Polymer-coated porous magnetic solid-phase extraction material, its preparation method and application

Abstract

The present invention discloses a polymer-coated porous magnetic solid-phase extraction material, its preparation method and application, which relates to the technical field of magnetic solid-phase extraction. It includes a porous matrix, and the internal pores of the porous matrix are loaded with γ-Fe2O3 nanoparticles, and the surface of the γ-Fe2O3 nanoparticles is coated with a polymer layer. All the iron in the γ-Fe2O3 nanoparticles is trivalent iron, with more stable properties and being difficult to be oxidized, so there will be no problem of magnetic decline and / or magnetic instability after long-term storage. In addition, by controlling the loading amount of the γ-Fe2O3 nanoparticles, the magnetism of the polymer-coated porous magnetic solid-phase extraction material can be regulated to obtain a polymer-coated porous magnetic solid-phase extraction material with better magnetism. The present invention also coats a polymer layer on the surface of the γ-Fe2O3 nanoparticles to prevent the magnetic nanoparticles on the porous matrix from falling off, and will not cause blockage of the detection instrument and / or contamination of the sample.

Description

Technical Field

[0001] The present invention relates to the technical field of magnetic solid phase extraction, and in particular, to a polymer-coated porous magnetic solid phase extraction material, a preparation method thereof, and an application thereof. Background Art

[0002] Magnetic solid phase extraction (MSPE) technology is a kind of dispersive solid phase extraction technology using magnetic or magnetizable materials as adsorbent matrices. Its working principle includes adding magnetic solid phase extraction materials to a sample solution to adsorb analytes, and then implementing magnetic separation through an external magnetic field. The magnetic solid phase extraction materials adsorbed with analytes are separated from the liquid matrix. Compared with traditional solid phase extraction technology, the phase separation process of magnetic solid phase extraction is more efficient, the operation is simpler, filtration is not required, and low-concentration trace extraction can be achieved only by using a small amount of adsorbent and a short equilibration time. It has very high extraction capacity and extraction efficiency. In addition, it is easy to elute without using a large amount of organic solvents, and the magnetic solid phase extraction materials are easy to recover and can be reused repeatedly, having excellent application prospects.

[0003] The magnetic properties of magnetic solid phase extraction materials are one of the key influencing factors for realizing the separation and purification of substances. Therefore, improving the magnetic properties of magnetic solid phase extraction materials and / or realizing the adjustable magnetic properties of magnetic solid phase extraction materials is one of the common goals pursued in this field. In addition, since magnetic solid phase extraction materials are used as detection products, avoiding the shedding of magnetic particles in the magnetic solid phase extraction materials and / or the combination of magnetic particles with analytes during the detection process is also an important problem that needs to be solved urgently in this field. At the same time, existing magnetic solid phase extraction materials generally have problems of poor magnetic properties and / or unstable magnetism after long-term placement.

[0004] To solve any of the above problems, in view of this, the present invention is specifically proposed. Summary of the Invention

[0005] The purpose of the present invention is to provide a polymer-coated porous magnetic solid phase extraction material, a preparation method thereof, and an application thereof.

[0006] The present invention is implemented as follows:

[0007] In a first aspect, the present invention provides a polymer-coated porous magnetic solid phase extraction material, including a porous matrix, on the internal pores of which γ-Fe2O3 nanoparticles are loaded, and a polymer layer is coated on the surface of the γ-Fe2O3 nanoparticles.

[0008] Second aspect, the present invention provides a method for preparing a magnetic solid-phase extraction material according to any one of the foregoing embodiments, including in-situ growth of Fe3O4 nanoparticles on the internal pores of a porous matrix, followed by calcination of the porous matrix with Fe3O4 nanoparticles to obtain a porous matrix loaded with γ-Fe2O3 nanoparticles, and then coating a polymer layer on the surface of the γ-Fe2O3 nanoparticles by precipitation polymerization method.

[0009] Third aspect, the present invention provides an application of a magnetic solid-phase extraction material according to any one of the foregoing embodiments or a magnetic solid-phase extraction material prepared by the preparation method according to any one of the foregoing embodiments in any field of catalysis, medical detection, food detection or cosmetic detection.

[0010] The present invention has the following beneficial effects:

[0011] The present invention provides a polymer-coated porous magnetic solid-phase extraction material, its preparation method and application. By loading γ-Fe2O3 nanoparticles on the internal pores of a porous matrix, all of the inside of the γ-Fe2O3 nanoparticles is trivalent iron, and its properties are more stable and difficult to be oxidized. There will be no problem of magnetic decline and / or magnetic instability after long-term placement. In addition, by controlling the loading amount of γ-Fe2O3 nanoparticles, the magnetism of the polymer-coated porous magnetic solid-phase extraction material can be regulated to obtain a polymer-coated porous magnetic solid-phase extraction material with better magnetism. The present invention also coats a polymer layer on the surface of the γ-Fe2O3 nanoparticles to prevent the magnetic nanoparticles on the porous matrix from falling off, and will not cause blockage of the detection instrument and / or contamination of the sample. Description of the Drawings

[0012] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required to be used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention, and therefore should not be regarded as limiting the scope. For those of ordinary skill in the art, other related drawings can be obtained based on these drawings without creative efforts.

[0013] Figure 1 It is a flowchart of the preparation method of the polymer-coated porous magnetic solid-phase extraction material provided by the embodiment of the present invention;

[0014] Figure 2 It is a schematic diagram of the polymer coating process provided by the embodiment of the present invention;

[0015] Figure 3 It is a scanning electron microscope image of the polymer-coated porous magnetic solid-phase extraction material provided by Example 1 of the present invention;

[0016] Figure 4SEM image of the polymer-coated porous magnetic solid-phase extraction material provided in Example 2 of the present invention;

[0017] Figure 5 SEM image of the polymer-coated porous magnetic solid-phase extraction material provided in Example 3 of the present invention;

[0018] Figure 6 SEM image of the polymer-coated porous magnetic solid-phase extraction material provided in Example 4 of the present invention;

[0019] Figure 7 SEM image of the polymer-coated porous magnetic solid-phase extraction material provided in Example 5 of the present invention;

[0020] Figure 8 SEM image of the polymer-coated porous magnetic solid-phase extraction material provided in Example 6 of the present invention;

[0021] Figure 9 Schematic diagram of the ultrasonic simulation test of the γ-Fe2O3 nanoparticle shedding effect of the product obtained in steps S02 and S03 provided in Example 6 of the present invention;

[0022] Figure 10 SEM image of the polymer-coated porous magnetic solid-phase extraction material provided in Example 7 of the present invention. Detailed implementation manners

[0023] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. For those conditions not specified in the embodiments, they are carried out according to conventional conditions or the conditions recommended by the manufacturer. For reagents or instruments whose manufacturers are not specified, they are all conventional products that can be obtained through commercial purchases.

[0024] The features and properties of the present invention will be further described in detail below in conjunction with the embodiments.

[0025] In a first aspect, the present invention provides a polymer-coated porous magnetic solid-phase extraction material, which includes a porous matrix. γ-Fe2O3 nanoparticles are loaded on the internal pores of the porous matrix, and a polymer layer is coated on the surface of the γ-Fe2O3 nanoparticles.

[0026] Among them, the polymer layer is coated on the surface of the γ-Fe2O3 nanoparticles to prevent the γ-Fe2O3 nanoparticles from falling off or contacting the sample to be detected, so that the polymer-coated porous magnetic solid-phase extraction material provided by the present invention will not cause blockage of the detection instrument and / or contamination of the sample during the detection process.

