Detection method of strong-toxicity new pollutant 6PPD-quinone

Abstract

The invention relates to the technical field of analysis and detection, in particular to a detection method of a strong-toxicity new pollutant 6PPD-quinone, which comprises the following steps: carrying out specific adsorption on 6PPD-quinone in a water sample to be detected by adopting a magnetic molecularly imprinted polymer, and eluting to obtain a sample solution enriched with 6PPD-quinone; and detecting the sample solution by adopting a monatomic colorimetric detection method. According to the method, the enrichment of the target object 6PPD-quinone is realized, the pretreatment step is simplified, and both hands of a detector are released; the method has the advantages that high-sensitivity and high-selectivity detection of the content of the 6PPD-content quinone is realized by combining with a monatomic colorimetric detection method, the limitation of large instruments is expected to be broken through, and a brand new solution is provided for on-site, rapid and low-cost monitoring of the ultra-trace 6PPD-quinone in the environment.

Description

Technical Field

[0001] This invention relates to the field of detection and analysis technology, specifically to a method for detecting a highly toxic new pollutant, 6PPD-quinone. Background Technology

[0002] 6PPD-quinone, a highly toxic emerging pollutant, is a product of ozone oxidation of the antioxidant 6PPD (N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine). It exhibits extremely high biotoxicity. Commercially, 6PPD is primarily used in automobile rubber tires to prevent rubber aging and cracking.

[0003] Currently, 6PPD-quinone has been widely detected in road runoff, surface water, sediments, soil, airborne particulate matter, sewage, and even deep-sea sediments worldwide, posing a new threat to aquatic ecosystems. When released into the environment, 6PPD-quinone oxidizes to form 6PPD-TPs (6PPD-Q, N-formyl-6PPD, N-(1,3-dimethylbutyl)-N'-phenyl-p-quinone, diimine, etc.), which are now widely detected in road runoff and surface water globally. Recent research indicates that 6PPD-TPs disrupt lipid and glucose metabolism in zebrafish in water, leading to liver damage and altering their behavioral patterns.

[0004] In existing technologies, the detection of 6PPD-quinone suffers from problems such as complex pretreatment, cumbersome procedures, and toxic reagents. Therefore, it is of great significance to develop a simple, safe, and sensitive detection method for 6PPD-quinone. Summary of the Invention

[0005] To address the above-mentioned technical problems, this invention provides a method for detecting the highly toxic novel pollutant 6PPD-quinone. This method achieves enrichment and aggregation of the target 6PPD-quinone, simplifies pretreatment operations, and frees up the hands of testing personnel. Combined with single-atom colorimetric detection, it achieves highly sensitive and selective detection of 6PPD-quinone content, potentially overcoming the limitations of large-scale instruments. This provides a novel solution for the on-site, rapid, and low-cost monitoring of ultra-trace 6PPD-quinone in the environment, avoiding the need for known standards in traditional LS-MS to detect specific 6PPD-quinone substances. This invention does not require knowledge of the specific type of 6PPD-quinone and can specifically identify all 6PPD-quinone substances containing a quinone group, making it simple and convenient.

[0006] To solve the above-mentioned technical problems, the present invention adopts the following technical solution: In a first aspect, the present invention 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, followed by elution to obtain a sample solution enriched with 6PPD-quinone; The sample solution was then analyzed using a single-atom colorimetric method. In this method, the single-atom material can catalyze a colorimetric reaction of 6PPD-quinone, and the content of 6PPD-quinone can be detected by ultraviolet-visible spectrophotometry.

[0007] This invention utilizes a magnetic molecularly imprinted polymer that specifically binds to 6PPD-quinone to enrich 6PPD-quinone in water samples, shortening the pretreatment time to 10 minutes. It also employs magnetic solid-phase extraction technology, relying on specific adsorption to "pull" trace amounts of the target compound from mL-level water samples, thus achieving the enrichment of 6PPD-quinone and simplifying pretreatment operations, freeing up the hands of testing personnel. Furthermore, it combines single-atom colorimetric detection, utilizing single-atom materials to catalyze a color reaction in 6PPD-quinone, resulting in a color change. Ultraviolet-visible spectrophotometry is then used to achieve highly sensitive and selective detection of 6PPD-quinone content. This invention combines the advantages of simplicity, intuitiveness, and suitability for on-site detection, and is expected to overcome the limitations of large-scale instruments, providing a novel solution for the on-site, rapid, and low-cost monitoring of ultra-trace 6PPD-quinone in the environment.

