Method for rapid screening and targeted quantification of PFAS in water body and application thereof

Abstract

The invention provides a method for rapid screening and targeted quantification of PFAS in a water body and application thereof, and belongs to the technical field of analytical chemistry. According to the method provided by the invention, continuous analysis of screening and quantitative detection of PFAS in the water body can be realized, comprehensive PFAS screening and quantitative analysis can be realized by using one-time SPE sample pretreatment on the premise of ensuring the analysis sensitivity and accuracy, separation and purification, qualitative identification and quantitative detection of perfluorinated compounds in the sample become a continuous process, and the method is simple and convenient to operate. The analysis efficiency of screening and quantitative detection is greatly improved. According to the method, 44 perfluorinated compounds are identified in a water body by combining targeted and suspected screening with a non-targeted screening technology.

Description

Technical Field

[0001] The present invention relates to the technical field of analytical chemistry, and in particular to a method for rapid screening and targeted quantification of PFAS in water and an application thereof. Background Art

[0002] Perfluoroalkyl and polyfluoroalkyl substances (PFAS) have high surface activity and high stability, and are widely used in metal electroplating, electronic products, paints, medical equipment, aircraft hydraulic fluids, carpets, waterproof and stain-resistant fabrics, non-stick cookware, cleaning products, aqueous film-forming foams, food contact paper and cosmetics. However, PFAS is a persistent and bioaccumulative environmental pollutant. At the same time, the types of PFAS are constantly updated, and there is an urgent need for improved methods to clarify the water storage characteristics of these pollutants.

[0003] With the development of mass spectrometry technology, researchers have developed a variety of methods to analyze the structure of compounds through mass spectra, such as using deep neural networks to predict compound fingerprints to assist in identifying compound structures. However, there are two main problems in monitoring PFAS in water bodies: first, there are many types of PFAS and a lack of standard substances. High-resolution mass spectrometry screening and identification research is still in its early stages, and the existing screening results are insufficient or not included in environmental supervision; second, although the targeted method of the tandem quadrupole mass spectrometer can sensitively detect PFAS compounds with standard substances, the coverage of PFAS diversity is limited. Therefore, in order to effectively monitor PFAS in water bodies, firstly, the categories and distribution of the main PFAS in water samples should be clarified by high-resolution mass spectrometry, and then precise quantification should be performed to improve the detection of PFAS in water bodies. However, at present, due to the differences in sample pretreatment methods and instrumental analysis methods, the existing water PFAS monitoring methods are mostly concentrated at the screening and identification or target quantification level, and comprehensive monitoring combining screening and targeting has not yet been achieved.

[0004] Therefore, there is an urgent need to provide a method for rapid, sensitive screening and accurate quantitative detection of PFAS pollutants in water. Summary of the invention

[0005] The purpose of the present invention is to provide a method for rapid screening and targeted quantification of PFAS in water and its application. The method provided by the present invention can rapidly, sensitively, screen and accurately quantify PFAS pollutants in water.

[0006] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0007] The present invention provides a method for rapid screening and targeted quantification of PFAS in water, comprising the following steps:

[0008] (1) Analyzing the PFAS standard solution using ultra-high performance liquid chromatography-quadrupole-electrostatic field orbital trap high-resolution mass spectrometry, optimizing the mass spectrometry conditions and chromatographic conditions of the ultra-high performance liquid chromatography-quadrupole-electrostatic field orbital trap high-resolution mass spectrometry, and obtaining a self-built high-resolution PFAS secondary screening mass spectrometry database; the self-built high-resolution PFAS secondary screening mass spectrometry database includes accurate charge-to-mass ratio, retention time, isotope ion peaks and fragment ions;

[0009] (2) Pre-treating the water sample to obtain a solution to be tested; the pre-treatment method is solid phase extraction, and the extraction column of the solid phase extraction is a WAX column.

