Magnetic solid phase extraction method and application thereof

Abstract

The application discloses a magnetic solid phase extraction method and application thereof, and belongs to the field of chemical analysis. The magnetic solid phase extraction method provided by the application uses ion pair reagents to assist magnetic solid phase extraction. The magnetic solid phase extraction method provided by the application can significantly improve the saturated adsorption capacity of polar compounds, and has obvious adsorption selectivity, and has the advantages of high sample pretreatment efficiency, rapid adsorption, simple separation operation, green environmental protection, and renewable use of magnetic adsorption materials, and has a wide application in detection of polar compounds.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of chemical analysis, and particularly relates to a magnetic solid phase extraction method and application thereof. BACKGROUND

[0002] When analyzing a target compound with strong polarity and ionization ability in a sample by liquid chromatography, poor retention or no retention often occurs on a reversed-phase chromatographic column. One solution is to use ion-pair chromatography, which is an analysis strategy in high-performance liquid chromatography by introducing an ion-pair reagent. The main principle is that the hydrophobic carbon chain of the association of the ion-pair reagent and the target compound and the hydrophobic retention between the stationary phase filler. Therefore, the adsorption performance of the filler, the ion-pair reagent and the acid-base ionization ability of the target compound should be considered. However, ion-pair chromatography still has the defects of poor adsorption performance, difficult separation operation and difficult regeneration of the filler. SUMMARY

[0003] In order to overcome the problems of the prior art, one of the purposes of the present application is to provide a magnetic solid phase extraction method, which can significantly improve the saturation adsorption capacity of polar compounds, has obvious adsorption selectivity, has the advantages of high sample pretreatment efficiency, rapid adsorption, simple separation operation, green environmental protection, and renewable use of magnetic adsorption materials.

[0004] The second purpose of the present application is to provide an application of the above-mentioned magnetic solid phase extraction method.

[0005] In order to achieve the above-mentioned purposes, the technical solution adopted by the present application is:

[0006] The first aspect of the present application provides a magnetic solid phase extraction method, which uses an ion-pair reagent to assist magnetic solid phase extraction.

[0007] Preferably, the magnetic solid phase extraction method comprises the following steps: mixing a target compound, an ion-pair reagent, a magnetic adsorption material and a buffer solution to obtain an adsorption reaction system, performing an adsorption reaction, and then desorbing the magnetic adsorption material adsorbed with the target compound to obtain a separated target compound; the target compound is dissociated in the buffer solution, and the dissociated target compound forms an electrically neutral association with the ion-pair reagent; the ion-pair reagent contains a carbon chain; the magnetic adsorption material comprises ferroferric oxide and carbon material.

[0008] In the present application, the ion pair reagent and the dissociated target compound have opposite charges, and can form an electrically neutral associated product through the electrostatic attraction between the anion and the cation. The carbon chain in the ion pair reagent can form a hydrophobic interaction with the magnetic adsorption material, so that the associated product can be adsorbed on the magnetic adsorption material, and the magnetic adsorption material can be separated by an external magnetic field or the like. Desorption of the magnetic adsorption material can achieve extraction or enrichment of the target compound.

[0009] Preferably, the target compound is a polar compound; further preferably, the polar compound is a polar compound that can be dissociated by acid, base or both; more preferably, the polar compound is a polar compound in an animal-derived food; more preferably, the polar compound includes polar marine toxins, polar antibiotics or a combination thereof; most preferably, the polar compound includes at least one of tetrodotoxin, moroxydine or domoic acid.

[0010] Preferably, the polar compound is extracted from an animal sample; further preferably, the extraction solution includes at least one of acetic acid, trichloroacetic acid, methanol or water.

[0011] Preferably, the biological sample includes at least one of puffer fish meat, chicken meat or scallop.

[0012] Preferably, tetrodotoxin can be extracted from puffer fish meat, moroxydine can be extracted from chicken meat, and domoic acid can be extracted from scallop.

[0013] Preferably, in the magnetic solid phase extraction method, when the target compound is an acidic compound, the reaction system is weakly acidic; when the target compound is a basic compound, the reaction system is weakly basic.

[0014] Preferably, the pH of the weakly acidic reaction system is 4-6; further preferably, the pH of the weakly acidic reaction system is 5-6.

[0015] Preferably, the pH of the weakly basic reaction system is 8-12; further preferably, the pH of the weakly basic reaction system is 9-10.

[0016] Preferably, in the magnetic solid phase extraction method, when the target compound is an acidic compound, the ion pair reagent is a cationic ion pair reagent; when the target compound is a basic compound, the ion pair reagent is an anionic ion pair reagent.

[0017] Preferably, the cationic pair reagent in the magnetic solid phase extraction method comprises at least one of dodecyl trimethyl ammonium chloride, tetrabutyl ammonium bromide or tetrabutyl ammonium sulfate; further preferably, the cationic pair reagent in the magnetic solid phase extraction method comprises dodecyl trimethyl ammonium chloride, tetrabutyl ammonium bromide or a combination thereof; more preferably, the cationic pair reagent in the magnetic solid phase extraction method is selected from tetrabutyl ammonium bromide.

[0018] Preferably, the anionic pair reagent in the magnetic solid phase extraction method is selected from C2-C13 perfluoroalkyl carboxylic acid; further preferably, the anionic pair reagent in the magnetic solid phase extraction method is selected from C3-C10 perfluoroalkyl carboxylic acid; more preferably, the anionic pair reagent in the magnetic solid phase extraction method is selected from C4-C7 perfluoroalkyl carboxylic acid.

[0019] In a weakly acidic reaction system, acidic compounds can present anionic dissociation state, thereby forming an electrically neutral complex with the cationic pair reagent through the electrostatic attraction between anions and cations; in a weakly basic reaction system, basic compounds can present cationic dissociation state, thereby forming an electrically neutral complex with the anionic pair reagent through the electrostatic attraction between anions and cations. The above electrically neutral complex is stably adsorbed on the magnetic adsorption material through the alkyl carbon chain of the ion pair reagent, so that the target compound is adsorbed on the magnetic adsorption material.

[0020] Preferably, the magnetic adsorption material is modified by coating the carbon material with ferroferric oxide.

[0021] The present application introduces ferroferric oxide into carbon material for magnetic modification, which endows the carbon material with superparamagnetic property, so that the magnetic adsorption material of the present application has the characteristics of magnetic separation and reusability. In addition, the carbon material modified by ferroferric oxide has good dispersion performance in the reaction solution, is not easy to aggregate, and has high saturated adsorption capacity. The carbon material not modified by ferroferric oxide has poor dispersion performance in the reaction solution, is easy to float on the surface of the liquid or aggregate in the solution, has extremely limited effective adsorption area and site for the target compound in the reaction solution, and has low adsorption capacity.

