A magnetic cation column [5] aromatic hydrocarbon porous polymer and its preparation method and application

Abstract

The present invention belongs to the technical field of new material preparation and analysis and detection, and specifically relates to a novel method for synthesizing a magnetic cationic column [5] aromatic hydrocarbon porous polymer PP5-1F-MNP and constructing a magnetic solid phase extraction-assisted high performance liquid chromatography-tandem mass spectrometry based on the PP5-1F-MNP. The PP5-1F-MNP of the present invention is based on Fe3O4 nanoparticles as the core, and the column [5] aromatic hydrocarbon porous polymer PP5-1F is coated on the outside of the Fe3O4 nanoparticles. PP5-1F is generated by an electrophilic substitution reaction between the column [5] aromatic hydrocarbon and 3-fluoropyridine, and then PP5-1F is reacted with FeCl3·6H2O by a one-pot solvent thermal method to prepare PP5-1F-MNP. The novel method of magnetic solid phase extraction-assisted high performance liquid chromatography-tandem mass spectrometry based on PP5-1F-MNP of the present invention can simultaneously detect C8-C 14 The invention provides a new method and idea for the enrichment and detection of PFCs in complex matrix samples, and also demonstrates the great potential of pillararomatic materials in the field of adsorption.

Description

Technical Field

[0001] The present invention belongs to the technical field of new material preparation and analysis and detection, and specifically relates to the synthesis of a new magnetic column [5] aromatic porous polymer (PP5-1F-MNP) and a new method for constructing a magnetic solid phase extraction assisted high performance liquid chromatography-tandem mass spectrometry (PP5-1F-MNP MSPE-HPLC-MS / MS) based on PP5-1F-MNP, and its application in the detection of perfluorinated compounds (PFCs) in environmental water samples. Background Art

[0002] Perfluorinated compounds (PFCs) are common persistent organic pollutants (POPs) widely used in consumer and industrial production. However, their accumulation has raised environmental safety concerns and has been detected worldwide, posing a threat to both ecosystems and human health. However, PFC levels in the environment are extremely low, and complex matrix effects exist, making conventional methods difficult to detect. Therefore, sample pretreatment is crucial.

[0003] Adsorption technology can enrich and separate PFCs and improve detection accuracy. Traditional adsorbents such as carbon nanotubes, activated carbon and graphene oxide have limitations, such as difficulty in separation and high regeneration costs. It is still necessary to continuously design and synthesize new adsorbent materials and develop highly sensitive and selective methods to detect and remove PFCs in the environment.

[0004] Pillar[n]arenes, as a new generation of macrocyclic compounds, are highly promising candidates for constructing supramolecular polymeric materials with enhanced performance and functionality, due to their unique pillared structure, nanoscale cavities, multifunctionalized groups, and excellent host-guest complexing capabilities. They are widely used in drug delivery platforms, fluorescent probes, sensors, detection, gas adsorption, water pollution treatment, and photocatalysis. Their unique structural characteristics endow them with excellent adsorption and recognition capabilities, enabling them to precisely capture and separate target compounds in complex environments. Furthermore, the presence of multifunctionalized groups provides pillar[n]arenes with abundant reaction sites, enabling their properties to be manipulated through chemical modification to meet the demands of adsorbing different pollutants.

[0005] Magnetic solid-phase extraction (MSPE) is a technique that uses magnetic or magnetizable materials as adsorbents to separate and pre-concentrate target analytes in a sample matrix. MSPE involves adding a magnetic adsorbent to a solution or suspension containing the target analyte. Once adsorption reaches equilibrium, an external magnetic field is applied to rapidly separate the solution from the magnetic material, improving extraction efficiency and analytical accuracy. This technology provides strong support for research in fields such as chemical analysis, environmental monitoring, and biomedicine. Summary of the Invention

[0006] In order to solve the problem that traditional methods for detecting PFCs are difficult to accurately and reliably determine their content, the present invention first generates a cationic column [5] aromatic hydrocarbon (PP5-1F) by an electrophilic substitution reaction between a brominated functional group column [5] aromatic hydrocarbon and 3-fluoropyridine, and then uses a one-pot solvent thermal method to react PP5-1F with FeCl3·6H2O in a high-pressure reactor to successfully construct a magnetic cationic column [5] aromatic hydrocarbon polymer material (PP5-1F-MNP). The present invention develops a magnetic column [5] aromatic hydrocarbon polymer material with both high-efficiency adsorption and easy separation and regeneration characteristics, and constructs a magnetic solid phase extraction-assisted high-performance liquid chromatography-tandem mass spectrometry method (PP5-1F-MNP MSPE-HPLC-MS / MS) based on the magnetic cationic column [5] aromatic hydrocarbon polymer material (PP5-1F-MNP) to detect PFCs in complex matrix samples, providing a new technical path for environmental protection and pollution control.

[0007] In order to accurately detect the content of PFCs at environmental concentration levels and in complex matrices, the present invention provides a magnetic cationic column [5] aromatic hydrocarbon polymer material PP5-1F-MNP. The PP5-1F-MNP has Fe3O4 nanoparticles as the core and is coated with a cationic column [5] aromatic hydrocarbon polymer PP5-1F on the outside of the Fe3O4 nanoparticles. The structural formula of the PP5-1F is as follows:

[0008]

[0009] The present invention also provides a method for preparing the PP5-1F-MNP, comprising the following steps:

[0010] (1) Preparation of 1,4-bis(2-bromoethoxy)benzene

[0011] In an ice-water bath at 0°C, hydroquinone dihydroxyethyl ether and triphenylphosphine are added to anhydrous acetonitrile, followed by slow addition of carbon tetrabromide under the protection of an inert gas (preferably nitrogen). The reaction system is then returned to room temperature and stirred at room temperature until the solution becomes clear and transparent (preferably for 3-6 hours). Cold water is then added to quench the reaction, and the product is purified (preferably recrystallized from methanol) and dried (preferably at 40°C under vacuum for 24 hours) to obtain 1,4-bis(2-bromoethoxy)benzene.

[0012] (2) Preparation of brominated functional group column [5] aromatic hydrocarbons

[0013] Paraformaldehyde is added to a solution of 1,4-bis(2-bromoethoxy)benzene (preferably a dichloroethane or dichloromethane solution of 1,4-bis(2-bromoethoxy)benzene), followed by addition of boron trifluoride etherate (BF3·O(C2H5)2), and stirred at room temperature for 4-8 hours. After the reaction is completed, the reaction is quenched with cold water, and the product is purified and dried to obtain brominated functional group column [5] aromatic hydrocarbons;

[0014] (3)PP5-1F

[0015] Add the brominated functional group column [5] aromatic hydrocarbon to 3-fluoropyridine, and heat the reaction mixture under reflux with stirring for 8-12 hours. After the reaction is completed, a yellow solid is obtained, which is purified (preferably by recrystallization from diethyl ether) and dried to obtain PP5-1F (preferably dried in vacuo at 40°C for 24 hours).

[0016] (4)PP5-1F-MNP

[0017] PP5-1F was added to ethylene glycol and ultrasonically dissolved. FeCl3·6H2O and sodium acetate were then added. After ultrasonic dispersion, the mixture was stirred evenly at room temperature. The mixture was then transferred to a polytetrafluoroethylene reactor and reacted at 100-250°C for 8-12 hours (preferably at 200°C for 10 hours). The mixture was washed and dried to obtain a black magnetic column [5] aromatic polymer PP5-1F-MNP.

[0018] Preferably, in said (4), anhydrous ethanol and deionized water are used for alternate washing, and said drying is: vacuum drying at 40° C. for 24 h.

[0019] Preferably, in step (1), the molar ratio of hydroquinone dihydroxyethyl ether to triphenylphosphine is 1:(2-3), and the molar ratio of triphenylphosphine to carbon tetrabromide is 1:1. Optimally, the molar ratio of hydroquinone dihydroxyethyl ether, triphenylphosphine and carbon tetrabromide is 5:12:12.

