CN114836045A - Mg/Zn-MOF-74@ Fe 3 O 4 Magnetic composite material and application thereof in aflatoxin enrichment - Google Patents
Mg/Zn-MOF-74@ Fe 3 O 4 Magnetic composite material and application thereof in aflatoxin enrichment Download PDFInfo
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Abstract
The invention discloses Mg/Zn-MOF-74@ Fe 3 O 4 A magnetic composite material and application thereof in enriching aflatoxin. The invention successfully prepares the Fe with uniform particle size and strong magnetic responsiveness by adopting a hydrothermal method 3 O 4 Magnetic nanoparticles. Then synthesizing a hollow-structure organic framework material Mg/Zn-MOF-74 mixing two metals Mg/Zn by using an ion exchange method, and assembling Fe layer by layer 3 O 4 The amino on the surface is compounded with Mg/Zn metal of a metal framework material, and Mg/Zn-MOF-74@ Fe is rapidly synthesized under the microwave-assisted action 3 O 4 . Due to Zn in the material 2+ Can react with aflatoxin B 1 The beta-dicarbonyl in the structure generates stable chemical bonding effect, so the application of the material in magnetic solid phase extraction can realize the aflatoxin B in food 1 The maximum adsorption capacity can reach 8.921 mg/g. Mg/Zn-MOF-74@ Fe prepared by the invention 3 O 4 Compared with the traditional pretreatment method, the method has the advantages of high separation speed, high extraction efficiency, environmental friendliness, low price and the like.
Description
Technical Field
The invention belongs to the field of food safety and magnetic nano materials, and particularly relates to Mg/Zn-MOF-74@ Fe 3 O 4 A magnetic composite material and application thereof in enriching aflatoxin.
Background
The food is the basis of human survival, and the food safety has important significance for human health and national economy. However, food products are highly susceptible to fungal contamination during storage, transport and sale, producing mycotoxins with strong teratogenic, carcinogenic and mutagenic properties. At present, over hundreds of mycotoxins with different morphological structures have been discovered, among which aflatoxin B 1 (AFB 1 ) Is a small molecule metabolite produced by aspergillus flavus and aspergillus parasiticus and is considered to be the strongest carcinogen discovered so far. However, AFB 1 AFB is a disease that is usually present in food samples in trace or ultra trace amounts and in food in large amounts of starch, protein and fat, which greatly increases the difficulty of detection 1 The sufficient enrichment and extraction are the premise of accurate detection, and the efficient sample pretreatment method is as important as the sensitive analysis and detection technology.
The sample pretreatment is a basic link for processing a complex matrix sample, and aims to enrich and extract an object to be detected through chemical or physical action, so that the interference of the complex matrix is reduced, and the detection accuracy is improved. Currently, AFB 1 The sample pretreatment method mainly comprises liquid-liquid extraction, solid-phase extraction and immune affinity method. Wherein, the operations of rotary evaporation or nitrogen blow drying and the like are often needed to reduce the matrix interference generated by the organic phase in the liquid-liquid extraction operation process, which not only increases the complexity of the operation, but also causes serious harm to the health of experimenters; solid phase extraction despite extractionThe extraction efficiency is high, but centrifugation is needed when the substance to be detected is separated, which may cause some unnecessary interference or cause coprecipitation; the immune affinity method adopts antigen-antibody specific binding to separate a substance to be detected, has high selectivity, but is expensive and only can be used once, and simultaneously, the use of the immune affinity method is greatly limited due to the defects of poor stability and the like of immune reaction.
Aiming at the defects of the traditional pretreatment method, the invention develops the AFB enriched in food based on the magnetic solid phase extraction method 1 Magnetic nanomaterial (Mg/Zn-MOF-74@ Fe) 3 O 4 ) The material has the advantages of high separation speed, high extraction efficiency, environmental friendliness, low price and the like, and is AFB in food 1 The sample pretreatment work of (2) brings about a new method.
Disclosure of Invention
The invention aims to solve the problems of low adsorption efficiency, low extraction speed, high use cost and the like of the existing food sample pretreatment method, and provides Mg/Zn-MOF-74@ Fe 3 O 4 The magnetic composite material and the application thereof in enriching aflatoxin, and the material prepared by the method can efficiently and quickly enrich AFB in food 1 。
The technical scheme of the invention is as follows:
Mg/Zn-MOF-74@ Fe 3 O 4 A method of making a magnetic composite, the method comprising the steps of:
S1：Fe 3 O 4 preparing magnetic nanoparticles:
anhydrous sodium acetate (NaAc), ferric chloride hexahydrate (FeCl) 3 ·6H 2 O) and Sodium Dodecyl Sulfate (SDS) are evenly mixed and added into glycol solution for reaction to obtain a mixture; separating, washing and drying the obtained precipitate after the reaction is finished to obtain Fe 3 O 4 Magnetic nanoparticles;
s2: preparation of Mg/Zn-MOF-74:
respectively immersing the titanium sheets in magnesium nitrate hexahydrate (Mg (NO) 3 ) 2 ·6H 2 O) and hydrochloric acid solution; immersing the reacted titanium sheet into N, N-dimethyl formylAmine (DMF), 2, 5-dihydroxyterephthalic acid (DHTA) and zinc nitrate hexahydrate (Zn (NO) 3 ) 2 ·6H 2 O) ion exchange in the mixed solution; separating the obtained surface particles from the titanium plate after ion exchange is finished, washing and drying to obtain an Mg/Zn-MOF-74 material;
S3：Mg/Zn-MOF-74@Fe 3 O 4 the preparation of (1):
fe prepared in step S1 3 O 4 Uniformly mixing the magnetic nanoparticles and the Mg/Zn-MOF-74 prepared in the step S2, adding a DMF solution for reaction, separating, washing and drying the obtained precipitate to obtain the Mg/Zn-MOF-74@ Fe 3 O 4 A magnetic composite material.
Preferably, in step S1, anhydrous sodium acetate (NaAc), ferric chloride hexahydrate (FeCl) 3 ·6H 2 O) and Sodium Dodecyl Sulfate (SDS) in a molar ratio of (1-2): (2-4): 1.
preferably, in step S1, ethylene glycol and FeCl 3 ·6H 2 The ratio of O in mL/mmol is (2-4): 1.
preferably, in the step S1, the reaction condition is that the reaction is carried out at the temperature of 180-240 ℃ for 8-12 h.
Preferably, in step S1, the precipitate is separated from the liquid by applying a magnetic field.
Preferably, in step S1, the washing is performed by using deionized water and ethanol.
Preferably, in step S1, the drying conditions are: drying at 60-100 deg.C for 2-4 hr.
Further preferably, in step S1, anhydrous sodium acetate (NaAc), and ferric chloride hexahydrate (FeCl) 3 ·6H 2 O) to Sodium Dodecyl Sulfate (SDS) in a molar ratio of 1.3: 3.3: 1.
further preferably, in step S1, ethylene glycol and FeCl 3 ·6H 2 The ratio of O in mL/mmol is 2.5: 1.
further preferably, in the step S1, the reaction is performed at a temperature of 220 ℃ for 10 h.