[0022] Preferably, the average particle size of the ferroferric oxide in the magnetic adsorption material is 1-100 nm; further preferably, the average particle size of the ferroferric oxide in the magnetic adsorption material is 5-50 nm; more preferably, the average particle size of the ferroferric oxide in the magnetic adsorption material is 10-30 nm.

[0023] Preferably, the ferroferric oxide in the magnetic adsorption material is surface-modified ferroferric oxide; further preferably, the surface modifier of the ferroferric oxide in the magnetic adsorption material is oleic acid.

[0024] The nanoscale ferroferric oxide has a higher dispersion degree in the reaction solution, which is beneficial to improve the saturation adsorption capacity of the magnetic adsorption material; and the surface modification of the ferroferric oxide by using a surface modifier such as oleic acid can effectively reduce the agglomeration of the ferroferric oxide, so that the dispersion degree is further improved.

[0025] Preferably, the carbon material in the magnetic material comprises at least one of an aminated carbon material, a carboxylated carbon material, a hydroxylated carbon material or an oxidized carbon material.

[0026] Preferably, the carbon material in the magnetic adsorption material comprises at least one of a carbon fiber, a fullerene, a carbon aerogel, a carbon nanotube or graphene; further preferably, the carbon material in the magnetic adsorption material comprises at least one of a carbon fiber, a carbon aerogel, a carbon nanotube or graphene; and more preferably, the carbon material in the magnetic adsorption material comprises at least one of a carbon aerogel, a carbon nanotube or graphene.

[0027] Preferably, the carbon material is a nanocarbon material.

[0028] Preferably, the average inner diameter of the carbon nanotube in the carbon material is 1-10 nm; further preferably, the average inner diameter of the carbon nanotube in the carbon material is 2-8 nm; and more preferably, the average inner diameter of the carbon nanotube in the carbon material is 3-5 nm.

[0029] Preferably, the average outer diameter of the carbon nanotube in the carbon material is 3-25 nm; further preferably, the average outer diameter of the carbon nanotube in the carbon material is 5-20 nm; and more preferably, the average outer diameter of the carbon nanotube in the carbon material is 8-15 nm.

[0030] Preferably, the average length of the carbon nanotube in the carbon material is 30-70 nm; further preferably, the average length of the carbon nanotube in the carbon material is 35-65 nm; and more preferably, the average length of the carbon nanotube in the carbon material is 40-60 nm.

[0031] Preferably, the average thickness of the graphene in the carbon material is 0.5-7 nm; further preferably, the average thickness of the graphene in the carbon material is 0.6-6.8 nm; and more preferably, the average thickness of the graphene in the carbon material is 0.8-6.4 nm.

[0032] Preferably, the carbon material in the magnetic material comprises at least one of amino-carbon fiber, amino-fullerene, amino-carbon aerogel, amino-carbon nanotube, amino-graphene, carboxyl-carbon fiber, carboxyl-fullerene, carboxyl-carbon aerogel, carboxyl-carbon nanotube, carboxyl-graphene, hydroxyl-carbon fiber, hydroxyl-fullerene, hydroxyl-carbon aerogel, hydroxyl-carbon nanotube, hydroxyl-graphene, oxidized-carbon fiber, oxidized-fullerene, oxidized-carbon aerogel, oxidized-carbon nanotube or oxidized-graphene; more preferably, the carbon material in the magnetic material comprises at least one of amino-carbon nanotube, amino-graphene, carboxyl-carbon nanotube, carboxyl-graphene, hydroxyl-carbon nanotube, hydroxyl-graphene, oxidized-carbon nanotube or oxidized-graphene; and more preferably, the carbon material in the magnetic material comprises at least one of amino-carbon nanotube, amino-graphene, carboxyl-carbon nanotube or oxidized-graphene.

[0033] After the carbon material is functionally modified by aminoization, carboxylation, hydroxylation or oxidation, more active sites can be introduced into the carbon material, the saturation adsorption capacity of the magnetic adsorption material is improved, and the target compound has more stable adsorption retention; the nanoscale carbon material has a higher dispersion degree in the reaction solution, which is beneficial to improve the saturation adsorption capacity of the magnetic adsorption material; and the carbon fiber, fullerene, carbon aerogel, carbon nanotube or graphene has the characteristics of large specific surface area, excellent mechanical stability, excellent thermal stability and easy functional modification.

[0034] Preferably, the mass ratio of the ferroferric oxide and the carbon material in the magnetic adsorption material is (0.2-1.8):1; more preferably, the mass ratio of the ferroferric oxide and the carbon material in the magnetic adsorption material is (0.5-1.5):1; and more preferably, the mass ratio of the ferroferric oxide and the carbon material in the magnetic adsorption material is (0.8-1.2):1.

[0035] The mass ratio of the ferroferric oxide and the carbon material significantly affects the magnetic extraction effect: if the mass ratio of the ferroferric oxide and the carbon material is too high, too many ferroferric oxide magnetic particles are dispersed and gathered on the surface of the carbon material, which causes the adsorption efficiency of the magnetic adsorption material to decrease obviously; and if the mass ratio of the ferroferric oxide and the carbon material is too low, the prepared magnetic adsorption material becomes slow when separated by an external magnetic field, which is not conducive to the rapid dispersion extraction operation of the reaction solution.

[0036] Preferably, the magnetic adsorption material is prepared by reacting the ferroferric oxide and the carbon material in acetonitrile.

[0037] When the ferroferric oxide and the carbon material are dispersed in acetonitrile, they can be compounded in a self-assembly manner to generate the magnetic adsorption material.

[0038] Preferably, the molar ratio of the ion pair reagent to the target compound in the magnetic solid phase extraction method is (6-260): 1; more preferably, the amount ratio of the ion pair reagent to the target compound in the magnetic solid phase extraction method is (15-220); and more preferably, the amount ratio of the ion pair reagent to the target compound in the magnetic solid phase extraction method is (30-180): 1.

[0039] Preferably, the amount ratio of the magnetic adsorbent material to the target compound in the magnetic solid phase extraction method is (60-400) mg: 1 μmol; more preferably, the amount ratio of the magnetic adsorbent material to the target compound in the magnetic solid phase extraction method is (80-350) mg: 1 μmol; and more preferably, the amount ratio of the magnetic adsorbent material to the target compound in the magnetic solid phase extraction method is (100-300) mg: 1 μmol.

