A detection method of a new contaminant 6ppd-quinone with strong toxicity

Abstract

The application relates to the technical field of analysis and detection, in particular to a detection method for a strong-toxic new pollutant 6PPD-quinone, which comprises the following steps: adopting a magnetic molecular imprinting polymer to perform specific adsorption on 6PPD-quinone in a water sample to be detected, eluting, and obtaining a sample liquid rich in 6PPD-quinone; and then adopting a single-atom colorimetric detection method to detect the sample liquid. The method realizes the enrichment of the target 6PPD-quinone, simplifies the pretreatment steps, releases the hands of the detection personnel, and realizes the high-sensitivity and high-selectivity detection of the content of 6PPD-quinone by combining the single-atom colorimetric detection method, so that the method can break through the limitation of large instruments and provide a brand-new solution for realizing the on-site, rapid and low-cost monitoring of ultra-trace 6PPD-quinone in the environment.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of detection analysis, and in particular to a detection method of a strong virulence new pollutant 6PPD-quinone. BACKGROUND

[0002] The strong virulence new pollutant 6PPD-quinone, simply 6PPD-quinone (6PPD-quinone, simply 6PPDQ) is a new emerging pollutant that has attracted much attention in recent years. Its chemical nature is the product of the oxidation of antioxidant 6PPD (N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine) in the environment by ozone. It has extremely strong biological toxicity. Commercially, antioxidant 6PPD is mainly used in the rubber tires of automobiles to prevent the aging and cracking of rubber.

[0003] At present, 6PPD-quinone has been widely detected in global road runoff, surface water, sediments, soil, air particulate matter, domestic sewage, and even deep-sea sediments. It can pose a new threat to aquatic ecosystems. When 6PPD-quinone is released into the environment, it will oxidize to form 6PPD-TPs (6PPD-Q, N-formyl-6PPD, N-(1,3-dimethylbutyl)-N'-phenyl-p-quinone, diimine, etc.). These substances have been widely detected in global road runoff and surface water. Recent studies have shown that 6PPD-TPs can disrupt lipid and sugar metabolism in zebrafish, cause liver damage, and change their behavior patterns in water bodies.

[0004] In the prior art, the detection of 6PPD-quinone has the problems of complex pretreatment, cumbersome process, and toxic reagents used, therefore, it is of great significance to develop a simple, safe, and sensitive detection method for 6PPD-quinone. SUMMARY

[0005] In view of the above technical problems, the present application provides a detection method of a strong virulence new pollutant 6PPD-quinone. The method realizes the enrichment of the target 6PPD-quinone, simplifies the pretreatment operation, and releases the hands of the detection personnel; and in combination with a single-atom colorimetric detection method, realizes the high-sensitivity and high-selectivity detection of the content of 6PPD-quinone, which is expected to break through the limitations of large instruments, provide a new solution for realizing the on-site, rapid, and low-cost monitoring of ultra-trace 6PPD-quinone in the environment, and avoid the need for a plurality of standard substances in the traditional LS-MS to realize the detection of specific 6PPD-quinone substances. The present application does not need to know the specific types of 6PPD-quinone, and can specifically recognize all 6PPD-quinone substances containing quinone groups, which is simple and convenient.

[0006] To solve the above technical problems, the present application adopts the following technical solutions:

[0007] In a first aspect, the application provides a method for detecting a highly toxic new pollutant 6PPD-quinone, comprising: using a magnetic molecularly imprinted polymer to specifically adsorb 6PPD-quinone in a water sample to be tested, and then eluting to obtain a sample liquid enriched with 6PPD-quinone.

[0008] Then, the sample liquid is detected by using a single-atom colorimetric detection method, wherein the single-atom material can catalyze 6PPD-quinone to occur a color reaction, and the content of 6PPD-quinone is detected by using a UV-visible spectrophotometry method.

[0009] In the application, the magnetic molecularly imprinted polymer capable of specifically binding with 6PPD-quinone is used to enrich 6PPD-quinone in the water sample, so that the pretreatment time is shortened to 10 minutes; and the magnetic solid phase extraction technology is used to specifically adsorb the trace target from the mL level water sample, so as to realize the enrichment of the target 6PPD-quinone, simplify the pretreatment operation, and release the hands of the detection personnel. In combination with the single-atom colorimetric detection method, the single-atom material is used to catalyze 6PPD-quinone to occur a color reaction, and the color changes, and the UV-visible spectrophotometry colorimetric method is used to realize the high-sensitivity and high-selectivity detection of the content of 6PPD-quinone; the method has the characteristics of simplicity, directness, and suitability for on-site detection; and the method is expected to break through the limitation of large instruments, and provide a new solution for realizing the on-site, rapid, and low-cost monitoring of the ultra-trace 6PPD-quinone in the environment.

