CN113201093A

CN113201093A - Novel quercetin surface imprinted polymer and application thereof

Info

Publication number: CN113201093A
Application number: CN202110551577.1A
Authority: CN
Inventors: 何娟; 许红; 宋立新; 张云霞; 王慧格; 许鹏飞; 游利琴; 李媛媛
Original assignee: Henan University of Technology
Current assignee: Henan University of Technology
Priority date: 2021-05-20
Filing date: 2021-05-20
Publication date: 2021-08-03

Abstract

The invention relates to a novel quercetin surface imprinted polymer and application thereof, belonging to the field of analysis and detection materials. The surface-imprinted polymer MIL-88A @ MIPs loaded by MIL-88A is synthesized by adopting a surface imprinting technology. MIL-88A @ MIPs show excellent adsorption performance(when the concentration of quercetin is 30. mu.g mL^‑1When the adsorption capacity of MIL-88A @ MIPs is up to 8.14 mu g mg^‑1(ii) a And 36s is ready to complete adsorption). The solid-phase extraction column is used as column packing to be manufactured, a vacuum pump is not needed to apply pressure in the using process, the appropriate flow velocity can be kept, the experimental time is shortened compared with other self-made columns, and the working efficiency is improved. The MIL-88A @ MIPs SPE column is more beneficial to application in practical production life.

Description

Novel quercetin surface imprinted polymer and application thereof

Technical Field

The invention relates to a surface imprinted polymer, in particular to a novel quercetin surface imprinted polymer and application thereof, belonging to the field of analysis and detection materials.

Background

Cereals are easily polluted by mycotoxins in the processes of growth, storage and the like, and common mycotoxins include Aflatoxins (Aflatoxins), zearalenone and the like. The AFs are stable in property and greatly harmful to human and animal health, the types of the AFs are more, the structures of different types of the AFs are different, and the common aflatoxins G2, G1, B2 and B1(AFG2, AFG1, AFB2 and AFB1) are similar in structure and are four types of the AFs which are most harmful to human bodies. And AFB1 is more toxic and is evaluated as a natural carcinogen, so that the search of a proper AFs detection method is particularly important. The accuracy of the test results is based on reliable sample pre-processing. The surface imprinted polymer-solid phase extraction has a very good treatment effect in a complex sample matrix and is concerned by people.

Because AFs have strong toxicity and high price, the AFs are directly used as templates and threaten the physical health of researchers, and therefore, a proper analogue needs to be selected as a substitute of the AFs to serve as a synthetic template, and the safety coefficient of experiments is improved. In addition, the carrier is particularly important, the MIL-88A material is widely concerned in the aspects of analyzing medicines and biochemical samples because of the advantages of simple and quick synthesis conditions, easily available raw materials, high chemical corrosion resistance, low density, controllable pore size, large specific surface area and the like, but the MIL-88A has insufficient affinity selectivity for specific target substances and limited adsorption capacity, and the synthesis of the imprinted polymer on the surface of the MIL-88A material can enhance the adsorption performance and the specific selectivity for the target substances, so the synthesis of the surface imprinted polymer (MIL-88A @ MIPs) by using the MIL-88A material as the carrier has good application prospect.

Disclosure of Invention

The invention aims to provide a novel quercetin surface imprinted polymer, and a method for detecting aflatoxin in a grain sample is further explored by optimizing the surface imprinted polymer.

In order to realize the purpose of the invention, the invention takes a metal organic framework (MIL-88A) as a carrier, and selects quercetin with a structure similar to that of aflatoxin as a substitute template to prepare a novel surface imprinted polymer (MIL-88A @ MIPs).

The specific technical scheme is as follows: obtaining the quercetin surface imprinted polymer by the following method:

(1) adding MIL-88A into conical flask containing ethanol, sealing, and mixing with ultrasound.

(2) Adding quercetin and methacrylic acid (MAA) into a three-necked bottle containing ethanol, sealing, ultrasonically treating until the mixture is dissolved, adding ethylene glycol dimethacrylate (EDMA), and continuously ultrasonically treating Azobutyronitrile (AIBN) until the mixture is dissolved.