[0040] Preferably, the concentration of the ion pair reagent in the reaction system in the magnetic solid phase extraction method is 0.5-20 mmol / L; more preferably, the concentration of the ion pair reagent in the reaction system in the magnetic solid phase extraction method is 1-15 mmol / L; and more preferably, the concentration of the ion pair reagent in the reaction system in the magnetic solid phase extraction method is 2-10 mmol / L.

[0041] Preferably, the concentration of the magnetic adsorbent material in the reaction system in the magnetic solid phase extraction method is 5-30 mg / mL; more preferably, the concentration of the magnetic adsorbent material in the reaction system in the magnetic solid phase extraction method is 8-25 mg / mL; and more preferably, the concentration of the magnetic adsorbent material in the reaction system in the magnetic solid phase extraction method is 10-20 mg / mL.

[0042] Preferably, the concentration of the target compound in the reaction system in the magnetic solid phase extraction method is 30-220 μmol / L; more preferably, the concentration of the target compound in the reaction system in the magnetic solid phase extraction method is 45-205 μmol / L; and more preferably, the concentration of the target compound in the reaction system in the magnetic solid phase extraction method is 60-190 μmol / L.

[0043] Preferably, the adsorption reaction time in the magnetic solid phase extraction method is 3-40 min; more preferably, the adsorption reaction time in the magnetic solid phase extraction method is 5-30 min; and more preferably, the adsorption reaction time in the magnetic solid phase extraction method is 10-25 min.

[0044] Preferably, the desorption solution in the magnetic solid phase extraction method comprises an acetonitrile aqueous solution; further preferably, the acetonitrile aqueous solution has a volume concentration of 10-70%; more preferably, the acetonitrile aqueous solution has a volume concentration of 20-60%; more preferably, the acetonitrile aqueous solution has a volume concentration of 20-40%.

[0045] Preferably, the desorption solution further comprises formic acid or ammonia water; further preferably, the formic acid or ammonia water has a volume concentration of 0.1-0.5%; more preferably, the formic acid or ammonia water has a volume concentration of 0.2-0.4%.

[0046] When the target compound is an acidic compound, the desorption solution further comprises ammonia water; when the target compound is a basic compound, the desorption solution further comprises formic acid.

[0047] Preferably, the ratio of the amount of the desorption solution to the amount of the magnetic adsorption material in the magnetic solid phase extraction method is (3-10) mL: 50 mg; further preferably, the ratio of the amount of the desorption solution to the amount of the magnetic adsorption material in the magnetic solid phase extraction method is (3-8) mL: 50 mg; more preferably, the ratio of the amount of the desorption solution to the amount of the magnetic adsorption material in the magnetic solid phase extraction method is (4-5) mL: 50 mg.

[0048] Preferably, the desorption time in the magnetic solid phase extraction method is 2-40 min; further preferably, the desorption time in the magnetic solid phase extraction method is 5-30 min; more preferably, the desorption time in the magnetic solid phase extraction method is 10-20 min.

[0049] Preferably, the magnetic adsorption material is subjected to elution before desorption; further preferably, the elution solution comprises at least one of acetonitrile, methanol or water; more preferably, the elution solution comprises any one of an acetonitrile aqueous solution, methanol or a methanol aqueous solution.

[0050] The second aspect of the present application provides an application of the magnetic solid phase extraction method of the first aspect of the present application in detection of polar compounds.

[0051] In the application, the polar compound is the target compound in the magnetic solid phase extraction method.

[0052] Preferably, the detection method comprises high performance liquid chromatography (HPLC), mass spectrometry (MS) or a combination thereof; further preferably, the detection method is selected from high performance liquid chromatography tandem mass spectrometry (HPLC-MS / MS).

[0053] The present application has the following beneficial effects:

[0054] The magnetic solid phase extraction method provided by the application can significantly improve the saturated adsorption capacity of polar compounds, and has obvious adsorption selectivity, high sample pretreatment efficiency, rapid adsorption, simple separation operation, green environmental protection, and the like, and has the advantages of recyclable use of the composite filler, and the like, and has a wide application in the detection of polar compounds.

[0055] Specifically, compared with the prior art, the application has the following advantages:

[0056] 1. In the weakly acidic reaction system, the acidic compound can present an anion dissociation state, so as to form an electrically neutral complex with the cationic reagent through the electrostatic attraction between the anion and the cation; in the weakly basic reaction system, the basic compound can present a cation dissociation state, so as to form an electrically neutral complex with the anionic reagent through the electrostatic attraction between the anion and the cation. The above-mentioned electrically neutral complex is stably adsorbed and retained by the magnetic adsorption material through the alkyl carbon chain of the ion pair reagent, so as to adsorb the target compound on the magnetic adsorption material. Meanwhile, the carbon material in the magnetic adsorption material is modified by a functional group, and the functional group connected to the carbon material can produce electrostatic adsorption with the target compound, so as to further enhance the adsorption. The ion pair reagent assisted magnetic solid phase extraction method can improve the defects of the traditional solid phase extraction process, such as low effective adsorption amount of strong polar compounds, poor recovery rate and poor reproducibility of quantitative results.

[0057] 2. The magnetic solid phase extraction method can significantly improve the saturated adsorption capacity of strong polar compounds, and has obvious adsorption selectivity, high sample pretreatment efficiency, rapid adsorption, simple separation operation, green environmental protection, and the like, and has the advantages of recyclable use of the composite filler, and the like, and has a wide application in the detection of polar compounds.

[0058] 3. The magnetic adsorption material prepared by the application still has an adsorption efficiency of greater than 88.0% after 10 cycles of regeneration and recycling, and has stable and excellent adsorption performance, and has the value of regeneration and recycling, and can save analysis cost. The magnetic adsorption material prepared by the application has a strong application potential as a magnetic solid phase extraction material for detecting strong polar compounds in animal-derived food. BRIEF DESCRIPTION OF DRAWINGS

[0059] Figure 1 The adsorption rate column chart of Examples 1 to 12.

[0060] Figure 2 The adsorption rate curve chart of Examples 1 to 3, Examples 13 to 27 and Comparative Examples 1 to 3.

[0061] Figure 3The bar chart shows the adsorption rates of Examples 1-3, Examples 28-37, and Comparative Examples 4-17.

[0062] Figure 4 The bar chart shows the adsorption rates of Examples 1-3, Examples 38-52, and Comparative Examples 18-20.

[0063] Figure 5 The bar chart shows the adsorption rates of Examples 1-3, Examples 53-58, and Comparative Examples 21-26.