Further preferably, in the step S1, the ultrapure water and the absolute ethyl alcohol are washed five times.
Further preferably, in the step S1, drying is performed at a temperature of 80 ℃ for 2.5 h.
Preferably, in the step S2, Mg (NO) 3 ) 2 ·6H 2 The molar ratio of O to hydrochloric acid is (1-3): 1.
preferably, in step S2, DMF, DHTA and Zn (NO) 3 ) 2 ·6H 2 The proportion of O is (120-: (2-5): 1.
preferably, in the step S2, the reaction condition is 100-150 ℃ for reaction for 12-48 h.
Preferably, in step S2, the washing is performed by deionized water.
Preferably, in the step S2, the drying condition is 60 to 100 ℃ for 2 to 4 hours.
Further preferably, in the step S2, Mg (NO) 3 ) 2 ·6H 2 The molar ratio of O to hydrochloric acid is 2: 1.
further preferably, in step S2, DMF, DHTA and Zn (NO) 3 ) 2 ·6H 2 The ratio of O in mL/mmol/mmol was 150: 3: 1.
further preferably, in the step S2, the reaction condition is that the reaction is carried out at a temperature of 130 ℃ for 24 h.
Further preferably, in the step S2, the washing is performed five times by using ultrapure water.
Further preferably, in the step S2, the drying condition is drying at a temperature of 80 ℃ for 2.5 h.
Preferably, in the step S3, Fe 3 O 4 The mass ratio of the Mg/Zn-MOF-74 to the Mg/Zn-MOF-74 is (3-6): 1.
preferably, in the step S3, Fe 3 O 4 The ratio to DMF in mg/mL was (3-5): 1.
preferably, in the step S3, the reaction condition is that the reaction is carried out at the temperature of 120-140 ℃ for 1-3 h.
The separation adopts an external magnetic field to separate the sediment from the liquid.
The drying conditions are as follows: drying at 80-120 deg.C for 2-5 hr.
Further preferably, in the step S3, Fe 3 O 4 The mass ratio of Mg/Zn-MOF-74 is 4.8: 1.
further preferably, in the step S3, Fe 3 O 4 The ratio to DMF in mg/mL was 4: 1.
further preferably, in the step S3, the reaction condition is a temperature of 130 ℃ for 2 h.
Further preferably, in the step S3, the washing is performed five times by using DMF and methanol, respectively.
Further preferably, in step S3, the drying conditions are: drying at 100 deg.C for 3 h.
Mg/Zn-MOF-74@ Fe prepared by the method 3 O 4 Magnetic composite material for enriching and extracting aflatoxin B in food 1 。
Preferably, the application comprises the steps of:
(1) crushing and grinding a solid food sample by using a wall breaking machine, sieving the ground solid food sample, and storing the ground solid food sample in a dry room-temperature environment; transferring the crushed food sample into a centrifuge tube, adding a mixed extraction solution to extract the sample, centrifuging, discarding the precipitate, and collecting supernatant to obtain a pretreated food sample; the mixed extraction solution is a mixed solution of water and methanol, wherein the volume ratio of water to methanol is 7-10: 1;
transferring the liquid food sample into a centrifuge tube, adding the mixed extraction solution to extract the sample, centrifuging to remove the precipitate, and collecting the supernatant to obtain a pretreated liquid food sample; the mixed extraction solution is a mixed solution of water and methanol, wherein the volume ratio of water to methanol is 7-10: 1;
(2) mixing Mg/Zn-MOF-74@ Fe 3 O 4 Adding the mixture into the pretreated food sample obtained in the step (1), carrying out vortex mixing at room temperature to complete adsorption, and then carrying out Mg/Zn-MOF-74@ Fe adsorption 3 O 4 Separating from the solution; the adsorbed Mg/Zn-MOF-74@ Fe is subsequently 3 O 4 Mixing with the elution solution, and ultrasonically eluting the loaded aflatoxin B 1 Magnetic separation to extract Mg/Zn-MOF-74@ Fe 3 O 4 Obtained byWith aflatoxin B 1 Eluting solution N of 2 And (5) drying, and using residues for subsequent detection.
Preferably, in the step (1), the mixed extraction solution is a mixed solution of water and methanol, wherein the volume ratio of water to methanol is (7-10): 1.
further preferably, in the step (1), the volume ratio of water to methanol is 9: 1.
preferably, in step (1), the sieve is an 80-120 mesh sieve.
Further preferably, in the step (1), the sieve is a 100-mesh sieve.
Preferably, in the step (1), the extraction is ultrasonic extraction, wherein the ultrasonic time is 2-5 min.
Further preferably, in the step (1), the ultrasonic time is 3 min.
Preferably, in the step (1), the ratio of the food (solid or liquid) sample to the mixed extraction solution is 1: (2-5).
Further preferably, in the step (1), the ratio of the food (solid or liquid) sample to the mixed extraction solution in g/mL or volume ratio is 1: 3.
preferably, in the step (1), the centrifugation is carried out for 5-15min under the condition of 6000-8000 r/min.
Further preferably, in the step (1), the centrifugation is carried out for 10min under the condition of 7000 r/min.
Preferably, in the step (2), Mg/Zn-MOF-74@ Fe 3 O 4 Ratio to pretreated food sample in mg/mL 1: (2-5).
Further preferably, in the step (2), Mg/Zn-MOF-74@ Fe 3 O 4 Ratio to pretreated food sample in mg/mL 1: 3.
preferably, in the step (2), the adsorption time is 1-5 min.
Further preferably, in the step (2), the adsorption time is 3 min;
preferably, in the step (2), the turbine mixing is to mix evenly in a turbine rotator at 450-.
Preferably, in the step (2), the separation is to separate the magnetic adsorbent from the liquid under the action of an external magnetic field.
Preferably, in the step (2), the elution solution is formic acid, acetone, methanol or acetonitrile solution or a combination thereof.
Further preferably, in the step (2), the solvent is acetonitrile solution.
Preferably, in the step (2), the ratio of Mg/Zn-MOF-74 to the elution solution is (3-10) in Mg/mL: 1.
further preferably, in the step (2), the ratio of Mg/Zn-MOF-74 to the elution solution is 5: 1.
preferably, in the step (2), the elution solution has a pH of 5 to 10.
Further preferably, in the step (2), the elution solution has a pH of 6.
Preferably, in the step (2), the elution conditions are as follows: eluting for 2-5min under ultrasonic condition.
Further preferably, in the step (2), the elution is carried out for 3min under ultrasonic conditions.
Preferably, in the step (2), the blow drying is carried out at 75-85 ℃ and N 2 The flow rate is 0.3-0.6 mL/min.
Further preferably, in the step (2), the blow drying is carried out at 80 ℃ and N 2 The flow rate was 0.5 mL/min.