[0010] (3) Analyzing the test solution obtained in step (2) by ultra-high performance liquid chromatography-quadrupole-electrostatic field orbital trap high-resolution mass spectrometry to obtain mass spectrum data of the test solution, and performing targeted screening on the mass spectrum data of the test solution according to the self-built high-resolution PFAS secondary screening mass spectrum database obtained in step (1) to obtain targeted screening results; screening the mass spectrum data of the test solution according to the accurate charge-to-mass ratio, isotope ion peaks and fragment ions of the PFAS mass spectrum database to obtain suspected screening results; performing characteristic peak screening and identification on the mass spectrum data of the test solution according to the carbon-fluorine mass ratio characteristics of PFAS to obtain non-targeted screening results;

[0011] (4) performing quantitative analysis on the solution to be tested, including: analyzing the PFAS standard solution obtained in step (1) using liquid chromatography-tandem quadrupole mass spectrometry to obtain an MRM quantitative parameter optimization result; and then analyzing the solution to be tested using liquid chromatography-tandem quadrupole mass spectrometry based on the MRM quantitative parameter optimization result to obtain a quantitative analysis result of the solution to be tested;

[0012] The pre-treatment conditions of the solution to be tested in step (3) and step (4) are the same.

[0013] Preferably, the self-built high-resolution PFAS secondary screening mass spectrometry database in step (1) contains 26 perfluorinated compounds, and the 26 perfluorinated compounds are: perfluorobutane carboxylic acid, perfluoropentane carboxylic acid, perfluorobutane sulfonic acid, perfluorohexane carboxylic acid, perfluoropentane sulfonic acid, perfluorobutane sulfonamide, 2,3,3,3-trifluoro-2-(1,1,2,2,3,3-trifluoropropane)-propane acid perfluoro(2-methyl-3-oxahexanoic acid), perfluoroheptane carboxylic acid, 4 .8-dioxa-3H-perfluorononanoic acid, perfluorohexane sulfonic acid, perfluorooctane carboxylic acid, perfluoroheptane sulfonic acid, 6:2 fluorotelomer sulfonic acid, perfluorononane carboxylic acid, perfluorooctane sulfonic acid, 6:2 chlorinated polyfluoroalkyl ether sulfonate, perfluorononane sulfonic acid, perfluorodecane carboxylic acid, perfluoroundecane carboxylic acid, perfluorodecane sulfonic acid, 8:2 chloropolyfluoroalkyl ether sulfonate, perfluorododecane carboxylic acid, perfluorotridecane carboxylic acid, perfluorotetradecane carboxylic acid, perfluorohexadecane carboxylic acid and perfluorooctadecane carboxylic acid.

[0014] Preferably, the mass spectrometry conditions in step (1) include: collision energy of 10-46 eV; automatic gain control target of 1e6; maximum ion injection time of 100 ms; injection scan cycle number of 20; and mass-to-charge ratio isolation window of 1.5 m / z.

[0015] Preferably, the chromatographic conditions in step (1) include: a chromatographic column of X-Bridge TMBEH C18; and 0.2 mM ammonium formate-water solution and methanol as chromatographic mobile phases.

[0016] Preferably, the targeted screening conditions in step (3) include: the mass deviation range of the accurate charge-to-mass ratio (m / z) is ±0.001Da; the retention time (RT) window threshold is 20sec; the fitting threshold of the isotope ion distribution signal matching is 75%, and the mass deviation range is ±0.002Da; the intensity deviation of the mass spectrometry signal is 25%.

[0017] Preferably, the PFAS mass spectrum database in step (3) comprises one or more of: a database of 34 perfluorinated substances in NIST, a database of 61 PFAS screening in MoNA, a database of 57 perfluorinated substances in MzCloud, and a database of 48,646 fluorinated substances in Duke specLibrary.

[0018] Preferably, the method for performing characteristic peak screening on the mass spectral data of the test solution according to the carbon-fluorine mass ratio characteristics of PFAS in step (3) includes: after extracting the characteristic peaks from the mass spectral data of the test solution, performing PFAS priority screening based on Python code, filtering the carbon mass defect-carbon mass ratio in the range of -0.5 to 0.5; the Kendrick mass defect (KMD) homologous sequences are CF2 and CF2O, and the screening range is 0 to 0.15; the mass deviation range is ±0.002Da to analyze potential PFAS characteristics, and screen perfluorinated compounds with confidence levels 2b to 3b.