[0064] Figure 6 The bar chart shows the adsorption rates of Examples 1-3, Examples 59-73, and Comparative Examples 27-29.

[0065] Figure 7 The bar chart shows the adsorption rates of Examples 1-3 and Examples 74-85.

[0066] Figure 8 The bar chart shows the adsorption rates of Examples 1-3, Examples 86-91, and Comparative Examples 30-35.

[0067] Figure 9 The bar chart shows the adsorption rates of Examples 1-3, Examples 92-97, and Comparative Examples 36-41.

[0068] Figure 10 The bar chart shows the adsorption rates of Examples 1-3 and Examples 98-109.

[0069] Figure 11 The adsorption capacities are those of Examples 1-3, Examples 59-73, and Comparative Examples 27-29. Detailed Implementation

[0070] The following specific embodiments further illustrate the content of the present invention in detail. It should also be understood that the following embodiments are only for further explanation of the present invention and should not be construed as limiting the scope of protection of the present invention. Non-essential improvements and adjustments made by those skilled in the art based on the principles described herein are all within the scope of protection of the present invention. The specific process parameters, etc., in the following examples are merely examples within a suitable range; that is, those skilled in the art can make selections within a suitable range based on the description herein, and are not intended to be limited to the specific data in the examples below. Unless otherwise specified, the raw materials, reagents, or apparatus used in the following embodiments and comparative examples can be obtained from conventional commercial sources or by existing known methods.

[0071] Preparation Example 1

[0072] Preparation of magnetic adsorption material Fe3O4@MWCNTs-COOH:

[0073] 0.5 g of oleic acid coated Fe3O4 microspheres (particle size 20 nm, purity > 99.5%) and 1.0 g of carboxyl functionalized carbon nanotubes (MWCNTs-COOH, inner diameter 3-5 nm, outer diameter 8-15 nm, length ~ 50 mm, purity > 99.9%) were uniformly dispersed in acetonitrile solvent, mixed with a glass rod for 5 min, and then left to stand for 30 min. The magnetic adsorbent material was separated by a strong magnet, washed with ethanol and ultrapure water alternately for 2-3 times, and dried at 60°C under vacuum for 8 h. The product was ground and used.

[0074] Preparation Example 2

[0075] Preparation of magnetic adsorbent material Fe3O4@GO:

[0076] 0.5 g of oleic acid coated Fe3O4 microspheres (particle size 20 nm, purity > 99.5%) and 0.5 g of graphene oxide (GO, thickness 0.8-6.4 nm, purity > 99%) were uniformly dispersed in acetonitrile solvent, mixed with a glass rod for 5 min, and then left to stand for 30 min. The magnetic adsorbent material was separated by a strong magnet, washed with ethanol and ultrapure water alternately for 2-3 times, and dried at 60°C under vacuum for 8 h. The product was ground and used.

[0077] Preparation Example 3

[0078] Preparation of magnetic adsorbent material Fe3O4@MWCNTs-NH2:

[0079] 0.5 g of oleic acid coated Fe3O4 microspheres (particle size 20 nm, purity > 99.5%) and 1.5 g of amino functionalized carbon nanotubes (MWCNTs-NH2, inner diameter 3-5 nm, outer diameter 8-15 nm, length ~ 50 mm, purity > 99.9%) were uniformly dispersed in acetonitrile solvent, mixed with a glass rod for 5 min, and then left to stand for 30 min. The magnetic adsorbent material was separated by a strong magnet, washed with ethanol and ultrapure water alternately for 2-3 times, and dried at 60°C under vacuum for 8 h. The product was ground and used.

[0080] Preparation Example 4

[0081] Preparation of magnetic adsorbent material Fe3O4@G-NH2:

[0082] 0.5 g of oleic acid coated Fe3O4 microspheres (particle size 20 nm, purity > 99.5%) and 1.0 g of amino functionalized graphene (G-NH2, thickness 0.8-6.4 nm, purity > 99%) were uniformly dispersed in acetonitrile solvent, mixed with a glass rod for 5 min, and then left to stand for 30 min. The magnetic adsorbent material was separated by a strong magnet, washed with ethanol and ultrapure water alternately for 2-3 times, and dried at 60°C under vacuum for 8 h. The product was ground and used.

[0083] Preparation Example 5

[0084] Extraction of the target compound tetrodotoxin:

[0085] A puffer fish meat sample 5.0 g was weighed into a 50 mL polyacrylamide test tube, 15 mL of acetic acid-methanol solution (1:99, v / v) was added, mixed by vortex shaking, extracted by ultrasonic for 5 min, centrifuged at 4000 rpm for 10 min, and the supernatant was transferred. The sample residue was extracted once more with 10 mL of acetic acid-methanol solution (1:99, v / v), and the extract was combined to prepare a tetrodotoxin extract solution with a concentration of 156.25 μmol / L, which was ready for use.

[0086] Preparation Example 6

[0087] Extraction of the target compound morpholinuron:

[0088] A chicken meat sample 5.0 g was weighed into a 50 mL polyacrylamide test tube, 15 mL of trichloroacetic acid-methanol solution (1:99, v / v) was added, mixed by vortex shaking, extracted by ultrasonic for 5 min, centrifuged at 4000 rpm for 10 min, and the supernatant was transferred. The sample residue was extracted once more with 10 mL of trichloroacetic acid-acetonitrile solution (1:99, v / v), and the extract was combined to prepare a morpholinuron extract solution with a concentration of 156.25 μmol / L, which was ready for use.

[0089] Preparation Example 7

[0090] Extraction of the target compound domoic acid:

[0091] A scallop sample 5.0 g was weighed into a 50 mL polyacrylamide test tube, 15 mL of methanol-water solution (90:10, v / v) was added, mixed by vortex shaking, extracted by ultrasonic for 5 min, centrifuged at 4000 rpm for 10 min, and the supernatant was transferred. The sample residue was extracted once more with 10 mL of methanol-water solution (90:10, v / v), and the extract was combined to prepare a domoic acid extract solution with a concentration of 156.25 μmol / L, which was ready for use.

[0092] Preparation Examples 8-15

[0093] Preparation Examples 8-15 prepared the magnetic adsorbent material Fe3O4@MWCNTs-COOH, which was different from Preparation Example 1 in that the amount of Fe3O4 microspheres added was different. The amount of Fe3O4 microspheres added in Preparation Examples 8-15 is shown in Table 1.

