Hollow magnetic material, preparation thereof and application of hollow magnetic material in food detection pretreatment

Abstract

The invention discloses a hollow magnetic material as well as preparation and application thereof in food detection pretreatment, and belongs to food detection analysis. The hollow magnetic MgFe-LDH is synthesized through a one-step method, the MgFe-LDH is in a hollow flower-ball shape, black Fe3O4 balls are stacked on the hollow flower-ball shape of the MgFe-LDH, the hollow magnetic MgFe-LDH is used for magnetic solid phase extraction (MSPE) of quinoline carboxylic acid antibacterial drugs in honey samples, compared with a traditional adsorbent, the magnetic MgFe-LDH is easily dissolved by acid, and the magnetic Fe3O4 balls are not prone to being dissolved by the acid. In the extraction process, H2SO4 is selected to dissolve materials to replace a traditional organic solvent extraction mode, so that the extraction process is more efficient and green. The method for detecting the quinoline carboxylic acid antibacterial drugs in the food by using the hollow magnetic MgFe-LDH as the adsorbent provided by the invention has the advantages of wide linear range (0.03-7mg. L <-1 >), low detection limit (0.023-0.036 mg. L <-1 >), high correlation coefficient (greater than 0.9988), good precision (4.4-9.3%), high extraction recovery rate (83.8-104.3%) and the like.

Description

Technical Field

[0001] The invention belongs to the field of food detection and analysis, and specifically relates to a hollow magnetic material and a preparation method thereof and an application thereof in food detection pre-treatment. Background Art

[0002] The information disclosed in this background technology section is only intended to enhance the understanding of the overall background of the invention, and should not be necessarily regarded as an admission or any form of suggestion that the information constitutes the prior art already known to those skilled in the art.

[0003] Quinoline carboxylic acid antibiotics are a class of compounds containing quinoline rings and carboxylic acid groups in their molecular structures. They inhibit bacterial DNA gyrase and hinder the replication of bacterial DNA, thereby achieving an antibacterial effect, and play an important role in preventing bees from foul septicemia and septicemia. However, feeding bees with large amounts of quinoline carboxylic acid antibiotics will cause them to remain in honey, eventually entering the human body through the food chain, and continue to accumulate, causing systemic damage. Therefore, establishing an effective monitoring and analysis method is of great significance to avoid the accumulation of trace amounts of quinoline carboxylic acid antibiotics in honey in the food chain.

[0004] The sample pretreatment process is an important step to remove the interference of other substances in the target. At present, the commonly used pretreatment processes mainly include solid phase extraction (SPE), solid phase microextraction (SPME), dispersed solid phase extraction (DSPE) and magnetic solid phase extraction (MSPE). Compared with other pretreatment technologies, magnetic solid phase extraction (MSPE) is widely used due to its simple operation, fast separation speed and avoidance of column clogging. Li et al. prepared Fe3O4 / MIL-100 (Fe) / GO) for magnetic solid phase extraction of enrofloxacin in milk, and the recovery rate of the established method ranged from 85.7 to 106.2%, with a relative deviation of less than 2.86%. Li et al. prepared polyethylene-functionalized Fe3O4 / bentonite particles for magnetic solid phase extraction of three typical quinoline carboxylic acid antibacterial drugs in chicken, and found that the spiked recovery rate was between 83.9 and 98.7%, with a relative deviation of less than 6.8%. Reza et al. prepared all-green nanosponges for magnetic solid phase extraction of quinolinecarboxylic acid antibiotics in environmental water samples, and obtained a good detection limit (0.25-500 ng / mL) with the help of HPLC-UV analysis method.