[0020] Preferably, in step (2), the molar ratio of 1,4-bis(2-bromoethoxy)benzene, paraformaldehyde and boron trifluoride etherate is 1:(0.5-3):(0.5-1.5), most preferably 1:1:1.

[0021] Preferably, in step (3), the ratio of pillar[5]arene to 3-fluoropyridine is 0.3-1.2 mmol: 5-10 mL.

[0022] Preferably, in step (4), the molar ratio of PP5-1F to FeCl3·6H2O and sodium acetate is (0.05-0.5):1:(2-8), and most preferably 0.15:1:4.

[0023] Preferably, in step (4), the ratio of PP5-1F to ethylene glycol is 0.5-2 g:10-30 mL.

[0024] The present invention also provides a method for detecting PFCs content based on magnetic solid phase extraction-high performance liquid chromatography tandem mass spectrometry of the PP5-1F-MNP:

[0025] (1) Chromatographic conditions

[0026] Chromatographic column: C18 column;

[0027] Mobile phase A: 5 mmol / L ammonium acetate aqueous solution, mobile phase B: acetonitrile;

[0028] Flow rate: 0.4 mL / min;

[0029] Column temperature: 40°C;

[0030] Gradient elution conditions:

[0031] Time (min) Mobile phase A (v / v%) Mobile phase B (v / v%) 0-1 90 10 1-5 90-10 10-90 5-8 10 90 8-10 10-90 90-10

[0032] (2) Mass spectrometry conditions

[0033] PFCs were analyzed using an electrospray ionization (ESI) source in negative ion mode and multiple reaction monitoring (MRM) mode. Nebulizer gas flow rate: 3 L / min, heating gas flow rate: 10 L / min, drying gas flow rate: 10 L / min, interface temperature: 300°C, DL temperature: 250°C, heating block temperature: 400°C, and each MRM dwell time was 12 ms.

[0034] (3) Magnetic solid phase extraction step

[0035] After mixing PP5-1F-MNP with the PFCs sample solution to be tested, vortexing is performed on a vortex mixer for 2-15 minutes (preferably 5 minutes) to ensure that the PP5-1F-MNP adsorbent fully and selectively adsorbs the PFCs. An external magnet is used to quickly and effectively separate the PP5-1F-MNP adsorbent from the solution. The PP5-1F-MNP is washed with pure water to remove PFCs not adsorbed on the surface. A desorption solution (preferably dichloromethane, ethyl acetate, acetone, methanol or acetonitrile, most preferably acetonitrile) is added and vortexed for 3-15 minutes (preferably 8 minutes) to desorb the PFCs adsorbed by the PP5-1F-MNP. After separating the PP5-1F-MNP from the solution, a certain amount of the solution is taken, concentrated to dryness, and then the desorption solution is added to redissolve the PFCs. The re-dissolved solution is subjected to HPLC-MS / MS detection.

[0036] Preferably, the ratio of the PP5-1F-MNP adsorbent to the desorption liquid is (5-20) mg: (3-13) mL; more preferably 15 mg: 7 mL.

[0037] Preferably, the dosage ratio of the PP5-1F-MNP adsorbent to the sample solution is (5-20) mg: (3-13) mL; more preferably 15 mg: 10 mL.

[0038] Preferably, when the reconstituted solution is subjected to HPLC-MS / MS detection, the content of PFCs is detected using the internal standard method. 13 C8-PFOA and 13 C8-PFOS was used as an internal standard.

[0039] Preferably, the PFCs are long-chain PFCs with a carbon chain of not less than 8, more preferably C8-C 14 Long chain PFCs, most preferably C8-C 14 perfluorocarboxylic acids and / or perfluorosulfonic acids.

[0040] This study used PP5-1F-MNP as a magnetic solid-phase extraction (MSPE) adsorbent to investigate the adsorption of PFCs. The researchers found that PP5-1F-MNP was effective for eight long-chain PFCs. By optimizing the MSPE conditions, they established a PP5-1F-MNP-MSPE HPLC-MS / MS method for the detection of these eight PFCs. The method was then applied to quantitative analysis of PFCs in water samples from Nanhu Lake, Donghu Lake, and Tangxun Lake in Wuhan, as well as rainwater.

[0041] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0042] 1. The present invention is the first to react bromine functional group column [5] aromatic hydrocarbons with 3-fluoropyridine to generate cationic column [5] aromatic hydrocarbons (PP5-1F) for C8-C 14 The long-chain PFCs have excellent adsorption properties, and the adsorption recovery rate can reach more than 70%. The maximum adsorption capacity for perfluorooctanoic acid (PFOA), perfluorosulfonic acid (PFOS) and perfluoroundecanoic acid (PFUnDA) are 42.02, 62.11 and 64.94 mg / g, respectively.

[0043] 2. The magnetic adsorbent of the present invention has a simple preparation process, low cost, and ideal adsorption effect. After adsorption is completed, it is easy to effectively separate from the system and can be recycled, making it suitable for industrial production.

[0044] 3. This invention has developed a new method of magnetic solid phase extraction assisted high performance liquid chromatography-tandem mass spectrometry, which can simultaneously perform quantitative analysis of 8 kinds of PFCs. The linear range of this method for 8 kinds of long-chain PFCs is in the range of 2.0ng / L to 100ng / L. The correlation coefficient R 2The linearity is greater than 0.9964. The LOD range is 1.0–2.8 ng / L, the LOQ range is 2.0–10.0 ng / mL, and the RSD range is 1.7–6.3%. The method can be used to detect PFCs in real-world water samples, such as lake water and rainwater. Spiked recoveries range from 84.8% to 104.7%, with RSDs from 0.61% to 13.1%. The developed method exhibits excellent linearity, high recovery, low detection limit, high sensitivity, and excellent reproducibility, making it crucial for accurately assessing environmental exposure levels and health risks. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] Figure 1 is the H NMR spectrum of pillar [5] aromatic hydrocarbon in Example 1;

[0046] Figure 2 is the carbon NMR spectrum of pillar [5] aromatic hydrocarbon in Example 1;

[0047] Figure 3 is the H NMR spectrum of the cationic column [5]arene (PP5-1F) in Example 1;

[0048] Figure 4 is the carbon NMR spectrum of the cationic column [5] aromatic hydrocarbon (PP5-1F) in Example 1;

[0049] Figure 5 is the infrared spectra of PP5-1F and PP5-1F-MNP in Example 1;

[0050] Figure 6 (A) and (B) are field emission scanning electron micrographs of Fe3O4 nanoparticles with scale bars of 2 μm and 800 nm, respectively; (C) and (D) are field emission scanning electron micrographs of PP5-1F-MNPs with scale bars of 2 μm and 800 nm, respectively;

[0051] Figure 7 (A) and (B) are transmission electron micrographs of Fe3O4 nanoparticles with scale bars of 500 nm and 200 nm, and (C) and (D) are transmission electron micrographs of PP5-1F-MNPs with scale bars of 2 μm and 200 nm;

[0052] Figure 8 is the nitrogen adsorption-desorption isotherm and pore size distribution of PP5-1F-MNP in Example 1;

[0053] Figure 9 is a graph showing the hysteresis loops of Fe3O4 nanoparticles and PP5-1F-MNPs in Example 1;

[0054] Figure 10is the water contact angle diagram of Fe3O4 nanoparticles and PP5-1F-MNPs in Example 1;

[0055] Figure 11 This is a graph showing the adsorbent quality optimization results in Example 2;

[0056] Figure 12 This is a diagram showing the optimization results of adsorption time in Example 2;

[0057] Figure 13 2 is a graph showing the optimization results of the desorption liquid type in Example 2;

[0058] Figure 14 2 is a graph showing the optimization results of the desorption liquid volume in Example 2;

[0059] Figure 15 This is a graph showing the desorption time optimization results in Example 2;

[0060] Figure 16 is the adsorption isotherm of PP5-1F-MNP for three PFCs in Example 2;

[0061] Figure 17 is a chromatogram of a mixed standard of eight PFCs and two isotopic internal standards in Example 2;

[0062] Figure 18 This is a full scan of the eight PFCs and two isotope internal standards in Example 2 in negative ion mode. DETAILED DESCRIPTION

[0063] The applicant will now describe the technical solutions of the present invention in detail with reference to specific examples. However, it should be understood that the following examples are intended only to illustrate the present invention and are not intended to limit the scope of protection claimed in the claims. The experimental methods used in the following examples are conventional methods unless otherwise specified; the materials and reagents used are all commercially available unless otherwise specified.