[0094] Table 1 Amount of Fe3O4 microspheres added in Preparation Examples 8-15

[0095]

[0096] Example 1

[0097] A magnetic solid phase extraction method, comprising the following steps:

[0098] Take 5 mL of the tetrodotoxin extract solution described in Preparation Example 5 into a 15 mL polyacrylamide test tube, add 1 mL of PBS buffer solution and mix uniformly. Add 1 mL of ion pair reagent of perfluoroheptanoic acid with a concentration of 50 mmol / L, mix uniformly, then add 1.1 mL of 25 wt% ammonia water to adjust the pH to 9, add methanol to 10 mL, add 50 mg of the magnetic adsorbent material Fe3O4@MWCNTs-COOH described in Preparation Example 1, perform vortex oscillation for adsorption reaction for 15 min, discard the reaction sample solution, sequentially wash the magnetic adsorbent material with 5 mL of methanol-water (80:20, v / v) and 5 mL of methanol, then add 4 mL of formic acid-acetonitrile-water solution (0.4:40:60, v / v / v) as a desorption solution, perform oscillation for desorption for 10 min, separate by a strong magnet, collect the desorption solution, and use it for HPLC-MS / MS determination.

[0099] In this example, the concentration of the ion pair reagent in the adsorption reaction system is 5 mmol / L, the concentration of the magnetic adsorbent material in the adsorption reaction system is 5 mg / mL, and the concentration of tetrodotoxin in the adsorption reaction system is 78.125 μmol / L.

[0100] Example 2

[0101] A magnetic solid phase extraction method, comprising the following steps:

[0102] Take 5 mL of the morpholinyl guanidine extract solution described in Preparation Example 6 into a 15 mL polyacrylamide test tube, add 1 mL of PBS buffer solution and mix uniformly. Add 1 mL of ion pair reagent of perfluorobutyric acid with a concentration of 100 mmol / L, mix uniformly, then add 1.5 mL of 25 wt% ammonia water to adjust the pH to 10, add acetonitrile to 10 mL, add 50 mg of the magnetic adsorbent material Fe3O4@GO described in Preparation Example 2, perform vortex oscillation for adsorption reaction for 20 min, discard the reaction sample solution, sequentially wash the magnetic adsorbent material with 5 mL of acetonitrile-water (60:40, v / v) and 5 mL of acetonitrile, then add 5 mL of formic acid-acetonitrile-water solution (0.2:20:80, v / v / v) as a desorption solution, perform oscillation for desorption for 15 min, separate by a strong magnet, collect the desorption solution, and use it for HPLC-MS / MS determination.

[0103] In this example, the concentration of the ion pair reagent in the adsorption reaction system is 10 mmol / L, the concentration of the magnetic adsorbent material in the adsorption reaction system is 5 mg / mL, and the concentration of tetrodotoxin in the adsorption reaction system is 78.125 μmol / L.

[0104] Example 3

[0105] A magnetic solid phase extraction method, comprising the following steps:

[0106] Transfer 5 mL of the cartougenin extract solution described in Preparation Example 7 into a 15 mL polyacrylamide test tube, add 1 mL of PBS buffer solution and mix uniformly. Add 1 mL of tetrabutylammonium bromide ion pair reagent with a concentration of 20 mmol / L, mix uniformly, then add formic acid to adjust the pH to 5, add methanol to make up to 10 mL, add 100 mg of the magnetic adsorbent material Fe3O4@MWCNTs-NH2 described in Preparation Example 3, perform vortex oscillation for adsorption reaction for 15 min, discard the reaction sample solution, sequentially wash the magnetic adsorbent material with 5 mL of acetonitrile-water (40:60, v / v) and 5 mL of acetonitrile, then add 4 mL of ammonia water-acetonitrile-water solution (0.3:60:40, v / v / v) as the desorption solution, perform vortex oscillation for desorption for 15 min, separate by a strong magnet, collect the desorption solution, and use it for HPLC-MS / MS determination.

[0107] In this example, the concentration of the ion pair reagent in the adsorption reaction system is 2 mmol / L, the concentration of the magnetic adsorbent material in the adsorption reaction system is 10 mg / mL, and the concentration of the tetrodotoxin in the adsorption reaction system is 78.125 μmol / L.

[0108] Examples 4-6

[0109] Examples 4-6 differ from Example 1 in that the magnetic adsorbent materials of Examples 4-6 are Fe3O4@GO, Fe3O4@MWCNTs-NH2 and Fe3O4@GO-NH2 described in Preparation Examples 2-4, respectively.

[0110] Examples 7-9

[0111] Examples 7-9 differ from Example 2 in that the magnetic adsorbent materials of Examples 7-9 are Fe3O4@GO, Fe3O4@MWCNTs-NH2 and Fe3O4@GO-NH2 described in Preparation Examples 2-4, respectively.

[0112] Examples 10-12

[0113] Examples 10-12 differ from Example 3 in that the magnetic adsorbent materials of Examples 10-12 are Fe3O4@GO, Fe3O4@MWCNTs-NH2 and Fe3O4@GO-NH2 described in Preparation Examples 2-4, respectively.

[0114] Examples 13-17

[0115] Examples 13-17 differ from Example 1 in that the magnetic adsorbent materials of Examples 13-17 are the magnetic adsorbent materials described in Preparation Examples 8-12, respectively.

[0116] Examples 18-22

[0117] Examples 18-22 differ from Example 2 in that the magnetic adsorbent material of Examples 18-22 is the magnetic adsorbent material described in Preparation Examples 8-12, respectively.

[0118] Examples 23-27

[0119] Examples 23-27 differ from Example 3 in that the magnetic adsorbent material of Examples 23-27 is the magnetic adsorbent material described in Preparation Examples 8-12, respectively.

[0120] Examples 28-31

[0121] Examples 28-31 differ from Example 1 in that the pH at which the adsorption reaction is performed in Examples 28-31 is 8, 10, 11, 12, respectively.

[0122] Examples 32-35

[0123] Examples 32-35 differ from Example 2 in that the pH at which the adsorption reaction is performed in Examples 32-35 is 8, 9, 11, 12, respectively.

[0124] Examples 36-37

[0125] Examples 36-37 differ from Example 3 in that the pH at which the adsorption reaction is performed in Examples 36-37 is 4, 6, respectively.

[0126] Examples 38-42

[0127] Examples 38-42 differ from Example 1 in that the concentration of the ion pair reagent in the adsorption reaction system in Examples 38-42 is 0.5, 1, 2, 10, 15 mmol / L, respectively.