[0005] Layered double hydroxides (LDHs) are a class of layered nanostructured materials composed of metal cations and interlayer anions. Due to their large specific surface area, unique layered structure, and exchangeability of interlayer anions, they are widely used as adsorbents to remove a variety of pollutants. At the same time, LDHs have the characteristics of weak alkalinity and are easily dissolved by a variety of acids. They can be used as soluble adsorbents in sample pretreatment processes. Tang et al. prepared three MgAl-LDHs to extract and separate from samples, and then used 8% trifluoroacetic acid (TFA) to dissolve the materials for solid phase extraction of aromatic acids. Arghavani-Beydokhtii et al. prepared Pb-Cr-RY15 / RB5-LDH to extract and separate from samples, and then used 2 mol / L TFA to dissolve the materials for dispersed solid phase extraction of metal cations and anionic azo dyes.

[0006] Therefore, there are few studies in the prior art on the use of LDHs as an adsorbent for the analysis of trace amounts of quinoline carboxylic acid antibacterial drugs in honey. LDHs as an adsorbent has great application potential in the analysis of quinoline carboxylic acid antibacterial drugs. Summary of the invention

[0007] In order to overcome the deficiencies of the prior art, the purpose of the present invention is to provide a hollow magnetic material and its preparation and application in food pretreatment. The present invention synthesizes hollow magnetic MgFe-LDH by a one-step method, which is used for magnetic solid phase extraction (MSPE) of quinoline carboxylic acid antibacterial drugs in honey samples. Compared with other methods, magnetic solid phase extraction is simple to operate, time-saving and low-cost. In addition, compared with traditional adsorbents, magnetic MgFe-LDH is easily dissolved by acid. Taking advantage of this feature, H2SO4 is used to dissolve the material during the extraction process instead of the traditional organic solvent extraction method, making the extraction process more efficient and green.

[0008] In order to achieve the above object, the technical solution of the present invention is:

[0009] In a first aspect, the present invention provides a hollow magnetic material, wherein the hollow magnetic material is MgFe-LDH, which is in the shape of a hollow flower ball, and black Fe3O4 balls are accumulated on the hollow flower ball of MgFe-LDH.

[0010] In a second aspect, the present invention provides a method for preparing the hollow magnetic material, comprising the following steps:

[0011] The magnesium source and the iron source are dissolved in organic solvents respectively, mixed and then the hollow magnetic MgFe-LDH material is prepared by hydrothermal co-precipitation method.

[0012] In one or more embodiments, the magnesium source is magnesium acetate, such as magnesium acetate tetrahydrate. Other magnesium salts (such as magnesium sulfate, magnesium nitrate, etc.) have been proven to be unfeasible and cannot form the hollow magnetic MgFe-LDH material of the present invention.

[0013] In one or more embodiments, the iron source is ferric chloride, such as ferric chloride hexahydrate. Other iron sources, such as ferric sulfate, are not as effective as ferric chloride.

[0014] In one or more embodiments, the organic solvent is ethylene glycol.

[0015] In one or more embodiments, the usage ratio of magnesium source, iron source and organic solvent is (1-2 g):(0.1-0.5 g):(50-100 mL), preferably (1-1.5 g):(0.1-0.2 g):(50-60 mL).

[0016] In one or more embodiments, the mixing is followed by stirring for 2-6 hours.

[0017] In one or more embodiments, the specific steps of the hydrothermal co-precipitation method are: the mixed solution is reacted by hydrothermal method, cooled to room temperature, and the precipitate is separated by a magnet, washed and dried.

[0018] Furthermore, the hydrothermal method has a reaction temperature of 180-220°C, preferably 190-210°C, and a reaction time of 6-8h. If the temperature is too low, such as 120°C, only LDH can be formed, and Fe3O4 cannot be generated. In the present invention, magnetic LDH is synthesized in one step, and Fe3O4 is successfully loaded on MgFe-LDH.

[0019] Furthermore, the precipitate is a black precipitate, which is washed multiple times with pure water and anhydrous ethanol and dried at 60-80° C. overnight.