[0019] Preferably, the method for performing characteristic peak screening on the mass spectral data of the test solution according to the carbon-fluorine mass ratio characteristics of PFAS in step (3) includes: after extracting the characteristic peaks from the mass spectral data of the test solution, performing PFAS priority screening based on Python code, filtering the carbon mass defect-carbon mass ratio in the range of -0.5 to 0.5; the Kendrick mass defect (KMD) homologous sequences are CF2 and CF2O, and the screening range is 0.85 to 1; the mass deviation range is ±0.002Da to analyze potential PFAS characteristics, and screen perfluorinated compounds with confidence levels 2b to 3b.

[0020] Preferably, in step (3), the identification of characteristic peak screening of the mass spectrum data of the test solution according to the carbon-fluorine mass ratio characteristics of PFAS includes: after extracting characteristic peaks and PFAS priority screening from the mass spectrum data of the test solution, using Compound Discoverer 3.3 software to predict the PFAS molecular formula, and presetting the element formula as C 1-20 , H 0-20 , F 2-40 , O 2-6 , N 0-4 , P 0-2 , S 0-2 , Cl 0-2 and I 0-2 ; The ring and double bond equivalence (RDBE) range is set to 1.5 to 10.5.

[0021] The present invention also provides the application of the method for rapid screening and targeted quantification of PFAS in water bodies described in the above technical scheme to the detection of PFAS in wastewater, wherein the wastewater includes one or more of lakes, reservoirs, rivers and factory water.

[0022] The invention provides a method for rapid screening and targeted quantification of PFAS in water. The invention uses ultra-high performance liquid chromatography-quadrupole-electrostatic field orbital trap high-resolution mass spectrometry (UPLC-Q-Orbitrap) to perform high-resolution mass non-targeted spectral screening and identification on a PFAS standard solution to obtain a high-resolution PFAS secondary screening mass spectrometry database (FullMS / ddMS2); performs targeted screening on the mass spectrometry data of the solution to be tested according to the obtained self-built high-resolution PFAS secondary screening mass spectrometry database to obtain a targeted screening result; screens the mass spectrometry data of the solution to be tested according to the accurate charge-to-mass ratio, isotope ion peaks and fragment ions of the PFAS mass spectrometry database to obtain a suspected screening result; performs characteristic peak screening and identification on the mass spectrometry data of the solution to be tested according to the carbon-fluorine mass ratio characteristics of PFAS to obtain a non-targeted screening result; and finally establishes a quantitative analysis method for the solution to be tested, comprising: analyzing the PFAS standard solution by using liquid chromatography-tandem quadrupole mass spectrometry (UPLC-MS / MS) to obtain an MRM quantitative parameter optimization result.

[0023] The method provided by the present invention is a continuous analysis of non-targeted screening of PFAS in water samples by ultra-high performance liquid chromatography-quadrupole-electrostatic field orbital trap high-resolution mass spectrometry and UPLC-MS / MS quantitative analysis. Under the premise of ensuring analytical sensitivity and accuracy, comprehensive screening of PFAS in water samples and characteristic PFAS quantification can be completed using a single SPE sample pretreatment, so that the separation, qualitative and quantitative analysis of perfluorinated compounds in samples become a continuous process, greatly improving the analytical efficiency of screening and quantitative detection.