[0010] Preferably, the magnetic molecularly imprinted polymer is formed by wrapping a layer of molecularly imprinted polymer shell on the outside of the activated Fe3O4 nanoparticles.

[0011] Preferably, the activated Fe3O4 nanoparticles are activated Fe3O4 nanoparticles modified by carboxyl and double bond.

[0012] Preferably, the preparation method of the activated Fe3O4 nanoparticles comprises:

[0013] Fe3O4 nanoparticles are added into a sodium citrate aqueous solution, and after reaction at 50-60 DEG C and 300-400 rpm for 12-18 h, the Fe3O4 nanoparticles are separated by magnetism, washed with pure water for 2-3 times, and washed with ethanol once, to obtain a carboxylated Fe3O4 nanoparticle wet cake;

[0014] Then, the carboxylated Fe3O4 nanoparticle wet cake is added into a silane coupling agent reaction solution, and after reaction at 50-60 DEG C water bath and 300-400 rpm for 6-8 h, the Fe3O4 nanoparticles are separated by magnetism, washed with ethanol for 2-3 times, and then dried at 50-60 DEG C under vacuum until the weight is constant, to obtain the activated Fe3O4 nanoparticles modified with carboxyl and double bond on the surface.

[0015] The application uses sodium citrate containing carboxylic acid functional groups and silane coupling agent containing double bond functional groups to cooperatively modify Fe3O4 nanoparticles, and simultaneously introduces active bifunctional groups, "double bond (-CH=CH2) and carboxylate (-COO-)", on the surface of the Fe3O4 nanoparticles, to provide more active anchor points for the synthesis of subsequent molecularly imprinted polymers, to obtain active Fe3O4 nanoparticles with high dispersity, high reactivity and high magnetic thermal stability, which are significantly superior to single double bond or carboxylic acid modification. And both double bond (-CH=CH2) and carboxylate (-COO-) have negative charges and can cooperatively and specifically bind to the quinone group on 6PPD-quinone, so that the activated Fe3O4 nanoparticles can specifically adsorb 6PPD-quinone in the water sample, to realize the enrichment of 6PPD-quinone.

[0016] Preferably, the mass ratio of Fe3O4 nanoparticles, sodium citrate water and silane coupling agent is 1: (0.02-0.05): (0.01-0.05); and / or

[0017] The silane coupling agent reaction solution is prepared by dissolving the silane coupling agent in a solvent, wherein the solvent is prepared by mixing anhydrous ethanol and water in a volume ratio of 9:1; and / or

[0018] The mass percentage of silane coupling agent in the dry weight of Fe3O4 nanoparticles is 1%-3%; and / or

[0019] The silane coupling agent includes KH-570 or VTES.

[0020] Preferably, the preparation method of Fe3O4 nanoparticles comprises: under the protection of nitrogen, mixing a divalent iron salt aqueous solution and a trivalent iron salt aqueous solution as a reaction system, adding an ammonia aqueous solution to the above reaction system at 1-3 drops per second in a 500-800 rpm, 50-60°C water bath, until the pH value of the above reaction system is 10-12;

[0021] Then, under the protection of nitrogen, continue stirring at 500-800 rpm, 50-60°C water bath for 30-60 min, continue stirring and cool to room temperature, adsorb the solid with a strong magnet, wash the solid with pure water for 3-5 times, magnetically separate, until the supernatant is neutral and clear, then wash 1-2 times with ethanol, and vacuum dry at 50-60°C to constant weight to obtain Fe3O4 nanoparticles.

[0022] Preferably, the divalent iron salt aqueous solution is prepared by dissolving 100-120 mL of pure water per mole of divalent iron salt; the trivalent iron salt aqueous solution is prepared by dissolving 100-120 mL of pure water per mole of trivalent iron salt; and / or

[0023] The divalent iron salt is FeCl2·4H2O, and the trivalent iron is FeCl3·6H2O; and / or

[0024] The molar ratio of FeCl2*4H2O and FeCl3*6H2O is 1:(1.5-2); and / or

[0025] The mass concentration of the ammonia solution is 25%-28%.