[0027] In addition, the polymer layer can be made of non-functional materials such as divinylbenzene (DVB) and N-vinylpyrrolidone (NVP). Functional materials such as sodium vinyl sulfonate, methacrylic acid, and methacryloyloxyethyl trimethyl ammonium chloride can also be added to the polymer layer to obtain a magnetic solid-phase extraction material with cation exchange function and / or anion exchange function. Therefore, the polymer-coated porous magnetic solid-phase extraction material provided by the present invention has stronger applicability.

[0028] Furthermore, all of the iron in the γ-Fe2O3 nanoparticles is trivalent iron, which has more stable properties and is difficult to be oxidized. After long-term storage, there will be no problems such as magnetic decline and / or magnetic instability. Therefore, when performing magnetic solid-phase extraction with the polymer-coated porous magnetic solid-phase extraction material provided by the present invention, it is safer to use, will not contaminate the sample to be measured, has adjustable magnetism, and the magnetic properties are stable after long-term storage, and there will be no magnetic decline, showing broad application prospects.

[0029] In an alternative embodiment, the loading amount of γ-Fe2O3 nanoparticles on the porous matrix is 5-30%, and the thickness of the polymer layer is 1-3 nm.

[0030] When a magnetic solid-phase extraction material with stronger magnetism is needed, the loading amount of γ-Fe2O3 nanoparticles on the porous matrix can be increased, and vice versa.

[0031] Controlling the thickness of the polymer layer within the above range can not only prevent the γ-Fe2O3 nanoparticles from falling off, but also ensure that the magnetic properties of the magnetic solid-phase extraction material will not be affected.

[0032] Preferably, the magnetization intensity of the polymer-coated porous magnetic solid-phase extraction material is 10-25 emu / g, which can meet the usage requirements of application fields with high magnetic property requirements for magnetic solid-phase extraction materials.

[0033] Preferably, the polymer-coated porous magnetic solid-phase extraction material comprises a plurality of polymer-coated magnetic porous microspheres. The particle size of each polymer-coated magnetic porous microsphere is 5-25 μm, the average pore diameter is 4-60 nm, the pore volume is 0.5-1.5 cm 2 / g, and the specific surface area ≥ 400 m 2 / g.

[0034] More preferably, the average pore diameter of each polymer-coated magnetic porous microsphere is 5-8 nm, the pore volume is 0.7-1.2 cm 2 / g, and the specific surface area is 680-780 m 2 / g.

[0035] Existing magnetic porous microspheres are usually polydisperse microspheres with uneven particle sizes, which is not conducive to the batch repeatability of the production process of magnetic porous microspheres and will also affect sample detection. The magnetic solid-phase extraction material provided by the present invention has more uniform particle sizes of individual polymer-coated magnetic porous microspheres, which is conducive to achieving batch repeatability in the production process of magnetic porous microspheres and is conducive to sample detection.

[0036] In addition, the porosity and specific surface area of the polymer-coated magnetic porous microspheres provided by the present invention are both large. Therefore, the adsorption capacity of the polymer-coated porous magnetic solid-phase extraction material provided by the present invention for the sample to be detected is improved.

[0037] In an alternative embodiment, the outer surface of the porous matrix and the surfaces of the γ-Fe2O3 nanoparticles in the internal pores are both coated with a polymer layer.

[0038] Preferably, the raw material of the polymer layer is a comonomer, and the comonomer includes a non-functional comonomer, and the non-functional comonomer includes any one of divinylbenzene (DVB), vinylpyrrolidone (NVP), styrene (St), glycidyl methacrylate (GMA), and ethylene glycol dimethacrylate (EGDMA).

[0039] In an alternative embodiment, the comonomer further includes a functional comonomer, and the functional comonomer includes a cation exchange resin monomer and / or an anion exchange resin monomer.

[0040] The cation exchange resin monomer includes any one of sodium vinyl sulfonate and methacrylic acid.

[0041] The anion exchange resin monomer is methacryloyloxyethyl trimethyl ammonium chloride.

[0042] Of course, the functional comonomer can also be other types of comonomers or other components in the above types of comonomers to endow the polymer-coated porous magnetic solid-phase extraction material with different functions. Therefore, the polymer-coated porous magnetic solid-phase extraction material provided by the present invention has stronger adjustability.

[0043] The raw material properties of the porous matrix also have a significant impact on the performance of the finally obtained magnetic solid-phase extraction material. At present, most magnetic porous microspheres have uneven particle sizes, poor monodispersity, and even agglomeration phenomena, which affect the process of magnetic solid-phase extraction. Preferably, the raw material of the porous matrix includes any one of HLB polymers, polystyrene, and polydivinylbenzene, and it is required that the particle sizes of the porous matrix are uniform and the monodispersity is excellent.

[0044] In a second aspect, the present invention provides a method for preparing a magnetic solid-phase extraction material according to any one of the foregoing embodiments, including in-situ growing Fe3O4 nanoparticles on the internal pores of a porous matrix, then calcining the porous matrix with Fe3O4 nanoparticles to obtain a porous matrix loaded with γ-Fe2O3 nanoparticles, and then coating a polymer layer on the surface of the γ-Fe2O3 nanoparticles by precipitation polymerization.

[0045] The existing methods for preparing magnetic solid-phase extraction materials are mainly one-step methods. The one-step method is to pre-prepare magnetic nanoparticles, mix the magnetic nanoparticles with the reaction monomers of the porous matrix and react simultaneously to prepare the magnetic solid-phase extraction material in one step. The corresponding method is mainly suspension polymerization. Suspension polymerization has been developed earlier, but due to the uncontrollability of the suspension polymerization process, most of the magnetic porous microspheres prepared are polydisperse microspheres with uneven particle sizes, which is not conducive to the batch repeatability of the production process of magnetic solid-phase extraction materials and is not conducive to sample detection.

[0046] For example, the prior art CN115894978A discloses a magnetic solid-phase extraction microsphere and its preparation method. This method requires pre-preparing oleic acid-modified Fe3O4 magnetic fluid, and then preparing the magnetic solid-phase extraction microsphere in one step by suspension polymerization. Among them, the oleic acid hydrophobicity on the surface of the Fe3O4 magnetic fluid may cause non-specific adsorption, and the magnetic solid-phase extraction microspheres prepared by the one-step method of suspension polymerization are obviously found to have uneven particle sizes and poor monodispersity under microscopic observation.

[0047] The prior art CN116099519A discloses a magnetic solid-phase extraction material, its preparation method and application. By coating a layer of silica on the surface of Fe3O4 magnetic nanoparticles, then bonding a silane containing a double bond, and then through the method of suspension polymerization, a magnetic solid-phase extraction microsphere with a dispersed structure is prepared in one step. Although this method can protect the magnetic nanoparticles, the magnetic solid-phase extraction microspheres are still prepared by suspension polymerization, and the particle size is difficult to accurately control, which is not conducive to the batch repeatability of the performance of the magnetic solid-phase extraction microspheres.

[0048] The prior art CN106867021B discloses a method for preparing magnetic porous polymer microspheres, which includes coating magnetic Fe2O3 nanoparticles with oleic acid, and then swelling the magnetic Fe2O3 nanoparticles into the pores of porous polymer microspheres crosslinked by glycidyl methacrylate and ethylene glycol dimethacrylate to obtain magnetic porous polymer microspheres. This method prepares magnetic porous polymer microspheres by a two-step process. However, in the loading process of magnetic Fe2O3 nanoparticles, the magnetic fluid swells into the pores of the polymer microspheres, and the filling process cannot be controlled, which easily causes more magnetic nanoparticles to adhere to the surface of the polymer microspheres, posing a risk of shedding during use, and will also cause contamination to the sample and inevitable losses to the subsequent detection instruments.