Optimally, Fe 3 O 4 The specific preparation method of the magnetic nanoparticles comprises the following steps:
FeCl 3 ·6H 2 o (10.0mmol) and NaAc (4.0mmol) were added to 25mL of ethylene glycol, followed by 3.0mmol of SDS, and the mixture was stirred at 400r/min for 15 to 30 min. The solution was then transferred to a 50mL synthesis vessel and heated at 220 ℃ for 10 h. After cooling to room temperature, magnetic separation of Fe 3 O 4 The black precipitate was separated from the remaining solution, and then the resulting Fe was repeatedly washed five times with deionized water (ultrapure water) and absolute ethanol 3 O 4 Magnetic nanoparticles until the supernatant is neutral. Finally, vacuum drying at 80 deg.C for 2.5h with vacuum drying oven to obtain superparamagnetism Fe 3 O 4 The magnetic nanoparticles are stored at 4 ℃ for later use。
The specific preparation method of Mg/Zn-MOF-74 is as follows:
a titanium plate having a diameter of about 10mm and a thickness of about 3mm was prepared, and washed with methanol and ultrapure water several times. The cleaned titanium sheet was immersed in 10mol/L NaOH for 8h, and then the treated titanium sheet was immersed in 1mL of 0.1mol/L hydrochloric acid for 1h and then in 1mL of 0.2mol/L Mg (NO) 3 ) 2 ·6H 2 And O1 h. After the reaction was completed, the titanium plate, 0.3mmol DHTA, 0.1mmol Zn (NO) 3 ) 2 ·6H 2 Adding O and 15mLDMF into a polytetrafluoroethylene reactor, heating for 24h at 130 ℃, cooling to room temperature, washing with ultrapure water for five times, scraping a sample on the surface of the titanium sheet, putting the sample into a vacuum drying oven at 80 ℃ for drying for 2.5h, and storing at 4 ℃ for later use.
Mg/Zn-MOF-74@Fe 3 O 4 The specific preparation method comprises the following steps:
100mg of Fe prepared for the first purpose 3 O 4 Adding the magnetic nanoparticles and 20.83Mg of Mg/Zn-MOF-74 prepared for the second purpose into a 25mLDMF solution, uniformly stirring, transferring to a microwave reactor, reacting at 130 ℃ for 2h, cooling to room temperature, carrying out magnetic separation to obtain a brownish black compound, washing with DMF and methanol for five times respectively, and finally drying in an oven at 100 ℃ for 3h to obtain Mg/Zn-MOF-74@ Fe 3 O 4 A magnetic composite material. Mg/Zn-MOF-74@ Fe 3 O 4 Enriching aflatoxin B in food 1 The specific method comprises the following steps:
(1) a10 g solid food sample is ground and ground by a wall breaking machine, sieved by a 100-mesh sieve and stored in a dry room temperature environment. Transferring the crushed food sample into a 50mL centrifuge tube, adding 30mL methanol water solution (1:9/v: v), shaking thoroughly, ultrasonically extracting for 3min, and centrifuging at 7000r/min for 10 min. This procedure was repeated three times and the supernatants were pooled in a new 50mL centrifuge tube. The resulting food extract was collected and stored at 4 ℃.
10mL of the liquid food sample was transferred to a 50mL centrifuge tube, 30mL of an aqueous methanol solution (1:9/v: v) was added thereto, sufficiently shaken, ultrasonically extracted for 3min, and then centrifuged at 7000r/min for 10 min. This procedure was repeated three times and the supernatants were pooled in a new 50mL centrifuge tube. The resulting food extract was collected and stored at 4 ℃.
(2) Adding 5.0mg of Mg/Zn-MOF-74@ Fe 3 O 4 Adding into 15mL of above food extractive solution, mixing the mixed solution at room temperature at 500r/min by vortex for 3min, and adding Mg/Zn-MOF-74@ Fe under the action of external magnetic field 3 O 4 Separating from the solution, 1mL of acetonitrile at pH 6 was mixed with Mg/Zn-MOF-74@ Fe 3 O 4 Mixing, performing ultrasonic treatment at room temperature for 3min to treat AFB 1 And (4) carrying out desorption. After magnetic separation, the resulting elution solution is treated with N 2 Blow-drying (80 ℃, 0.5mL/min), and using the residue for subsequent detection.
The reaction principle is as follows: the invention is based on an ion exchange method and a hydrothermal method, and Mg is introduced on the surface of a titanium plate by destroying the surface protective film of the titanium plate through chemical corrosion 2+ Since Mg is stronger in active form than Zn, Zn is formed 2+ Is more easily accepted by lone pair electrons, and Mg is carried out on the basis of the lone pair electrons 2+ With Zn 2+ The ion exchange of (a) forms a mixed metal Ti-Mg// Zn. And then mixing the titanium plate with DHTA, carrying out a solvothermal reaction under the hydrothermal action, and forming Mg/Zn-MOF-74 with a hollow structure by utilizing the coordination of 2, 5-dihydroxyterephthalic acid and Mg/Zn metal. Finally passing through Fe 3 O 4 The amino group of the metal-inorganic composite material is compounded with Mg/Zn metal of a metal framework material, and Mg/Zn-MOF-74@ Fe is quickly synthesized under the microwave-assisted action 3 O 4 . Mg/Zn-MOF-74@ Fe dispersed in solution during adsorption 3 O 4 Zn of (2) 2+ Can be reacted with AFB 1 The mesodicarbonyl structures are tightly bound, and in addition, Mg/Zn-MOF-74@ Fe 3 O 4 Surface charge and AFB 1 The electrostatic adsorption force between the two can further improve the adsorption effect. After the adsorption is finished, under the action of an external magnetic field and the action of a desorption solvent, the AFB in the food can be easily realized 1 Separation and purification.
Compared with the traditional pretreatment method, the method is based on Mg/Zn-MOF-74@ Fe 3 O 4 Enriching AFB in food 1 The method has the following advantages:
(1) the pretreatment material is novel. Mg/Zn-MOF-74@ Fe prepared by the invention 3 O 4 Reacting Mg/Zn-MOF-74 withFe 3 O 4 The magnetic MOFs material formed by combining the magnetic nanoparticles and the MSPE is applied to sample pretreatment. The material has the characteristics of structural adaptability, flexibility, high porosity and the like of MOFs materials and the advantage of superparamagnetism of magnetic nanoparticles, can realize effective separation of target objects under the action of an external magnetic field, and has physical and chemical properties incomparable with those of a single material.
(2) The pretreatment cost is low. Mg/Zn-MOF-74@ Fe prepared by the invention 3 O 4 The used raw materials are all common materials which are simple and easy to obtain, and the price is low; and the material consumes less reagent in the pretreatment process, can be repeatedly recycled, and greatly reduces the pretreatment cost.
(3) The pretreatment efficiency is high. Mg/Zn-MOF-74@ Fe prepared by the invention 3 O 4 Has good dispersibility and high specific surface area, and can provide enough adsorption sites and AFB 1 And combining to realize a rapid mass transfer process. Analysis of AFB under optimal conditions 1 Adsorption capacity of Mg/Zn-MOF-74@ Fe 3 O 4 For AFB 1 The maximum adsorption capacity of the adsorbent is 8.921mg/g, which is superior to other pretreatment methods.
