

[0069] Example 2

[0070] Steps 1, 2 and 3 are consistent with Example 1.

[0071] Step 4: Synthesis of amphiphilic magnetic solid phase extraction material (HLB-1)

[0072] Magnetic microspheres were prepared using the method of suspension polymerization. First, 750 ml of a 5 mg / ml hydroxypropyl methylcellulose solution was added to a 2 L round-bottom flask as the water phase; 15 ml of magnetic nanoparticles prepared in step 3 were solvent exchanged with toluene, then 45 ml of divinylbenzene, 30 ml of N-vinylpyrrolidone and 0.75 g of AIBN were added, stirred uniformly as the oil phase, and added to the water phase. The suspension was stirred at a speed of 700 rpm, and the temperature was gradually increased to 75°C. After 20 hours of reaction, the product was separated with a magnetic separator, and the magnetic microspheres were washed with cyclohexane and anhydrous ethanol, respectively, and finally dried at 60°C under vacuum to obtain a brown powder.

[0073] Step 5: Synthesis of weak cation exchange magnetic solid phase extraction material (WCX)

[0074] Take about 10 grams of magnetic microspheres prepared in step 4, disperse them in 500 ml of dimethylacetamide, pour them into a 1000 ml three-necked flask, then add 16.4 g of p-chloromethylbenzoic acid and 1.6 ml of anhydrous tin tetrachloride, and stir at a temperature of 70°C for 15 hours. After the reaction is completed, the product is separated with a magnetic separator, and washed with 5% acetic acid solution, ultrapure water and anhydrous ethanol, respectively, three times. After drying, the obtained magnetic microspheres are the weak cation exchange function magnetic solid phase extraction material.

[0075] Step 6: Synthesis of weak anion exchange magnetic solid phase extraction material (WAX)

[0076] Take 10 grams of magnetic microspheres prepared in step 5, disperse them in MES buffer solution with pH value of 6.0, add 4.65 grams of EDC and 3.45 grams of NHS, stir at room temperature for 6 hours. Then, drop N, N-diethyl ethylenediamine (DEED, 3.48 grams) dissolved in MES (100 milliliters) into the activated magnetic microsphere suspension, stir at room temperature for 24 hours. Finally, separate the product with a magnetic separator, wash several times with ultrapure water to remove excess raw materials, and vacuum dry to obtain a functionalized magnetic solid-phase extraction material with weak anion exchange.

[0077] Example 3

[0078] Steps 1, 2, 3, 4 and 5 are consistent with Example 2.

[0079] Synthesis of a magnetic solid-phase extraction material with restricted access (RAM)

[0080] Take 10 grams of magnetic microspheres prepared in step 5, disperse them in MES buffer solution with pH value of 6.0, add 4.65 grams of EDC and 3.45 grams of NHS, stir at room temperature for 6 hours. Then, drop N, N-diethyl ethylenediamine (DEED, 3.48 grams) dissolved in MES (100 milliliters) into the activated magnetic microsphere suspension, stir at room temperature for 24 hours. Finally, separate the product with a magnetic separator, wash several times with ultrapure water to remove excess raw materials, and vacuum dry to obtain a functionalized magnetic solid-phase extraction material with weak anion exchange.

[0081] Figure 6 The infrared spectra of several magnetic materials are shown. Due to the presence of polypyrrolidone (PVP), HLB has a strong C=O stretching vibration absorption peak at 1685 cm -1 , which is a characteristic peak of PVP; 1284 cm -1 is the C-N stretching vibration absorption peak. 1000-650 cm -1 Strong absorption peaks appear, which are the out-of-plane bending vibration peaks of benzene ring C-H, introduced by diethylbenzene polymerization, and the same absorption peaks are also observed in HPM, WCX and HLB-2. The infrared spectrum of WCX appears characteristic absorption peaks of carboxyl at 1747 and 1230 cm -1 , which are the C=O stretching vibration peak and the coupling peak of O-H in-plane bending vibration and C=O stretching vibration of carboxylic acid, respectively, indicating that carboxyl groups have been successfully introduced into HPM. After coupling with an amino-containing compound, HLB-2 obtained at 1694 cm -1 has an infrared characteristic peak of amide group.