[0049] In the present invention, a prepared porous matrix is used, and Fe3O4 nanoparticles are in-situ grown on the internal pores of the porous matrix to carry out a two-step reaction. The obtained magnetic solid-phase extraction material has uniform particle size and strong monodispersity, which is beneficial to the batch repeatability in the production process of the magnetic solid-phase extraction material and is beneficial to sample detection. At the same time, the method of in-situ growing Fe3O4 nanoparticles does not require pre-preparation of magnetic nanoparticles, so the manufacturing cost is reduced, the preparation method is simple, and the growth process of Fe3O4 nanoparticles is controllable.

[0050] In addition, the magnetic nanoparticles on the surface of the existing magnetic solid-phase extraction material are composed of Fe3O4. Fe3O4 is easily oxidized when placed in air for a long time, resulting in problems such as a decrease in magnetic performance and / or magnetic instability. Therefore, the inventor proposes to use a calcination method to convert the Fe3O4 nanoparticles loaded in the internal pores of the porous matrix into stable γ-Fe2O3 nanoparticles. All the iron in the γ-Fe2O3 nanoparticles is in the form of Fe 3+ while the iron in Fe3O4 has both Fe 2+ and Fe 3+ . Therefore, γ-Fe2O3 nanoparticles are more stable than Fe3O4 and are difficult to be oxidized, thus ensuring the long-term magnetic performance of the magnetic solid-phase extraction material.

[0051] Currently, the method of coating a polymer layer on the surface of magnetic nanoparticles mainly uses suspension polymerization. By dispersing a porous matrix with magnetic nanoparticles in a polymer solution for suspension polymerization, a polymer layer is coated on the surface of the porous matrix with magnetic nanoparticles. However, this method cannot control the thickness of the polymer layer and easily affects the internal porosity of the porous matrix. Finally, the obtained magnetic porous microspheres of the polymer-coated magnetic solid-phase extraction material have non-uniform particle size, which affects the detection effect of the magnetic solid-phase extraction material.

[0052] In the present invention, a polymer layer is coated on the surface of a porous matrix loaded with γ-Fe2O3 nanoparticles by precipitation polymerization. The thickness of the polymer layer and the porosity inside the porous structure can be controlled by adding the amount of comonomer, and a magnetic solid-phase extraction material coated with a polymer with uniform particle size and large porosity can be obtained.

[0053] As Figure 1 shown in the flowchart, in some embodiments, a method for preparing a magnetic solid-phase extraction material coated with a polymer provided by the present invention includes the following steps:

[0054] S01. Loading Fe3O4 nanoparticles

[0055] In an alternative embodiment, the method for in-situ growing Fe3O4 nanoparticles on the internal pores of the porous matrix includes: loading magnetic metal salts on the internal pores of the porous matrix by the immersion method, and then in-situ growing Fe3O4 nanoparticles on the internal pores of the porous matrix by the coprecipitation method.

[0056] S011. Immersion method

[0057] In an alternative embodiment, in order to improve the loading capacity of the magnetic metal salts on the porous matrix, the immersion method includes dispersing the porous matrix in a magnetic metal salt solution under a protective atmosphere and then performing ultrasonic immersion.

[0058] Preferably, in order to achieve the effect of adjustable magnetic properties of the magnetic solid-phase extraction material, the number of times the porous matrix is immersed in the magnetic metal salt solution can be adjusted. For example, it can be immersed 2 times.

[0059] Preferably, the concentration of the magnetic metal salt in the magnetic metal salt solution is 0.05 - 0.40 g / ml, for example, it can be any value among 0.05 g / ml, 0.10 g / ml, 0.15 g / ml, 0.20 g / ml, 0.25 g / ml, 0.30 g / ml, 0.35 g / ml or 0.40 g / ml, or the range value between any two values, or the point value within the range value.

[0060] Preferably, the dispersion ratio of the porous matrix to the magnetic metal salt solution is 1 g: 15 - 25 mL. For example, the volume of the magnetic metal salt solution required for each gram of the porous matrix can be any value among 15 mL, 17 mL, 19 mL, 21 mL, 23 mL or 25 mL, or the range value between any two values, or the point value within the range value.

[0061] Since the magnetic component of the magnetic solid-phase extraction material provided by the present invention is an iron-containing substance, the magnetic metal salt should also be an iron salt. Preferably, the magnetic metal salt includes Fe 2+ salt and Fe 3+ salt.

[0062] Preferably, the concentration of Fe 2+ salt in the magnetic metal salt solution is 0.1 - 0.2 g / mL; the concentration of Fe 3+ salt in the magnetic metal salt solution is 0.1 - 0.2 g / mL. More preferably, the concentration of Fe 2+ salt in the magnetic metal salt solution is 0.14 - 0.16 g / mL; the concentration of Fe 3+ salt in the magnetic metal salt solution is 0.18 - 0.19 g / mL.

[0063] Preferably, the Fe 2+ salt includes any one of ammonium ferrous sulfate, ferrous sulfate, and ferrous chloride; the Fe 3+ salt includes any one of ammonium ferric sulfate, ferric sulfate, ferric chloride, and ferric nitrate.

[0064] Preferably, the time of ultrasonic soaking is 10 - 15 h, for example, it can be any value among 10 h, 11 h, 12 h, 13 h, 14 h, or 15 h, or the range value between any two values, or the point value within the range value.

[0065] Preferably, room temperature soaking is maintained during ultrasonic soaking. More preferably, the temperature of ultrasonic soaking is 25 °C.

[0066] Preferably, after ultrasonic soaking, it further includes separating the porous matrix loaded with magnetic metal salt from the liquid and then cleaning. During the ultrasonic soaking process, the magnetic metal salt will be loaded on the surface of the porous matrix, including the outer surface and the surface of the internal pores. In order to ensure that the finally obtained magnetic solid-phase extraction material has good monodispersity and avoid agglomeration between magnetic porous microspheres, it is necessary to remove the magnetic metal salt on the outer surface of the porous matrix through cleaning.

[0067] Preferably, the separation method can adopt methods such as centrifugation and filtration.

[0068] Cleaning can be carried out by rinsing with a cleaning solution, and the number of cleaning times is 2 - 5 times. The method of rinsing with a cleaning solution can quickly remove the magnetic metal salt on the surface of the porous matrix, and at the same time can retain the magnetic metal salt in the pores, ensuring the magnetic properties and dispersion properties of the finally obtained magnetic porous microspheres.

[0069] In the embodiments of the present invention, unless otherwise specified, the cleaning solution used in the cleaning step includes but is not limited to any one of ethanol, water, and methanol.

[0070] In the embodiments of the present invention, unless otherwise specified, the protective atmosphere includes any one of nitrogen and argon; preferably nitrogen.

[0071] S012. Coprecipitation method

[0072] In an alternative embodiment, the co-precipitation method includes dispersing a porous matrix loaded with a magnetic metal salt in a solution system under a protective atmosphere, adjusting the pH value of the solution system to 8-10, and then heating for reaction.

[0073] By using the immersion method to load the magnetic metal salt into the internal pores of the porous matrix, and then through the co-precipitation method, adjusting the pH of the solution system, so that the magnetic metal salt on the porous matrix can in-situ react to generate Fe3O4 nanoparticles under the above alkaline conditions, achieving the effect of loading Fe3O4 nanoparticles in the internal pores of the porous matrix.

[0074] To promote the in-situ reaction for generating Fe3O4 nanoparticles, preferably, the temperature of the heating reaction is 65-75 °C, and the reaction time is 4-10 h.

[0075] Preferably, the method for adjusting the pH value of the solution system includes adding a base to the solution system.