[0008] Preferably, the magnetic molecularly imprinted polymer is formed by coating activated Fe3O4 nanoparticles with a layer of molecularly imprinted polymer shell.

[0009] Preferably, the activated Fe3O4 nanoparticles are generated by modifying Fe3O4 nanoparticles with carboxyl groups and double bonds.

[0010] Preferably, the method for preparing activated Fe3O4 nanoparticles includes: Fe3O4 nanoparticles were added to an aqueous solution of sodium citrate and reacted at 50-60℃ and 300-400 rpm for 12-18 hours. After magnetic separation, the mixture was washed 2-3 times with pure water and once with ethanol to obtain a wet cake of carboxylated Fe3O4 nanoparticles. The carboxylated Fe3O4 nanoparticle wet cake was then added to the silane coupling agent reaction solution and reacted in a water bath at 50-60℃ and 300-400 rpm for 6-8 h. After magnetic separation, the nanoparticles were washed 2-3 times with ethanol and then dried under vacuum at 50-60℃ to constant weight to obtain activated Fe3O4 nanoparticles with carboxyl groups and double bonds on the surface.

[0011] This invention employs sodium citrate containing carboxylic acid functional groups and silane coupling agents containing double bond functional groups to synergistically modify Fe3O4 nanoparticles. Simultaneously, active bifunctional groups, "double bonds (-CH=CH2) and carboxylate groups (-COO-)," are introduced onto the surface of the Fe3O4 nanoparticles, providing more active anchoring sites for subsequent molecularly imprinted polymer synthesis. This results in highly dispersible, highly reactive, and highly magnetothermal stable Fe3O4 nanoparticles, significantly superior to those with single double bonds or carboxylic acid modification. Furthermore, both the double bonds (-CH=CH2) and carboxylate groups (-COO-) carry negative charges, enabling them to synergistically and specifically bind to the quinone group on 6PPD-quinone. This allows the activated Fe3O4 nanoparticles to specifically adsorb 6PPD-quinone from water samples, achieving the enrichment of 6PPD-quinone.

[0012] Preferably, the mass ratio of Fe3O4 nanoparticles, sodium citrate solution, and silane coupling agent is 1:(0.02-0.05):(0.01-0.05); and / or The silane coupling agent reaction solution is prepared by dissolving the silane coupling agent in a solvent, wherein the solvent is prepared by anhydrous ethanol and water in a volume ratio of 9:1; and / or The silane coupling agent accounts for 1%-3% of the dry weight of Fe3O4 nanoparticles; and / or Silane coupling agents include: KH-570 or VTES.

[0013] Preferably, the preparation method of Fe3O4 nanoparticles includes: under nitrogen protection, mixing divalent iron salt aqueous solution and trivalent iron salt aqueous solution as a reaction system, and adding ammonia aqueous solution dropwise to the above reaction system at 1-3 drops / second in a water bath at 500-800 rpm and 50-60°C until the pH value of the above reaction system is 10-12; Continue stirring under nitrogen protection in a 50-60°C water bath at 500-800 rpm for 30-60 minutes. Then, continue stirring and cool to room temperature. Adsorb the solid with a strong magnet, and then wash the solid with pure water 3-5 times by ultrasonication. Perform magnetic separation until the supernatant is neutral and clear. Wash with ethanol 1-2 times, and then vacuum dry at 50-60°C to constant weight to obtain Fe3O4 nanoparticles.

[0014] Preferably, the aqueous solution of ferrous salt is prepared by dissolving one mole of ferrous salt in 100-120 mL of pure water; the aqueous solution of ferric salt is prepared by dissolving one mole of ferric salt in 100-120 mL of pure water; and / or The divalent iron salt is FeCl2·4H2O, and the trivalent iron is FeCl3·6H2O; and / or The molar ratio of FeCl2·4H2O and FeCl3·6H2O is 1 : (1.5-2); and / or The mass concentration of the ammonia solution is 25%-28%.