[0082] Application of novel magnetic solid phase extraction material for dispersive solid phase extraction

[0083] The amphiphilic dispersion structure magnetic solid phase extraction material obtained in the above examples can be used to extract organic compounds in aqueous solution, and its use method is similar to that of the commonly used Oasis HLB silica gel solid phase extraction material, except that it does not need to be filled into a column, but uses a magnetic attraction device.

[0084] The specific use method is as follows: similar to the conventional solid phase extraction material, first take 10 mg of the hydrophilic-lipophilic balanced water-wettable polymer-coated magnetic solid phase extraction material synthesized in Example 1, disperse it in 5 mL of methanol for activation, after magnetic separation, disperse it in 10 mL of the solution to be tested, shake well for 5 minutes to complete the adsorption of the components to be tested, use 5 mL of acetonitrile aqueous solution (5%) to clean the magnetic microspheres, then transfer the magnetic microspheres to 5 mL of acetonitrile and shake for 3 minutes to complete the elution, the eluent can be further concentrated using a nitrogen purifier, and finally the concentrated liquid is detected by liquid chromatography.

[0085] For other examples of magnetic solid phase extraction materials synthesized with similar or different adsorption mechanisms, the operation steps are consistent with the above method, except that the activation and elution solutions need to be replaced with mixed solvents with corresponding properties, such as the magnetic solid phase extraction material (WCX) synthesized in step ⑤ of Example 1, which needs to be activated and eluted using a methanol solution containing 5% acetic acid.

[0086] The above only describes the preferred embodiments of the present application, and it should be noted that for ordinary skilled persons in the art, several improvements and refinements can be made without departing from the principles of the present application, and these improvements and refinements should also be considered within the scope of protection of the present application.

Claims

1. A method for preparing a magnetic solid phase extraction material, comprising the following steps: A) bonding a double bond-containing silane to the surface of silica-coated Fe3O4 nano-magnetic particles to obtain double bond-functionalized magnetic nanoparticles; B) using a hydroxypropyl methylcellulose solution as an aqueous phase, using an organic monomer, double bond-functionalized magnetic nanoparticles and azobisisobutyronitrile as an oil phase, adding the oil phase to the aqueous phase, stirring and dispersing, performing suspension polymerization, and drying to obtain polymer-coated dispersed magnetic microspheres; the organic monomer includes divinylbenzene, and optionally other monomers; the other monomers include one or more of styrene, methyl acrylate, N-vinyl pyrrolidone, N-methyl acrylamide, acrylonitrile, and acrylic acid; C) grafting carboxyl groups to the surface of the polymer-coated magnetic microspheres through a Friedel-Crafts reaction; D) coupling an amino-containing compound to the surface of the magnetic microspheres grafted with carboxyl groups through a carboxyl activation method to obtain a magnetic solid phase extraction material.

2. The production method according to claim 1, characterized by, The Fe3O4 nano-magnetic particles are prepared by a solvothermal method.

3. The preparation method according to claim 1, characterized in that, The double bond-containing silane is one or more of 3-(trimethoxysilyl) methyl methacrylate, vinyltrimethoxysilane, vinyltriethoxysilane, and vinyltri(2-methoxyethoxy)silane.

4. The method of claim 1, wherein, In step C), a compound containing a benzoic acid group is modified to the surface of the polymer-coated magnetic microspheres through a Friedel-Crafts reaction.

5. The production method according to claim 4, characterized by, The catalyst for the Friedel-Crafts reaction is anhydrous tin tetrachloride, and the compound containing a benzoic acid group is p-chloromethyl benzoic acid.

6. The method of claim 1, wherein, EDC / NHS is used as a carboxyl activation reagent in step D); The amino-containing compound includes one or more of ethanolamine, amino polyethylene glycol, taurine, N, N-diethyl ethylenediamine, and (2-aminoethyl) trimethylammonium chloride hydrochloride.

7. The magnetic solid phase extraction material prepared by the method of any one of claims 1-6; the magnetic solid phase extraction material is a microsphere with a dispersed structure, the inside of the microsphere is a cross-linked network formed by magnetic nanoparticles and a polymer containing divinylbenzene, and the surface of the microsphere is grafted with a functional group containing an amino group through a carboxyl group, which is used to provide different adsorption mechanisms.

8. Use of the magnetic solid phase extraction material of claim 7 in solid phase extraction.

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