[0076] Preferably, the added base includes any one of ammonia water, sodium hydroxide, and potassium hydroxide. The concentration and mass of the added base are such that the pH of the final solution system satisfies 8-10.

[0077] Preferably, the solution system includes any one of ethanol, methanol, propanol, and n-butanol. In the present invention, unless otherwise specified, the system for dispersing the material containing the porous matrix is the same as the above solution system.

[0078] Preferably, the dispersion ratio of the porous matrix to the solution system is 1 g: 10-20 mL. For example, each gram of the porous matrix needs to be dispersed in any value of 10 mL, 12 mL, 14 mL, 16 mL, 18 mL, or 20 mL, or the range value between any two values, or the point value within the range value of the magnetic metal salt solution.

[0079] Preferably, after the co-precipitation reaction ends, it further includes cleaning the porous matrix with Fe3O4 nanoparticles.

[0080] The cleaning includes first rinsing with the solution system, and then rinsing with a weak acid. The number of times of rinsing with the weak acid is one or two, and the pH of the weak acid is 0-2.

[0081] Preferably, the weak acid includes any one of dilute hydrochloric acid, dilute sulfuric acid, and dilute nitric acid. Preferably, the concentration of the weak acid is 0.1-0.3 mol / L.

[0082] Rinsing with the solution system can also remove the Fe3O4 nanoparticles on the outer surface of the porous matrix. In order to minimize the Fe3O4 nanoparticles on the outer surface of the porous matrix, after rinsing with the solution system, it further includes rinsing with a weak acid to better remove the Fe3O4 nanoparticles on the outer surface of the porous matrix.

[0083] Preferably, after the coprecipitation reaction is completed, the number of times of rinsing with the solution system is 2 to 5 times.

[0084] The present invention uses the immersion method and the coprecipitation method to directly grow Fe3O4 nanoparticles on the internal pores of the porous matrix without pre-synthesizing magnetic nanoparticles (such as Fe3O4 nanoparticles) or pre-preparing magnetic fluids, reducing the production cost of the magnetic solid-phase extraction material. Moreover, the loading process is simple, highly controllable, has mild reaction conditions, and simple reaction equipment, and is suitable for large-scale batch production.

[0085] S02, calcination

[0086] In an alternative embodiment, the parameters of the calcination include: the calcination temperature is 250 to 300 °C, the calcination time is 2 to 4 h, and the heating rate is 4 to 6 °C / min.

[0087] Preferably, the calcination process can be carried out using a tube furnace.

[0088] Preferably, there is no special requirement for the reaction atmosphere during the calcination process, and the calcination can be carried out in an air atmosphere.

[0089] Preferably, after the calcination is completed, the porous matrix loaded with γ-Fe2O3 nanoparticles is cooled to room temperature, such as 25 °C, for standby.

[0090] The calcination process can transform the Fe3O4 nanoparticles in the internal pores of the porous matrix into γ-Fe2O3 nanoparticles with higher magnetic responsiveness and better chemical stability, extending the service life of the magnetic solid-phase extraction material, and the magnetic strength and magnetic stability of the magnetic solid-phase extraction material will not be significantly affected after long-term storage.

[0091] Preferably, to ensure the transformation of Fe3O4 nanoparticles into γ-Fe2O3 nanoparticles and avoid deformation or decomposition of the porous matrix, the calcination temperature needs to be lower than the thermal decomposition temperature of the porous matrix. This can be achieved by selecting the material of the porous matrix and controlling the calcination temperature within the above range.

[0092] S03, polymer coating

[0093] In an alternative embodiment, the precipitation polymerization method includes dispersing the porous matrix loaded with γ-Fe2O3 nanoparticles in a dispersant, adding a comonomer and an initiator under a protective atmosphere, and heating and reacting after sufficient dispersion.

[0094] By coating a polymer on the outer surface of the porous matrix loaded with γ-Fe2O3 nanoparticles, that is, on the outer surface of the porous matrix and the surface of the γ-Fe2O3 nanoparticles in the internal pores, a polymer layer is formed, which can avoid the non-specific adsorption of the magnetic solid-phase extraction material to the sample to be detected, prevent the γ-Fe2O3 nanoparticles from falling off at the same time, and the coating method process is controllable.

[0095] Preferably, the dispersion ratio of the porous matrix loaded with γ-Fe2O3 nanoparticles in the dispersant is 1 g: 5-35 mL. That is, 5-35 mL of dispersant is required to disperse every gram of the porous matrix loaded with γ-Fe2O3 nanoparticles.

[0096] The dispersant includes a solvent and a dispersion promoter; the solvent provides a reaction environment for the coating process of the polymer, and the dispersion promoter can promote the dispersion degree of the porous matrix loaded with γ-Fe2O3 nanoparticles in the dispersant and ensure the uniformity of the polymer coating.

[0097] The solvent includes polar solvents and / or non-polar solvents.

[0098] Preferably, the polar solvent includes any one of acetonitrile, ethanol, dimethyl sulfoxide and dimethylacetamide; the non-polar solvent includes any one of toluene, cyclohexane, benzene and xylene; the dispersion promoter includes any one of polyvinylpyrrolidone, polyvinyl alcohol, sodium polyacrylate and carboxymethyl cellulose.

[0099] In order to adapt to different types of polymer coating processes, preferably, the solvent in the dispersant is a mixture of polar solvents and non-polar solvents, and the volume ratio of the polar solvent to the non-polar solvent is 2-4: 1-3; the concentration of the dispersion promoter in the dispersant is 1.7-4.0%.

[0100] Preferably, the process of dispersing the porous matrix loaded with γ-Fe2O3 nanoparticles in the dispersant is stirring dispersion, and the reaction atmosphere during the stirring process is a protective atmosphere.

[0101] Preferably, the stirring speed is 200-300 rpm and the stirring time is 20-40 min.

[0102] Preferably, the comonomer includes the functional comonomer and the non-functional comonomer as described above. Such as Figure 2As shown, for example, the comonomer can be a mixture of divinylbenzene (DVB) and vinylpyrrolidone (NVP) to form a porous magnetic solid-phase extraction material coated with HLB; when the comonomer is a mixture of divinylbenzene and styrene (St), a porous magnetic solid-phase extraction material coated with polystyrene (PS) is formed; when the comonomer is a mixture of divinylbenzene, vinylpyrrolidone and a carboxyl monomer, a porous magnetic solid-phase extraction material with weak cation exchange is formed; when the comonomer is a mixture of divinylbenzene, vinylpyrrolidone and a sulfonic acid monomer, a porous magnetic solid-phase extraction material with strong cation exchange is formed; when the comonomer is a mixture of divinylbenzene, vinylpyrrolidone and a quaternary ammonium-based monomer, an anion-exchange porous magnetic solid-phase extraction material is formed. It should be noted that the method provided by the present invention can be applied to the preparation of non-functional porous magnetic solid-phase extraction materials and can also be applied to the preparation of functional porous magnetic solid-phase extraction materials.

[0103] Preferably, the comonomer is a mixture of diethylvinylbenzene (DVB) and vinylpyrrolidone (NVP), and the volume ratio of the two is 0.8 - 1.2:0.8 - 1.2.

[0104] Preferably, the mass ratio of the initiator to the porous matrix loaded with γ-Fe2O3 nanoparticles is 0.1 - 0.5:5.

[0105] Preferably, after adding the comonomer and the initiator, sufficient dispersion is carried out, including stirring dispersion and / or ultrasonic dispersion; more preferably, it is stirring dispersion and ultrasonic dispersion.

[0106] Preferably, after adding the comonomer and the initiator, stir and disperse for 20 - 40 min, and then carry out ultrasonic dispersion.