[0064] The information of PFCs standards and some reagents used in the following examples is shown in Table 1 below:

[0065] Table 1

[0066] Reagent name Reagent specifications Manufacturer Perfluorobutyric acid (PFBA) ≥98％ Aladdin Reagent Co., Ltd. Perfluorobutanesulfonic acid (PFBS) ≥98％ Bidex Pharmaceutical Technology Co., Ltd. Perfluorohexanoic acid (PFHxA) ≥97％ Sigma Reagent Co., Ltd. Perfluoropentanoic acid (PFPeA) ≥97％ Bailingwei Technology Co., Ltd. Perfluoroheptanoic acid (PFHpA) ≥99％ Bidex Pharmaceutical Technology Co., Ltd. Perfluorooctanoic acid (PFOA) ≥96％ Sigma Reagent Co., Ltd. Perfluorooctane sulfonic acid (PFOS) 100 μg / mL Bailingwei Technology Co., Ltd. Perfluorononanoic acid (PFNA) ≥98％ Bailingwei Technology Co., Ltd. Perfluorodecanoic acid (PFDA) ≥98.0％ Aladdin Reagent Co., Ltd. Perfluoroundecanoic acid (PFUnDA) ≥97.0％ Aladdin Reagent Co., Ltd. Perfluorododecanoic acid (PFDoDA) ≥95.0％ Aladdin Reagent Co., Ltd. Perfluorotridecanoic acid (PFTrDA) ≥97％ Sigma Reagent Co., Ltd. Perfluorotetradecanoic acid (PFTeDA) ≥96％ Bailingwei Technology Co., Ltd. <![CDATA[ 13 C8-perfluorooctane carboxylic acid ( 13 C8-PFOA) ≥99％ Wellington Laboratory, Canada <![CDATA[ 13 C8-PFOS ( 13 C8-PFOS)]]> ≥99％ Wellington Laboratory, Canada Methanol Chromatographically pure German Merk Reagent Company Acetonitrile Chromatographically pure German Merk Reagent Company acetone Chromatographically pure Thermo Fisher Scientific 1,2-Dichloromethane Chromatographically pure Thermo Fisher Scientific n-hexane Chromatographically pure Aladdin Reagent Co., Ltd. Ammonium acetate Chromatographically pure Sinopharm Chemical Reagent Co., Ltd. Yibao purified water ― China Resources C'estbon Beverages (Changsha) Co., Ltd. Paraformaldehyde (Cat. No. C104188) AR Aladdin Reagent Co., Ltd.

[0067] Example 1: Preparation and characterization of magnetic cation column [5] aromatic porous polymer

[0068]

[0069] A method for preparing a magnetic pillar[5] aromatic porous polymer BrBP[5]-MNP comprises the following steps:

[0070] (1) Preparation of 1,4-bis(2-bromoethoxy)benzene

[0071] Under 0°C ice-water bath conditions, 50.4mmol of hydroquinone dihydroxyethyl ether and 120mmol of triphenylphosphine (PPh3) were added to 300mL of acetonitrile, and then 120mmol of carbon tetrabromide (CBr4) was slowly added under nitrogen protection. The ice bath was removed and the reaction system was returned to room temperature (room temperature in this application refers to 25°C). Stir at room temperature for 4 hours until the solution became clear and transparent. Then, an appropriate amount of cold water (ultrapure water at room temperature, the same below) was added to the reaction mixture to quench the reaction. The solid was collected by filtration and washed with methanol / water (60:40, v / v) to obtain the product as a white flaky solid. Finally, 1,4-bis(2-bromoethoxy)benzene was obtained by vacuum drying at 40°C for 24 hours with a yield of 85%.

[0072] (2) Preparation of brominated functional group column [5] aromatic hydrocarbons

[0073] 11.5 mmol of paraformaldehyde (in this application, the molecular weight of paraformaldehyde is calculated as 30.03) was added to a solution of 1,4-bis(2-bromoethoxy)benzene (11.5 mmol) in 1,2-dichloroethane (200 mL). Subsequently, 11.5 mmol of BF3·O(C2H5)2 was added and stirred at room temperature for 6 h. The reaction process was monitored by thin layer chromatography. After the reaction was completed, the mixture was quenched with (2×100 mL) of cold water. After extraction with a saturated dichloromethane solution of sodium chloride, the organic phase was dried over anhydrous Na2SO4, concentrated under reduced pressure, and purified by silica gel column chromatography (eluent: petroleum ether / dichloromethane = 1:1, v / v). Finally, it was dried in vacuo at 40°C for 24 h to obtain a white powder of brominated functional group column [5] aromatic hydrocarbon. The yield of this step was 41%.

[0074] (3) Preparation of PP5-1F

[0075] 0.3 mmol of column [5] aromatic hydrocarbon was added to 5 mL of anhydrous 3-fluoropyridine, and the reaction mixture was heated under reflux and stirred for 10 h. After the reaction was completed, a yellow solid was obtained. After recrystallization with ether, it was vacuum-dried at 40 ° C for 24 h to obtain PP5-1F. The yield of this step was 90%.

[0076] (4) Preparation of PP5-1F-MNPs

[0077] 0.3 mmol PP5-1F was added to 20 mL anhydrous ethylene glycol and dissolved by ultrasonication. 2 mmol FeCl3·6H2O and 8 mmol sodium acetate were then added. After ultrasonic dispersion, the mixture was stirred at room temperature for 30 min. The mixture was then transferred to a 100 mL polytetrafluoroethylene reactor and reacted at 200°C for 10 h. The mixture was then cooled to room temperature and washed alternately with ethanol and deionized water under an external magnetic field for 5 times each. After washing, the mixture was filtered and the filter cake was dried in a vacuum drying oven at 40°C for 24 h to obtain a black magnetic column [5] aromatic polymer PP5-1F-MNP. The yield of this step was 60%.

[0078] (5) Preparation of Fe3O4 nanoparticles

[0079] 20 mmol of FeCl₃·6H₂O was added to a three-necked flask containing 100 mL of ethylene glycol. After ultrasonic dispersion for 20 minutes, 80 mmol of sodium acetate was added and mechanical stirring was carried out at room temperature for 30 minutes. The resulting homogeneous yellow solution was transferred to a sealed polytetrafluoroethylene reactor and reacted at 200°C for 10 hours. The reaction was then cooled to room temperature and washed alternately with ethanol and deionized water five times each under an external magnetic field. After washing, the black product was dried in a vacuum oven at 25°C for 12 hours to obtain Fe₃O₄ nanoparticles.

[0080] The PP5-1F, PP5-1F-MNP, and Fe3O4 nanoparticles prepared in this example were characterized, and the results are as follows:

[0081] (1) NMR analysis

[0082] The present invention uses the AVANCE III nuclear magnetic resonance spectrometer of Bruker BioSpin Company of Switzerland to perform structural analysis on column [5] aromatic hydrocarbons and PP5-1F. The solvent of column [5] aromatic hydrocarbons is deuterated chloroform, and its H spectrum and C spectrum are as follows Figure 1 、 2 As shown, the solvent of PP5-1F is deuterated methanol, and its H spectrum and C spectrum are as follows Figure 3 、 4 shown.