Drawings
FIG. 1 is a representation of four different MOF-74@ Fe samples from example 2 3 O 4 The supernatant ion release profile of (a);
FIG. 2 shows the difference n [ Mg ] in example 2 2+ ]：n[Zn 2+ ]Ratio of Mg/Zn-MOF-74@ Fe 3 O 4 The particle size distribution map of (a);
FIG. 3 is a scanning electron microscope image of example 3: FIG. 3a is Fe in example 3 3 O 4 Scanning electron microscopy images of (a);
FIG. 3b is the Mg/Zn-MOF-74@ Fe example 3 3 O 4 Scanning electron microscopy images of (a);
FIG. 4 is the Mg/Zn-MOF-74@ Fe example 3 3 O 4 In the infrared spectrum
FIG. 5 is the Mg/Zn-MOF-74@ Fe example 3 3 O 4 X-ray diffraction patterns of (a);
FIG. 6 shows Mg ^ 4 in example 3Zn-MOF-74@Fe 3 O 4 A hysteresis loop diagram of (1);
FIG. 7 is the Mg/Zn-MOF-74@ Fe example 4 3 O 4 Enriching AFB in food 1 Schematic diagram of (1);
FIG. 8 is the Mg/Zn-MOF-74@ Fe example 6 3 O 4 Adsorption of AFB 1 Front and back infrared spectrograms;
FIG. 9 is the Mg/Zn-MOF-74@ Fe example 6 3 O 4 Adsorption of AFB 1 Fitting graph of the adsorption model;
FIG. 10 is the Mg/Zn-MOF-74@ Fe example 6 3 O 4 Reusability map of (2);
FIG. 11 is the Mg/Zn-MOF-74@ Fe example 7 3 O 4 Enriching AFB with immunoaffinity column 1 Chromatogram comparison of (a).
Detailed Description
The present invention is described in further detail below with reference to the attached drawings and examples, and it should be understood by those skilled in the art that the examples are only for the understanding of the present invention patent and should not be construed as the specific limitations of the present invention patent.
Test materials
Aflatoxin B 1 (1 mg/mL): purchased from Shanghai-derived leaf Biotech, Inc. N, N-dimethylformamide (DMF, analytical grade), 2, 5-dihydroxyterephthalic acid (DHTA, analytical grade): purchased from Shanghai Aladdin Biotechnology, Inc. Acetonitrile (chromatographically pure), formic acid (chromatographically pure): purchased from siemer feishel technologies, usa. Ferric chloride hexahydrate (FeCl) 3 ·6H 2 O), sodium acetate (NaAc), Sodium Dodecyl Sulfate (SDS), magnesium nitrate hexahydrate (Mg (NO) 3 ) 2 ·6H 2 O), zinc nitrate hexahydrate (Zn (NO) 3 ) 2 ·6H 2 O): purchased from the Chinese pharmaceutical group.
Example 1 preparation of Mg/Zn-MOF-74@ Fe 3 O 4 Method (2)
(1)Fe 3 O 4 Preparation of magnetic nanoparticles
FeCl is added 3 ·6H 2 O (10.0mmol) and NaAc (4.0mmol) were added to 25mL of ethylene glycol (50mL beaker, convenient forStirring), adding 3.0mmol SDS, and magnetically stirring at 400r/min for 15-30 min. The yellow clear mixed solution was then transferred to a 50mL synthesis vessel and heated at 220 ℃ for 10 h. After cooling to room temperature, Fe was separated by magnetic separation 3 O 4 The black precipitate was separated from the remaining solution, followed by repeated washing of the resulting Fe with deionized water and absolute ethanol 3 O 4 Magnetic nanoparticles until the supernatant is neutral. Finally, the prepared magnetic nanoparticles are placed in a vacuum drying oven to be dried for 2.5 hours in vacuum at the temperature of 80 ℃, and the obtained Fe with superparamagnetism 3 O 4 The magnetic nanoparticles were stored at 4 ℃ until use.
(2) Preparation of Mg/Zn-MOF-74
A titanium plate having a diameter of about 10mm and a thickness of about 3mm was prepared, and washed with methanol and ultrapure water several times. The cleaned titanium sheet is soaked in 10mol/L NaOH for 8h, and then the treated titanium sheet is immersed in 1mL of 0.1mol/L hydrochloric acid for 1h and then immersed in 1mL of 0.1mol/L Mg (NO) 3 ) 2 ·6H 2 And O1 h. After the reaction was completed, the titanium plate, 0.3mmol DHTA, 0.1mmol Zn (NO) 3 ) 2 ·6H 2 Adding O and 15mLDMF into a polytetrafluoroethylene reactor (microwave-assisted heating), heating at 130 ℃ for 24h, cooling to room temperature, washing with ultrapure water for five times, scraping a sample on the surface of the titanium sheet, drying in a vacuum drying oven at 80 ℃ for 2.5h, and storing at 4 ℃ for later use.
(3)Mg/Zn-MOF-74@Fe 3 O 4 Preparation of
100mg of Fe prepared in step (1) 3 O 4 Adding the magnetic nanoparticles and 20.83Mg of Mg/Zn-MOF-74 prepared in the step (2) into a 25mLDMF solution, uniformly stirring, transferring to a microwave reactor, reacting at 130 ℃ for 2h, cooling to room temperature, carrying out magnetic separation (with an additional magnet) to obtain a brownish black compound, washing with DMF and methanol for five times respectively, and finally drying in an oven (or a vacuum drying oven at 80 ℃ and under-0.6 Mpa) at 100 ℃ for 3h to obtain Mg/Zn-MOF-74@ Fe 3 O 4 A magnetic composite material.
Example 2 selection and optimization of synthetic raw materials
(1) Fe was prepared according to the procedure (1) of example 1 3 O 4 Magnetic propertyA nanoparticle;
(2) preparing Mg/Zn-MOF-74 according to the step (2) of example 1;
preparation of Mg-MOF-74: immersing the pretreated titanium sheet into 1mL of 0.1mol/L Mg (NO) 3 ) 2 ·6H 2 O1 h. After the reaction was complete, the titanium plate, 0.3mmol DHTA and 5mL DMF were added to a Teflon reactor (microwave assisted heating) and heated at 130 ℃ for 24 h. The titanium sheet pretreatment method, the cleaning and drying method of Mg-MOF-74, were kept the same as in step (2) of example 1.
Preparation of Zn-MOF-74: pretreated titanium sheet, 0.3mmol DHTA and 1mmol Zn (NO) 3 ) 2 ·6H 2 O and 15mLDMF were added to a Teflon reactor (microwave assisted heating) and heated at 130 ℃ for 24 h. The titanium sheet pretreatment method and the cleaning and drying method of Zn-MOF-74 were the same as in step (2) of example 1.