[0107] Preferably, the time for ultrasonic dispersion when adding the comonomer and the initiator for sufficient dispersion is 2 - 4 h.

[0108] Preferably, after adding the comonomer and the initiator and sufficient dispersion, the temperature for the temperature-raising reaction is 65 - 75 °C, and the reaction time is 12 - 36 h.

[0109] Preferably, the initiator includes any one of azo initiators, benzoyl peroxide, ammonium persulfate and potassium persulfate. The azo initiator can be, for example, azobisisobutyronitrile.

[0110] Preferably, after the reaction is completed, it further includes washing and drying the porous magnetic solid-phase extraction material coated with the polymer.

[0111] Preferably, the washing includes washing with a washing solution to remove the excess residual polymer on the surface. The number of washing times is 3 - 8 times.

[0112] Preferably, the drying temperature is 55~65°C and the drying time is 12~36 h.

[0113] In a third aspect, the present invention provides an application of a magnetic solid-phase extraction material according to any one of the foregoing embodiments or a magnetic solid-phase extraction material prepared by the preparation method according to any one of the foregoing embodiments in any field of catalysis, medical detection, food detection or cosmetic detection.

[0114] Example 1

[0115] This example provides a polymer-coated porous magnetic solid-phase extraction material, and its preparation method is as follows:

[0116] S01. Loading Fe3O4 nanoparticles

[0117] S011. Immersion method: Under a nitrogen atmosphere, 150 g of ammonium ferrous sulfate, 185 g of ammonium ferric sulfate and 1000 mL of water are successively added to a reaction vessel to obtain a magnetic metal salt solution. Weigh 50 g of a porous matrix and place it in the magnetic metal salt solution for ultrasonic dispersion, stir evenly at room temperature (25°C), and simultaneously ultrasonically immerse for 12 h, then centrifuge and vacuum dry. Repeat the above steps once to load the magnetic metal salt twice on the surface of the porous matrix. After the second ultrasonic immersion and centrifugation, redisperse the porous matrix loaded with the magnetic metal salt with ethanol, and then quickly wash it twice with ethanol to remove the magnetic metal salt on the outer surface of the porous matrix.

[0118] S012. Under a nitrogen atmosphere, disperse the porous matrix obtained in step S011 in 500 ml of ethanol, add 0.2 mol / L ammonia water (28 wt%), adjust the pH to 8, and react at 70°C for 4 h to obtain a porous matrix with Fe3O4 nanoparticles. Then use a magnet to separate the porous matrix with Fe3O4 nanoparticles, wash it three times with anhydrous ethanol, and finally rinse it with 0.2 mol / L hydrochloric acid to remove the residual Fe3O4 nanoparticles on the surface of the porous matrix, thus obtaining a porous matrix with Fe3O4 nanoparticles.

[0119] S02. Calcination

[0120] Place the porous matrix with Fe3O4 nanoparticles obtained in step S012 in a tube furnace. Under an air atmosphere, heat the tube furnace to 275°C at a rate of 5°C / min, and hold it at 275°C for 3 h. Then, after cooling to room temperature of 25°C, obtain a porous matrix loaded with γ-Fe2O3 nanoparticles.

[0121] S03. Polymer coating

[0122] Weigh 5 g of the porous matrix loaded with γ-Fe2O3 nanoparticles obtained in the S02 step, disperse it in a solvent composed of 75 mL of acetonitrile and 50 mL of toluene, then add 3 g of polyvinylpyrrolidone to the above solvent, mix all the materials evenly, and stir at a speed of 250 rpm for 30 min under a nitrogen atmosphere.

[0123] In another container, mix 3 mL of divinylbenzene (DVB), 3 mL of N-vinylpyrrolidone (NVP) and 0.3 g of azobisisobutyronitrile (AIBN) evenly to obtain a polymer solution. Drop the polymer solution into the above stirred system, continue stirring for 30 min, and then ultrasonically disperse for 3 h. Then raise the temperature of the whole system to 70 °C and continue the reaction for 24 h. After the reaction is completed, wash and centrifuge 5 times with ethanol, and dry at 60 °C for 24 h to obtain a polymer-coated porous magnetic solid-phase extraction material.

[0124] Among them, the porous matrix used in this example was purchased from Suzhou NanoFC Technology Co., Ltd., and the polymer microspheres had a model of UniBPC5, a material of hydrophilic-lipophilic balance (HLB) polymer, a particle size of 5 μm, an average pore diameter of 10 nm, a CV of 2.5%, and a thermal weight loss temperature of 350 °C. Therefore, the polymer-coated porous magnetic solid-phase extraction material obtained in this example was denoted as MUniBPC5.

[0125] Place the MUniBPC5 obtained in this example under a scanning electron microscope for observation, and obtain the results as Figure 3 shown. It can be seen from Figure 3 that the surface of the magnetic porous polymer microspheres is smooth, the particle size is uniform, and there are no magnetic particles growing on the surface. Therefore, it has good monodispersity.

[0126] The MUniBPC5 obtained in this example is reddish-brown. The particle size of MUniBPC5 was detected by the Coulter counting method to be 5 μm, and it has good suspension. The magnetization intensity of MUniBPC5 was detected by a vibrating sample magnetometer (VSM) to be 15 emu / g, showing superparamagnetism. From the N2 adsorption-desorption isotherm, the specific surface area of MUniBPC5 was 688 m 2 / g, the pore volume was 0.8 cm 3 / g, and the average pore diameter was 6.3 nm.

[0127] Example 2

[0128] This example provides a polymer-coated porous magnetic solid-phase extraction material, and its preparation method is similar to that of Example 1, except for the choice of the porous matrix.

[0129] The porous matrix used in this example was purchased from Suzhou NanoFC Tech Co., Ltd., and it was a polymer microsphere with the model number UniBPC10. The material was a hydrophilic-lipophilic balance (HLB) polymer, with a particle size of 10 μm, an average pore diameter of 10 nm, and a CV of 2.5%. Therefore, the polymer-coated porous magnetic solid-phase extraction material obtained in this example was denoted as MUniBPC10.

[0130] The MUniBPC10 obtained in this example was placed under a scanning electron microscope for observation, and the results were as Figure 4 shown. As can be seen from Figure 4 this, the surface of the magnetic porous polymer microspheres was smooth, the particle sizes were uniform, and no magnetic particles grew on the surface. Therefore, it had good monodispersity.

[0131] The MUniBPC10 obtained in this example was reddish-brown. The Coulter counting method was used to detect that the particle size of MUniBPC10 was 10 μm, and it had good suspension properties. The magnetization intensity of MUniBPC10 was detected by a vibrating sample magnetometer (VSM) to be 18 emu / g, showing superparamagnetism. From the N2 adsorption-desorption isotherm, it was known that the specific surface area of MUniBPC10 was 553 m 2 / g, the pore volume was 0.8 cm 3 / g, and the average pore diameter was 5.6 nm.

[0132] Example 3

[0133] This example provides a polymer-coated porous magnetic solid-phase extraction material, and its preparation method is similar to that of Example 1, except for the choice of the porous matrix.

[0134] The porous matrix used in this example was purchased from Suzhou NanoFC Tech Co., Ltd., and it was a polymer microsphere with the model number UniBPC25. The material was a hydrophilic-lipophilic balance (HLB) polymer, with a particle size of 25 μm, an average pore diameter of 13 nm, and a CV of 2.5%. Therefore, the polymer-coated porous magnetic solid-phase extraction material obtained in this example was denoted as MUniBPC25.

[0135] The MUniBPC25 obtained in this example was placed under a scanning electron microscope for observation, and the results were as Figure 5 shown. As can be seen from Figure 5 this, the surface of the magnetic porous polymer microspheres was smooth, the particle sizes were uniform, and no magnetic particles grew on the surface. Therefore, it had good monodispersity.