[0024] The method of the present invention can identify n:2 hydroxy fluorocarbon chain terminal sulfonic acid (OH-n:2FTSAs, n=4), n:3 fluorocarbon chain butyrate (n:3FTBs, n=2,3), n:1:2 fluorocarbon chain butyrate (n:1:2FTBs, n=2,3), unsaturated polyfluoroalkyl acid (UPFAs, n=4) in source water and factory water. The present invention uses suspected screening combined with non-targeted screening technology to identify 27 new perfluorinated compounds without standard comparison. The perfluorinated compounds with a quantitative detection rate of PFAS greater than 50% are PFBA, PFPeA, PFBS, PFHxA, FBSA, GenX, PFHpA, PFOA, PFHpS, FTSA (6 / 2), PFNA, PFOS, F53B (6 / 2), PFDA, and PFUdA. Among them, the highest median was PFOA (5.43ng / L) and the maximum was FTSA (6 / 2) (147.07ng / L). BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1This is the total ion current (TIC) diagram of 26 PFAS mixed standard solutions analyzed by UPLC-Q-Orbitrap in the present invention;

[0026] Figure 2 The high-resolution mass spectrometry screening process and results of PFAS in water bodies according to an embodiment of the present invention;

[0027] Figure 3 This is the identification result of targeted screening of PFAS in water using a self-built high-resolution PFAS secondary screening mass spectrometry database in an embodiment of the present invention;

[0028] Figure 4 The identification results of screening PFAS in water using the PFAS screening mass spectrometry database in an embodiment of the present invention;

[0029] Figure 5 This is a diagram of the quantitative detection results of PFAS in water samples in a specific embodiment of the present invention. DETAILED DESCRIPTION

[0030] The present invention provides a method for rapid screening and targeted quantification of PFAS in water, comprising the following steps:

[0031] (1) Analyzing the PFAS standard solution using ultra-high performance liquid chromatography-quadrupole-electrostatic field orbital trap high-resolution mass spectrometry, optimizing the mass spectrometry conditions and chromatographic conditions of the ultra-high performance liquid chromatography-quadrupole-electrostatic field orbital trap high-resolution mass spectrometry, and obtaining a self-built high-resolution PFAS secondary screening mass spectrometry database; the self-built high-resolution PFAS secondary screening mass spectrometry database includes accurate charge-to-mass ratio, retention time, isotope ion peaks and fragment ions;

[0032] (2) Pre-treating the water sample to obtain a solution to be tested; the pre-treatment method is solid phase extraction, and the extraction column of the solid phase extraction is a WAX column.

[0033] (3) Analyzing the test solution obtained in step (2) by ultra-high performance liquid chromatography-quadrupole-electrostatic field orbital trap high-resolution mass spectrometry to obtain mass spectrum data of the test solution, and performing targeted screening on the mass spectrum data of the test solution according to the self-built high-resolution PFAS secondary screening mass spectrum database obtained in step (1) to obtain targeted screening results; screening the mass spectrum data of the test solution according to the accurate charge-to-mass ratio, isotope ion peaks and fragment ions of the PFAS mass spectrum database to obtain suspected screening results; performing characteristic peak screening and identification on the mass spectrum data of the test solution according to the carbon-fluorine mass ratio characteristics of PFAS to obtain non-targeted screening results;

[0034] (4) performing quantitative analysis on the solution to be tested, including: analyzing the PFAS standard solution obtained in step (1) using liquid chromatography-tandem quadrupole mass spectrometry to obtain an MRM quantitative parameter optimization result; and then analyzing the solution to be tested using liquid chromatography-tandem quadrupole mass spectrometry based on the MRM quantitative parameter optimization result to obtain a quantitative analysis result of the solution to be tested;

[0035] The pre-treatment conditions of the solution to be tested in step (3) and step (4) are the same.

[0036] The present invention uses UPLC-Q-Orbitrap to analyze PFAS standard solutions, optimizes the mass spectrometry conditions and chromatographic conditions of the UPLC-Q-Orbitrap, and obtains a self-built high-resolution PFAS secondary screening mass spectrometry database. In the present invention, the self-built high-resolution PFAS secondary screening mass spectrometry database includes accurate charge-to-mass ratio, retention time, isotope ion peaks and fragment ions.