[0128] Examples 43-47

[0129] Examples 43-47 differ from Example 2 in that the concentration of the ion pair reagent in the adsorption reaction system in Examples 43-47 is 0.5, 1, 2, 5, 15 mmol / L, respectively.

[0130] Examples 48-52

[0131] Examples 48-52 differ from Example 3 in that the concentration of the ion pair reagent in the adsorption reaction system in Examples 48-52 is 0.5, 1, 5, 10, 15 mmol / L, respectively.

[0132] Examples 53-55

[0133] Examples 53-55 differ from Example 1 in that the concentration of the magnetic adsorbent material in the adsorption reaction system of Examples 53-55 is 10, 15, 20 mg / mL, respectively.

[0134] Examples 56-58

[0135] Examples 56-58 differ from Example 2 in that the concentration of the magnetic adsorbent material in the adsorption reaction system of Examples 56-58 is 10, 15, 20 mg / mL, respectively.

[0136] Examples 59-61

[0137] Examples 59-61 differ from Example 3 in that the concentration of the magnetic adsorbent material in the adsorption reaction system of Examples 59-61 is 5, 15, 20 mg / mL, respectively.

[0138] Examples 62-66

[0139] Examples 62-66 differ from Example 1 in that the adsorption reaction time of Examples 62-66 is 5, 10, 20, 25, 30 min, respectively.

[0140] Examples 67-71

[0141] Examples 67-71 differ from Example 2 in that the adsorption reaction time of Examples 67-71 is 5, 10, 15, 25, 30 min, respectively.

[0142] Examples 72-76

[0143] Examples 72-76 differ from Example 3 in that the adsorption reaction time of Examples 72-76 is 5, 10, 20, 25, 30 min, respectively.

[0144] Examples 77-80

[0145] Examples 77-80 differ from Example 1 in that the volume ratio of formic acid, acetonitrile, and water in the desorption solution of Examples 77-80 is 0.1:40:60, 0.2:40:60, 0.3:40:60, 0.5:40:60, respectively, i.e. the volume concentration of formic acid in the desorption solution is 0.1, 0.2, 0.3, 0.5%, respectively.

[0146] Examples 81-84

[0147] Examples 81-84 differ from Example 2 in that the volume ratio of formic acid, acetonitrile, water in the desorption solution of Examples 81-84 is 0.1:20:80, 0.3:20:80, 0.4:20:80, 0.5:20:80, respectively, i.e. the volume concentration of formic acid in the desorption solution is 0.1, 0.3, 0.4, 0.5%, respectively.

[0148] Examples 85-88

[0149] Examples 85-88 differ from Example 3 in that the volume ratio of ammonia, acetonitrile, water in the desorption solution of Examples 85-88 is 0.1:50:50, 0.2:50:50, 0.4:50:50, 0.5:50:50, respectively, i.e. the volume concentration of ammonia in the desorption solution is 0.1, 0.2, 0.4, 0.5%, respectively.

[0150] Examples 89-90

[0151] Examples 89-90 differ from Example 1 in that the volume ratio of formic acid, acetonitrile, water in the desorption solution of Examples 89-90 is 0.4:20:80, 0.4:40:60, respectively, i.e. the volume concentration of acetonitrile in the desorption solution is 20, 60%.

[0152] Examples 91-92

[0153] Examples 91-92 differ from Example 2 in that the volume ratio of formic acid, acetonitrile, water in the desorption solution of Examples 91-92 is 0.2:40:60, 0.2:60:40, respectively, i.e. the volume concentration of acetonitrile in the desorption solution is 40, 60%.

[0154] Examples 93-94

[0155] Examples 93-94 differ from Example 3 in that the volume ratio of ammonia, acetonitrile, water in the desorption solution of Examples 93-94 is 0.3:20:80, 0.3:60:40, respectively, i.e. the volume concentration of acetonitrile in the desorption solution is 20, 60%.

[0156] Examples 95-96

[0157] Examples 95-96 differ from Example 1 in that the amount of the desorption solution used in Examples 95-96 is 3, 5 mL.

[0158] Examples 97-98

[0159] Examples 97-98 differ from Example 2 in that the amount of the desorption solution used in Examples 97-98 is 3, 4 mL.

[0160] Examples 99-100

[0161] Examples 99-100 differ from Example 3 in that the amount of desorption solution used in Examples 99-100 is 3, 5 mL.

[0162] Examples 101-104

[0163] Examples 101-104 differ from Example 1 in that the time for which desorption is carried out in Examples 101-104 is 2, 5, 15, 20 min.

[0164] Examples 105-108

[0165] Examples 105-108 differ from Example 2 in that the time for which desorption is carried out in Examples 105-108 is 2, 5, 10, 20 min.

[0166] Examples 109-112

[0167] Examples 109-112 differ from Example 3 in that the time for which desorption is carried out in Examples 109-112 is 2, 5, 10, 20 min.

[0168] Comparative Examples 1-3

[0169] Comparative Examples 1-3 differ from Example 1 in that the magnetic adsorbent material used in Comparative Examples 1-3 is the magnetic adsorbent material described in Preparation Examples 13-15, respectively.

[0170] Comparative Examples 4-7

[0171] Comparative Examples 4-7 differ from Example 1 in that the pH at which adsorption is carried out in Comparative Examples 4-7 is 4, 5, 6, 7, respectively.

[0172] Comparative Examples 8-11

[0173] Comparative Examples 8-11 differ from Example 2 in that the pH at which adsorption is carried out in Comparative Examples 8-11 is 4, 5, 6, 7, respectively.

[0174] Comparative Examples 12-17

[0175] Comparative Examples 12-17 differ from Example 3 in that the pH at which adsorption is carried out in Comparative Examples 12-17 is 7, 8, 9, 10, 11, 12, respectively.

[0176] Comparative Example 18

[0177] Comparative Example 18 differs from Example 1 in that the concentration of the ion pair reagent in the adsorption reaction system in Comparative Example 18 is 0.2 mmol / L.

[0178] Comparative Example 19

[0179] Comparative Example 19 differs from Example 2 in that the concentration of the ion pair reagent in the adsorption reaction system of Comparative Example 19 is 0.2 mmol / L.

[0180] Comparative Example 20

[0181] Comparative Example 20 differs from Example 3 in that the concentration of the ion pair reagent in the adsorption reaction system of Comparative Example 20 is 0.2 mmol / L.

[0182] Comparative Example 21

[0183] Comparative Example 21 differs from Example 1 in that the concentration of the magnetic adsorbent material in the adsorption reaction system of Comparative Example 21 is 2 mg / mL.