[0083] (2) Fourier transform infrared spectroscopy (FT-IR)

[0084] The present invention uses the NEXUS 470 infrared spectrometer from Niolet, USA, to characterize the characteristic functional groups of PP5-1F and PP5-1F-MNP. Potassium bromide is used as the substrate for tableting to obtain infrared spectral data of the samples. The test wavelength range is 4000-500cm -1 , the results are as follows Figure 5 shown. Figure 5PP5-1F at 1503cm -1 , 1593cm -1 The peak at 1590 cm-1 of PP5-1F-MNP -1 The peak at 1285cm is the stretching vibration peak of the benzene ring skeleton; PP5-1F at 1285cm -1 and PP5-1F-MNP at 1349 cm -1 The peak at 578 cm is the stretching vibration peak of the CF bond on the benzene ring, indicating that the reaction between pillar[5]arene and 3-fluoropyridine is successful, confirming the existence of the CF bond in the material. -1 The peak at is the stretching vibration peak of the Fe-O bond, indicating that the magnetization of PP5-1F was successful. The characteristic peaks of the Fe-O bond and the CF bond in the spectrum indicate that PP5-1F was successfully modified with magnetic nanoparticles.

[0085] (3) Field emission scanning electron microscopy (SEM)

[0086] The present invention used a field emission scanning electron microscope (SU8010) manufactured by HITACHI, Japan, to conduct preliminary analysis of the size and morphology of the synthesized materials. The procedure was as follows: Fe3O4 nanoparticles and PP5-1F-MNP powder were evenly adhered to a sample stage using conductive adhesive. The size and morphology of the materials were observed using the electron microscope. Figure 6 (A) and (B) show SEM images of Fe3O4 nanoparticles with a scale of 2μm and 800nm, respectively. It can be clearly seen from the images that Fe3O4 is spherical with uniform size and good dispersion. Figure 6 (C) and (D) show SEM images of PP5-1F-MNPs at scales of 2 μm and 800 nm, respectively. The irregular morphology of the PP5-1F-MNPs is evident. Compared to (A) and (B), some Fe₃O₄ is successfully encapsulated within the PP5-1F-MNPs, but some is incompletely encapsulated, resulting in a rough, uneven surface. This is presumably due to an excess of Fe₃O₄ and its tendency to agglomerate during the reaction.

[0087] (4) Transmission scanning electron microscopy (TEM)

[0088] The morphology of Fe3O4 nanoparticles and PP5-1F-MNPs was further characterized using a TALOS F200X transmission electron microscope (from Thermo Fisher Scientific, USA). The material samples were ground and ultrasonically dispersed onto a copper mesh with anhydrous ethanol. Testing was performed after the ethanol evaporated. Figure 7(A) and (B) show TEM images of Fe3O4 nanoparticles with scales of 500nm and 200nm, respectively. It can be seen from the figures that each Fe3O4 nanoparticle has a clear spherical outline, a smooth surface and uniform size. Figure 7 (C) and (D) show the TEM images of PP5-1F-MNP with a scale of 2μm and 200nm, respectively. It can be seen from the figures that the Fe3O4 nanoparticles are encapsulated inside and their surface is covered with a transparent shell structure. The results are consistent with the results of scanning electron microscopy.

[0089] (5) Nitrogen physical adsorption and desorption

[0090] This study used a nitrogen adsorption-desorption instrument (ASAP 2020) manufactured by Micromeritics (USA) to characterize the pore structure of PP5-1F-MNPs, including pore size and specific surface area. The procedure was as follows: N adsorption-desorption experiments were performed at 77 K. The specific surface area and pore size of the PP5-1F-MNPs were calculated using the BET method and the Barrett-Joyner-Halenda (BJH) model. Figure 8 From the adsorption-desorption isotherm in (A), we can see that the adsorption and desorption behavior of PP5-1F-MNP conforms to the H1 loop characteristics of the typical IV type isotherm. This phenomenon shows that there is a significant hysteresis phenomenon in the adsorption and desorption process, indicating the existence of mesoporous structure in the material. Figure 8 As shown in (B), the specific surface area of PP5-1F-MNP calculated using the BJH model is 89.05 m 2 / g, and the average pore size is 19.28 nm, which fully confirms that PP5-1F-MNP is a material with mesoporous characteristics.

[0091] (6) Hysteresis loop analysis (VSM)

[0092] The saturation magnetization values of Fe3O4 nanoparticles and PP5-1F-MNPs were measured using a 7074 vibrating sample magnetometer from Lake Shore, USA, to comprehensively evaluate their magnetic properties. Figure 9 The hysteresis loop curves of Fe3O4 and PP5-1F-MNP show that the saturation magnetization value of Fe3O4 nanoparticles is 45.0emu / g, and the saturation magnetization value of PP5-1F-MNP is 12.7emu / g. Compared with Fe3O4, the magnetization value decreases, indicating that the magnetization value of Fe3O4 will decrease after being successfully coated by PP5-1F, but PP5-1F-MNP still has strong paramagnetism, and the material can be quickly separated from the solution by an external magnetic field in a short time, thereby improving the adsorption efficiency.

[0093] (7) Water contact angle analysis (CA)

[0094] This study used an OCA20 water contact angle analyzer from Dataphysics, Germany, to test the hydrophilicity and hydrophobicity of the synthesized materials. The procedure was as follows: Appropriate amounts of Fe₃O₄ and PP5-1F-MNP were weighed and pressed into a disc-shaped sheet. A water droplet was then placed on the surface of the sheet, and the angle between the droplet and the surface was measured. Figure 10 The water contact angles of Fe3O4 nanoparticles and PP5-1F-MNPs are shown in the figure. The water contact angle of Fe3O4 is 94.9°, and the water contact angle of PP5-1F-MNP is 56.2°. After successful magnetization, the water contact angle of PP5-1F-MNP decreases, indicating that it is hydrophilic and can better contact with aqueous solutions.

[0095] Example 2: Investigation of PP5-1F-MNP-based magnetic solid phase extraction-assisted high performance liquid chromatography-tandem mass spectrometry method

[0096] Chromatographic conditions:

[0097] Chromatographic column: Waters ACQUITY UPLC C18 column (1.7 μm, 2.1 × 100 mm);

[0098] Mobile phase A: 5 mmol / L ammonium acetate aqueous solution; mobile phase B: acetonitrile;

[0099] Flow rate: 0.4 mL / min; column temperature: 40°C;

[0100] Gradient elution conditions:

[0101] Time (min) Mobile phase A (v / v%) Mobile phase B (v / v%) 0-1 90 10 1-5 90-10 10-90 5-8 10 90 8-10 10-90 90-10

[0102] Mass spectrometry conditions:

[0103] High performance liquid chromatography-tandem mass spectrometry (HPLC-MS-8050) electrospray ionization (ESI) produced by Shimadzu, Japan was used. The mass spectrometry parameters were as follows: nebulizing gas flow rate: 3 L / min, heating gas flow rate: 10 L / min, drying gas flow rate: 10 L / min, interface temperature: 300°C, DL temperature: 250°C, heating block temperature: 400°C, and each MRM dwell time was 12 ms.

[0104] First, in negative ion mode, a full scan was performed on the 13 PFCs standards and 2 internal standards shown in Table 2 to determine the precursor ions. Secondly, multiple fragmentation voltages were set in combination with the found precursor ions, and the corresponding fragmentation voltages were obtained by product ion scanning. Based on the abundance of the fragment ions, the one with the highest abundance was selected as the quantitative ion, and the one with the second highest abundance was selected as the qualitative ion, and the parent-daughter ion pairs corresponding to the 15 substances were obtained. Finally, based on the determined parent-daughter ion pairs, the collision energy was optimized, and the instrument parameters in MS and MS / MS were optimized as a whole to establish a multiple reaction monitoring mode method (MRM). The optimized MRM analysis parameters for the 13 PFCs and two isotopic internal standards are shown in Table 2:

[0105] Table 2: Mass spectrometric parameters of 13 PFCs and two isotopic internal standards

[0106]

[0107] 1. Study on adsorption effect

[0108] Preparation of standard stock solutions: Weigh 10 mg of each of the 13 PFCs standards and dissolve them in 10 mL of chromatography-grade acetonitrile to prepare 1 mg / mL standard stock solutions, which were then stored in a refrigerator at 4°C.