[0037] In the present invention, the self-built high-resolution PFAS secondary screening mass spectrometry database preferably includes 26 perfluorinated compounds, and the 26 perfluorinated compounds preferably include perfluorobutane carboxylic acid, perfluoropentane carboxylic acid, perfluorobutane sulfonic acid, perfluorohexane carboxylic acid, perfluoropentane sulfonic acid, perfluorobutane sulfonamide, 2,3,3,3-trifluoro-2-(1,1,2,2,3,3-trifluoropropane)-propane acid perfluoro(2-methyl-3-oxahexanoic acid), perfluoroheptane carboxylic acid, 4 .8-dioxa-3H-perfluorononanoic acid, perfluorohexane sulfonic acid, perfluorooctane carboxylic acid, perfluoroheptane sulfonic acid, 6:2 fluorotelomer sulfonic acid, perfluorononane carboxylic acid, perfluorooctane sulfonic acid, 6:2 chlorinated polyfluoroalkyl ether sulfonate, perfluorononane sulfonic acid, perfluorodecane carboxylic acid, perfluoroundecane carboxylic acid, perfluorodecane sulfonic acid, 8:2 chlorinated polyfluoroalkyl ether sulfonate, perfluorododecane carboxylic acid, perfluorotridecane carboxylic acid, perfluorotetradecane carboxylic acid, perfluorohexadecane carboxylic acid and perfluorooctadecane carboxylic acid. The present invention adopts the above-mentioned standard substances to construct a rich PFAS database.

[0038] The present invention has no special limitation on the concentration and preparation method of the PFAS standard solution, and the standard solution can be prepared by a conventional method. In an embodiment of the present invention, the concentration of the PFAS standard solution can be: 0.1 μg / L, 0.2 μg / L, 1 μg / L, 5 μg / L, 10 μg / L, 20 μg / L and 100 μg / L, and the concentration of the internal standard in the standard solution can be 5 μg / L.

[0039] In an embodiment of the present invention, the internal standard in the standard solution is preferably a mixed internal standard, and the mixed internal standard is 13C4-PFBA, 13C5-PFPeA, 13C5-PFHxA, 13C4-PFHpA, 13C8-PFOA, 13C9-PFNA, 13C6-PFDA, 13C7-PFUdA, 13C2-PFDoA, 13C2-PFTeDA, 13C3-PFBS, 13C3-PFHxS and 13C8-PFOS.

[0040] In the present invention, the device used for UPLC-Q-Orbitrap time-sharing is preferably Thermo Fisher QExactive TM Combined quadrupole Orbitrap TM For mass spectrometer, data acquisition and processing preferably use TraceFinder5.1 and CompoundDiscover3.3 software.

[0041] The method for optimizing the mass spectrometry conditions and chromatographic conditions of the UPLC-Q-Orbitrap in the present invention is not particularly limited, and conventional optimization methods may be used.

[0042] In the present invention, the self-built high-resolution PFAS secondary screening mass spectrometry conditions preferably include: the acquisition mode is FullMS / ddMS2, the electrospray ionization source negative ion mode (ESI - ); ion spray voltage: -4500V; declustering voltage: 55V; entrance voltage: 10V; collision chamber exit voltage: 12V; temperature: 500℃; air curtain: 35.0psi; collision gas: 8psi; spray gas: 50psi; dry gas: 50psi; mass range: 70~1000m / z; sheath gas flow rate: 60; auxiliary gas flow rate: 25; scan gas flow rate: 2; spray voltage: 3.6kV; capillary temperature: 300℃; S-lens RF level: 50; auxiliary gas heater temperature: 370℃ ; Full scan MS parameters: Resolution: 70,000; Collision energy (NCE) range is 10 to 46 eV; Automatic gain control (AGC) target value: 1e6; Maximum ion injection time (IT): 100 ms; Spectrum data type, center point; MS2 parameters related to secondary scan: Resolution: 17,500; AGC target: 1e5; Maximum IT: 50 ms; Number of cycles: 20; Number of injection scan cycles is 20; Mass-to-charge ratio (m / z) isolation window: 1.5 m / z; Fixed first mass: 50.0 m / z.