[0026] Preferably, the preparation method of the magnetic molecularly imprinted polymer comprises:

[0027] The template molecule 6PPD-quinone and the functional monomer methacrylic acid are dissolved in the porogen, and ultrasonic pre-assembly is performed for 30 min;

[0028] The above activated Fe3O4 nanoparticles and ethylene glycol dimethacrylate crosslinking agent are further added, and the whole process is deoxygenated by nitrogen, and the reaction is performed at 400-500 rpm for at least 30 min; then the initiator is continuously added, and the reaction is performed at 60-70 DEG C oil bath and 400-500 rpm for 12-24 h under a nitrogen environment; then the solid is separated by a strong magnet, and the solid is washed with the eluent until no template molecule 6PPD-quinone is present in the eluent; then the solid is washed with methanol until neutral, and vacuum drying is performed at 50-60 DEG C until the weight is constant, thereby obtaining the magnetic molecularly imprinted polymer.

[0029] Preferably, the molar ratio of the template molecule 6PPD-quinone, the methacrylic acid monomer and the ethylene glycol dimethacrylate crosslinking agent is 1:(6-8):(35-40).

[0030] The carboxyl group of the functional monomer methacrylic acid (MAA) can form strong hydrogen bonds with the quinone group and the amino group of the 6PPD-quinone, which helps the activated Fe3O4 nanoparticles to be combined with the functional monomer methacrylic acid firmly. The crosslinking agent ethylene glycol dimethacrylate (EGDMA) forms a rigid three-dimensional network on the surface of the activated Fe3O4 nanoparticles, and a polymer shell is formed.

[0031] The porogen is prepared from acetonitrile / toluene in a volume ratio of 1:(1-4); the ratio helps the polymer chain to be moderately curled and precipitated out during the polymerization process, and a loose and porous structure is formed.

[0032] The initiator includes any one of azobisisobutyronitrile, dibenzoyl peroxide or tert-butyl hydroperoxide;

[0033] The mass of the initiator accounts for 0.5%-1% of the total mass of the monomer and the crosslinking agent;

[0034] The eluent is prepared from methanol / acetic acid in a volume ratio of 9:1.

[0035] The methanol / acetic acid system of the present application can effectively destroy the hydrogen bond, and is the best choice for eluting the template molecule, and the elution must be thorough, otherwise the subsequent adsorption performance will be seriously affected.

[0036] Preferably, the magnetic molecularly imprinted polymer is used for specific adsorption of 6PPD-quinone in the water sample to be tested, and then elution is performed to obtain a sample liquid enriched with 6PPD-quinone. The specific steps are as follows:

[0037] S1, filtering the water sample collected from a river near an industrial zone through a 0.45 μm glass fiber membrane to remove suspended particles, adjusting the pH to 7.0 to obtain a pretreated water sample;

[0038] S2, weighing 10 mg of the magnetic molecularly imprinted polymer and dispersing it in 100 mL of the pretreated water sample, and vortexing for 15-20 min;

[0039] Then, a strong magnet is added, and stirring is performed for 1-2 min, followed by solid-liquid separation, vortex washing of the solid with 3%-5% methanol aqueous solution for 1-2 min, magnetic separation, vortex washing with acetic acid and methanol (volume ratio of 1:50) as eluent for at least 2 times, each time for 5-10 min, and combining the eluent;

[0040] The eluent is blown dry under a gentle nitrogen flow, and then redissolved with 100 μL of mobile phase 50%-70% acetonitrile aqueous solution, vortexed and mixed to obtain a sample liquid enriched with 6PPD-quinone.

[0041] The present application uses the magnetic separation solid phase extraction technology of the magnetic molecularly imprinted polymer to realize the enrichment of 6PPD-quinone in the water sample, avoids the frequent centrifugation and column passing procedures in the traditional pretreatment, greatly shortens the pretreatment time, and the magnetic molecularly imprinted polymer (MMIPs) can be repeatedly used for more than 5 times without obvious performance decrease, and has high cost effectiveness. BRIEF DESCRIPTION OF DRAWINGS

[0042] Figure 1 The standard curve between the linear fitting absorbance (Y) and the 6PPD-quinone concentration (X) of the present application. DETAILED DESCRIPTION

[0043] The endpoints of the ranges and any values disclosed herein are not limited to the precise values stated. The endpoints of the ranges and the values are approximate values which are understood to encompass values approximating these. For ranges, the endpoints are understood to be independently combinable with each other and with the single points to create new ranges. These new ranges are understood to be specifically disclosed herein.