[0020] As a preferred technical solution, the preparation method of the hollow magnetic material is as follows: dissolving magnesium acetate tetrahydrate in ethylene glycol, recorded as solution A, dissolving ferric chloride hexahydrate in ethylene glycol, recorded as solution B, dropping solution B into solution A at room temperature and stirring for 2 to 6 hours, transferring into a high-pressure reactor and heating to 180 to 220° C. and maintaining for 6 to 8 hours, cooling to room temperature, separating the black precipitate with a magnet, washing with pure water and anhydrous ethanol for multiple times, and drying at 60 to 80° C. overnight.

[0021] In a third aspect, the present invention provides the use of the hollow magnetic material in food pre-testing. Preferably, the food test is the detection and analysis of quinolinecarboxylic acid antibiotics in food.

[0022] Furthermore, the food is honey, including loquat honey, lemon honey, wolfberry honey, jujube honey, acacia honey and the like.

[0023] Furthermore, the quinolinecarboxylic acid antibacterial drugs include but are not limited to norfloxacin (NOR), ofloxacin (OFL), ciprofloxacin hydrochloride (CIP-HCl), and enrofloxacin (ENRO).

[0024] In a fourth aspect, the present invention provides a method for enriching and extracting quinolinecarboxylic acid antibacterial drugs, comprising the following steps:

[0025] The hollow magnetic material is used as an adsorption extractant, mixed with a sample to be tested, extracted by standing with a magnet, the liquid is removed, an acid solution is added and standing to dissolve, thereby obtaining a solution containing quinolinecarboxylic acid antibiotics.

[0026] In one or more embodiments, the ratio of the hollow magnetic material, the sample to be tested and the acid solution is (5-25 mg):(50-70 mL):(15-25 μL), preferably (10-25 mg):(50-70 mL):(15-25 μL), and further preferably (15-20 mg):(50-70 mL):(15-25 μL).

[0027] In one or more embodiments, the concentration of the sample to be tested is 500-800 ng / g.

[0028] In one or more embodiments, the mixing is further subjected to shaking treatment at 30-40° C. for 5-15 min.

[0029] In one or more embodiments, during extraction, the pH is 4-10, preferably 6-10, and more preferably 6-8.

[0030] In one or more embodiments, the extraction time is 5-40 min, preferably 5-15 min.

[0031] In one or more embodiments, the acid is CH3COOH, H2SO4, HNO3 or HCl, preferably HNO3 or H2SO4, and more preferably H2SO4. The concentration of the acid solution is 5-7 mol / L.

[0032] In one or more embodiments, when the acid solution is added and allowed to dissolve, the acid dissolution time is 5-120 min, preferably 30-120 min, and more preferably 50-70 min.

[0033] In a fifth aspect, the present invention provides a method for detecting quinolinecarboxylic acid antibiotics in food, wherein the detection method utilizes the above-mentioned method for enriching and extracting quinolinecarboxylic acid antibiotics to pre-treat the test sample to obtain a test sample, and then conducts testing on the test sample.

[0034] Furthermore, the samples were tested by high performance liquid chromatography, and the test conditions were as follows: Ultimate 3000 liquid chromatograph (Thermo Fisher, USA) equipped with a diode detector and a C18 chromatographic column (Agilent, 5 μm, 4.6×250 mm), the wavelength was 280 nm, the mobile phase was methanol / 0.1-0.2 mol / L phosphoric acid water (triethylamine adjusted to pH 3) (30 / 70, v / v), the flow rate was 1-3 mL / min, the injection volume was 18-20 μL, the injection time was 10-15 min, and the column temperature was 25-30°C.

[0035] One or some of the above technical solutions have the following advantages or beneficial effects:

[0036] (1) The present invention synthesizes hollow magnetic MgFe-LDH by a one-step method and is used for magnetic solid phase extraction (MSPE) of quinoline carboxylic acid antibacterial drugs in honey samples.

[0037] (2) The present invention adopts magnetic solid phase extraction, which is simple to operate, time-saving and low-cost compared with other methods.