[0043] In the present invention, the chromatographic conditions preferably include: the chromatographic column is X-BridgeTMBEH C18; ammonium formate-water solution and methanol are used as chromatographic mobile phases, the ammonium formate-water solution is mobile phase A, the methanol is mobile phase B, and the concentration of the ammonium formate-water solution is preferably 2mmol / L. The present invention adopts the above mass spectrometry conditions and chromatographic conditions to make the high-resolution PFAS secondary screening mass spectrometry database more accurate.

[0044] After obtaining the self-built high-resolution PFAS secondary screening mass spectrometry database, the water sample was pre-treated to obtain the solution to be tested.

[0045] The present invention has no special limitation on the type of the water sample, and any conventional water sample can be used. In the present invention, the water sample preferably includes one or more of lakes, reservoirs, rivers and factory water.

[0046] In the present invention, the pretreatment method is solid phase extraction, and the extraction column of the solid phase extraction is a WAX column. The present invention uses a WAX column for solid phase extraction, which has an excellent adsorption effect on PFAS in the water to be tested, can fully enrich the PFAS in the water to be tested, and will improve the accuracy of the test results.

[0047] In the present invention, the solid phase extraction method comprises activation, sample loading, elution, nitrogen blowing and re-dissolution performed in sequence.

[0048] In an embodiment of the present invention, the activation reagent is preferably 5% ammonia methanol solution, methanol and pure water. The present invention can activate the solidified extraction column by using the above reagents to improve the adsorption effect of PFAS.

[0049] In an embodiment of the present invention, the volume of the sampled test solution is preferably 200 mL, the concentration of the internal standard in the test solution may be 5 ng / mL, and the internal standard is the mixed internal standard described in the above technical solution.

[0050] In the present invention, the elution method may be to firstly elute with a buffer solution and then to elute with pure water under negative pressure. In an embodiment of the present invention, the buffer solution may be a 25 mmol / L ammonium acetate-acetic acid buffer solution (pH=4), and the volume of the buffer solution may be 5 mL; and the time for the pure water elution under negative pressure may be 15 min.

[0051] In an embodiment of the present invention, the elution may be performed by sequentially eluting with 5 mL of methanol and 7 mL of 5% ammonia methanol acetonitrile (20:80).

[0052] In an embodiment of the present invention, the temperature of the nitrogen blowing may be 40°C.

[0053] In an embodiment of the present invention, the reconstitution solvent may be a mixed solution of methanol and water, the volume ratio of methanol to water may be 1:3, the reconstitution volume may be 1.0 mL, the reconstitution vortex time may be 3 min, the reconstituted solution may be centrifuged at 12000 for 5 min, and the supernatant may be taken to obtain the test solution.

[0054] After obtaining the solution to be tested, the present invention uses UPLC-Q-Orbitrap to analyze the solution to be tested to obtain mass spectrum data of the solution to be tested, and performs targeted screening on the mass spectrum data of the solution to be tested according to the self-built high-resolution PFAS secondary screening mass spectrum database to obtain targeted screening results; the mass spectrum data of the solution to be tested is screened according to the accurate charge-to-mass ratio, isotope ion peaks and fragment ions of the PFAS mass spectrum database to obtain suspected screening results; according to the carbon-fluorine mass ratio characteristics of PFAS, the mass spectrum data of the solution to be tested is screened and identified for characteristic peaks to obtain non-targeted screening results.

[0055] In the present invention, the mass spectrometry conditions and chromatographic conditions for analyzing the PFAS standard solution using UPLC-Q-Orbitrap are the same as those for analyzing the test solution using UPLC-Q-Orbitrap. The present invention uses the same mass spectrometry conditions and chromatographic conditions to improve the accuracy of the screening results.

[0056] In the present invention, the targeted screening conditions preferably include: the mass deviation range of the accurate charge-to-mass ratio (m / z) is ±0.001Da; the retention time (RT) window threshold is 20sec; the fitting threshold of the isotope ion distribution signal matching is 75%, the mass deviation range is ±0.002Da; the intensity deviation of the mass spectrometry signal is 25%. The present invention adopts the above conditions for screening, which is more conducive to improving the accuracy of the screening results.