(3) Transferring the mixed solution in the step (1) into the solution in the step (2), and stirring and contacting at room temperature; and then heating for reaction, and drying after the reaction is finished to obtain the quercetin surface imprinted polymer template.

(4) Wrapping a quercetin surface imprinted polymer template with filter paper, and eluting by using a Soxhlet extraction tube, wherein the eluent is a mixed solution of acetonitrile and water (8:2 v/v). And detecting the extracting solution of the polymer at intervals in the elution process. Until no quercetin can be detected, finally, drying the polymer to obtain a quercetin surface imprinted polymer, which is called-88A @ MIPs for short.

The mass of the AIBN is 4 percent of the total mass of monomer methacrylic acid (MAA) and cross-linking agent ethylene glycol dimethacrylate (EDMA).

And (3) preparing the synthesized MIL-88A @ MIPs which are eluted and removed from the template as column packing into a solid phase extraction column, and optimizing the extraction conditions. The solid phase extraction column is used for processing actual samples such as grains and the like, and then HPLC-FD is used for detection, so that a sensitive, efficient and reliable AFs detection method is explored.

The selection of the template and different carrier materials can influence the adsorption performance of the surface imprinted polymer, and the invention has the advantages that: 1. the analog quercetin of AFs is used as a substitute of the AFs to serve as a synthesis template, and the synthesized imprinted polymer MIL-88A @ MIPs has unique selective and specific adsorption capacity on the AFs and higher experimental safety coefficient.

2. The MIL-88A @ MIPs is used as an adsorbent to prepare a solid phase extraction column, and the maximum adsorption capacity of the MIL-88A @ MIPs is 8.14 mu g mg^-1And 36s can reach adsorption equilibrium. Optimizing solid phase extraction conditions to obtain: the eluent was acetonitrile, water ═ 8:2(v/v), and the elution volume was 2.5 mL. Establishing a method for detecting trace aflatoxin in a grain sample. The evaluation of the method proves that the detection limit of the method on aflatoxin B1, B2, G1 and G2 in a sample matrix is 0.06 mug kg^-1、0.08μg kg^-1、0.08μg kg^-1And 0.05. mu.gkg^-1The quantitative limit is 0.20 mug kg^-1、0.25μg kg^-1、0.25μg kg^-1And 0.17. mu.g kg^-1. In the spiked recovery experiments, the recovery ranged from 60.21% to 115.97% with a relative standard deviation of 1.61% to 5.32%. In the comparative experiment and the actual sample detection experiment, the self-made column has good recovery effect on AFB1, AFB2, AFG1 and AFG2 in the sample.

3. The solid phase extraction column prepared by taking MIL-88A @ MIPs as column packing shows more unique practical value in the using process, MIL-88A is relatively more environment-friendly during synthesis, and the specific surface area is overlarge, so that the column pressure of the prepared solid phase extraction column is smaller. In previous experiments, it was found that most of the self-made solid phase extraction columns require external pressure to achieve a proper flow rate. The solid phase extraction column prepared by the invention does not need external pressure, and the natural flow rate is equivalent to that of an immunoaffinity column, so that the solid phase extraction column has greater practicability and higher economic value in practical application.

The surface imprinted polymer solid phase extraction column prepared by the invention has better selective recognition and adsorption on a target object; the method can replace a commercial column sold in the market to carry out sample pretreatment on the mycotoxin in the grains, and has higher cost performance and stable performance; the established detection method is reliable and has lower detection limit. Has good popularization and application prospect.

Drawings

FIG. 1 is a flow chart of the present invention, wherein, the synthesis route of |: MIL-88A @ MIPs; use flow chart of MIL-88A @ MIPs SPE column.

FIG. 2 is a graph of infrared spectra, wherein (a) MIPs, (b) MIL-88A @ MIPs, and (c) MIL-88A.

FIG. 3 is SEM scanning electron microscope and transmission electron microscope images, wherein (A) MIL-88A, (B) MIL-88A @ MIPs, and C and D are MIL-88A @ MIPs.

FIG. 4 is a graph of particle size distribution for MIL-88A and MIL-88A @ MIPs.

FIG. 5 is an XRD pattern for MIL-88A and MIL-88A @ MIPs.