[0038] (3) The hollow magnetic MgFe-LDH provided by the present invention is used as an adsorbent. Compared with traditional adsorbents, the magnetic MgFe-LDH is easily dissolved by acid. Taking advantage of this feature, H2SO4 is used to dissolve the material during the extraction process instead of the traditional organic solvent extraction method, making the extraction process more efficient and green.

[0039] (4) Through single factor optimization of the five factors affecting the extraction efficiency, an MSPE-HPLC-UV method was established under the optimal conditions to determine the four quinoline carboxylic acid antibiotics. This method has a wide linear range (0.03-7 mg.L -1 ), lower detection limit (0.024-0.036mg.L -1 ), high correlation coefficient (>0.9988) and good precision (4.3-9.4%), high extraction recovery rate (83.3-104.8%) and other advantages. Therefore, the method for detecting quinolinecarboxylic acid antibiotics in food using hollow magnetic MgFe-LDH as an adsorbent provided by the present invention is a green, efficient and reliable method for detecting quinolinecarboxylic acid antibiotics in honey samples. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] The accompanying drawings in the specification, which constitute a part of the present invention, are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0041] Figure 1Scanning electron microscope (SEM) and transmission electron microscope (TEM) of the hollow magnetic MgFe-LDH material prepared in Example 1 of the present invention; wherein (a) is a SEM image, and (b) is a TEM image;

[0042] Figure 2 Scanning electron microscopy (SEM) of the material prepared in Comparative Example 1 of the present invention;

[0043] Figure 3 The effect of sample pH on the extraction effect in Example 4 of the present invention;

[0044] Figure 4 The effect of sample extraction time on the extraction effect in Example 4 of the present invention;

[0045] Figure 5 The effect of the adsorbent dosage on the extraction effect in Example 4 of the present invention;

[0046] Figure 6 The effect of the type of acid on the extraction effect in Example 4 of the present invention;

[0047] Figure 7 This is the effect of the acid dissolution time on the extraction effect in Example 4 of the present invention. DETAILED DESCRIPTION

[0048] In order to enable those skilled in the art to more clearly understand the technical solution of the present invention, the technical solution of the present invention will be described in detail below in conjunction with specific embodiments.

[0049] Example 1

[0050] Preparation of hollow magnetic MgFe-LDH materials

[0051] Dissolve 1.0 g of magnesium acetate tetrahydrate in 40 mL of ethylene glycol, recorded as solution A, and dissolve 0.19 g of ferric chloride hexahydrate in 10 mL of ethylene glycol, recorded as solution B. Add solution B dropwise into solution A at room temperature and stir for 4 hours. Then transfer the solution into a high-pressure reactor, heat to 200°C and keep it for 8 hours. After cooling to room temperature, separate the black precipitate with a magnet, wash it three times with pure water and anhydrous ethanol, and dry it at 60°C overnight.

[0052] Figure 1 Scanning electron microscope (SEM) and transmission electron microscope (TEM) of magnetic MgFe-LDH. It can be found that MgFe-LDH is in the shape of a hollow flower ball, and black Fe3O4 balls are accumulated on the hollow flower ball of MgFe-LDH. The flower ball-like structure increases the surface area of ​​the material.

[0053] Comparative Example 1

[0054] The difference from Example 1 is that magnesium acetate tetrahydrate is replaced with magnesium nitrate, and other conditions are the same. The results show that Figure 2 As shown, it does not form a hollow ball.

[0055] Example 2

[0056] A method for enriching and extracting quinoline carboxylic acid antibacterial drugs-magnetic solid phase extraction experiment

[0057] 15 mg of magnetic MgFe-LDH prepared in Example 1 was added to a conical flask containing 60 mL of sample, shaken at 35°C for 10 min, then the conical flask was taken out and placed on a magnet to stand, then the supernatant was poured out, 20 μL of 6 mol / L H2SO4 was added and the material was dissolved for 20 min. The solution containing the target pollutant was injected into HPLC for quantitative analysis.