Preparation of Mg/Ca-MOF-74: immersing the pretreated titanium sheet into 1mL of 0.1mol/L Mg (NO) 3 ) 2 ·6H 2 And O1 h. After the reaction was completed, the titanium plate, 0.3mmol DHTA, 0.1mmol Ca (NO) 3 ) 2 And 5ml of DMMF was added to the polytetrafluoroethylene reactor and heated at 130 ℃ for 24 hours using a microwave-assisted heating method. The titanium sheet pretreatment method, the cleaning and drying method of Mg/Ca-MOF-74, were kept the same as in step (2) of example 1.
(3) Fe was added according to the procedure (3) of example 1 3 O 4 The magnetic nanoparticles are respectively assembled with four different MOF-74 layers by layers, the weight of the added MOF-74 is respectively controlled to be Mg/Zn-MOF-74(20.83Mg), Mg-MOF-74(16.57Mg), Zn-MOF-74(15.77Mg) and Mg/Ca-MOF-74(25.47Mg), other conditions are kept unchanged, and the ion release amount, the mass density, the specific surface area, the adsorption time and the maximum adsorption amount ratio of a supernatant are compared with that of the four different MOF-74@ Fe 3 O 4 Stability, physical structure and adsorption properties.
FIG. 1 shows different metal elements MOF-74@ Fe 3 O 4 The amount of ion released. The results show that, before the ion exchange modification, Mg-MOF-74@ Fe 3 O 4 And Zn-MOF-74@ Fe 3 O 4 The total ion release over 20 days was 0.61. mu. mol/L and 1.2. mu. mol/L. After the modification, the mixture is subjected to a thermal treatment,Mg/Ca-MOF-74@Fe 3 O 4 the ion release amount of the zinc oxide is obviously improved, and Mn/Zn-MOF-74@ Fe 3 O 4 Then compared with the single metal element MOF-74@ Fe 3 O 4 The ion release was reduced by 51% and 103%, indicating that Mn/Zn-MOF-74@ Fe 3 O 4 The structure is stable, which shows that the MOF-74@ Fe modified by the Mn/Zn ion exchange method 3 O 4 Has good stability.
TABLE 1 different synthetic metal pairs MOF-74@ Fe 3 O 4 Mass density, specific surface area, adsorption time and AFB 1 Influence of maximum adsorption amount.
Table 1 shows the different metal elements MOF-74@ Fe 3 O 4 Mass density, specific surface area, adsorption time and maximum adsorption amount. The results show that the bimetallic MOF-74@ Fe 3 O 4 Has a specific surface area and a mass density which are obviously higher than those of MOF-74@ Fe of single metal (Mg and Zn) 3 O 4 Description of the bimetallic MOF-74@ Fe 3 O 4 The porous structure is more obvious, more adsorption sites can be provided, so that the adsorption equilibrium time is obviously reduced and the adsorption capacity is larger. Although Mg/Zn-MOF-74@ Fe obtained by selectively exchanging Ca/Mn and Zn/Mn with an organic ligand solution by an ion exchange method 3 O 4 And Mg/Ca-MOF-74@ Fe 3 O 4 The crystal nuclei can be modified by fine-tuning, but the use of Mn/Zn as metal binding sites for MOF-74@ Fe 3 O 4 The modification effect of specific surface area and mass density is better.
Synthesis of different n [ Mg ] s according to step (2) of example 1 2+ ]：n[Zn 2+ ]Mg/Zn-MOF-74 of (a), control of n [ Mg ] in the raw material 2 + ]：n[Zn 2+ ]The ratio of the synthetic raw materials is determined by examining the particle size distribution of the synthesized Mg/Zn-MOF-74, while the other conditions are kept unchanged, namely (6: 4), (7: 3), (8: 2) and (9: 1).
FIG. 2 is a diagram of the synthesis of different n [ Mg ] by ion exchange 2+ ]：n[Zn 2+ ]Particle size distribution diagram of (c). It can be seen from FIG. 2 that with n [ Mg ] 2+ ]：n[Zn 2+ ]Increased of (a) Mg/Zn-MOF-74@ Fe synthesized 3 O 4 When n [ Mg ] is gradually increased 2+ ]：n[Zn 2+ ]Is 9: 1, the particle size distribution is uniform and the peak width is narrowest, indicating that Mg is the major part of the material, with n [ Mg ] 2+ ]The material is mature, and the appearance, structure and uniformity of the material are further improved. Thus, n (Mg) is selected 2+ )：n(Zn 2+ ) 9: 1 as a synthesis condition, a novel magnetic material having a good property and shape can be obtained.
Example 3 Mg/Zn-MOF-74@ Fe 3 O 4 Structural characterization of
Preparation of Mg/Zn-MOF-74@ Fe by the method of example 1 3 O 4 。
(1) Scanning Electron Microscope (SEM) characterization
FIG. 3 is Fe 3 O 4 And Mg/Zn-MOF-74@ Fe 3 O 4 Scanning electron microscopy images of (a). As shown in FIG. 3, Fe 3 O 4 The nanoparticles and the Mg/Zn-MOF-74 metal framework are mutually crosslinked and combined to form a clear regular hexagon cluster structure, and the size is about 380-480 nm. Wherein the sizes of the regular hexagonal cluster structures of each region are different, the obvious crystal growth is supposed to occur in the high-temperature synthesis process, and the electron microscope visually proves that Mg/Zn-MOF-74@ Fe 3 O 4 And (4) synthesizing. This indicates that Fe 3 O 4 The nanoparticles were successfully incorporated into the Mg/Zn-MOF-74 metal framework.
(2) Energy Dispersive (EDS) characterization
Table 2 is Mg/Zn-MOF-74@ Fe 3 O 4 The material consists of C, H, O, Mg and Zn five elements shown in Table 2, and Fe is verified 3 O 4 Combination of nanoparticles and Mg/Zn-MOF-74 Metal skeleton, and ratio of carbon element to Metal element [ C (Mg + Zn)]About 3.78, indicating that a 2, 5-dihydroxyterephthalic acid molecule containing eight carbon atoms in Mg/Zn-MOF-74 can effectively react with two metal ions (Mg) 2+ Or Zn 2+ ) And (4) coordination.