[0015] Preferably, the method for preparing the magnetic molecularly imprinted polymer includes: The template molecule 6PPD-quinone and the functional monomer methacrylic acid were dissolved in a porogen and pre-assembled by ultrasound for 30 min. Then, the activated Fe3O4 nanoparticles and ethylene glycol dimethacrylate crosslinking agent were added, and nitrogen gas was purged throughout the process to remove oxygen. The reaction was carried out at 400-500 rpm for at least 30 minutes. Then, the initiator was added, and the reaction was carried out in a nitrogen environment at 60-70℃ in an oil bath at 400-500 rpm for 12-24 hours. The solid was then separated with a strong magnet and washed with eluent until no template molecule 6PPD-quinone was found in the eluent. The solid was then washed with methanol until neutral and dried under vacuum at 50-60℃ to constant weight to obtain the magnetic molecularly imprinted polymer.

[0016] Preferably, the molar ratio of the template molecule 6PPD-quinone, methacrylic acid monomer and ethylene glycol dimethacrylate crosslinking agent is 1:(6-8):(35-40).

[0017] The carboxyl group of the functional monomer methacrylic acid (MAA) can form strong hydrogen bonds with the quinone group and amino group of 6PPD-quinone, which helps to firmly bind the activated Fe3O4 nanoparticles to the functional monomer methacrylic acid. The crosslinking agent ethylene glycol dimethacrylate (EGDMA) forms a rigid three-dimensional network on the surface of the activated Fe3O4 nanoparticles, thus forming a polymer shell.

[0018] The pore-forming agent is made of acetonitrile / toluene in a volume ratio of 1:(1-4); this ratio helps the polymer chains to curl up and precipitate during polymerization, forming a loose and porous structure.

[0019] The initiator includes any one of azobisisobutyronitrile, benzoyl peroxide, or tert-butyl hydroperoxide; The initiator accounts for 0.5%-1% of the total mass of the monomer and crosslinking agent; The eluent was prepared from methanol and acetic acid in a volume ratio of 9:1.

[0020] The methanol / acetic acid system of this invention can effectively break hydrogen bonds and is the best choice for eluting template molecules. It is essential to elute completely, otherwise it will seriously affect the subsequent adsorption performance.

[0021] Preferably, the specific steps for using a magnetically imprinted polymer to specifically adsorb 6PPD-quinone into the water sample, followed by elution, to obtain a sample solution enriched with 6PPD-quinone are as follows: S1. Water samples collected from rivers near the industrial area are filtered through a 0.45 μm glass fiber membrane to remove suspended particles and the pH is adjusted to 7.0 to obtain pretreated water samples. S2. Weigh 10 mg of the magnetic molecularly imprinted polymer and disperse it in 100 mL of the pretreated water sample, then vortex for 15-20 min. Add a strong magnet and stir for 1-2 minutes to separate the solid and liquid. Wash the solid with a 3%-5% methanol aqueous solution by vortexing for 1-2 minutes. Separate magnetically and wash at least twice with acetic acid and methanol in a volume ratio of 1:50 as the eluent, vortexing for 5-10 minutes each time. Combine the eluents. The eluent was dried under a gentle nitrogen stream, then reconstituted with 100 μL of 50%-70% acetonitrile aqueous solution as mobile phase. After vortexing, a sample solution enriched with 6PPD-quinone was obtained.

[0022] This invention utilizes magnetic molecularly imprinted polymers (MMIPs) and magnetic separation solid-phase extraction technology to enrich 6PPD-quinone in water samples, avoiding the cumbersome traditional pretreatment procedures of frequent centrifugation and column chromatography, thus greatly shortening the pretreatment time. Furthermore, MMIPs can typically be reused more than 5 times without significant performance degradation, resulting in high cost-effectiveness. Attached Figure Description

[0023] Figure 1 This is a standard curve showing the relationship between absorbance (Y) and 6PPD-quinone concentration (X) for linear fitting according to the present invention. Detailed Implementation