[0044] Example 1

[0045] 1. Preparation of magnetic molecularly imprinted polymer (MMIPs)

[0046] 1) Synthesis of Fe3O4 nanoparticles

[0047] Under nitrogen protection, 1 mol, 100 ml Fe 2+ and 2 mol, 100 ml Fe 3+ The mixed solution is used as the reaction system, and the ammonia solution is added to the reaction system at a rate of 1 drop per second at 500 rpm and a water bath temperature of 60°C. If the reaction system is observed to immediately turn black, it indicates that Fe3O4 nanoparticles begin to form. Continue to add the 28% ammonia solution until the pH value of the reaction system stabilizes between 10. Perform precipitation “aging” for 60 min under constant temperature and vigorous stirring to make the precipitated crystals grow more complete and the particle size more uniform. After the reaction is completed, continue to stir under nitrogen protection until room temperature, use a strong magnet to adsorb the black particles, and pour off the supernatant,

[0048] Wash with pure water, ultrasonic assistance, magnetic separation, and pour off the supernatant. Repeat this process 5 times until the supernatant becomes neutral (pH ≈ 7) and clear. Finally, wash twice with ethanol and dry at 60°C under vacuum to constant weight to obtain Fe3O4 nanoparticles;

[0049] 2) Activation of Fe3O4 nanoparticles

[0050] Add 40 mM sodium citrate aqueous solution to 1 mg of Fe3O4 nanoparticles, stir at 400 rpm at 60°C for 18 h, and perform priming carboxylation. After magnetic separation, wash with pure water 3 times and ethanol 1 time to remove free sodium citrate, and obtain a wet cake of carboxylated Fe3O4 nanoparticles.

[0051] Add the wet cake of carboxylated Fe3O4 nanoparticles to 50 ml of 1% silane coupling agent reaction solution, stir at a water bath temperature of 60°C for 8 h, magnetically separate, wash with ethanol 3 times, and dry at 60°C under vacuum to constant weight to obtain superparamagnetic activated Fe3O4 nanoparticles modified with “carboxyl + double bond” bifunctional groups.

[0052] The mass percentage of silane coupling agent in the dry weight of Fe3O4 nanoparticles is 1%.

[0053] The solvents used in the silane coupling agent reaction solution include anhydrous ethanol: water in a volume ratio of 9:1.

[0054] The preparation method of the silane coupling agent reaction solution includes: in a 50 ml volumetric flask, add 45 mL of anhydrous ethanol, 2 μL of silane coupling agent (KH-570, abbreviated as MPS), vortex for 10 s, then add glacial acetic acid dropwise to adjust the pH to 4-5, and stand at room temperature for 15 min to complete the silane pre-hydrolysis (the solution becomes slightly turbid, which is normal);

[0055] Then add 5 mL of deionized water, shake well, and supplement with anhydrous ethanol to 50 mL scale to obtain 1-2 μL / 50 mL, i.e. the silane reaction solution.

[0056] 3) Synthesis of magnetic molecularly imprinted polymers (MMIPs)

[0057] 0.1 mmol of template molecule 6PPD-quinone, 0.8 mmol of functional monomer methacrylic acid (MAA) were dissolved in 200 ml of porogen made of acetonitrile / toluene in a volume ratio of 4:1, and ultrasonic pre-assembly was performed for 30 min to obtain a pre-assembly solution;

[0058] Then 100 mg of activated Fe3O4 nanoparticles and 4 mmol of ethylene glycol dimethacrylate as a crosslinking agent were added to the above pre-assembly solution, and stirring was performed at 500 rpm for 30 min in a nitrogen environment, so as to completely remove oxygen in the reaction system, because oxygen is a polymerization inhibitor for free radicals;

[0059] 32.8 mg of initiator azobisisobutyronitrile was added to the above reaction system while maintaining a nitrogen environment, and the reaction was carried out in an oil bath at 60°C for 24 h. After the reaction, it was observed that the solution gradually became an opaque milky white suspension, accompanied by polymer precipitation. After the reaction was completed, the solid was adsorbed by a strong magnet, and the solid product was repeatedly washed with eluent methanol / acetic acid solution in a volume ratio of 9:1 until no template molecule 6PPD-quinone was detected in the eluent. Then the product was washed with methanol until it was neutral, and then the obtained product was placed in a vacuum drying oven at 60°C until the weight was constant, to obtain magnetic molecularly imprinted polymers (MMIPs).