TABLE 2 Mg/Zn-MOF-74@ Fe 3 O 4 The distribution table of the contents of the elements (Fe, C, O, Mg, Zn)
| Element(s) | Ratio (%) |
| Fe | 44.67 |
| C | 15.12 |
| O | 36.21 |
| Mg | 1.74 |
| Zn | 2.26 |
| Total of | 100 |
(3) Infrared Spectroscopy (FT-IR) characterisation
FIG. 4 is the Mg/Zn-MOF-74@ Fe 3 O 4 An infrared spectrum of (1). As shown, Mg/Zn-MOF-74@ Fe 3 O 4 At 600cm -1 And 3400cm -1 Nearby Fe 3 O 4 The same absorption peaks for Fe-O and O-H; and at 1680cm -1 And 1585cm -1 There are stronger absorption peaks corresponding to characteristic absorption peaks of C ═ O and C ═ C, respectively, which illustrates that of Mg/Zn-MOF-74Formation of metal frame skeleton and Fe 3 O 4 Effectively combined to form a novel magnetic material Mg/Zn-MOF-74@ Fe with special functional groups 3 O 4 。
(4) Characterization by X-ray diffraction (XRD)
FIG. 5 is Mg/Zn-MOF-74@ Fe 3 O 4 Crystal structure of (2). As shown, Fe 3 O 4 The six typical 2 theta angles of (1), (220), (35.5), (311), (43.2), (400), (53.4), (422), and (511), (440) diffraction peaks (JCPDS NO.75e0449), and the element peaks of Mg/Zn-MOF-74 at 2 theta angles of 6.79 and 11.75, respectively, corresponding to the Mg and Zn elements in the material, illustrate the feasibility of synthesizing the bimetallic structure MOF-74 by the ion exchange method. Mg/Zn-MOF-74@ Fe 3 O 4 The XRD pattern of (A) and the diffraction peaks of the first two are completely verified, and the element peak of Mg/Zn-MOF-74 is at Mg/Zn-MOF-74@ Fe 3 O 4 A reduced XRD pattern of (A), indicating that Mg/Zn-MOF-74@ Fe 3 O 4 Is one kind of Fe 3 O 4 Shell-like crystals covering the surface of Mg/Zn-MOF-74.
(5) Saturation Magnetization (VSM) characterization
FIG. 6 is Fe 3 O 4 And Mg/Zn-MOF-74@ Fe 3 O 4 The magnetic hysteresis curve of (A) is shown in the graph, Mg/Zn-MOF-74@ Fe 3 O 4 From Fe 3 O 4 The yield of 65.13emu/g was reduced to 48.78emu/g, indicating that Mg/Zn-MOF-74 and Fe are not magnetic 3 O 4 Grafting was successful. Although Mg/Zn-MOF-74@ Fe 3 O 4 Of relatively pure saturation magnetization of Fe 3 O 4 Slightly reduced, but still able to meet the requirements of rapid separation under magnetic field.
Example 4A coating based on Mg/Zn-MOF-74@ Fe 3 O 4 Enriching aflatoxin B in food 1 Method (2)
(1) 10g of solid food sample was ground and ground (wall breaking machine), sieved through 100 mesh sieve and stored in dry room temperature environment. Transferring the crushed solid food sample into a 50mL centrifuge tube, adding 30mL methanol water solution (1:9/v: v), fully shaking, ultrasonically extracting for 3min, and centrifuging at 7000r/min for 10 min. This procedure was repeated three times and the supernatants were pooled in a new 50mL centrifuge tube. The resulting food extract was collected and stored at 4 ℃.
10mL of the liquid food sample was transferred to a 50mL centrifuge tube, 30mL of an aqueous methanol solution (1:9/v: v) was added thereto, sufficiently shaken, ultrasonically extracted for 3min, and then centrifuged at 7000r/min for 10 min. This procedure was repeated three times and the supernatants were pooled in a new 50mL centrifuge tube. The resulting food extract was collected and stored at 4 ℃.
(2) As shown in FIG. 7, 5.0Mg of Mg/Zn-MOF-74@ Fe prepared in example 1 was added 3 O 4 Adding into 15mL of above food extractive solution, mixing the mixed solution at room temperature with 500r/min vortex for 3min, and adding Mg/Zn-MOF-74@ Fe under the action of external magnetic field (small magnet) 3 O 4 Separating from the solution, 1mL of acetonitrile at pH 6 was mixed with Mg/Zn-MOF-74@ Fe 3 O 4 Mixing, performing ultrasonic treatment at room temperature for 3min to treat AFB 1 And (4) carrying out desorption. After magnetic separation, the resulting eluate is treated with N 2 Blow-drying (60 ℃, 0.5mL/min), and using the residue for subsequent detection.
Example 5 Mg/Zn-MOF-74@ Fe 3 O 4 Enriching aflatoxin B in food 1 Condition optimization of
(1) Preparation of a labeled sample: accurately weighing 10g solid food sample or 10mL liquid food sample, and adding 1mL AFB with concentration of 0.05, 0.5, and 5(ng/mL) 1 Standard solution, and the standard sample was prepared in the same manner as in the step (1) of example 4.
(2) Optimization of adsorption time
Enrichment of AFB in spiked samples by the procedure of step (2) of example 4 1 Controlling the turbine rotation time to be 1min, 2min, 3min and 4min respectively, keeping other conditions unchanged, and investigating the Mg/Zn-MOF-74@ Fe by HPLC (high performance liquid chromatography) recovery rate 3 O 4 For AFB 1 The adsorption effect of (1).
As shown in Table 3, the recovery rate was significantly increased when the adsorption time was increased from 1min to 3min, and did not change significantly with the increase in adsorption time, indicating AFB 1 And Mg/Zn-MOF-74@ Fe 3 O 4 To achieveComplete contact and adsorption equilibrium is achieved. Therefore, 3min was chosen as the adsorption time for this experiment to ensure the best extraction efficiency.
TABLE 3 different adsorption times Mg/Zn-MOF-74@ Fe 3 O 4 For AFB 1 Adsorption effect of
(3) Optimization of elution solution type
Enrichment of AFB in spiked samples according to the procedure of step (2) of example 4 1 After adsorption equilibrium, selecting four eluent pairs of Mg/Zn-MOF-74@ Fe of methanol, acetonitrile, acetone and methanol 3 O 4 Elution was carried out with the other conditions remaining unchanged and Mg/Zn-MOF-74@ Fe was investigated by HPLC determination of recovery 3 O 4 For AFB 1 The adsorption effect of (1).
The investigation result is shown in table 4, the desorption capacity of acetonitrile is obviously higher than that of the other three eluents, and the recovery rate is as high as 92.1%, which shows that the acetonitrile can more effectively destroy the binding force between the adsorbent and the target object, thereby improving the AFB 1 From Mg/Zn-MOF-74@ Fe 3 O 4 In the elution, acetonitrile was selected as the elution solution
TABLE 4 different elution solutions Mg/Zn-MOF-74@ Fe 3 O 4 For AFB 1 Adsorption effect of
(4) Optimization of elution time
Enrichment of AFB in spiked samples by the procedure of step (2) of example 4 1 After adsorption equilibrium, controlling the elution time to be 1min, 2min, 3min and 4min respectively, and keeping other conditions unchanged, and measuring by HPLCRecovery Rate investigation of Mg/Zn-MOF-74@ Fe 3 O 4 For AFB 1 The adsorption effect of (1).
The results are shown in Table 5, where the recovery rate gradually increased with increasing elution time and became stable after 3min, indicating that Mg/Zn-MOF-74@ Fe 3 O 4 And AFB 1 The hydrogen bonds and the electrostatic adsorption force completely disappear within 3min under the organic environment. Therefore, 3min is considered to be the optimal elution time.