FIG. 6 shows the measurement of the adsorption performance of the polymer of the present invention, A: isothermal adsorption curve; b, Frondlich isothermal adsorption model; c, adsorption rate curve; and D, a pseudo-second-order dynamic adsorption model.

FIG. 7 is a histogram of the present invention's optimization of eluents.

FIG. 8 is an optimization of elution volumes according to the present invention.

FIG. 9 is a comparison of chromatograms for detection columns, wherein a: MIL-88A @ MIPs SPE column; b: an immunoaffinity column.

Detailed Description

To better illustrate the invention, the following examples are given:

liquid chromatography conditions: a C18 column (150mm by 4.6mm, 5 μm); the mobile phase is methanol-water (45:55, v/v); flow rate: 0.8mL min^-1(ii) a Sample introduction amount: 10 mu L of the solution; column temperature: 30 ℃; the excitation wavelength is 360nm, and the emission wavelength is 440 nm.

The percentages are by mass unless otherwise specified below. All the reagents are commercially available.

Example 1

1. Synthesis of MIL-88A

5mmol (1.3515g) of FeCl were weighed₃·6H₂O, 5mmol (0.5804g) of fumaric acid and 30mL of deionized water were placed in a container of 1In a 00mL reaction kettle, stirring for 1h at room temperature by magnetons, and uniformly mixing. Taking out the magneton, sealing the kettle, and reacting at 65 ℃ for 12 h. Standing overnight, naturally cooling, taking out the product, washing with water and ethanol in sequence, filtering, and oven drying in a vacuum drying oven to obtain MIL-88A for use.

2. Preparation of MIL-88A @ MIPs

(1) MIL-88A (1g) was added to a conical flask (150mL) containing 50mL of ethanol, sealed and sonicated for 50min to mix.

(2) 0.3mmol (0.0859g) of quercetin and 1.8mmol (0.1550g) of MAA were added to a three-necked flask (250mL) containing 30mL of ethanol, the flask was sealed and sonicated until dissolved, and 15mmol (2.9733g) of EDMA and 0.1251g of AIBN (the mass of which is 4% of the total mass of the monomers and crosslinker) were added and sonication continued until dissolved.

(3) The mixed solution in (1) was completely transferred to the three-necked flask in (2), and first, the mixed solution was mechanically stirred at room temperature for 30min to be sufficiently contacted. Then the temperature is raised to 85 ℃ for reaction, and the reaction is kept for 5 h. Filtering and drying; obtaining the surface imprinted polymer template.

(4) Wrapping a quercetin surface imprinted polymer template with filter paper, and eluting by using a Soxhlet extraction tube, wherein the eluent is a mixed solution of acetonitrile and water (8:2 v/v). And detecting the extracting solution of the polymer at intervals in the elution process. Until no template is detected, and finally, the polymer is dried to obtain a final product (MIL-88A @ MIPs) for later use.

3. Preparation and characterization of MIL-88A @ MIPs

The process for preparing MIL-88A @ MIPs as shown in fig. 1, the reaction time may affect the polymer yield, and excessive yield may result in excessive polymer coating on the surface of MIL-88A; when the amount of the polymer is too small, incomplete coating occurs, and the polymerization rate is also affected by the room temperature during the reaction, so that it is necessary to control the reaction time by observing the polymerization intermittently.

(1) As shown in FIG. 2, 1613cm^-1And 1698cm^-1The bands at (a) are due to the symmetrical and asymmetrical vibrational modes of the carbonyl group in the fumaric acid. Furthermore, at 3137-3720cm^-1The broadband of (a) is due to the O-H of water molecules in air. At 649cm^-1And 669cm^-1The absorption band of (B) corresponds to MIL-88The Fe-O coordination bond on A, the peak appears in both MIL-88A and MIL-88A @ MIPs, and the MIL-88A @ MIPs is indicated, so that the MIL-88A participates in the surface imprinted polymer template (MIL-88A @ MIPs). 2951cm^-1And 2983cm^-1The characteristic peak is caused by stretching vibration of C-H on saturated carbon, and the peak appears in MIPs and MIL-88A @ MIPs at the same time, which indicates that the MIPs participates in the surface imprinted polymer template (MIL-88A @ MIPs). The two phenomena exist simultaneously and mutually prove that: MIPs are polymerized on the surface of MIL-88A, so that the corresponding surface imprinted polymer (MIL-88A @ MIPs) is successfully obtained.