[0184] Comparative Example 22

[0185] Comparative Example 22 differs from Example 2 in that the concentration of the magnetic adsorbent material in the adsorption reaction system of Comparative Example 22 is 2 mg / mL.

[0186] Comparative Example 23

[0187] Comparative Example 23 differs from Example 3 in that the concentration of the magnetic adsorbent material in the adsorption reaction system of Comparative Example 23 is 2 mg / mL.

[0188] Comparative Example 24

[0189] Comparative Example 24 differs from Example 1 in that the adsorption reaction time of Comparative Example 24 is 2 min.

[0190] Comparative Example 25

[0191] Comparative Example 25 differs from Example 2 in that the adsorption reaction time of Comparative Example 25 is 2 min.

[0192] Comparative Example 26

[0193] Comparative Example 26 differs from Example 3 in that the adsorption reaction time of Comparative Example 26 is 2 min.

[0194] Comparative Examples 27-28

[0195] Comparative Examples 27-28 differ from Example 1 in that the volume ratio of formic acid, acetonitrile, and water in the desorption solution of Comparative Examples 27-28 is 0.4:80:20, 0.4:100:0, respectively, i.e. the volume concentration of acetonitrile in the desorption solution is 80%, 100%.

[0196] Comparative Examples 29-30

[0197] Comparative Examples 29-30 differ from Example 2 in that the volume ratio of formic acid, acetonitrile, water in the desorption solution of Comparative Examples 29-30 is 0.2:80:20, 0.2:100:0, i.e. the volume concentration of acetonitrile in the desorption solution is 80%, 100%.

[0198] Comparative Examples 31-32

[0199] Comparative Examples 31-32 differ from Example 3 in that the volume ratio of ammonia, acetonitrile, water in the desorption solution of Comparative Examples 31-32 is 0.3:80:20, 0.3:100:0, i.e. the volume concentration of acetonitrile in the desorption solution is 80%, 100%.

[0200] Comparative Examples 33-34

[0201] Comparative Examples 33-34 differ from Example 1 in that the amount of desorption solution used in Comparative Examples 33-34 is 1 mL, 2 mL.

[0202] Comparative Examples 35-36

[0203] Comparative Examples 35-36 differ from Example 2 in that the amount of desorption solution used in Comparative Examples 35-36 is 1 mL, 2 mL.

[0204] Comparative Examples 37-38

[0205] Comparative Examples 37-38 differ from Example 3 in that the amount of desorption solution used in Comparative Examples 37-38 is 1 mL, 2 mL.

[0206] Performance test

[0207] 1) Adsorption rate: test the adsorption rate of Examples 1-73 and Comparative Examples 1-29.

[0208] 2) Desorption rate: test the desorption rate of Examples 74-109 and Comparative Examples 30-41.

[0209] 3) Adsorption capacity: test the adsorption capacity of Examples 1-3, Examples 59-73 and Comparative Examples 27-29. The adsorption capacity is the mass of polar drugs adsorbed by 1 g of magnetic adsorbent material; the saturated adsorption capacity is the mass of polar drugs that can be adsorbed by 1 g of magnetic adsorbent material at most.

[0210] Test results and analysis

[0211] In Preparation Examples 1-4, magnetic Fe3O4 microspheres and functionalized carbon nanotubes or functionalized graphene were dispersed in acetonitrile solvent to prepare magnetic adsorbent materials by ultrasonic-assisted self-assembly. Figure 1 The column chart of adsorption rate of Examples 1-12 is shown in FIG. 1. Figure 1It can be seen that the four kinds of magnetic nanocomposites of Preparation Examples 1-4 show different adsorption selectivity for the three polar drugs of tetrodotoxin, morpholin guanidine and domoic acid, Fe3O4@MWCNTs-COOH and Fe3O4@GO have better adsorption selectivity for tetrodotoxin and morpholin guanidine, and Fe3O4@MWCNTs-NH2 and Fe3O4@G-NH2 have better adsorption selectivity for domoic acid.

[0212] Figure 2 For the adsorption rate curves of Examples 1-3, Examples 13-27 and Comparative Examples 1-3, from Figure 2 It can be seen that the mass ratio of magnetic Fe3O4 microspheres and functionalized carbon nanotubes or functionalized graphene will significantly affect the effect of magnetic dispersion extraction technology. If the mass ratio of Fe3O4 magnetic particles and functionalized carbon nanotubes or functionalized graphene is too high, too many Fe3O4 magnetic particles will be dispersed and aggregated on the surface of the carbon material, causing the adsorption capacity of the magnetic adsorption material to decrease significantly. If the mass ratio of Fe3O4 magnetic particles and functionalized carbon nanotubes or functionalized graphene is too low, the prepared magnetic material will become slow to be gathered and separated by a strong magnet, which is not conducive to the rapid dispersion extraction operation of the reaction liquid "liquid-solid".

[0213] Then, Fe3O4@MWCNTs-COOH, Fe3O4@GO and Fe3O4@MWCNTs-NH2 magnetic materials were selected to optimize the conditions and steps of ion pair reagent assisted magnetic solid phase extraction method suitable for tetrodotoxin, morpholin guanidine and domoic acid.

[0214] Figure 3 For the adsorption rate column chart of Examples 1-3, Examples 28-37 and Comparative Examples 4-17, from Figure 3It can be seen that the effective adsorption rates of Fe3O4@MWCNTs-COOH and Fe3O4@GO materials on tetrodotoxin and morpholin guanidine are greater than 90.1% in weak alkaline reaction system with pH of 8-12. In weak alkaline buffer system, tetrodotoxin and morpholin guanidine can present cationic dissociation state, can form electric neutral conjugate with ion pair reagent, and can be stably adsorbed and reserved by alkyl carbon chain and magnetic nanomaterial; meanwhile, the carboxyl negative ions on the surface of Fe3O4@MWCNTs-COOH and Fe3O4@GO can also produce ionic electrostatic adsorption between polar drug protonated functional groups. In weak acid reaction system with pH of 4-6, the effective adsorption rate of Fe3O4@MWCNTs-NH2 material on domoic acid is greater than 96.0%. In weak acid buffer system, domoic acid can present anion dissociation state, can form electric neutral conjugate with ion pair reagent, and can be stably adsorbed and reserved by alkyl carbon chain and magnetic nanomaterial; meanwhile, the amino protonated functional groups on the surface of Fe3O4@MWCNTs-NH2 can also produce ionic electrostatic adsorption between polar drug negative ion functional groups.