TABLE 5 different elution times Mg/Zn-MOF-74@ Fe 3 O 4 For AFB 1 Adsorption effect of (2)
(5) Optimization of elution solution pH
Enrichment of AFB in spiked samples by the procedure of step (2) of example 4 1 After adsorption equilibrium, adjusting the pH values of the eluent to be 4.0, 5.0, 6.0 and 7.0 respectively, keeping other conditions unchanged, and investigating the recovery rate by HPLC (high performance liquid chromatography) to investigate Mg/Zn-MOF-74@ Fe 3 O 4 For AFB 1 The adsorption effect of (1).
As shown in table 6, the highest recovery rate was obtained at pH 6.0, at which AFB was obtained 1 The adsorption amount of (2) is the largest.
TABLE 6 Mg/Zn-MOF-74@ Fe at different pH 3 O 4 For AFB 1 Adsorption effect of
Example 6 Mg/Zn-MOF-74@ Fe 3 O 4 Enriching aflatoxin B 1 Performance test of
Mg/Zn-MOF-74@Fe 3 O 4 Enriching aflatoxin B 1 Performance test experimental methods were performed according to example 4, with conditions according to the optimum conditions of example 5.
(1)Mg/Zn-MOF-74@Fe 3 O 4 Adsorption capacity test of
FIG. 8 is the Mg/Zn-MOF-74@ Fe 3 O 4 Adsorption of AFB 1 From the preceding and following FT-IR images, Mg/Zn-MOF-74@ Fe is shown in FIG. 8 3 O 4 After the material is adsorbed, the thickness is 1730cm -1 AFB appears on the left and right 1 Characteristic peak of (A), which indicates the material pair AFB 1 Has effective adsorption effect.
FIG. 9 is Mg/Zn-MOF-74@ Fe 3 O 4 Adsorption of AFB 1 The Langmuir model and the Freundlich model respectively have higher correlation with the actual adsorption curve at different concentrations. When balancing AFB 1 At concentrations below 60mg/L, the adsorption isotherms can be embedded in the Langmuir model. But balancing AFB 1 At concentrations above 60mg/L, AFB is evident 1 The model is more suitable. This indicates that initially Mg/Zn-MOF-74@ Fe 3 O 4 For AFB 1 Is adsorbed in a single layer, and C e Then multilayer heterogeneous adsorption (C) e Remaining AFB for adsorption when equilibrium is reached 1 Concentration). The adsorption capacity of the adsorbent is usually the maximum adsorption capacity of the Langmuir model, so that the Mg/Zn-MOF-74@ Fe is calculated from the adsorption equilibrium equation 3 O 4 For AFB 1 The maximum adsorption amount of (a) was 8.921 mg/g.
Langmuir model:
freundlich model:
adsorption equilibrium equation:
in the formula Q e Is Mg/Zn-MOF-74@ Fe 3 O 4 The adsorption capacity (mg/g) of the material at the adsorption equilibrium; c e Residual AFB for adsorption equilibrium 1 Concentration; q L 、max、b、K f N is a fitting parameter; c 0 Initial AFB as a solution 1 Concentration (. mu.g/L); m is added Mg/Zn-MOF-74@ Fe 3 O 4 Mass (mg) of (c); v is AFB 1 Volume of solution (mL).
(2)Mg/Zn-MOF-74@Fe 3 O 4 Reusability test of
Accurately weigh 1.0g Mg/Zn-MOF-74@ Fe 3 O 4 Placing in a 1.5mL centrifuge tube, adding 1mL AFB with concentration of 1ng/mL, 5ng/mL, 10ng/mL 1 The standard solution was shaken at room temperature for 3min, and then the adsorption and desorption were repeated five times in accordance with the step (2) of example 4 under an applied magnetic field.
As shown in FIG. 10, Mg/Zn-MOF-74@ Fe was detected after 5 consecutive adsorption and desorption under the optimum conditions 3 O 4 Adsorbing three different concentrations of AFB 1 The recovery rate is still kept above 85 percent, and the RSD is less than 5 percent, which indicates that the Mg/Zn-MOF-74@ Fe 3 O 4 Can be repeatedly used for more than 5 times.
Example 7 Mg/Zn-MOF74@ Fe 3 O 4 Enriching AFB with immunoaffinity column 1 Comparison of (2)
The enrichment method of the immunoaffinity column comprises the following steps: 10.0g of a solid food sample (after being sufficiently ground and sieved with a 80-mesh sieve) or 10mL of a liquid food sample was weighed in a conical flask, 100mL of an acetonitrile/water (10/90, v/v) mixed solution was added thereto, and mixed on a shaker at room temperature for 20 min. The mixture was filtered and 10mL of the filtrate was diluted to 50mL with PBS. And (3) restoring the immunoaffinity column preserved at 4 ℃ in advance to room temperature, taking 25mL of the sample liquid, transferring the sample liquid into a glass syringe barrel, connecting an air pump with the other end of the syringe to adjust the dropping speed, and controlling the liquid to flow out at the speed of 1-2 drops/second until air enters the column. After discarding the remaining liquid, 2mL of methanol eluent was added to the immunoaffinity column, and the eluent was collected in a centrifuge tube, filtered through a 0.22 μm filter and used for HPLC assay analysis.
Mg/Zn-MOF-74@Fe 3 O 4 Enrichment of AFB 1 Reference is made to example 4.
FIG. 11 is an AFB enrichment of two methods 1 Chromatogram of the labeled sample, Mg/Zn-MOF-74@ Fe, shown in FIG. 11 3 O 4 AFB similar to immunoaffinity column 1 Peak area, which indicates Mg/Zn-MOF-74@ Fe basis 3 O 4 The magnetic solid phase extraction technology adsorbs AFB in a real sample 1 The reliability of (2).
TABLE 7 Mg/Zn-MOF-74@ Fe 3 O 4 Comparison with immunoaffinity column in labeled food samples
The results in Table 7 show that Mg/Zn-MOF-74@ Fe 3 O 4 For AFB in real samples 1 Can maintain excellent adsorption capacity, has the recovery rate of 88.47-101.44% and has little effect compared with the immunoaffinity column. The lower Relative Standard Deviation (RSD) also indicates that this process has good stability and can be used as a commercial process. Furthermore Mg/Zn-MOF-74@ Fe 3 O 4 The method also has the characteristics of simple synthesis, high adsorption efficiency, high separation speed and the like, and has the advantages of incomparable treatment speed and cost of other pretreatment materials.
The above embodiments are merely preferred technical solutions of the present invention, and should not be construed as limiting the present invention, and features in the embodiments and examples in the present application may be arbitrarily combined with each other without conflict. The protection scope of the present invention is defined by the claims, and includes equivalents of technical features of the claims. I.e., equivalent alterations and modifications within the scope hereof, are also intended to be within the scope of the invention.