(2) A in a scanning electron microscope picture 3 shows that MIL-88A presents a uniform hexagonal rod-shaped structure, the granularity is obvious, and the surface is smooth; in fig. 3, B shows that MIL-88A @ MIPs also have a rod-like structure, which is rougher and fluffy in surface and has a cluster shape and a honeycomb-like hole in surface compared with MIL-88A. As can be seen from the transmission electron microscope images C and D in FIG. 3, the MIL-88A @ MIPs takes the MIL-88A as a core, the surface of the MIL-88A @ MIPs is wrapped by the MIPs layer, and the wrapped MIPs layer is uniform and complete and well covered on the surface of the MIL-88A, so that strong evidence is provided for successful synthesis of the MIL-88A @ MIPs.

(3) From FIG. 4, it can be seen that MIL-88A is 4.02 μm, and MIL-88A @ MIPs is 6.38. mu.m. The MIL-88A particles are influenced by the heating condition and the stirring degree before heating in the reaction process, so that the growing degree of the MIL-88A is unbalanced; MIL-88A @ MIPs can continuously observe the state of polymerization during the polymerization process, so that the particle size control is better.

(4) As can be seen from FIG. 5, MIL-88A shows characteristic peaks at 10.46 degrees and 11.97 degrees, and MIL-88A @ MIPs not only contains the above characteristic peaks, but also shows characteristic peaks at 22.67 degrees and 28.70 degrees, which indicates that MIL-88A @ MIPs also contains new substances on the basis of MIL-88A. The characteristic peaks of the two substances in an XRD pattern are relatively sharp, which shows that the grain sizes of MIL-88A and MIL-88A @ MIPs are relatively large and the crystallinity is relatively good.

(5) Measurement of adsorption Properties: isothermal adsorption experimental data for MIL-88A @ MIPs and MIPs are shown as a in fig. 6. The concentration of the template solution is 0-30 mu g mL^-1In the range of (1), the adsorption of the MIL-88A @ MIPs to the template shows a straight-line rising trend, and the maximum adsorption capacity of the MIL-88A @ MIPs can reach8.14μg mg^-1The adsorption capacity is obviously higher than that of MIPs. Data fitting of MIL-88A @ MIPs and MIPs for adsorption of template molecules in the static state linear forms of Freundlich are shown in fig. 6B, with the constant coefficients of the above equation calculated according to equation (2).

The formulas are respectively as follows:

where Qe is the equilibrium adsorption (. mu.g mg)^-1)，C_eIs the equilibrium concentration (μ g mL)^-1)，

The linearized isothermal equation is shown in table 1:

TABLE 1 parameters of Freundlich's isothermal equation and pseudo-second order kinetic model

The adsorption of MIL-88A @ MIPs and MIPs to the template is more suitable for the Freundlich isothermal model, which indicates that the adsorption is multi-layered. Wherein the n value of MIL-88A @ MIPs is larger than MIPs, and the former is easier to adsorb. As shown in C in FIG. 6, MIL-88A @ MIPs showed a fast adsorption rate in adsorption kinetics experiments, and the adsorption saturation could be reached within 1 minute. The adsorption kinetics data were fit calculated with reference to D in fig. 6, and the data calculated according to equation (3) are shown in the pseudo-second order adsorption model in table 1. Adsorption of quercetin on MIPs and MIL-88A @ MIPs is more prone to chemisorption. Therefore, the adsorption mode of the MIPs and the MIL-88A @ MIPs to the quercetin follows pseudo second order kinetics, and the adsorption process is more prone to chemical adsorption.

Pseudo second-stage:

wherein t (min) is the adsorption time; qt and Qe (μ g mg)^-1) The adsorption capacity of MIL-88A @ MIPs at any time t and at equilibrium is respectively; k2 (mg. mu.g)^-1min^-1) Is the adsorption rate is alwaysAnd (4) counting.