[0058] Example 3

[0059] The solution containing the target pollutant prepared in Example 2 was analyzed by high performance liquid chromatography: The analysis and determination of the four quinoline carboxylic acid antibacterial drugs used an Ultimate 3000 liquid chromatograph (ThermoFisher, USA) equipped with a diode detector and a C18 chromatographic column (Agilent, 5μm, 4.6×250mm). The wavelength was 280nm, the mobile phase was methanol / 0.1mol / L phosphoric acid water (triethylamine adjusted to pH 3) (30 / 70, v / v), the flow rate was 1mL / min, the injection volume was 20μL, the injection time was 15min, and the column temperature was 30°C.

[0060] Example 4 Optimization of extraction conditions

[0061] The successful extraction of quinoline carboxylic acid antibacterial drugs by magnetic MgFe-LDH requires the optimization of magnetic solid phase extraction conditions to obtain a higher extraction recovery rate. Therefore, the extraction conditions of honey samples containing 600 ng / g of norfloxacin (NOR), ofloxacin (OFL), ciprofloxacin hydrochloride (CIP-HCl), and enrofloxacin (ENRO) were optimized from the perspectives of pH, adsorption time, adsorption dose, acid type, and acid dissolution time.

[0062] 1. Effect of pH

[0063] The pH value will affect the charge state of the adsorbent surface and the form of the pollutants in the environment, which in turn affects the extraction effect of magnetic MgFe-LDH on quinoline carboxylic acid antibiotics. This experiment studied the effect of magnetic MgFe-LDH on the extraction of four quinoline carboxylic acid antibiotics at a pH between 2 and 12. The results are shown in Figure 3It can be found that when the pH is between 2-6, the material's extraction recovery rate for four quinoline carboxylic acid antibacterial drugs increases significantly. When the pH is 6, the extraction efficiency reaches the optimal level. As the pH continues to increase, the material's extraction recovery of the target object first decreases slowly and then decreases rapidly. This is because when the pH in the solution is lower than 6, the magnetic MgFe-LDH dissolves and the layered structure is destroyed, which in turn affects the extraction effect. When the pH is between 6-10, the electrostatic attraction between the magnetic MgFe-LDH and the target decreases, and the extraction recovery rate decreases slowly. It also shows that the magnetic MgFe-LDH has a good pH buffering capacity. When the pH is greater than 12, the negatively charged surface of the material produces electrostatic repulsion with the negatively charged target pollutants, resulting in a significant decrease in its extraction recovery rate.

[0064] 2. Effect of extraction time

[0065] In order to achieve the highest extraction recovery rate in the shortest time, the extraction time needs to be optimized. This experiment studied the effect of magnetic MgFe-LDH on the extraction of four quinoline carboxylic acid antibiotics within 0-40min. Figure 4 It can be found that the extraction recovery rate increases with time, and reaches the optimal level when it reaches 10 minutes. This is because the magnetic MgFe-LDH has a large specific surface area, and it is continuously dispersed in the solution through oscillation, resulting in a shorter mass transfer path, which promotes the extraction of the target by the material. Therefore, in order to ensure higher extraction efficiency, the extraction time of 10 minutes is determined as the optimal extraction time.

[0066] 3. Effect of adsorbent dosage

[0067] In order to improve the extraction efficiency, the amount of adsorbent was optimized. In this experiment, 0-25 mg of magnetic MgFe-LDH was added to explore the effect of adsorbent dosage on magnetic solid phase extraction of quinoline carboxylic acid antibacterial drugs with magnetic MgFe-LDH. Figure 5 It can be found that the extraction recovery rate of magnetic MgFe-LDH for four quinoline carboxylic acid antibacterial drugs increases with the increase of adsorbent dosage. When the adsorbent dosage is 15 mg, the extraction recovery rate reaches the optimal level and then decreases slightly. This is mainly because when the amount of adsorbent increases to 15 mg, the adsorption reaches saturation. At this time, the excess adsorbent cannot be completely dissolved by the acid, resulting in a decrease in the extraction recovery rate. Therefore, in order to ensure higher extraction efficiency, the adsorbent dosage of 15 mg is determined as the optimal adsorbent dosage.