[0136] The obtained MUniBPC25 in this example is reddish-brown. The particle size of MUniBPC25 is detected by the Coulter counting method to be 25 μm, and it has good suspension. The magnetization intensity of MUniBPC25 is detected by a vibrating sample magnetometer (VSM) to be 18 emu / g, showing superparamagnetism. From the N2 adsorption-desorption isotherm, the specific surface area of MUniBPC25 is 769 m 2 / g, and the pore volume is 1.1 cm 3 / g, with an average pore diameter of 9.1 nm.

[0137] Example 4

[0138] This example provides a polymer-coated porous magnetic solid-phase extraction material. Its preparation method is similar to that of Example 1, with the only difference being the choice of the porous matrix.

[0139] The porous matrix used in this example is purchased from Suzhou NanoMicro Technologies Co., Ltd., with the model number UniPS10-100, made of polystyrene, a particle size of 10 μm, an average pore diameter of 10 nm, and a CV of 2.5%. Therefore, the polymer-coated porous magnetic solid-phase extraction material obtained in this example is denoted as MUniPS10-100.

[0140] The obtained MUniPS10-100 in this example is placed under a scanning electron microscope for observation, and the result is as Figure 6 shown. It can be Figure 6 seen that the surface of the magnetic porous polymer microspheres is smooth, the particle size is uniform, and there are no magnetic particles growing on the surface. Therefore, it has good monodispersity.

[0141] The obtained MUniPS10-100 in this example is reddish-brown. The particle size of MUniPS10-100 is detected by the Coulter counting method to be 10 μm, and it has good suspension. From the N2 adsorption-desorption isotherm, the specific surface area of MUniPS10-100 is 775 m 2 / g, and the pore volume is 1.0 cm 3 / g, with an average pore diameter of 7.0 nm.

[0142] Example 5

[0143] This example provides a polymer-coated porous magnetic solid-phase extraction material. Its preparation method is similar to that of Example 1, with the only difference being the choice of the porous matrix.

[0144] The porous matrix used in this example was purchased from Suzhou NanoFC Technology Co., Ltd., with the model number UniPS10-300, made of polystyrene, a particle size of 10 μm, an average pore diameter of 30 nm, and a CV of 2.5%. Therefore, the polymer-coated porous magnetic solid-phase extraction material obtained in this example is denoted as MUniPS10-300.

[0145] The MUniPS10-300 obtained in this example was placed under a scanning electron microscope for observation, and the results are as Figure 7 shown. It can be seen from Figure 7 that the surface of the magnetic porous polymer microspheres is smooth, the particle size is uniform, and there are no magnetic particles growing on the surface. Therefore, it has good monodispersity.

[0146] The MUniPS10-300 obtained in this example is reddish-brown. The particle size of MUniPS10-300 was detected by the Coulter counting method to be 10 μm, and it has good suspension. From the N2 adsorption-desorption isotherm, it can be known that the specific surface area of MUniPS10-300 is 453 m 2 / g, the pore volume is 0.8 cm 3 / g, and the average pore diameter is 22.0 nm.

[0147] Example 6

[0148] This example provides a polymer-coated porous magnetic solid-phase extraction material, and its preparation method is similar to that of Example 1, except that the selection of the porous matrix is different.

[0149] The porous matrix used in this example was purchased from Suzhou NanoFC Technology Co., Ltd., with the model number UniPS10-1000, made of polystyrene, a particle size of 10 μm, an average pore diameter of 100 nm, and a CV of 2.5%. Therefore, the polymer-coated porous magnetic solid-phase extraction material obtained in this example is denoted as MUniPS10-1000.

[0150] The MUniPS10-1000 obtained in this example was placed under a scanning electron microscope for observation, and the results are as Figure 8 shown. It can be seen from Figure 8 that MUniPS10-1000 has a super-large pore structure on its surface.

[0151] The products of steps S02 and S03, namely the porous matrix loaded with γ-Fe2O3 nanoparticles and MUniPS10-1000, were ultrasonically treated for 30 min, and the results are as Figure 9 shown. It can be seen from Figure 9It can be seen that after ultrasonic treatment of the porous matrix loaded with γ-Fe2O3 nanoparticles without a polymer layer coating, the solution is light red, which is the color of γ-Fe2O3 nanoparticles; while after ultrasonic treatment of MUniPS10-1000, the solution is transparent and colorless, indicating that coating the surface of the porous matrix with a polymer layer can prevent the γ-Fe2O3 nanoparticles from falling off.

[0152] The obtained MUniPS10-1000 in this example is reddish-brown. The particle size of MUniPS10-1000 was detected by the Coulter counting method to be 10 μm, and it has good suspension. From the N2 adsorption-desorption isotherm, the specific surface area of MUniPS10-1000 is 74 m 2 / g, the pore volume is 1.1 cm 3 / g, and the average pore diameter is 60.0 nm.

[0153] Example 7

[0154] This example provides a polymer-coated porous magnetic solid-phase extraction material. Its preparation method is similar to that of Example 1, except that in the polymer solution of step S03, styrene (St) is used to replace N-vinylpyrrolidone (NVP).

[0155] The polymer-coated porous magnetic solid-phase extraction material obtained in this example is denoted as MUniBPC5@PS.

[0156] The obtained MUniBPC5@PS in this example was observed under a scanning electron microscope, and the results are as Figure 10 shown. It can be Figure 10 seen that the surface of the magnetic porous polymer microspheres is smooth and no magnetic particles grow on the surface, indicating that the method provided in the embodiments of the present invention can not only be applied to porous matrices made of HLB polymer materials, but also to porous matrices made of polystyrene materials, and the applicability of this method is stronger.

[0157] The obtained MUniBPC5@PS in this example was tested by the N2 adsorption-desorption isotherm. It can be known that the specific surface area of MUniBPC5@PS is 598 m 2 / g, the pore volume is 0.7 cm 3 / g, and the average pore diameter is 7.4 nm.

[0158] Example 8

[0159] This example provides a polymer-coated porous magnetic solid-phase extraction material. Its preparation method is similar to that of Example 1, except that in the polymer solution of step S03, 2 mL of sodium vinyl sulfonate is also added as a functional comonomer to prepare a weakly cation-exchange and polymer-coated porous magnetic solid-phase extraction material, denoted as MUniBPC5-WCX.

[0160] The surface of the obtained MUniBPC5-WCX in this example contains carboxyl groups and can be used for weak cation exchange. After detection, the carboxyl ion exchange capacity is 621 μmol / g.

[0161] Example 9

[0162] This example provides a polymer-coated porous magnetic solid-phase extraction material. Its preparation method is similar to that of Example 1, except that in the polymer solution in step S03, 2 mL of methacrylic acid is further added as a functional comonomer to obtain a strongly cation-exchangeable and polymer-coated porous magnetic solid-phase extraction material, denoted as MUniBPC5-SCX.

[0163] The surface of the obtained MUniBPC5-SCX in this example contains sulfonic acid groups and can be used for strong cation exchange. After detection, the sulfonic acid group ion exchange capacity is 1.1 mmol / g.

[0164] Example 10

[0165] This example provides a polymer-coated porous magnetic solid-phase extraction material. Its preparation method is similar to that of Example 1, except that in the polymer solution in step S03, 2 mL of methacryloyloxyethyl trimethyl ammonium chloride is further added as a functional comonomer to obtain an anion-exchangeable and polymer-coated porous magnetic solid-phase extraction material, denoted as MUniBPC5-MAX.

[0166] The surface of the obtained MUniBPC5-MAX in this example contains quaternary ammonium salt groups and can be used for anion exchange. After detection, the quaternary ammonium salt group ion exchange capacity is 0.22 mmol / g.