Example 2

1. Measurement of adsorption Properties of MIL-88A @ MIPs

In static adsorption experiments, eight groups of 10mg MIL-88A @ MIPs were weighed and then added to a solution containing 4mL (0.5, 1, 5, 8, 10, 15, 20, 30 μ g mL) of each^-1) Shaking and mixing quercetin standard solution in a centrifuge tube, and standing for 1 h. Filtering, and measuring with ultraviolet-visible spectrophotometer. Substituting the value into a standard solution curve equation configured under the same condition to obtain the concentration of the quercetin in the supernatant, and calculating the adsorption quantity of MIL-88A @ MIPs under the corresponding concentration by using an adsorption quantity formula (1).

In the dynamic adsorption experiment, eight groups of 10mg MIL-88A @ MIPs are weighed and respectively filled in a container with 4mL of 10 mu g mL^-1In 12 centrifuge tubes of the quercetin template standard solution, oscillating for adsorption, standing for 0.08, 0.1, 0.2, 0.3, 0.4, 0.6, 0.8 and 1 minute, quickly filtering the supernatant, measuring by using an ultraviolet-visible spectrophotometer to determine the amount of the quercetin remaining in the solution at different adsorption times, obtaining the adsorption amount of MIL-88A @ MIPs at corresponding time by using a formula (1), and drawing an adsorption dynamic curve.

Wherein C is₀Is the concentration of template before adsorption (. mu.g mL)^-1)，C₁Is the concentration of template after adsorption (. mu.g mL)^-1) And V is the volume of the solution (4mL), and m is the mass (mg) of MIL-88A @ MIPs.

2. Preparation of the actual samples

The actual samples were extracted according to GB 5009.22-2016. After pulverizing the sample, 5.0 + -0.1 g of the sample was added with 20mL of acetonitrile/water (84:16, v/v) solution, shaken for 20min, and filtered through glass fiber filter paper. 4mL of the filtrate was taken, and 46mL of 1% Tween-20 PBS buffer was added to obtain a sample matrix solution.

3. Preparation of MIL-88A @ MIPs SPE column

The MIL-88A @ MIPs prepared by the method is used as an adsorbent of an MIL-88A @ MIPs SPE column. Wet-packed columns, 150mg of MIL-88A @ MIPs wetted with methanol, were transferred completely to empty SPE columns with a frit on the bottom. Then, another sieve plate is used to cover the adsorbent on the upper layer, and the adsorbent particles are kept at a proper distance by pressing, so that the home-made MIL-88A @ MIPs SPE column has good performance and keeps lower column pressure when in use. The column was purified by passing methanol (10mL) and water (15mL) through a MIL-88A @ MIPs SPE cartridge. When the deionized water from the purification step is about to completely exit the MIL-88A @ MIPs SPE column, a volume of sample extract is added, the flow rate is maintained at about 2-3 drops/sec, the sample extract flows through the home-made column, and the AFs in the extract are retained in the adsorbent in the column. Then, with 2.5mL of acetonitrile: the AFs retained in the MIL-88A @ MIPs SPE cartridge were taken out by a solution of water (8:2, v/v), filtered through an organic filter head and transferred to a sample vial. The amount of AFs carried over from the eluate was measured by HPLC-FD, and the recovery of AFs from the MIL-88A @ MIPs SPE column was calculated.

4. Optimization of solid phase extraction conditions

(1) Optimization of elution eluent

The ability of various solvents to separate AFs retained in MIL-88A @ MIPs SPE columns was evaluated. Based on this, a suitable solvent was selected as the eluent to remove impurities from the MIL-88A @ MIPs SPE column and to recover the AFs from the MIL-88A @ MIPs SPE column. Organic solvents such as acetone and ethyl acetate are tried, and due to the fact that the polarity of the organic solvents is large, more impurities are often brought out of an MIL-88A @ MIPs SPE column, and when the retention time of the impurities is the same as that of AFs, the accuracy of an experimental result is greatly influenced, namely, the recovery rate exceeds 200%. AFs in the sample are trace components, so small amounts of impurities also have a large effect. Methanol was selected as the eluent through the experiments.