[0024] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0025] Example 1 1. Preparation of Magnetic Molecularly Imprinted Polymers (MMIPs) 1) Synthesis of Fe3O4 nanoparticles Under nitrogen protection, 1 mol, 100 ml Fe 2+ and 2 mol, 100 ml Fe 3+Using the mixed solution as the reaction system, ammonia solution was added dropwise at a rate of 1 drop / second at 500 rpm and a water bath temperature of 60°C. If the reaction system immediately turned black, it indicated that Fe3O4 nanoparticles had begun to form. 28% ammonia solution was continued to be added until the pH of the reaction system stabilized around 10. The mixture was then stirred vigorously at a constant temperature for 60 minutes to allow for precipitation and aging, which resulted in more complete crystal growth and more uniform particle size. After the reaction was complete, the mixture was stirred under nitrogen protection until room temperature. The black particles were then adsorbed using a strong magnet, and the supernatant was discarded. The supernatant was washed again with pure water, ultrasonically assisted, and magnetically separated. The supernatant was discarded. This process was repeated 5 times until the supernatant became neutral (pH≈7) and clear. Finally, the supernatant was washed twice with ethanol and dried under vacuum at 60 °C to constant weight to obtain Fe3O4 nanoparticles. 2) Activation of Fe3O4 nanoparticles Then, 40 mM sodium citrate aqueous solution was added to 1 mg of Fe3O4 nanoparticles, and the mixture was stirred at 60℃ and 400 rpm for 18 h to carry out basal carboxylation. After magnetic separation, the mixture was washed three times with pure water and once with ethanol to remove free sodium citrate, and a wet cake of carboxylated Fe3O4 nanoparticles was obtained. The carboxylated Fe3O4 nanoparticle wet cake was added to 50 ml of 1% silane coupling agent reaction solution, stirred for 8 h in a water bath at 60 °C, magnetically separated, washed 3 times with ethanol, and vacuum dried at 60 °C to constant weight to obtain superparamagnetic activated Fe3O4 nanoparticles modified with "carboxyl + double bond" bifunctional groups.

[0026] The silane coupling agent accounts for 1% of the dry weight of Fe3O4 nanoparticles.

[0027] The solvent used in the silane coupling agent reaction solution includes anhydrous ethanol and water in a volume ratio of 9:1.

[0028] The preparation method of the silane coupling agent reaction solution includes: adding 45 mL of anhydrous ethanol and 2 μL of silane coupling agent (KH-570, abbreviated as MPS) to a 50 mL volumetric flask, vortexing for 10 s, then adding glacial acetic acid to adjust the pH to 4-5, and letting it stand at room temperature for 15 min to complete the silane pre-hydrolysis (the solution becoming slightly turbid is normal). Add 5 mL of deionized water, shake well, and bring the volume up to 50 mL with anhydrous ethanol to obtain 1-2 μL / 50 mL, which is the silane reaction solution.

[0029] 3) Synthesis of Magnetic Molecularly Imprinted Polymers (MMIPs) 0.1 mmol of the template molecule 6PPD-quinone and 0.8 mmol of the functional monomer methacrylic acid (MAA) were dissolved in 200 ml of a porogen prepared by acetonitrile / toluene in a volume ratio of 4:1. The mixture was sonicated for 30 min to obtain a pre-assembled solution. Then, 100 mg of activated Fe3O4 nanoparticles and 4 mmol of ethylene glycol dimethacrylate were added to the above pre-assembled solution as crosslinking agents. The mixture was stirred at 500 rpm for 30 min in a nitrogen atmosphere to completely remove oxygen from the reaction system, as oxygen is an inhibitor of free radical polymerization. Maintaining a nitrogen atmosphere, 32.8 mg of the initiator azobisisobutyronitrile was added to the above reaction system. After reacting in an oil bath at 60°C for 24 hours, the solution gradually turned into an opaque milky white suspension with polymer precipitation. After the reaction was completed, the solid was adsorbed with a strong magnet and the solid product was repeatedly washed with a methanol / acetic acid solution with a volume ratio of 9:1 until the template molecule 6PPD-quinone was undetectable in the eluent. After washing with methanol until neutral, the obtained product was placed in a vacuum drying oven at 60°C until constant weight, yielding magnetic molecularly imprinted polymers (MMIPs).

[0030] Functional monomer: Methacrylic acid (MAA), whose carboxyl group 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.

[0031] 2. Magnetic solid phase extraction (MSPE) enrichment and purification of water samples to be tested. 1) Sample pretreatment Water samples collected from rivers near the industrial area were 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 (at which hydrogen bonding is strongest).