[0068] 4. Influence of acid type

[0069] The study found that LDHs will gradually dissolve in an environment with a pH value less than 4. Therefore, by using this property, 20 μL of 6 mol / L CH3COOH, H2SO4, HNO3 and HCl were added to dissolve the extracted Fe3O4@FeMgAl-LDH to release four quinoline carboxylic acid antibacterial drugs. The experimental results are shown in Figure 6 It can be found that compared with the other three acids, the extraction recovery rate of the four quinoline carboxylic acid antibacterial drugs obtained by dissolving the material with H2SO4 is the highest. Therefore, in order to ensure higher extraction efficiency, H2SO4 is used as the best acid type for dissolving the material.

[0070] 5. Influence of acid dissolution time

[0071] The time of acid dissolution of materials is a major factor affecting the extraction efficiency. This experiment studied the effect of H2SO4 dissolving magnetic MgFe-LDH on magnetic solid phase extraction of four quinoline carboxylic acid antibacterial drugs within 0-120 min. The results are as follows Figure 7 As shown in the figure, it can be found that the extraction recovery rate of the material for the four quinoline carboxylic acid antibiotics increases with the increase of acid dissolution time. When the acid dissolution time is 60 minutes, the material is completely dissolved and the extraction reaches the optimal level. Then, with the increase of acid dissolution time, the extraction recovery rate remains unchanged.

[0072] Example 5 Methodology Verification

[0073] Based on the optimal single factor conditions, the method of analyzing and determining quinoline carboxylic acid antibacterial drugs by magnetic solid phase extraction of magnetic MgFe-LDH and HPLC-UV was validated, including the linear correlation range, correlation coefficient (R 2 ), limit of detection (LOD), limit of quantification (LOQ) and intra-day and inter-day precision parameters. -1 Within the linear range, a linear curve was drawn through the relationship between the peak area and the corresponding concentration of the target, and the correlation coefficient was obtained. Combined with the linear curve, LOD and LOQ were calculated according to 3 times and 10 times the signal-to-noise ratio. The intra-day and inter-day precision parameters were calculated based on the results of 6 repeated tests per day within three days.

[0074] Table 1 summarizes the experimental parameters for the method validation. The linear range of the four quinoline carboxylic acid antibacterial drugs, OFL, NOR, CIP-HCl, and ENRO, is 0.03-7 mg.L -1 , the LOD values ​​were 0.024, 0.033, 0.024, and 0.036 mg.L -1 , LOQ were 0.087, 0.110, 0.081, 0.120 mg.L -1 , the linear correlation coefficients R of four quinoline carboxylic acid antibacterial drugs 2The range was between 0.9988-0.9999, and the good intra-day and inter-day precisions were between 4.3-9.4% and 5.3-8.1%, respectively. All parameters indicated that the MSPE-HPLC-UV based on magnetic MgFe-LDH was a sensitive and reliable method for the analysis of quinolinecarboxylic acid antimicrobial drugs.

[0075] Table 1 MSPE-HPLC-UV method validation parameters based on Fe3O4@FeMgAl-LDH

[0076]

[0077] Example 6 Sample Analysis

[0078] The MSPE-HPLC-UV method with magnetic MgFe-LDH was used to analyze and detect four quinoline carboxylic acid antibiotics in loquat honey, lemon honey, wolfberry honey, jujube honey, and acacia honey under the optimal conditions. No quinoline carboxylic acid antibiotics were detected in the blank samples. In order to evaluate the accuracy of the method, the actual sample was tested by adding the target standard solution to the honey. The results are shown in Table 2. The spiked levels of quinoline carboxylic acid antibiotics (0.05, 1 μg.g -1 The recovery of honey was between 83.3% and 104.8%, and the RSD was between 2.1% and 10.5%. Therefore, this method can be applied to the determination of quinolinecarboxylic acid antibacterial drugs in honey.