[0109] 0.1 ng / mL PFCs mixed standard solution: Take 50 μL of 1 mg / mL standard stock solutions of 13 PFCs respectively, mix them, add 350 μL of acetonitrile to dilute to 50 μg / mL mixed standard solution, and then dilute the 50 μg / mL mixed standard solution with acetonitrile to 0.1 ng / mL mixed standard solution.

[0110] Prepare standard internal standard solution: 13 C8-PFOA and 13 Two C8-PFOS compounds were used as internal standard substances, and were dissolved in chromatography-grade acetonitrile to prepare solutions with a concentration of 50 μg / mL, which were then stored in a refrigerator at 4°C.

[0111] 10ng / mL internal standard mixed solution: take 50μg / mL 13 C8-PFOA and 13 200 μL of each C8-PFOS solution was mixed and 600 μL of acetonitrile was added to dilute it to a 10 μg / mL internal standard mixed solution, and then the 10 μg / mL internal standard mixed solution was diluted with acetonitrile to a 10 ng / mL internal standard mixed solution.

[0112] Prepare a standard curve: accurately pipette the above 50 μg / mL mixed standard solution, dilute it with HPLC grade acetonitrile, and prepare a series of mixed standard solutions with concentrations of 0.01 ng / mL, 0.02 ng / mL, 0.05 ng / mL, 0.1 ng / mL, 0.2 ng / mL, 0.5 ng / mL, 1 ng / mL, 2 ng / mL, 5 ng / mL, 10 ng / mL, 20 ng / mL, 50 ng / mL, and 100 ng / mL, respectively. Centrifuge for 3 minutes, take 90 μL of the supernatant and add 10 μL of the internal standard mixed solution with a concentration of 10 ng / mL ( 13 C-PFOA and 13 C-PFOS), vortex mix, centrifuge for 3 minutes, take 70μL into the injection bottle, HPLC-MS / MS direct injection, injection volume 5μL, each variable is measured in parallel three times. The concentration of each compound is the horizontal axis (X), and the peak area of each compound is compared with the corresponding internal standard (the internal standard of perfluorocarboxylic acid is 13 C8-PFOA, the internal standard for perfluorosulfonic acid is 13 The standard curve was drawn with the peak area ratio of C8-PFOS (the same below) as the ordinate (Y).

[0113] PP5-1F-MNP was used as a magnetic solid phase extraction adsorbent to conduct an adsorption-desorption experiment on PFCs. The specific steps are as follows:

[0114] Place 10 mg of the PP5-1F-MNP adsorbent obtained in Example 1 in a 50 mL centrifuge tube and add 10 mL of a 0.1 ng / mL mixed standard solution of 13 PFCs. Vortex the solution for 5 minutes on a vortex mixer to ensure that the PP5-1F-MNP adsorbent fully and selectively adsorbs the PFCs. Use an external magnet to quickly separate the PP5-1F-MNP adsorbent from the solution. Then, add 5 mL of pure water to elute any PFCs not adsorbed on the PP5-1F-MNP surface. Separate the solid adsorbent from the solution again using a magnet. Add 5 mL of acetonitrile as a desorption solution and vortex for 5 minutes to desorb the PFCs adsorbed by the PP5-1F-MNP. Attach a magnet to the outside of the centrifuge tube to hold the material in place. Allow the solution to settle. Remove 4 mL of the supernatant and blow dry using a nitrogen blower. 200 μL of chromatography-grade acetonitrile was added to redissolve the PFCs. The redissolved solution was centrifuged for 3 min, and 90 μL of the supernatant was taken and 10 μL of 10 ng / mL of acetonitrile was added to it. 13 C8-PFOA and 13 After the C8-PFOS internal standard mixed solution is mixed evenly, 70 μL is taken for HPLC-MS / MS mass spectrometry detection, the mass spectrometry injection volume is 5 μL, and the parallel determination is performed three times.

[0115] Calculate the ratio of the peak area of perfluorocarboxylic acid or perfluorosulfonic acid to its corresponding internal standard, substitute it into the above standard curve equation, and obtain the actual sample concentration.

[0116] Recovery rate calculation: Recovery rate (%) = actual sample concentration / theoretical calculated concentration × 100%, where the theoretical calculated concentration is the concentration of the known standard solution.

[0117] The recovery rate of 13 PFCs after adsorption by PP5-1F-MNP was analyzed. The results showed that PP5-1F-MNP material showed a certain adsorption capacity for 8 long-chain PFCs, namely PFOA, PFOS, PFNA, PFDA, PFUnDA, PFDoDA, PFTrDA and PFTeDA. The adsorption effect of PP5-1F-MNP material on the above 8 long-chain PFCs was better than that on short-chain PFCs (PFBS, PFBA, PFPeA, PFHxA, PFHpA). The main reasons may be: First, PP5-1F-MNP is a magnetic cationic column [5] aromatic polymer that can effectively adsorb PFCs through electrostatic forces. With the increase of carbon chain length, the pKa values of 13 PFCs gradually decreased, indicating that their acidity increased. In neutral or weakly alkaline solutions, these PFCs will lose protons and exist in anionic state, which makes PP5-1F-MNP have a higher adsorption capacity for long-chain PFCs. Secondly, the PP5-1F-MNP material contains F atoms, which can adsorb PFCs through FF interactions. As the carbon chain increases, the number of F atoms in PFCs increases, the FF interaction is enhanced, and the adsorption effect is enhanced. Therefore, PP5-1F-MNP has a relatively good adsorption effect on long-chain PFCs. Finally, the PP5-1F-MNP material contains a rigid cavity structure. PFCs of different sizes can selectively enter the cavity of the PP5-1F-MNP material through host-guest interaction. The molecular size of long-chain PFCs is larger than that of short-chain PFCs. Long-chain PFCs are less likely to come out of the cavity of the PP5-1F-MNP material, so the adsorption effect of long-chain PFCs is better. Experimental results show that PP5-1F-MNP has the ability to selectively adsorb C8 to C 14 The PP5-1F-MNP material has the potential to be used as an adsorbent material for magnetic solid-phase extraction. Subsequent experiments will investigate the adsorption conditions of the PP5-1F-MNP material for the eight long-chain PFCs to determine its optimal adsorption performance.

[0118] 2. Optimization of adsorption-desorption conditions (8 long-chain PFCs)

[0119] To optimize the adsorption and desorption conditions, a single-factor experimental design was employed. The experiments focused on the following key factors: adsorbent dosage, adsorption time, desorption solution type, desorption solution volume, and desorption time. To ensure the accuracy and reliability of the experimental results, three replicates were conducted for each variable. This study further explored the adsorption performance of the PP5-1F-MNP adsorbent for PFCs, aiming to achieve optimal adsorption results.

[0120] Preparation of mixed standard solutions of 8 PFCs: Take 50 μL of 1 mg / mL standard stock solutions of PFOA, PFOS, PFNA, PFDA, PFUnDA, PFDoDA, PFTrDA and PFTeDA respectively, mix them, add 600 μL of acetonitrile to dilute them into 50 μg / mL mixed standard solution, and then dilute the 50 μg / mL mixed standard solution with acetonitrile to 0.1 ng / mL mixed standard solution.