[0032] 2) Magnetic Solid Phase Extraction (MSPE) Step Accurately weigh 10 mg of magnetic molecularly imprinted polymer (MMIPs) and disperse it in 100 mL of pretreated water sample. Vortex for 15-20 min to allow the 6PPD-quinone in the water sample to be fully and specifically adsorbed by the magnetic molecularly imprinted polymer (MMIPs). Add a strong magnet and stir for 1-2 minutes to fully adsorb MMIPs. After solid-liquid separation and discarding the supernatant, add 3%-5% methanol aqueous solution and vortex wash for 1-2 minutes. After magnetic separation, discard the washing liquid to remove weakly adsorbed dry impurities. Add 1 mL of acetic acid-methanol solution (volume ratio 1:50) as the elution solvent, vortex for 5-10 min, repeat the elution once, and combine the eluents (acetic acid can break hydrogen bonds, which can help methanol to elute the target 6PPD-quinone efficiently). The eluent was dried under a gentle nitrogen stream, redissolved in 100 μL of the initial mobile phase of 50% acetonitrile aqueous solution, and vortexed to obtain a sample solution enriched with 6PPD-quinone. This sample was then transferred to a reagent bottle for single-atom colorimetric detection.

[0033] 3. Single-atom colorimetric detection method 1) Prepare the reaction system: Step 1: Prepare the reaction mother liquor Buffer solution: Take 0.2 M acetate-sodium acetate buffer (pH = 4.0) and store at room temperature for later use.

[0034] Catalyst working solution: Take an appropriate amount of Fe-NC SACs single-atom catalyst stock solution, dilute it with ultrapure water and vortex to ensure that it is fully dispersed, and prepare a working suspension with a concentration of 20 μg / mL.

[0035] Working substrate solution: Take the organic solvent stock solution of TMB (e.g., 2.0 mM) and dilute it with the above-mentioned acetate-sodium acetate buffer to prepare a 2.2 mM TMB aqueous working solution. This step can reduce the proportion of organic solvent in the final system.

[0036] Oxidizing agent working solution: Take 30% of the H2O2 stock solution, dilute it with ultrapure water, and prepare a 100 mM H2O2 working solution. This solution should be stored away from light and at low temperature, and should be prepared fresh before use.

[0037] Standards: The stock solution of 6PPD-quinone standard was serially diluted with ultrapure water to prepare a series of working standard solutions with concentration gradients (0 nM, 20 nM, 50 nM, 100 nM, 200 nM, 500 nM). Sample solution: A sample solution enriched with 6PPD-quinone obtained by magnetic solid phase extraction (MSPE) using magnetic molecularly imprinted polymers.

[0038] Step 2: Assemble the reaction system Strictly follow the order and dosage when adding reagents to each labeled 1.5 mL centrifuge tube: 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.

[0039] 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.

[0040] 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.

[0041] Step 3: Initiating the reaction 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.

[0042] Step 4: Incubation and Monitoring 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.

[0043] 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, with the linear regression equation being Y = 0.0003902*X + 0.4301 and a correlation coefficient of 0.9997. The linear range of the working curve is 20–500 nM. The detection limit is 18.5 nM.

[0044] 2) Calculate the concentration of 6PPD-quinone in the sample solution: 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.

[0045] In the detection method of the present invention, magnetic molecularly imprinted polymers are used to enrich 6PPD-quinone in water samples using magnetic separation solid phase extraction technology, avoiding the cumbersome traditional pretreatment process of frequent centrifugation and column chromatography, and greatly shortening the pretreatment time; moreover, magnetic molecularly imprinted polymers (MMIPs) can usually be reused more than 5 times without significant performance degradation, and are cost-effective.

[0046] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A method for detecting a highly toxic new pollutant, 6PPD-quinone, characterized in that, include: Magnetic molecularly imprinted polymers were used to specifically adsorb 6PPD-quinone into the water sample to be tested, and then eluted to obtain a sample solution enriched with 6PPD-quinone. The sample solution was then analyzed using a single-atom colorimetric method. The single-atom material catalyzes a colorimetric reaction of 6PPD-quinone, and the content of 6PPD-quinone is detected by ultraviolet-visible spectrophotometry.

2. The detection method according to claim 1, characterized in that, The magnetic molecularly imprinted polymer is formed by encapsulating activated Fe3O4 nanoparticles with a molecularly imprinted polymer shell.

3. The detection method according to claim 2, characterized in that, The activated Fe3O4 nanoparticles are generated by modifying and activating Fe3O4 nanoparticles with carboxyl groups and double bonds.