[0079] Table 2 Analysis and detection results of quinoline carboxylic acid antibacterial drugs in honey

[0080]

[0081]

[0082] Comparison of Example 7 with other methods

[0083] By comparing the existing methods of extracting quinoline carboxylic acid antibiotics in the environment, the superiority of the developed method was evaluated from the aspects of linear range, recovery rate, LOD, and consumption of organic solvent for extraction. The results are shown in Table 3. It can be seen that the method developed in this study has a wider linear range and better extraction performance than other methods; and compared with the pretreatment method of solid phase extraction, magnetic solid phase extraction is simple and easy to operate, saving time; when extracting the target, acid dissolution is more environmentally friendly than the method of eluting with organic solvents. Therefore, this technology is an efficient and green sample pretreatment method for detecting quinoline carboxylic acid antibiotics in honey.

[0084] Table 3 Comparison with existing research methods of quinoline carboxylic acid antibacterial drugs

[0085]

[0086] In this study, hollow magnetic MgFe-LDH was synthesized by coprecipitation method and used as an adsorbent for magnetic solid phase extraction. It was combined with high performance liquid chromatography to analyze and determine four quinoline carboxylic acid antibacterial drugs in five different honey samples. Through condition optimization, the optimal conditions for magnetic solid phase extraction were obtained as follows: under pH=6, 15 mg of adsorbent was added to the sample, oscillated for 10 min, H2SO4 was used to dissolve the material for 60 min, and then the detection was performed. The MSPE-HPLC-UV method established under the optimal conditions had a wide linear range, simple operation, high extraction recovery rate, no organic solvent was used, and was environmentally friendly. In summary, this study provides a green, efficient and reliable method for the detection of quinoline carboxylic acid antibacterial drugs in honey samples.

[0087] [1]Tian, ​​J.; Hu, J.; Yang, F.; Tang, T.; Guo, J.; Qin, W. Polyamidoaminedendrimers as off-column binding agent and in-columnpseudostationary phase for efficient and sensitive capillary electrophoretic analysis of fluoroquinolones in chicken muscles. Food Chemistry 2014,157,498-503.https: / / doi.org / 10.1016 / j.foodchem.2014.02.070

[0088] [2]Li,Y.;Zhang,Z.;Li,J.;Li,H.;Chen,Y.;Liu,Z.Simple, stable and sensitive electrogeneratedchemiluminescence detector for high-performance liquid chromatography and its application in direct determination of multiple fluoroquinolone residues in milk.Talanta 2011,84(3),690-695.https: / / doi.org / 10.1016 / j.talanta.2011.01.068

[0089] [3] Herrera-Herrera, AV; Ravelo-Pérez, LM; Hernández-Borges, J.; Afonso, MM; Palenzuela, JA; Rodríguez-Delgado, M. Oxidized multi-walled carbonnanotubes for the dispersive solid-phase extraction of quinolone antibiotics from water samples using capillary electrophoresis and large volume samplestacking with polarity switching. Journal of Chromatography A 2011,1218(31),5352-5361.https: / / doi.org / 10.1016 / j.chroma.2011.06.031

[0090] [4]Hee-Jung, C.; M, AE-AA; Ayman, G.; Gi-Min, S.; Hee, Y.; Dong-Cheol, S.; Jin-Suk, K.; Jae-Han, S.; Ji-Yoon, J.; Soon-Ho, L.; et al.Monitoring of fluoroquinolone residual levels in chicken eggs by microbiological assay and confirmation by liquid chromatography.Biomedical chromatography:BMC 2008,22(1),92-99.https: / / doi.org / 10.1002 / BMC.900

[0091] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A hollow magnetic material, characterized in that: The hollow magnetic material is MgFe-LDH, which is in the shape of a hollow flower ball, and black Fe3O4 balls are accumulated on the hollow flower ball of MgFe-LDH.