[0121] Adsorbent dosage: First, the effect of the quality of PP5-1F-MNP adsorbent on the adsorption effect of PFCs was studied. 5 mg, 8 mg, 10 mg, 15 mg, 20 mg and 25 mg of PP5-1F-MNP material were accurately added to 6 50 mL centrifuge tubes respectively. Then, 10 mL of a mixed standard solution of 8 PFCs with a concentration of 0.1 ng / mL was added to each centrifuge tube. The specific steps of the experiment were carried out according to the adsorption-desorption experiment in 1. The results are shown in Figure 2. Figure 11 The results showed that: in the early stage, as the mass of the adsorbent increased, the recovery rate of PFCs also increased, and the optimal extraction recovery rate was reached at 15 mg. This may be because as the mass of PP5-1F-MNP increased, its specific surface area also increased accordingly, and the adsorption sites on the surface of the material also increased accordingly, and the adsorption process mainly occurred on the surface of the adsorbent, so the recovery efficiency was improved. Secondly, the increase in the mass of the adsorbent means an increase in its total adsorption capacity, which can better remove PFCs from the solution. However, the increase in the mass of the adsorbent does not always improve the adsorption effect linearly, because when the adsorbent reaches a certain amount, the adsorption effect may tend to saturation. Considering the economic benefits, 15 mg of PP5-1F-MNP material was finally selected as the optimal adsorbent dosage for subsequent experimental studies.

[0122] Adsorption time: The adsorption process is a dynamic equilibrium process. The adsorption time is also one of the important factors affecting the adsorption effect of the material. It is necessary to optimize the adsorption time and change the adsorption time. The adsorption was carried out for 2 minutes, 5 minutes, 8 minutes, 10 minutes, 12 minutes and 15 minutes respectively. The amount of adsorbent was 15 mg. The rest of the experimental process was carried out according to 1. The results are as follows Figure 12As shown, the adsorption recovery rates of the eight PFCs increased with increasing adsorption time at shorter adsorption times, then decreased slightly after 10 minutes, ultimately leveling off. Adsorption-desorption is a complex dynamic equilibrium process characterized by the PFCs reaching a stable distribution state on the adsorbent surface and in the solution. At this point, no matter how long the adsorption time is increased, the recovery rate will not significantly improve. Therefore, to ensure effective adsorption while improving efficiency and avoid the waste of resources and reduced efficiency caused by excessively long adsorption times, 5 minutes was selected as the optimal adsorption time for the PP5-1F-MNP material for further optimization.

[0123] Type of desorption solvent: Different solvents have different desorption capacities for PFCs. In order to improve the adsorption efficiency of PP5-1F-MNP on PFCs, it is particularly important to select a suitable desorption solvent. Based on the above optimized conditions, six desorption solvents with different polarities were selected for optimization. The six desorption solvents are n-hexane, dichloromethane, ethyl acetate, acetone, methanol and acetonitrile. The results are shown in Figure 2. Figure 13 As shown, n-hexane had little elution effect on the eight PFCs, with recoveries of less than 10%. The other five organic solvents of varying polarity also exhibited varying elution effects on PFCs. Acetonitrile, when used as the desorption solvent, achieved the highest recovery of all eight PFCs. This is likely due to acetonitrile's strong elution capacity and polarity, which effectively interacted with the PFCs, disrupting the electrostatic forces between the adsorbent and the PFCs, thereby enabling desorption. Therefore, acetonitrile was selected as the optimal desorption solvent for subsequent investigations.

[0124] Desorption liquid volume: The desorption process is a kinetic process, and changes in the desorption liquid volume will affect the desorption rate. A larger desorption liquid volume may accelerate the desorption rate because it can take the desorbed PFCs away from the PP5-1F-MNP adsorbent surface faster, thereby reducing the possibility of re-adsorption of the desorbed PFCs. However, in order to ensure that the extraction recovery rate is maximized while avoiding unnecessary solvent waste, the amount of desorption liquid is optimized. According to the adsorption-desorption experiment in 1, based on the above optimal conditions, 3mL, 5mL, 7mL, 9mL, 11mL, and 13mL of chromatographic grade acetonitrile were added during elution. The results are shown in Figure 2. Figure 14 As shown in the figure, the adsorption effect of PFCs is relatively good when the desorption liquid volume is 7 mL. Among them, PFOA, PFOS, PFUnDA and PFDoDA have the highest adsorption recovery rate when the desorption liquid volume is 7 mL, and the other compounds do not change much, so 7 mL is selected as the optimal desorption liquid volume.

[0125] Desorption time: Desorption time is also one of the important factors affecting adsorption efficiency. It is necessary to optimize the desorption time according to the specific adsorption system and target to achieve the best adsorption efficiency. According to the adsorption-desorption experiment in 1, on the basis of the above optimal conditions, vortex elution was performed for 3 minutes, 5 minutes, 8 minutes, 10 minutes, 12 minutes and 15 minutes respectively. The results are as follows Figure 15 As shown in the figure, for most PFCs, the adsorption efficiency slightly increases with increasing desorption time when the vortex elution time is 3-8 minutes, and the adsorption efficiency is highest at 8 minutes. At 10-15 minutes, the adsorption efficiency of PFCs decreases with increasing desorption time. This may be because when the PFC concentration decreases or when other competing adsorbates are present, the adsorbed molecules may desorb from the adsorbent, resulting in a decrease in adsorption capacity. Therefore, 8 minutes is selected as the optimal desorption time.

[0126] In summary, the optimal conditions for using PP5-1F-MNP as a magnetic solid-phase extraction adsorbent are: 15 mg of PP5-1F-MNP adsorbent, 5 minutes of adsorption time, 7 mL of acetonitrile as the desorption solution, and 8 minutes of desorption time. After optimizing the adsorption-desorption conditions, efficient extraction of eight long-chain PFCs was achieved, yielding significant results.

[0127] 3. Adsorption isotherm experiment

[0128] To fully understand the adsorption characteristics of PP5-1F-MNPs for PFCs, reveal the interaction mechanism between PP5-1F-MNPs and PFCs, and accurately evaluate their adsorption capacity for PFCs, three PFCs were selected as research objects for adsorption isotherm experiments: PFOA, PFOS, and PFUnDA. PFOS and PFOA, as the main representatives of PFCs, are widely present in the environment. Currently, the Stockholm Convention and its related compounds have been included in the list of controlled substances to restrict their global use. PFUnDA, as a representative of long-chain PFCs, is difficult to degrade due to its stability and environmental persistence, and is widely present in environmental media. Exploring the adsorption behavior of PP5-1F-MNPs for PFOS, PFOA, and PFUnDA is of great significance for PFCs enriched in the environment.

[0129] Adsorption isotherm experiment: 10 mL of the above three PFCs mixed standard solutions diluted with ultrapure water at different concentrations were added to 15 mg of PP5-1F-MNP adsorbent material (the preparation process refers to the other PFCs mixed standard solutions mentioned above). The concentrations were: 100 ng / mL, 200 ng / mL, 500 ng / mL, 1 μg / mL, 2 μg / mL, 5 μg / mL, 10 μg / mL, 20 μg / mL, 50 μg / mL, 75 μg / mL, 100 μg / mL, 150 μg / mL, 200 μg / mL. The mixture was vortexed on a vortex mixer for 8 minutes, and an external magnet was used to separate the solution and the material. 1 mL of the upper solution was taken out and centrifuged. 90 μL of the supernatant was taken and 10 μL of 500 ng / mL was added. 13 C-PFOA and 13 The C-PFOS internal standard mixture was thoroughly mixed by vortex mixing and then detected by mass spectrometry. Each variable was repeated three times.

[0130] The adsorption capacity of PFCs is calculated as follows:

[0131]

[0132] Among them, Q e (mg / g) is the equilibrium adsorption capacity; C0 (μg / mL) is the initial concentration of PFCs; C e (μg / mL) is the equilibrium concentration of PFCs (obtained by mass spectrometry after adsorption equilibrium); V (mL) is the volume of PFCs solution; W (mg) is the mass of PP5-1F-MNP.

[0133] The results are as follows Figure 16 As shown in the figure, with the gradual increase of the initial concentration of a series of standard solutions, the adsorption capacity of PP5-1F-MNP for PFOA, PFOS, and PFUnDA also showed a corresponding increasing trend, which indicates that the surface active sites of PP5-1F-MNP can still effectively interact with these difficult-to-degrade PFCs under high concentration conditions, thereby enriching and removing them from the solution.