[0167] Comparative Example 1

[0168] This comparative example provides a polymer-coated porous magnetic solid-phase extraction material, and its preparation method is as follows:

[0169] S01. Loading Fe3O4 nanoparticles

[0170] S011. Immersion method: Under a nitrogen atmosphere, 150 g of ammonium ferrous sulfate, 185 g of ammonium ferric sulfate, and 1000 mL of water are successively added to a reaction vessel to obtain a magnetic metal salt solution. Weigh 50 g of a porous matrix and place it in the magnetic metal salt solution for ultrasonic dispersion, stir evenly at room temperature (25 °C), and simultaneously perform ultrasonic immersion for 12 h, then centrifuge to load the magnetic metal salt on the surface of the porous matrix once. Then, redisperse the porous matrix loaded with the magnetic metal salt with ethanol and quickly wash it twice with ethanol to remove the magnetic metal salt on the outer surface of the porous matrix.

[0171] S012. Under a nitrogen atmosphere, disperse the porous matrix obtained in step S011 in 800 ml of ethanol, add 0.2 mol / L ammonia water (28 wt%), adjust the pH to 9, and react at 70 °C for 8 h to obtain a porous matrix with Fe3O4 nanoparticles. Then, use a magnet to separate the porous matrix with Fe3O4 nanoparticles, wash it three times with absolute ethanol, and finally rinse it with 0.1 mol / L hydrochloric acid to remove the residual Fe3O4 nanoparticles on the surface of the porous matrix, thus obtaining a porous matrix with Fe3O4 nanoparticles.

[0172] S02. Calcination

[0173] Place the porous matrix with Fe3O4 nanoparticles obtained in step S012 in a tube furnace. Under an air atmosphere, heat the tube furnace to 250 °C at a rate of 5 °C / min, and hold at 250 °C for 3 h. Then, after cooling to room temperature of 25 °C, obtain a porous matrix loaded with γ-Fe2O3 nanoparticles.

[0174] S03. Polymer coating

[0175] Weigh 5 g of the porous matrix loaded with γ-Fe2O3 nanoparticles obtained in step S02, disperse it in a solvent formed by 50 mL of acetonitrile and 75 mL of toluene, then add 3 g of polyvinylpyrrolidone to the above solvent, mix all the materials evenly, and stir at a speed of 250 rpm for 30 min under a nitrogen atmosphere.

[0176] In another container, mix 1 mL of divinylbenzene (DVB), 1 mL of N-vinylpyrrolidone (NVP), and 0.1 g of azobisisobutyronitrile (AIBN) evenly to obtain a polymer solution. Drop the polymer solution into the above stirred system, continue to stir for 30 min, and then ultrasonically disperse for 3 h. Then, heat the whole system to 70 °C and continue to react for 24 h. After the reaction is completed, wash and centrifuge 5 times with ethanol, and dry at 60 °C for 24 h to obtain a polymer-coated porous magnetic solid-phase extraction material.

[0177] Among them, the porous matrix used in this example is the same as that in Example 1. Denote the polymer-coated porous magnetic solid-phase extraction material obtained in this example as MUniBPC5-1.

[0178] The MUniBPC5-1 obtained in this comparative example is detected by a vibrating sample magnetometer (VSM), and its magnetization intensity is 10 emu / g, and its magnetism is poorer than that in Example 1. From the N2 adsorption-desorption isotherm, the specific surface area of MUniBPC5-1 is 740 m 2 / g, the pore volume is 1.1 cm 3 / g, and the average pore diameter is 8.2 nm.

[0179] Comparative Example 2

[0180] This comparative example provides a polymer-coated porous magnetic solid-phase extraction material, and its preparation method is as follows:

[0181] S01. Loading Fe3O4 nanoparticles

[0182] S011. Immersion method: Under a nitrogen atmosphere, 100 g of ammonium ferrous sulfate, 123 g of ammonium ferric sulfate, and 1000 mL of water were successively added to a reaction vessel to obtain a magnetic metal salt solution. 50 g of a porous matrix was weighed and ultrasonically dispersed in the magnetic metal salt solution, stirred evenly at room temperature (25 °C), and ultrasonically immersed for 12 h at the same time, centrifuged, and vacuum dried. The above steps were repeated twice to load the magnetic metal salt on the surface of the porous matrix three times. After the third ultrasonic immersion and centrifugation, the porous matrix loaded with the magnetic metal salt was redispersed with ethanol, and then washed twice with ethanol to remove the magnetic metal salt on the outer surface of the porous matrix.

[0183] S012. Under a nitrogen atmosphere, the porous matrix obtained in step S011 was dispersed in 800 ml of ethanol, 0.2 mol / L ammonia water (28 wt%) was added to adjust the pH to 9, and the reaction was carried out at 70 °C for 8 h to obtain a porous matrix with Fe3O4 nanoparticles. Then, the porous matrix with Fe3O4 nanoparticles was separated by a magnet, washed three times with absolute ethanol, and finally rinsed with 0.1 mol / L hydrochloric acid to remove the residual Fe3O4 nanoparticles on the surface of the porous matrix, and a porous matrix with Fe3O4 nanoparticles was prepared.

[0184] S02. Calcination

[0185] The porous matrix with Fe3O4 nanoparticles obtained in step S012 was placed in a tube furnace. Under an air atmosphere, the temperature in the tube furnace was raised to 300 °C at a rate of 5 °C / min and maintained at 300 °C for 3 h, and then cooled to room temperature of 25 °C to obtain a porous matrix loaded with γ-Fe2O3 nanoparticles.

[0186] S03. Polymer coating

[0187] 5 g of the porous matrix loaded with γ-Fe2O3 nanoparticles obtained in step S02 was weighed, dispersed in a solvent formed by 100 mL of acetonitrile and 25 mL of toluene, and then 3 g of polyvinylpyrrolidone was added to the above solvent. The materials were mixed evenly and stirred at a speed of 250 rpm for 30 min under a nitrogen atmosphere.

[0188] In another container, 5 mL of divinylbenzene (DVB), 5 mL of vinylpyrrolidone (NVP), and 0.5 g of azobisisobutyronitrile (AIBN) were mixed evenly to obtain a polymer solution. The polymer solution was added dropwise to the above-mentioned stirred system. After continuous stirring for 30 min, ultrasonic dispersion was carried out for 3 h. Then the whole system was heated to 70 °C and reacted continuously for 24 h. After the reaction was completed, it was washed with ethanol and centrifuged 5 times, and dried at 60 °C for 24 h to obtain a polymer-coated porous magnetic solid-phase extraction material.

[0189] Among them, the porous matrix used in this example was the same as that in Example 1. The polymer-coated porous magnetic solid-phase extraction material obtained in this example was denoted as MUniBPC5-2.

[0190] The MUniBPC5-2 obtained in this comparative example was detected by a vibrating sample magnetometer (VSM), and the magnetization intensity was 25 emu / g, showing superparamagnetism. From the N2 adsorption-desorption isotherm, the specific surface area of MUniBPC5-2 was 438 m 2 / g, the pore volume was 0.5 cm 3 / g, and the average pore diameter was 4.1 nm.

[0191] The specific surface area, average pore diameter, and pore volume of MUniBPC5-2 obtained by loading Fe3O4 nanoparticles three times decreased significantly, affecting the use requirements of the magnetic solid-phase extraction material for preparing hydrophilic-lipophilic balance (HLB) polymer-based spheres.