4. The detection method according to claim 3, characterized in that, The method for preparing the activated Fe3O4 nanoparticles includes: Fe3O4 nanoparticles were added to an aqueous solution of sodium citrate and reacted at 50-60℃ and 300-400 rpm for 12-18 hours. After magnetic separation, the mixture was washed 2-3 times with pure water and once with ethanol to obtain a wet cake of carboxylated Fe3O4 nanoparticles. The carboxylated Fe3O4 nanoparticle wet cake was then added to a silane coupling agent reaction solution and reacted in a water bath at 50-60°C and 300-400 rpm for 6-8 hours. After magnetic separation, the nanoparticles were washed 2-3 times with ethanol and then vacuum dried at 50-60°C to constant weight to obtain the activated Fe3O4 nanoparticles with carboxyl groups and double bonds on their surface.

5. The detection method according to claim 4, characterized in that, The mass ratio of the Fe3O4 nanoparticles, sodium citrate solution, and silane coupling agent is 1:(0.02-0.05):(0.01-0.05); and / or 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 The silane coupling agent accounts for 1%-3% of the dry weight of the Fe3O4 nanoparticles; and / or The silane coupling agent includes: KH-570 or VTES.

6. The detection method according to claim 5, characterized in that, The preparation method of the Fe3O4 nanoparticles includes: Under nitrogen protection, a mixture of ferrous salt aqueous solution and ferric salt aqueous solution is used as a reaction system. Ammonia solution is added dropwise to the reaction system at 1-3 drops / second in a water bath at 500-800 rpm and 50-60°C until the pH value of the reaction system is 10-12. Continue stirring for 30-60 minutes in a water bath at 50-60°C and 500-800 rpm under nitrogen protection. Then, continue stirring and cool to room temperature. Adsorb the solid with a strong magnet, and then wash the solid with pure water 3-5 times by ultrasonication. Perform magnetic separation until the supernatant is neutral and clear. Wash with ethanol 1-2 times, and then vacuum dry at 50-60°C to constant weight to obtain the Fe3O4 nanoparticles.

7. The detection method according to claim 6, characterized in that, The ferrous salt aqueous solution is prepared by dissolving each mole of ferrous salt in 100-120 mL of pure water; the ferric salt aqueous solution is prepared by dissolving each mole of ferric salt in 100-120 mL of pure water; and / or The divalent iron salt is FeCl2·4H2O, and the trivalent iron is FeCl3·6H2O; and / or The molar ratio of FeCl2·4H2O and FeCl3·6H2O is 1:(1.5-2); and / or The mass concentration of the ammonia solution is 25%-28%.

8. The detection method according to claim 2, characterized in that, The method for preparing the magnetic molecularly imprinted polymer includes: The template molecule 6PPD-quinone and the functional monomer methacrylic acid were dissolved in a porogen and pre-assembled by ultrasound for 30 min. Then, the activated Fe3O4 nanoparticles and ethylene glycol dimethacrylate crosslinking agent are added, and nitrogen gas is purged throughout the process to remove oxygen. The reaction is carried out at 400-500 rpm for at least 30 minutes. Then, the initiator is added, and the reaction is carried out in a nitrogen environment at 60-70°C in an oil bath at 400-500 rpm for 12-24 hours. The solid is then separated with a strong magnet and washed with eluent until no template molecule 6PPD-quinone is found in the eluent. The solid is then washed with methanol until neutral and dried under vacuum at 50-60°C to constant weight to obtain the magnetic molecularly imprinted polymer.

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

1.

10. The detection method according to claim 1, characterized in that, The specific steps for using magnetic molecularly imprinted polymers to specifically adsorb 6PPD-quinone into the water sample, followed by elution, to obtain a sample solution enriched with 6PPD-quinone are as follows: S1. Water samples collected from rivers near the industrial area are filtered through a 0.45 μm glass fiber membrane to remove suspended particles and the pH is adjusted to 7.0 to obtain pretreated water samples. S2. Weigh 10 mg of the magnetic molecularly imprinted polymer and disperse it in 100 mL of the pretreated water sample, then vortex for 15-20 min. Add a strong magnet and stir for 1-2 minutes to separate the solid and liquid. Wash the obtained solid with a 3%-5% methanol aqueous solution by vortexing for 1-2 minutes. Separate magnetically and wash with acetic acid and methanol at a volume ratio of 1:50 by vortexing at least twice, each time for 5-10 minutes. Combine the eluents. The eluent was dried under a gentle nitrogen stream, redissolved in 100 μL of a 50%-70% acetonitrile aqueous solution as mobile phase, and vortexed to obtain a sample solution enriched with 6PPD-quinone.

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