[0134] To further reveal the adsorption mechanism of the three PFCs by the PP5-1F-MNP adsorbent material, the Langmuir and Freundlich adsorption isotherm models were used to fit and analyze the experimental data. The Langmuir adsorption isotherm equation assumes that the solid surface of the adsorbent is uniform, the adsorption capacity of all adsorption sites is the same, there is no interaction between the adsorbed molecules, and it belongs to a monolayer adsorption effect. Adsorption and desorption are two reversible processes that maintain a dynamic equilibrium. The Freundlich adsorption isotherm equation assumes that there is a phenomenon of non-uniform adsorption on the adsorbent surface, that is, the adsorption capacity of the surface adsorption sites is different. Multilayer adsorption means that the adsorbed molecules can continue to adsorb on already adsorbed molecules.

[0135] Langmuir adsorption isotherm equation:

[0136]

[0137] Among them, Q e (mg / g) is the equilibrium adsorption capacity; C e (μg / mL) is the equilibrium concentration of PFCs; Q m (mg / g) is the maximum adsorption capacity of PFCs; K L is the Langmuir adsorption constant.

[0138] Freundlich adsorption isotherm equation:

[0139]

[0140] Among them, Q e (mg / g) is the equilibrium adsorption capacity; K F is the Freundlich adsorption constant; is the heterogeneity constant.

[0141] Table 3 Fitting results of Langmuir equation and Freundlich equation

[0142]

[0143] Comparing the fitting results of the Langmuir and Freundlich adsorption isotherms (Table 3) reveals that the Langmuir model fitting correlation coefficients for PFOA, PFOS, and PFUnDA are 0.9955, 0.9976, and 0.9769, respectively. The Freundlich model fitting correlation coefficients are 0.9416, 0.9450, and 0.8073, respectively. The Langmuir model demonstrates greater accuracy in describing the adsorption behavior of PFCs onto PP5-1F-MNPs. The model shows that the adsorption process of PFCs on PP5-1F-MNP is mainly monolayer adsorption, which means that the adsorption sites on the adsorbent surface are evenly distributed, and each adsorption site can only adsorb one PFCs molecule, forming a dense monolayer adsorption layer. The maximum adsorption capacity can be calculated by the adsorption isotherm equation. The maximum adsorption capacities for perfluorooctanoic acid (PFOA), perfluorosulfonic acid (PFOS) and perfluoroundecanoic acid (PFUnDA) are 42.02, 62.11 and 64.94 mg / g, respectively.

[0144] 4. Methodological Validation

[0145] Preparation of mixed standard solutions of 8 PFCs: Take 50 μL of 1 mg / mL standard stock solutions of PFOA, PFOS, PFNA, PFDA, PFUnDA, PFDoDA, PFTrDA and PFTeDA respectively, mix them, add 600 μL of acetonitrile to dilute them into 50 μg / mL mixed standard solution, and then dilute the 50 μg / mL mixed standard solution with acetonitrile to 0.1 ng / mL mixed standard solution.

[0146] 1) System applicability

[0147] Take 90 μL of the evenly mixed 0.1 ng / mL mixed standard solution, add 10 μL of the 10 ng / mL internal standard mixed solution, mix evenly, and take 70 μL into the injection bottle. According to the chromatographic conditions in this example, the chromatogram of the standard is detected on a high performance liquid chromatography-mass spectrometer to obtain.

[0148] Figure 17 The chromatograms for a mixed solution of eight PFC standards and two isotopic internal standards are shown. Under the optimized chromatographic conditions, the eight PFCs eluted sequentially within 10 minutes, exhibiting sharp, tail-free peaks. This indicates no matrix effects during the analysis, and strong response signals were obtained, demonstrating the method's high efficiency and excellent separation performance.

[0149] Take 90 μL of the above 0.1 ng / mL mixed standard solution, add 10 μL of the 10 ng / mL internal standard mixed solution, mix well, and take 70 μL into the injection bottle. According to the mass spectrometry conditions in this example, a full scan mass spectrum is obtained by Q3 full scan detection on a high performance liquid chromatography-mass spectrometer.

[0150] Figure 18 This is a full scan of eight PFCs and two isotopic internal standards in negative ion mode. Because PFCs contain carboxyl or sulfonic acid functional groups, they are more susceptible to deprotonation, forming [MH]- molecular ion peaks. The [MH]- ions for the eight compounds can be seen in the figure.

[0151] 2) Linearity, limit of quantification, and limit of detection

[0152] The performance of the PP5-1F-MNP MSPE-HPLC-MS / MS analysis method was comprehensively evaluated under optimized magnetic solid phase extraction conditions. The linear range, intra-day and inter-day precision, and correlation coefficient (R 2 ), limit of detection (LOD, S / N ≥ 3) and limit of quantification (LOQ, S / N ≥ 10) to comprehensively evaluate the accuracy, reliability and sensitivity of the method. The specific operation process is as follows:

[0153] Eight PFC standard mixed solutions were precisely measured and diluted with HPLC-grade acetonitrile to concentrations of 0.01 ng / mL, 0.02 ng / mL, 0.05 ng / mL, 0.1 ng / mL, 0.2 ng / mL, 0.5 ng / mL, 1 ng / mL, 2 ng / mL, 5 ng / mL, 10 ng / mL, 20 ng / mL, 50 ng / mL, and 100 ng / mL. The solutions were centrifuged for 3 minutes. 90 μL of the supernatant was added to 10 μL of a 10 ng / mL internal standard mixed solution, vortexed, and centrifuged for 3 minutes. 70 μL of the centrifuged solution was transferred to a sample injection vial. Separately, two blank variables were prepared with HPLC-grade acetonitrile: a single blank (acetonitrile with internal standard mixed solution) and a double blank (pure acetonitrile without either analyte or internal standard). HPLC-MS / MS was performed with a 5 μL injection volume, and each variable was measured in triplicate.

[0154] A weighted linear regression was performed with the concentration of each compound (ng / mL) in the series of mixed standard solutions as the abscissa (X) and the ratio of the peak area of each compound to the corresponding internal standard peak area as the ordinate (Y). The signal-to-noise ratio S / N ≥ 3 was defined as the limit of detection (LOD), and S / N ≥ 10 was defined as the limit of quantification (LOQ). The RSD was calculated using the peak area ratios measured three times. The results are shown in Table 4. Within the linear range, there was a significant linear correlation between the peak area ratios of the eight long-chain PFCs and their concentrations, and the correlation coefficient R2 The LOD ranged from 1.0 to 2.8 ng / L, the LOQ ranged from 2.0 to 10.0 ng / L, and the RSD ranged from 1.7 to 6.3%. The experimental results showed that this method not only had high sensitivity but also had good linearity.

[0155] Table 4

[0156]

[0157] Example 3: Detection of PFCs in actual water samples

[0158] This experiment collected natural water samples from Nanhu Lake, Tangxun Lake, and Donghu Lake in Wuhan, Hubei Province, as well as rainwater from Wuhan itself. The collected water samples were stored in containers rinsed with deionized water to ensure sample purity. The samples were then filtered through a 0.22μm filter membrane to remove suspended particles and other impurities. Water samples not immediately used were stored in a refrigerator at 4°C, protected from light, to prevent possible contamination or deterioration.

[0159] PP5-1F-MNP was used as a magnetic solid phase extraction adsorbent to enrich PFCs in actual samples. First, 15 mg of PP5-1F-MNP material was accurately weighed, 10 mL of water sample was added thereto, and the material was vortexed on a vortex mixer for 5 minutes to allow the material to fully contact the environmental water sample. Then, the material was separated from the solution under the action of a magnet, and 5 mL of pure water was added to wash away the residual and unadsorbed PFCs on the surface of the material. Then, 7 mL of chromatographic grade acetonitrile was added and vortexed for 8 minutes to desorb the PFCs adsorbed on the material. Under the action of an external magnet, 4 mL of the supernatant was taken for nitrogen blowing, and finally, it was redissolved with 200 μL of acetonitrile solution, and 90 μL of the redissolved solution was taken. 10 μL of 10 ng / mL was added thereto. 13 C-PFOA and 13 The internal standard mixture of C-PFOS was vortex-mixed and then detected according to the chromatography and mass spectrometry conditions in Example 2, with each variable measured in triplicate.