[0060] Functional monomer: methacrylic acid (MAA), which can form strong hydrogen bonds with the quinone group and amino group of 6PPD-quinone. Crosslinking agent: ethylene glycol dimethacrylate (EGDMA), forming a rigid three-dimensional network.

[0061] 2. Magnetic solid phase extraction (MSPE) enrichment and purification of the water sample to be tested

[0062] 1) Pretreatment of the sample

[0063] The water sample collected from the river near the industrial zone was filtered through a 0.45 μm glass fiber membrane to remove suspended particles, and the pH was adjusted to 7.0 with HCl or NaOH (the hydrogen bond interaction is strongest at this pH).

[0064] 2) Magnetic solid phase extraction (MSPE) step

[0065] 10 mg of magnetic molecularly imprinted polymers MMIPs were accurately weighed and dispersed in 100 mL of the pretreated water sample, and vortex oscillation was performed for 15-20 min, so that the 6PPD-quinone in the water sample was fully adsorbed by the magnetic molecularly imprinted polymers MMIPs;

[0066] After adding a strong magnet, stirring for 1-2 min to fully adsorb the MMIPs, solid-liquid separation, discarding the supernatant, then adding 3%-5% methanol aqueous solution, vortex washing for 1-2 min, magnetic separation, and discarding the washing liquid to remove weakly adsorbed impurities;

[0067] Then add 1 mL of acetic acid-methanol solution with a volume ratio of 1:50 as eluent, vortex for 5-10 min, repeat the elution once, and combine the eluate (acetic acid can destroy hydrogen bonds and help methanol efficiently elute the target 6PPD-quinone);

[0068] The eluate is blown dry under a gentle stream of nitrogen, redissolved with 100 μL of the initial mobile phase 50% acetonitrile aqueous solution, vortexed and mixed, and then the 6PPD-quinone-enriched sample solution is obtained and transferred to a reagent bottle for single-atom colorimetric detection.

[0069] 3. Single-atom colorimetric detection method

[0070] 1) Preparation of reaction system:

[0071] First step: preparation of reaction mother liquor

[0072] Buffer solution: take 0.2 M acetic acid-sodium acetate buffer solution (pH = 4.0) and place it at room temperature for standby.

[0073] Catalyst working solution: take an appropriate amount of Fe-N-C SACs single-atom catalyst stock solution, dilute with ultrapure water, vortex, and shake to ensure its full dispersion, and prepare a working suspension with a concentration of 20 μg / mL.

[0074] Substrate working solution: take the organic solvent stock solution of TMB (such as 2.0 mM), dilute it with the above-mentioned acetic acid-sodium acetate buffer solution, and prepare a TMB aqueous working solution with a concentration of 2.2 mM. This step can reduce the proportion of organic solvents in the final system.

[0075] Oxidant working solution: take 30% H2O2 stock solution, dilute with ultrapure water, and prepare a H2O2 working solution with a concentration of 100 mM. This solution needs to be stored in the dark and at low temperature, and it should be prepared fresh.

[0076] Standard: dilute the 6PPD-quinone standard stock solution with ultrapure water to prepare a series of working standard solutions with a concentration gradient (0 nM, 20 nM, 50 nM, 100 nM, 200 nM, 500 nM);

[0077] Sample solution: the 6PPD-quinone-enriched sample solution obtained by magnetic solid phase extraction (MSPE) using magnetic molecularly imprinted polymers.

[0078] Second step: assembly of reaction system

[0079] Strictly follow the order and dosage when adding reagents to each labeled 1.5 mL centrifuge tube:

[0080] First, precisely pipette 700 μL of acetate-sodium acetate buffer (pH 4.0) into the tube. This is the main solvent for the reaction. Next, add 100 μL of a 20 μg / mL Fe-NC SACs catalyst working suspension to the tube. After adding, gently tap the tube wall to mix it initially.

[0081] Then, add 100 μL of 6PPD-quinone standard solution or the water sample solution to be tested, enriched and purified by magnetic solid phase extraction (MSPE), to the tube. For the blank control, add 100 μL of ultrapure water instead.