[0215] Figure 4 The adsorption rate column chart of Examples 1-3, Examples 38-52 and Comparative Examples 18-20 is shown in FIG. 1. Figure 4 It can be seen that the adsorption rate of the three polar drugs is greater than 85.4% when the concentration of ion pair reagent is 1 mmol / L.

[0216] Figure 5 The adsorption rate column chart of Examples 1-3, Examples 53-61 and Comparative Examples 21-23 is shown in FIG. 2. Figure 5 It can be seen that 2 mg / mL of magnetic adsorption material in the reaction system is not enough to provide effective adsorption on the three polar drugs, and when the magnetic adsorption material is greater than 10 mg / mL, the adsorption rate of Fe3O4@MWCNTs-COOH, Fe3O4@GO and Fe3O4@MWCNTs-NH2 magnetic materials on the three polar drugs is greater than 89.3%.

[0217] Figure 6 The adsorption rate column chart of Examples 1-3, Examples 62-76 and Comparative Examples 24-26 is shown in FIG. 3. Figure 6 It can be seen that the adsorption rate of the magnetic adsorption material and the polar drug is greater than 91.8% when the adsorption reaction time is 10 min.

[0218] Figure 7 The adsorption rate column chart of Examples 1-3, Examples 77-88 is shown in FIG. 4. Figure 7 It can be seen that the desorption rate of the polar drug in the desorption solution containing 0.1-0.5% formic acid and 0.1-0.5% ammonia is greater than 90%.

[0219] Figure 8The adsorption rate column chart of examples 1-3, examples 89-94 and comparative examples 27-32 is obtained from Figure 8 It can be seen that the desorption rate is greater than 84.6% when the acetonitrile volume concentration is 20-60%, which can meet the experimental analysis requirements.

[0220] Figure 9 The adsorption rate column chart of examples 1-3, examples 95-100 and comparative examples 33-38 is obtained from Figure 9 It can be seen that the polar drugs are not completely desorbed when the desorption solution amount is 1-3 mL; the polar drug desorption efficiency is greater than 92.5% when the desorption solution amount is 4-5 mL.

[0221] Figure 10 The adsorption rate column chart of examples 1-3, examples 101-112 is obtained from Figure 10 It can be seen that the polar drug desorption efficiency reaches more than 93% when the desorption is performed for 5 min.

[0222] Figure 11 The adsorption capacity of examples 1-3, examples 62-76 and comparative examples 24-26 is obtained from Figure 11 It can be seen that Fe3O4@MWCNTs-COOH, Fe3O4@GO and Fe3O4@MWCNTs-NH2 are used for 3 polar drug dynamic adsorption experiments, the adsorption capacity is calculated according to the concentration of each drug in the solution at different adsorption times, the saturated adsorption capacity of tetrodotoxin, morpholinoguanidine and domoic acid is about 37.1 mg / g, 26.4 mg / g and 75.9 mg / g, which is dozens of times of the adsorption efficiency of ordinary solid-phase extraction filler. It is shown that the ion pair reagent assisted magnetic solid-phase extraction method proposed in the application significantly improves the saturated adsorption capacity of the polar drug.

[0223] The magnetic adsorption materials prepared in preparation examples 1-4 are separated by an external magnetic field, and the adsorption rate is greater than 88% after 10 times of regeneration and utilization. Compared with the first use, the adsorption rate of the magnetic composite material decreases by less than 9%, which shows that the magnetic material can provide stable and excellent adsorption performance for the polar drug, and has recycling potential and value.

[0224] The ion pair reagent assisted magnetic solid-phase extraction method constructed in the application is applied to the extraction and enrichment of polar drugs in puffer fish meat, chicken and scallop samples, and the results show that the purified matrix has less interference, the sample purification effect is good, and no obvious matrix effect is observed during quantitative analysis. The three polar drugs have good standard addition recovery effect and excellent reproducibility, effectively improve the rapid enrichment and purification of the polar target drug in the complex matrix, and completely meet the quantitative analysis requirements of animal-derived samples.

Claims

1. A magnetic solid phase extraction method, characterized by, The method comprises the following steps: mixing a target compound, an ion pair reagent, a magnetic adsorbent material and a buffer solution to obtain an adsorption reaction system, and performing an adsorption reaction; and after the adsorption reaction, desorbing the magnetic adsorbent material to which the target compound is adsorbed to obtain a separated target compound. The method comprises the following steps: mixing a target compound, an ion pair reagent, a magnetic adsorbent material and a buffer solution to obtain an adsorption reaction system, and performing an adsorption reaction; and after the adsorption reaction, desorbing the magnetic adsorbent material to which the target compound is adsorbed to obtain a separated target compound. The target compound is a polar compound; the polar compound comprises at least one of tetrodotoxin, morpholinoguanidine or domoic acid. When the target compound is an acidic compound, the ion pair reagent is a cationic ion pair reagent; when the target compound is a basic compound, the ion pair reagent is an anionic ion pair reagent; the cationic ion pair reagent comprises at least one of dodecyltrimethylammonium chloride, tetrabutylammonium bromide or tetrabutylammonium sulfate; the anionic ion pair reagent is selected from C2-C13 perfluoroalkyl carboxylic acids. When the target compound is an acidic compound, the reaction system is weakly acidic; when the target compound is a basic compound, the reaction system is weakly alkaline; the pH of the weakly acidic reaction system is 4-6; the pH of the weakly alkaline reaction system is 9-10. The molar ratio of the ion pair reagent to the target compound is (6-260):1; the dosage ratio of the magnetic adsorbent material to the target compound is (60-400) mg:1 μmol.

2. The method of claim 1, wherein, The magnetic adsorbent material is a carbon material coated with magnetite; The carbon material comprises at least one of an amino-functionalized carbon material, a carboxyl-functionalized carbon material, a hydroxyl-functionalized carbon material or an oxidized carbon material; The carbon material comprises at least one of carbon fibers, fullerenes, carbon aerogels, carbon nanotubes or graphene; The mass ratio of the magnetite to the carbon material is (0.2-1.8):

1.

3. The method of claim 1, wherein, The concentration of the ion pair reagent in the reaction system is 0.5-20 mmol / L; The concentration of the magnetic adsorbent material in the reaction system is 5-30 mg / mL; The adsorption reaction time is 3-40 min; The desorption solution comprises an acetonitrile aqueous solution; The acetonitrile aqueous solution has a volume concentration of 10-70%; The dosage ratio of the desorption solution to the magnetic adsorbent material is (3-10) mL:50 mg; The desorption time is 2-40 min.

4. The method according to any one of claims 1-3 for detecting a polar compound.

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