Recovery of AFs from different organic solvents as shown in fig. 7, the higher the recovery, the stronger the elution of AFs from the solvent. And the proper eluent is selected, so that the solvent can be saved, and the recovery rate can be ensured. During the adsorption process, the target is adsorbed by the reserved holes on the MIL-88A @ MIPs due to the action of non-covalent bonds such as hydrogen bonds. When a solvent with weaker polarity is used as an eluent, only the target substance which is subjected to non-specific adsorption on the surface of MIL-88A @ MIPs can be eluted. However, it may be considered that the trace amount of the target substance is not enough, so that the solvent with the excessive polarity can elute more target substance and also bring more impurities, and the influence of the impurities on the analysis of the target substance must be considered. By experiment, the recovery rate of aflatoxin by 80% acetonitrile solution is found to reach 104.65%, so acetonitrile: water (8:2, v/v) is the elution solution.

Chromatograms prepared from data obtained by detecting aflatoxin under different eluent dosages are shown in fig. 8, wherein the higher the elution sequence is, the lower the recovery rate of the eluent with the same volume is until the target object cannot be detected. This indicates that the amount of eluent accumulated before this eluent in which AFs were not detected was sufficient to completely elute the target. From FIG. 8, it can be seen that when the elution volume is increased to 2mL, the target peaks of AFG2 and AFB1 can still be detected. When the elution amount was increased again by 0.5mL, the target peak was not detected, and thus the amount of the eluent was determined to be 2.5 mL. Through the experiment, the control of the flow rate is very important during elution, the flow rate is low, the eluent is in full contact with the AFs retained in the self-made column, the AFs can be better taken out of the column, and the recovery rate and the experimental accuracy are improved.

Example 3 method verification

(1) Reusability test

In the use process of repeating for 6 times, the recovery rate of the MIL-88A @ MIPs SPE column to the four toxins is maintained to be 83.05% -98.92%, and the performance is stable.

(2) Selectivity test

TABLE 2 Selective recovery of different toxins by MIL-88A @ MIPs SPE column

Adding different standard toxins into the same sample, extracting according to an AFs extraction method in national standard, and then respectively carrying out analysis and test by using an established detection method through an MIL-88A @ MIPs SPE column. The experimental results are shown in Table 2, and the recovery rates of the MIL-88A @ MIPs SPE column on AFB1, AFB2 and AFG1 are about 100 percent and the recovery rate on AFG2 is over 60 percent. The recovery rate of OTA and ZEA is obviously reduced by the MIL-88A @ MIPs SPE column, wherein the recovery rate of OTA is 9.24% by the MIL-88A @ MIPs SPE column, the recovery rate of ZEA is higher, but the recovery rate of ZEA is only 21.13%. The MIL-88A @ MIPs SPE column has the worst OTA recovery effect and the best AFB2 recovery effect. Experimental results prove that the MIL-88A @ MIPs SPE column has unique selective recognition capability on AFs.

(3) Method linearity

To assess the accuracy and precision of the method, and to exclude the adverse effect of the sample matrix on the standard curve, the linear equations, linear ranges and LODs, LOQs of AFB1, AFB2, AFG1 and AFG2 were therefore determined for the sample matrix system, as shown in table 3:

TABLE 3 Linear Curve, Linear Range, LOD and LOQ of the detection methods

In a linear range, the concentrations of AFB1, AFB2, AFG1 and AFG2 and the measured values all present a direct proportion relation; within this interval, the method is reliably applicable. The detection limits obtained by comparing the signals of the sample solution containing low concentration of AFs treated with the home-made column and the blank sample matrix with a signal-to-noise ratio of 3:1 are shown in Table 3 and are 0.060. mu.g kg^-1、0.08μg kg^-1、0.08μg kg^-1And 0.05. mu.g kg^-1(ii) a The limit of quantitation was 0.20. mu.g kg^-1，0.25μg kg^-1，0.25μg kg^-1And 0.17. mu.g kg^-1。

(4) Test for recovery with addition of standard

In the process of verifying the analysis method, in order to ensure the accuracy of the measurement result, AFB1, AFB2, AFG1 and AFG2 standard substances at three concentration levels are added into a blank sample matrix; in order to avoid the influence brought by the extraction efficiency of the sample, a common purple rice sample is particularly selected for a labeling experiment in the experiment. The results are shown in Table 4.