[0160] The experiment showed that no PFCs were detected in actual environmental water samples, which is consistent with the detection results of traditional biomass fluorinated material-assisted liquid chromatography-tandem mass spectrometry method and covalent organic framework material-assisted liquid chromatography-tandem mass spectrometry method.

[0161] The accuracy test was conducted using water samples from Lake Thomson. The specific steps are as follows:

[0162] First, dilute the 1 mg / L mixed standard solution (directly use the solution under the accuracy test item in Example 2) with the above-mentioned treated Thompson Lake water sample, and prepare three different concentration levels of test solutions: low (20 ng / L), medium (200 ng / L) and high (2000 ng / L). Take 10 mL of the test solution and add it to 15 mg of the PP5-1F-MNP material obtained in Example 1. Vortex on a vortex mixer for 5 minutes to allow the material to fully contact the environmental water sample, and then separate the material from the solution under the action of a magnet, and add 5 mL of pure water to wash away the residual and unabsorbed PFCs on the surface of the material. Then add 7 mL of chromatographic grade acetonitrile and vortex for 8 minutes to desorb the PFCs adsorbed on the material. Under the action of an external magnet, take 4 mL of the supernatant and blow it to dryness with nitrogen, and then redissolve it with 200 μL of acetonitrile. Take 90 μL of the redissolved solution and add 10 μL of a 10 ng / mL concentration to it. 13 C-PFOA and 13 The internal standard mixed solution of C-PFOS was vortex-mixed and then tested according to the chromatography and mass spectrometry conditions in Example 2. Each concentration was measured in parallel three times. The test results are shown in Table 5, where the RSD was calculated from the peak area ratio of the three measurements.

[0163] After spiking, the average recoveries of low, medium, and high concentrations ranged from 84.8% to 104.7%, with RSDs ranging from 0.61% to 13.1%. The established PP5-1F-MNP MSPE-HPLC-MS / MS method based on PP5-1F-MNP as a highly efficient adsorbent material exhibited good precision and stability, indicating that the PP5-1F-MNP material has the potential to be used in the enrichment and analysis of PFCs in actual environmental water samples.

[0164] Table 5

[0165]

Claims

1. A magnetic cationic column [5] aromatic hydrocarbon polymer material PP5-1F-MNP, wherein the PP5-1F-MNP has Fe3O4 nanoparticles as the core and the cationic column [5] aromatic hydrocarbon polymer PP5-1F is coated on the outside of the Fe3O4 nanoparticles. The structural formula of the PP5-1F is as follows: The preparation method of the PP5-1F-MNP comprises the following steps: (1) Preparation of 1,4-bis(2-bromoethoxy)benzene In an ice-water bath at 0°C, hydroquinone dihydroxyethyl ether and triphenylphosphine are added to anhydrous acetonitrile, followed by the slow addition of carbon tetrabromide under inert gas protection. The reaction system is then returned to room temperature and stirred at room temperature until the solution becomes clear and transparent. Cold water is then added to quench the reaction, and the product is purified and dried to obtain 1,4-bis(2-bromoethoxy)benzene. (2) Preparation of brominated functional group column [5] aromatic hydrocarbons Paraformaldehyde is added to a solution of 1,4-bis(2-bromoethoxy)benzene, followed by addition of boron trifluoride etherate, and stirred at room temperature for 4-8 hours. After the reaction is completed, the reaction is quenched with cold water, and the product is purified and dried to obtain brominated functional group column [5] aromatic hydrocarbons; (3)PP5-1F Add the brominated functional group column [5] aromatic hydrocarbon to 3-fluoropyridine, and heat the reaction mixture under reflux and stir for 8-12 hours. After the reaction is completed, a yellow solid is obtained, which is purified and dried to obtain PP5-1F; (4)PP5-1F-MNP PP5-1F was added to ethylene glycol and dissolved by ultrasonication. Then FeCl3·6H2O and sodium acetate were added. After ultrasonic dispersion, the mixture was stirred evenly at room temperature. Then the mixture was transferred to a reactor and reacted at 100-250℃ for 8-12h. The mixture was washed and dried to obtain black magnetic column [5] aromatic polymer PP5-1F-MNP.

2. The magnetic cationic column [5] aromatic polymer material PP5-1F-MNP according to claim 1, characterized in that In the step (4), anhydrous ethanol and deionized water are used for alternate washing, and the drying step is performed by vacuum drying at 40° C. for 24 h.

3. The magnetic cationic column [5] aromatic polymer material PP5-1F-MNP according to claim 1, characterized in that In step (1), the molar ratio of hydroquinone dihydroxyethyl ether to triphenylphosphine is 1:(2-3), and the molar ratio of triphenylphosphine to carbon tetrabromide is 1:1; and / or In step (2), the molar ratio of 1,4-bis(2-bromoethoxy)benzene, paraformaldehyde and boron trifluoride etherate is 1:(0.5-3):(0.5-1.5); and / or In step (3), the ratio of column [5] aromatic hydrocarbon to 3-fluoropyridine is 0.3-1.2 mmol: 5-10 mL; and / or In step (4), the ratio of PP5-1F to ethylene glycol is 0.5-2 g: 10-30 mL; and / or In step (4), the molar ratio of PP5-1F to FeCl3·6H2O and sodium acetate is (0.05-0.5):1:(2-8).

4. Use of the PP5-1F-MNP according to any one of claims 1 to 3 for adsorption of perfluorinated compounds contained in natural water bodies, wherein the natural water body is lake water or rainwater.

5. A method for detecting PFCs content based on magnetic solid phase extraction-high performance liquid chromatography tandem mass spectrometry of PP5-1F-MNP according to any one of claims 1 to 3: (1) Chromatographic conditions Chromatographic column: C18 column; Mobile phase A: 5 mmol / L ammonium acetate aqueous solution, mobile phase B: acetonitrile; Flow rate: 0.4 mL / min; Column temperature: 40°C; Gradient elution conditions: (2) Mass spectrometry conditions An electrospray ionization source was used in negative ion mode, and multiple reaction monitoring (MRM) was established to analyze each PFC. The nebulizer gas flow rate was 3 L / min, the heating gas flow rate was 10 L / min, the drying gas flow rate was 10 L / min, the interface temperature was 300°C, the DL temperature was 250°C, the heating block temperature was 400°C, and the dwell time for each MRM was 12 ms. (3) Magnetic solid phase extraction step After mixing PP5-1F-MNP with the PFCs sample solution to be tested, the mixture was vortexed for 2-15 minutes in a vortex mixer to ensure that the PP5-1F-MNP adsorbent fully and selectively adsorbed the PFCs. An external magnet was used to quickly and effectively separate the PP5-1F-MNP adsorbent from the solution. The PP5-1F-MNP was washed with pure water to remove PFCs not adsorbed on the surface. A desorption solution was added and vortexed for 3-15 minutes to desorb the PFCs adsorbed by the PP5-1F-MNP. After separating the PP5-1F-MNP from the solution, a certain amount of the solution was taken and concentrated to dryness. The desorption solution was then added to redissolve the PFCs. The re-dissolved solution was then used for HPLC-MS / MS detection.

6. The method according to claim 5, characterized in that The desorption liquid is dichloromethane, ethyl acetate, acetone, methanol or acetonitrile; and / or The ratio of the PP5-1F-MNP adsorbent to the desorption liquid is (5-20) mg: (3-13) mL; and / or When the reconstituted solution was subjected to HPLC-MS / MS detection, the content of PFCs was detected using the internal standard method. 13 C8-PFOA and 13 C8-PFOS was used as an internal standard.

7. The method according to claim 5, characterized in that The PFCs are long-chain PFCs with a carbon chain of not less than 8.

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