[0192] In summary, the polymer-coated porous magnetic solid-phase extraction materials provided in the embodiments of the present invention are all reddish-brown, indicating that the magnetic nanoparticles are well loaded on the corresponding porous matrix. And from the scanning electron microscope images of each embodiment, it is found that the particle sizes of the polymer-coated porous magnetic solid-phase extraction materials in each embodiment are uniform. On the one hand, it shows that the UniBPC series of porous matrices selected in the embodiments of the present invention have good particle size uniformity and excellent monodispersity. On the other hand, it also shows that the method provided in the embodiments of the present invention can obtain excellent magnetic properties (high magnetic responsiveness and superparamagnetism) and suspension properties while ensuring the particle size uniformity and monodispersity of the magnetic solid-phase extraction material. Moreover, the polymer-coated porous magnetic solid-phase extraction materials provided in the embodiments of the present invention have a large specific surface area, a large pore volume, and a large average pore diameter, which is beneficial to the magnetic solid-phase extraction material having excellent adsorption performance for the sample to be detected in the detection field, and can be applied to porous matrices of various materials, with broad application prospects.

[0193] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, various modifications and variations can be made to the present invention. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A polymer-coated porous magnetic solid phase extraction material, characterized in that: It comprises a porous matrix, wherein the internal pores of the porous matrix are loaded with γ-Fe2O3 nanoparticles, and the surface of the γ-Fe2O3 nanoparticles is coated with a polymer layer; The coating method of the polymer layer is a precipitation polymerization method, wherein the precipitation polymerization method is to disperse the porous matrix loaded with γ-Fe2O3 nanoparticles in a dispersant, add a comonomer and an initiator under a protective atmosphere to fully disperse the porous matrix, and then heat the mixture to react, wherein adding the comonomer and the initiator to fully disperse the porous matrix includes performing ultrasonic dispersion; The loading amount of the γ-Fe2O3 nanoparticles on the porous substrate is 5-30%, and the thickness of the polymer layer is 1-3 nm; And / or, the polymer-coated porous magnetic solid phase extraction material comprises a plurality of polymer-coated magnetic porous microspheres, each of which has a particle size of 5 to 25 μm, an average pore size of 4 to 60 nm, and a pore volume of 0.5 to 1.5 cm 2 / g, specific surface area ≥400 m 2 / g; And / or, the polymer-coated porous magnetic solid phase extraction material has a magnetization intensity of 10-25 emu / g.

2. The magnetic solid phase extraction material according to claim 1, characterized in that: The surfaces of the γ-Fe2O3 nanoparticles in the internal pores of the porous matrix are all coated with a polymer layer; and / or, the raw material of the polymer layer includes a comonomer, the comonomer includes a non-functional comonomer, and the non-functional comonomer includes any one of divinylbenzene, vinylpyrrolidone, styrene, glycidyl methacrylate and ethylene glycol dimethacrylate; And / or, the comonomer further comprises a functional comonomer, and the functional comonomer comprises a cation exchange resin monomer and / or an anion exchange resin monomer; And / or, the raw material of the porous matrix includes any one of HLB polymer, polystyrene and polydivinylbenzene.

3. A method for preparing a magnetic solid phase extraction material as claimed in claim 1 or 2, characterized in that: The method comprises in-situ growing Fe3O4 nanoparticles on the internal pores of the porous matrix, calcining the porous matrix with the Fe3O4 nanoparticles to obtain a porous matrix loaded with γ-Fe2O3 nanoparticles, and then coating the surface of the γ-Fe2O3 nanoparticles with the polymer layer by precipitation polymerization.

4. The preparation method according to claim 3, characterized in that: The precipitation polymerization method is to disperse the porous matrix loaded with γ-Fe2O3 nanoparticles in a dispersant, add comonomers and initiators under a protective atmosphere, fully disperse them, and then heat them for reaction; The dispersion ratio of the porous matrix loaded with γ-Fe2O3 nanoparticles in the dispersant is 1g: 5~35mL; The dispersant includes a solvent and a dispersant; the solvent includes a polar solvent and / or a non-polar solvent; The polar solvent includes any one of acetonitrile, ethanol, dimethyl sulfoxide and dimethylacetamide; the non-polar solvent includes any one of toluene, cyclohexane, benzene and xylene; the dispersant includes any one of polyvinyl pyrrolidone, polyvinyl alcohol, sodium polyacrylate and carboxymethyl cellulose; And / or, the solvent in the dispersant is a mixture of a polar solvent and a non-polar solvent, and the volume ratio of the polar solvent to the non-polar solvent is 2-4:1-3; the concentration of the dispersant in the dispersant is 1.7-4.0%; and / or, after adding the comonomer and the initiator, the temperature of the temperature-raising reaction is 65-75° C., and the reaction time is 12-36 hours; And / or, adding the comonomer and the initiator to fully disperse includes ultrasonic dispersion, and the ultrasonic dispersion time is 2 to 4 hours; and / or, the initiator comprises any one of an azo initiator, benzoyl peroxide, ammonium persulfate and potassium persulfate; And / or, after the reaction is completed, the method further comprises washing and drying the polymer-coated porous magnetic solid phase extraction material; And / or, the drying temperature is 55-65°C and the drying time is 12-36 hours.

5. The preparation method according to claim 3, characterized in that: The calcination parameters include: calcination temperature of 250-300° C., calcination time of 2-4 hours, and heating rate of 4-6° C. / min.

6. The preparation method according to claim 3, characterized in that: The method for in-situ growing the Fe3O4 nanoparticles on the internal pores of the porous matrix comprises: loading the magnetic metal salt on the internal pores of the porous matrix by immersion method, and then in-situ growing the Fe3O4 nanoparticles on the internal pores of the porous matrix by coprecipitation method.

7. The preparation method according to claim 6, characterized in that: The immersion method comprises dispersing the porous matrix in a magnetic metal salt solution under a protective atmosphere, and then immersing it ultrasonically; And / or, the porous substrate is ultrasonically immersed in the magnetic metal salt solution twice; and / or, the concentration of the magnetic metal salt in the magnetic metal salt solution is 0.05-0.40 g / ml; and / or, the dispersion ratio of the porous matrix to the magnetic metal salt solution is 1 g: 15-25 mL; And / or, the magnetic metal salt includes Fe 2+ Salt and Fe 3+ Salt; And / or, the Fe 2+ The salt includes any one of ferrous ammonium sulfate, ferrous sulfate and ferrous chloride; Fe 3+ The salt includes any one of ammonium ferric sulfate, ferric sulfate, ferric chloride and ferric nitrate; And / or, the ultrasonic immersion time is 10 to 15 hours.

8. The preparation method according to claim 7, characterized in that: The coprecipitation method comprises dispersing the porous matrix loaded with the magnetic metal salt in a solution system under a protective atmosphere, adjusting the pH value of the solution system to 8-10, and then heating for reaction; and / or, the heating reaction temperature is 65-75° C., and the reaction time is 4-10 hours; And / or, the method for adjusting the pH value of the solution system comprises adding a base to the solution system; and / or, the added alkali comprises any one of aqueous ammonia, sodium hydroxide and potassium hydroxide; And / or, the solution system includes any one of ethanol, methanol, propanol and n-butanol; And / or, after the coprecipitation reaction is completed, the porous matrix having the Fe3O4 nanoparticles is cleaned, wherein the cleaning comprises washing with a weak acid, the number of times of the weak acid washing is one or two, and the pH of the weak acid is 0-2; And / or, the weak acid includes any one of dilute hydrochloric acid, dilute sulfuric acid, and dilute nitric acid.

9. Use of the magnetic solid phase extraction material according to claim 1 or 2 or the magnetic solid phase extraction material prepared by the preparation method according to any one of claims 3 to 8 in any field of catalysis, medical testing, food testing or cosmetics testing.

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