[0082] Next, add 100 μL of 2.2 mM TMB working solution to the tube. At this point, the total volume of the reaction system reaches 1 mL. Tighten the cap and gently vortex by hand for 3-5 seconds to thoroughly mix the liquid in the tube.

[0083] Step 3: Initiating the reaction

[0084] Finally, use a pipette to quickly add 10 μL of 100 mM H2O2 working solution to each tube, immediately tighten the cap, and use a vortex mixer to shake vigorously for 5-10 seconds to ensure that H2O2 is instantly and evenly distributed throughout the solution.

[0085] Step 4: Incubation and Monitoring

[0086] Place all reaction tubes in a constant temperature water bath at 25°C and allow them to react in the dark for 20 minutes. Once the reaction time is up, immediately use a UV-spectrum spectrophotometer (1 cm path length cuvette) to measure the absorbance at a wavelength of 652 nm.

[0087] pass Figure 1 Linear fitting calculations show that when the concentration of 6PPD-quinone is in the range of 20–500 nM, the relationship between absorbance (Y) and 6PPD-quinone concentration (X) is linear. The linear regression equation is Y = 0.0003902*X + 0.4301, with a correlation coefficient of 0.9997. The linear range of the working curve is 20–500 nM. The detection limit is 18.5 nM.

[0088] 2) Calculate the concentration of 6PPD-quinone in the sample solution:

[0089] By substituting the absorbance measured from the unknown sample into the regression equation of the standard curve, the concentration of 6PPD-quinone in the sample can be calculated to be 23.5 nM.

[0090] In the detection method of the present application, the magnetic molecularly imprinted polymer realizes the enrichment of 6PPD-quinone in the water sample by using the magnetic separation solid phase extraction technology, avoids the frequent centrifugation and column passing procedures in the traditional and complicated pretreatment, greatly shortens the pretreatment time; and the magnetic molecularly imprinted polymer (MMIPs) can be repeatedly used for more than 5 times without obvious performance decline, and has high cost benefit.

[0091] The preferred embodiments of the present application are described in detail above, but the present application is not limited thereto. Within the technical concept range of the present application, various simple modifications can be made to the technical solutions of the present application, including the combination of various technical features in any other suitable manner, and these simple modifications and combinations should also be considered as the disclosed content of the present application, and all belong to the protection scope of the present application.

Claims

1. A method for detecting the highly toxic new pollutant 6PPD-quinone, characterized by, The application relates to a method for detecting 6PPD-quinone in water. The method comprises the following steps: specific adsorption of 6PPD-quinone in a water sample to be detected by using a magnetic molecular imprinting polymer, elution, and obtaining a sample liquid rich in 6PPD-quinone; detection of the sample liquid by using a single-atom colorimetric detection method, wherein a single-atom material can catalyze 6PPD-quinone to generate a color reaction, and the content of 6PPD-quinone is detected by using ultraviolet-visible spectrophotometry. The magnetic molecular imprinting polymer is formed by wrapping a molecular imprinting polymer shell on the outside of activated Fe3O4 nanoparticles. The activated Fe3O4 nanoparticles are activated by modifying carboxyl and double bonds on the Fe3O4 nanoparticles. The preparation method of the activated Fe3O4 nanoparticles comprises the following steps: adding Fe3O4 nanoparticles into a sodium citrate aqueous solution, reacting at 50-60 DEG C and 300-400 rpm for 12-18 h, magnetically separating, washing with pure water for 2-3 times, washing with ethanol once, and obtaining a carboxylated Fe3O4 nanoparticle wet cake; and adding the carboxylated Fe3O4 nanoparticle wet cake into a silane coupling agent reaction solution, reacting at 50-60 DEG C water bath and 300-400 rpm for 6-8 h, magnetically separating, washing with ethanol for 2-3 times, and vacuum drying at 50-60 DEG C until the weight is constant, so as to obtain the activated Fe3O4 nanoparticles with carboxyl and double bonds on the surface. The mass ratio of the Fe3O4 nanoparticles, the sodium citrate aqueous solution and the silane coupling agent is 1: (0.02-0.05): (0.01-0.05). The silane coupling agent reaction solution is formed by dissolving the silane coupling agent in a solvent, and the solvent is prepared by mixing anhydrous ethanol and water in a volume ratio of 9:

1. The mass percentage of the silane coupling agent in the dry weight of the Fe3O4 nanoparticles is 1%-3%.

2. The detection method according to claim 1, characterized in that, The silane coupling agent comprises KH-570 or VTES. The preparation method of the Fe3O4 nanoparticles comprises the following steps: mixing a divalent iron salt aqueous solution and a trivalent iron salt aqueous solution as a reaction system, adding an ammonia water solution into the reaction system at 1-3 drops per second under nitrogen protection, 500-800 rpm and 50-60 DEG C water bath, until the pH value of the reaction system is 10-12; and continuing to stir for 30-60 min under nitrogen protection, 50-60 DEG C water bath and 500-800 rpm, continuing to stir until the temperature is cooled to room temperature, adsorbing the solid by using a strong magnet, washing the solid with pure water for 3-5 times, magnetically separating until the supernatant is neutral and clear, washing with ethanol for 1-2 times, and vacuum drying at 50-60 DEG C until the weight is constant, so as to obtain the Fe3O4 nanoparticles. The divalent iron salt aqueous solution is formed by dissolving 100-120 mL of pure water per mole of divalent iron salt; and the trivalent iron salt aqueous solution is formed by dissolving 100-120 mL of pure water per mole of trivalent iron salt. The divalent iron salt is FeCl2.4H2O, and the trivalent iron salt is FeCl3.6H2O.

3. The detection method according to claim 2, characterized in that, The molar ratio of the FeCl2.4H2O and the FeCl3.6H2O is 1: (1.5-2). ​ ​ 4. The detection method according to claim 3, characterized in that, ​ ​ ​ The mass concentration of the ammonia solution is 25%-28%.

5. The method of claim 1, wherein The preparation method of the magnetic molecularly imprinted polymer comprises the following steps: The template molecule 6PPD-quinone and the functional monomer methacrylic acid are dissolved in a porogen, and ultrasonic pre-assembly is performed for 30 min; Then, the activated Fe3O4 nanoparticles and ethylene glycol dimethacrylate crosslinking agent are added, and the whole process is deoxygenated by nitrogen blowing, and the reaction is performed at 400-500 rpm for at least 30 min; then the initiator is continuously added, and the reaction is performed at 60-70 DEG C in an oil bath under the protection of nitrogen at 400-500 rpm for 12-24 h; then the solid is separated by a strong magnet, and the solid is washed with an eluent until no template molecule 6PPD-quinone is detected in the eluent; then the solid is washed with methanol until neutral, and vacuum drying is performed at 50-60 DEG C until the weight is constant, thereby obtaining the magnetic molecularly imprinted polymer.

6. The detection method according to claim 5, characterized in that, The molar ratio of the template molecule 6PPD-quinone, the methacrylic acid monomer and the ethylene glycol dimethacrylate crosslinking agent is 1:(6-8):(35-40); The porogen is prepared from acetonitrile / toluene in a volume ratio of 1:(1-4); The initiator comprises any one of azobisisobutyronitrile, dibenzoyl peroxide or tert-butyl hydroperoxide; The mass of the initiator accounts for 0.5%-1% of the total mass of the monomer and the crosslinking agent; The eluent is prepared from methanol / acetic acid in a volume ratio of 9:

1.

7. The method of claim 1, wherein, The specific steps of using the magnetic molecularly imprinted polymer to specifically adsorb 6PPD-quinone in a water sample to be tested, and then eluting to obtain a sample liquid rich in 6PPD-quinone are as follows: S1, filtering the water sample collected in the river near the industrial zone through a 0.45 mu m glass fiber membrane to remove suspended particles, adjusting the pH to 7.0, and obtaining a pretreated water sample; S2, dispersing 10 mg of the magnetic molecularly imprinted polymer in 100 mL of the pretreated water sample, and vortexing for 15-20 min; Then, a strong magnet is added, and stirring is performed for 1-2 min, and then solid-liquid separation is performed, and the obtained solid is vortexed and washed with 3%-5% methanol aqueous solution for 1-2 min; magnetic separation is performed, and then a volume ratio of 1:50 of acetic acid and methanol is used as an eluent to vortex and wash at least twice, each time for 5-10 min, and the eluents are combined; The eluent is blown dry under a gentle nitrogen stream, 100 mu L of mobile phase 50%-70% acetonitrile aqueous solution is used for redissolution, vortexing is performed after uniform mixing, and then a sample liquid rich in 6PPD-quinone is obtained.

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