TABLE 4 recovery with addition of standard

Example 5 comparison of MIL-88A @ MIPs SPE column with immunoaffinity column

The comparison between the MIL-88A @ MIPs SPE column and the immunoaffinity column is shown in FIG. 9, a chromatogram after the immunoaffinity column is processed is cleaner and more, and the fluctuation of the chromatogram after the MIL-88A @ MIPs SPE column is slightly more; as for the target peak, the two are not greatly different, the recovery effect of the immunoaffinity column on AFG2 is slightly better than that of the MIL-88A @ MIPs SPE column, but the recovery rate on AFB1, AFB2 and AFG1 is slightly lower than that of the MIL-88A @ MIPs SPE column. Namely, the performance of the MIL-88A @ MIPs SPE column can achieve the effect of the immunoaffinity column. Compared with the use effect, the MIL-88A @ MIPs SPE column is comparable to an immunoaffinity column, but the MIL-88A @ MIPs SPE column has obvious advantages in other aspects (low cost, reusability, convenience in storage and the like). Therefore, the MIL-88A @ MIPs SPE column can replace a commercial immunoaffinity column to be used for pretreatment of mycotoxin in a grain sample, and has great practical value.

The solid phase extraction column prepared by using MIL-88A @ MIPs as the adsorbent has smaller column internal pressure and is smoothly used. The MIL-88A @ MIPs SPE column has a high natural flow rate, although the MIL-88A @ MIPs SPE column is short in contact time with a target object, and the contact time of an eluent and the target object retained in the column is short, through a series of experiments such as comparison with an immunoaffinity column and labeled recovery, the MIL-88A @ MIPs SPE column is good in using effect, has high practical value, and is expected to be produced in large batches and put into market application.

EXAMPLE 6 actual sample analysis

The MIL-88A @ MIPs SPE column prepared by the method is used for detecting black beans (Glycine max (L.) merr), purple Rice (Polished Glutinous Rice) and wheat (Triticum aestivum L.) placed for more than one year, and different samples are observed to have different degrees of mildewing by visual observation, and part of the samples start to be vermin and even moths appear. The samples are detected to determine the content of AFs, and the mildew speed and degree of different samples show larger difference due to different shell hardness and water content.

The concentrations of AFB1, AFB2, AFG1 and AFG2 in the obtained sample extracts are shown in table 5. The results show that different samples have different growth conditions, so that the conditions of generating mycotoxins in the samples are greatly different, and the growth speed of each toxin is different. The toxin content in the sample is not only different due to different mildewing severity, but also the property of the sample has certain influence on the growth of the toxin.

TABLE 5 analysis of actual samples

^a: not detected.

Claims

1. The quercetin surface imprinted polymer is characterized by being prepared by the following method:

(1) adding MIL-88A into a conical flask containing ethanol, sealing, and ultrasonically mixing;

(2) adding quercetin and methacrylic acid (MAA) into a three-necked bottle containing ethanol, sealing, ultrasonically treating until the mixture is dissolved, adding ethylene glycol dimethacrylate (EDMA), and continuously ultrasonically treating Azobutyronitrile (AIBN) until the mixture is dissolved;

(3) transferring the mixed solution in the step (1) into the solution in the step (2), and stirring and contacting at room temperature; then heating to react, and drying after the reaction is finished to obtain a quercetin surface imprinted polymer template;

(4) wrapping a quercetin surface imprinted polymer template with filter paper, and eluting by using a Soxhlet extraction tube, wherein an eluent is a mixed solution of acetonitrile and water; and (3) detecting the extracting solution of the polymer at intervals in the elution process until no quercetin can be detected, and finally drying the polymer to obtain a quercetin surface imprinted polymer, which is called as-88A @ MIPs for short.

2. The quercetin surface imprinted polymer according to claim 1, wherein the AIBN mass is 4% of the total mass of the monomer methacrylic acid (MAA) and the crosslinker ethylene glycol dimethacrylate (EDMA); the volume ratio of the mixed solution of the eluent acetonitrile and water is 8: 2.

3. The use of quercetin surface-imprinted polymer according to claim 1 or 2, characterized in that MIL-88A @ MIPs as column packing is made into a solid phase extraction column, and the solid phase extraction column is used for selectively adsorbing aflatoxins AFG2, AFG1, AFB2 and AFB1 in cereals, eluting and enriching with mixed solution of acetonitrile and water, and then performing qualitative or quantitative detection by using HPLC-FD.