2. A method for preparing the hollow magnetic material according to claim 1, characterized in that: The following steps are involved: The magnesium source and the iron source are dissolved in organic solvents respectively, mixed and then the hollow magnetic MgFe-LDH material is prepared by hydrothermal co-precipitation method.

3. The preparation method according to claim 2, characterized in that: The magnesium source is magnesium acetate; The iron source is ferric chloride; The organic solvent is ethylene glycol; Preferably, the usage ratio of magnesium source, iron source and organic solvent is (1-2 g):(0.1-0.5 g):(50-100 mL), and more preferably (1-1.5 g):(0.1-0.2 g):(50-60 mL).

4. The preparation method according to claim 2, characterized in that: The specific steps of the hydrothermal coprecipitation method are: the mixed solution is reacted by hydrothermal method, cooled to room temperature, and the precipitate is separated by magnet, washed and dried; Preferably, the hydrothermal method has a reaction temperature of 180 to 220°C and a reaction time of 6 to 8 hours; Preferably, the precipitate is a black precipitate, which is washed multiple times with pure water and anhydrous ethanol and dried overnight at 60-80°C.

5. Use of the hollow magnetic material according to claim 1 in food pre-testing treatment.

6. The use according to claim 5, characterized in that: The food testing is the detection and analysis of quinoline carboxylic acid antibacterial drugs in food; Preferably, the food is honey, selected from one or more of loquat honey, lemon honey, wolfberry honey, jujube honey and acacia honey; Preferably, the quinolinecarboxylic acid antibacterial drug is selected from one or more of norfloxacin, ofloxacin, ciprofloxacin hydrochloride and enrofloxacin.

7. A method for enriching and extracting quinolinecarboxylic acid antibacterial drugs, characterized in that: The following steps are involved: The hollow magnetic material according to claim 1 is used as an adsorption extractant, mixed with a sample to be tested, extracted by standing with a magnet, the liquid is removed, an acid solution is added and stood to dissolve, and a solution containing quinolinecarboxylic acid antibacterial drugs is obtained.

8. The method according to claim 7, characterized in that The ratio of the hollow magnetic material, the sample to be tested and the acid solution is (5-25 mg): (50-70 mL): (15-25 μL), preferably (10-25 mg): (50-70 mL): (15-25 μL), and more preferably (15-20 mg): (50-70 mL): (15-25 μL); Preferably, the concentration of the sample to be tested is 500-800 ng / g; Preferably, the mixture is shaken at 30-40° C. for 5-15 min. Preferably, during extraction, the pH is 4-10, preferably 6-10, and more preferably 6-8; Preferably, the extraction time is 5-40 min, preferably 5-15 min; Preferably, the acid is CH3COOH, H2SO4, HNO3 or HCl, preferably HNO3 or H2SO4, more preferably H2SO4; the concentration of the acid solution is 5-7 mol / L; Preferably, when the acid solution is added and allowed to stand for dissolution, the acid dissolution time is 5-120 min, preferably 30-120 min, and more preferably 50-70 min.

9. A method for detecting quinolinecarboxylic acid antibacterial drugs in food, characterized in that: The detection method comprises pre-treating a sample to be tested by using the method for enriching and extracting quinolinecarboxylic acid antibacterial drugs according to claim 7 or 8 to obtain a test sample, and then testing the sample.

10. The method for detecting quinolinecarboxylic acid antibiotics in food according to claim 9, characterized in that: The test samples were tested by high performance liquid chromatography, and the test conditions were: using a liquid chromatograph equipped with a diode detector and a C18 chromatographic column, a wavelength of 280 nm, a mobile phase of methanol / 0.1-0.2 mol / L phosphoric acid water, where v / v=30 / 70, a flow rate of 1-3 mL / min, an injection volume of 18-20 μL, an injection time of 10-15 min, and a column temperature of 25-30°C.

Images