Claims (8)
1. Mg/Zn-MOF-74@ Fe 3 O 4 Preparation method of magnetic composite materialA method, characterized in that it comprises the steps of:
S1：Fe 3 O 4 preparing magnetic nanoparticles:
anhydrous sodium acetate (NaAc), ferric chloride hexahydrate (FeCl) 3 ·6H 2 O) and Sodium Dodecyl Sulfate (SDS) are evenly mixed and added into glycol solution for reaction to obtain a mixture; separating, washing and drying the obtained precipitate after the reaction is finished to obtain Fe 3 O 4 Magnetic nanoparticles;
s2: preparation of Mg/Zn-MOF-74:
respectively immersing the titanium sheets in magnesium nitrate hexahydrate (Mg (NO) 3 ) 2 ·6H 2 O) and hydrochloric acid solution; immersing the titanium sheet after reaction in N, N-Dimethylformamide (DMF), 2, 5-dihydroxyterephthalic acid (DHTA) and zinc nitrate hexahydrate (Zn (NO) 3 ) 2 ·6H 2 O) ion exchange in the mixed solution; separating the obtained surface particles from the titanium plate after ion exchange is finished, washing and drying to obtain an Mg/Zn-MOF-74 material;
S3：Mg/Zn-MOF-74 @ Fe 3 O 4 the preparation of (1):
fe prepared in step S1 3 O 4 Uniformly mixing the magnetic nanoparticles and the Mg/Zn-MOF-74 prepared in the step S2, adding a DMF solution for reaction, separating, washing and drying the obtained precipitate to obtain the Mg/Zn-MOF-74@ Fe 3 O 4 A magnetic composite material.
2. The Mg/Zn-MOF-74@ Fe of claim 1 3 O 4 The method for preparing the magnetic composite material is characterized in that in the step S1, anhydrous sodium acetate (NaAc) and ferric chloride hexahydrate (FeCl) 3 ·6H 2 O) and Sodium Dodecyl Sulfate (SDS) in a molar ratio of (1-2): (2-4): 1;
ethylene glycol and FeCl 3 ·6H 2 The ratio of O in mL/mmol is (2-4): 1;
the reaction condition is that the reaction is carried out for 8 to 12 hours at the temperature of 180 ℃ and 240 ℃;
separating precipitate and liquid by using an external magnetic field;
washing with deionized water and ethanol respectively;
the drying conditions are as follows: drying at 60-100 deg.C for 2-4 hr.
3. The Mg/Zn-MOF-74@ Fe of claim 1 3 O 4 A method for preparing a magnetic composite material is characterized in that,
in said step S2, Mg (NO) 3 ) 2 ·6H 2 The molar ratio of O to hydrochloric acid is (1-3): 1;
DMF, DHTA and Zn (NO) 3 ) 2 ·6H 2 The proportion of O is (120-: (2-5): 1;
the reaction condition is 100-150 ℃ for 12-48 h;
washing with deionized water;
the drying condition is drying at 60-100 deg.C for 2-4 h.
4. The Mg/Zn-MOF-74@ Fe of claim 1 3 O 4 The method for preparing a magnetic composite material, wherein in step S3, Fe 3 O 4 The mass ratio of the Mg/Zn-MOF-74 to the Mg/Zn-MOF-74 is (3-6): 1;
Fe 3 O 4 the ratio to DMF in mg/mL was (3-5): 1;
the reaction condition is that the reaction is carried out for 1 to 3 hours at the temperature of 120-140 ℃;
separating precipitate and liquid by using an external magnetic field;
washing with DMF and methanol respectively;
the drying conditions are as follows: drying at 80-120 deg.C for 2-5 hr.
5. Mg/Zn-MOF-74@ Fe prepared by the method of any one of claims 1 to 4 3 O 4 The magnetic composite material is used for enriching and extracting aflatoxin in food.
6. Use according to claim 5, characterized in thatThe method comprises the following steps: the application lies in extracting aflatoxin B 1 The method comprises the following steps:
(1) crushing and grinding a solid food sample by using a wall breaking machine, sieving the ground solid food sample, and storing the ground solid food sample in a dry room-temperature environment; then transferring the solid food sample into a centrifuge tube, adding the mixed extraction solution to extract the sample, centrifuging to remove the precipitate, and collecting the supernatant to obtain a pretreated solid food sample;
transferring the liquid food sample into a centrifuge tube, adding the mixed extraction solution to extract the sample, centrifuging to remove the precipitate, and collecting the supernatant to obtain a pretreated liquid food sample;
(2) mixing Mg/Zn-MOF-74@ Fe 3 O 4 Adding the mixture into the pretreated food sample obtained in the step (1), carrying out vortex mixing at room temperature to complete adsorption, and then carrying out Mg/Zn-MOF-74@ Fe adsorption 3 O 4 Separating from the solution; the adsorbed Mg/Zn-MOF-74@ Fe is subsequently 3 O 4 Mixing with the elution solution, and ultrasonically eluting the loaded aflatoxin B 1 Magnetic separation to extract Mg/Zn-MOF-74@ Fe 3 O 4 The obtained product contains aflatoxin B 1 Eluting solution N of 2 And (5) drying, and using residues for subsequent detection.
7. The use of claim 6, wherein in the step (1), the mixed extraction solution is a mixed solution of water and methanol, wherein the volume ratio of water to methanol is (7-10): 1;
in the step (1), the sieve is a sieve with 80 meshes to 120 meshes;
the extraction is ultrasonic extraction, wherein the ultrasonic time is 2-5 min;
the ratio of food (solid or liquid) sample to mixed extraction solution is 1: (2-5);
the centrifugation is carried out for 5-15min under the conditions of 6000-8000 r/min.
8. Use according to claim 6, wherein in step (2), Mg/Zn-MOF-74@ Fe 3 O 4 In proportion to the pretreated food samplemg/mL is 1: (2-5);
the adsorption time is 1-5 min;
the turbine mixing is to uniformly mix in a turbine rotator at the speed of 450-550 r/min;
the separation is to separate the magnetic adsorbent from the liquid under the action of an external magnetic field;
the kind of the elution solution is formic acid, acetone, methanol or acetonitrile solution or the combination thereof;
the ratio of Mg/Zn-MOF-74 to the elution solution is (3-10) in Mg/mL: 1;
the pH value of the elution solution is 5-10;
the elution conditions were: eluting for 2-5min under ultrasonic condition;
blowing at 75-85 deg.C and N 2 The flow rate is 0.3-0.6 mL/min.
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| CN114192117A (en) * | 2021-11-15 | 2022-03-18 | 南京医科大学 | Magnetic composite material and preparation method and application thereof |
| CN114409913A (en) * | 2022-01-11 | 2022-04-29 | 军事科学院军事医学研究院环境医学与作业医学研究所 | Magnetic metal organic framework material and preparation method and application thereof |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN116124925A (en) * | 2022-12-20 | 2023-05-16 | 河南工业大学 | Aflatoxin B 1 Determination method of double early warning molecules |
| CN116124925B (en) * | 2022-12-20 | 2023-11-21 | 河南工业大学 | Aflatoxin B 1 Determination method of double early warning molecules |
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