[0057] In the present invention, the PFAS mass spectrum database preferably includes one or more of: a database of 34 perfluorinated substances in NIST, a database of 61 PFAS screening in MoNA, a database of 57 perfluorinated substances in MzCloud, and a database of 48,646 fluorinated substances in Duke specLibrary.

[0058] In the present invention, the method for screening the characteristic peaks of the mass spectrometry data of the test solution according to the carbon-fluorine mass ratio characteristics of PFAS preferably includes: after extracting the characteristic peaks of the mass spectrometry data of the test solution, performing PFAS priority screening based on Python code, filtering the carbon mass defect-carbon mass ratio in the range of -0.5 to 0.5; the Kendrick mass defect (KMD) homologous sequences are CF2 and CF2O, and the screening range is 0 to 0.15; the mass deviation range is ±0.002Da to analyze potential PFAS characteristics, and screen perfluorinated compounds with confidence levels 2b to 3b.

[0059] In the present invention, according to the carbon-fluorine mass ratio characteristics of PFAS, the method for screening the characteristic peaks of the mass spectrometry data of the solution to be tested preferably includes: after extracting the characteristic peaks of the mass spectrometry data of the solution to be tested, performing PFAS priority screening based on Python code, filtering the carbon mass defect-carbon mass ratio in the range of -0.5 to 0.5; the Kendrick mass defect (KMD) homologous sequences are CF2 and CF2O, and the screening range is 0.85 to 1; the mass deviation range is ±0.002Da to analyze potential PFAS characteristics, and screen perfluorinated compounds with confidence levels 2b to 3b.

[0060] In the present invention, the identification of characteristic peak screening of the mass spectrum data of the test solution according to the carbon-fluorine mass ratio characteristics of PFAS includes: after extracting characteristic peaks and PFAS priority screening from the mass spectrum data of the test solution, using Compound Discoverer 3.3 software to predict the PFAS molecular formula, and presetting the element formula as C 1-20 , H 0-20 , F 2-40 , O 2-6 , N 0-4 , P 0-2 , S 0-2 , Cl 0-2 and I 0-2 The ring and double bond equivalence (RDBE) range is set to 1.5 to 10.5. The present invention adopts the above screening method to screen the test solution from multiple dimensions, thereby improving the comprehensiveness of the screening results.

[0061] The present invention performs quantitative analysis on a solution to be tested, comprising: analyzing the PFAS standard solution by using liquid chromatography-tandem quadrupole mass spectrometry to obtain an MRM quantitative parameter optimization result; and then analyzing the solution to be tested by using liquid chromatography-tandem quadrupole mass spectrometry according to the MRM quantitative parameter optimization result to obtain a quantitative analysis result of the solution to be tested.

[0062] In the present invention, the mass spectrometry conditions and chromatographic conditions for analyzing the PFAS standard solution using UPLC-Q-Orbitrap and the mass spectrometry conditions for analyzing the test solution using UPLC-MS / MS are the same. The present invention uses the same mass spectrometry conditions and chromatographic conditions for analysis, can perform quantitative analysis of PFAS in the test water sample, and improve the accuracy of the screening results.

[0063] The present invention also provides the application of the method for rapid screening and targeted quantification of PFAS in water bodies described in the above technical scheme to the detection of PFAS in water bodies, wherein the water bodies include one or more of lakes, reservoirs, rivers and factory water.

[0064] In the present invention, the screening flow chart of the method for rapid screening of PFAS in water for detecting PFAS in water is preferably as follows: Figure 2 As shown. Figure 2 It can be seen that the present invention uses a self-built high-resolution PFAS secondary screening mass spectrometry database to analyze the test solution and conduct targeted screening; then, the PFAS screening mass spectrometry database is used to conduct suspected screening of the test solution based on the precise charge-to-mass ratio, isotope peaks and fragment ions; then, non-targeted screening is performed using PFAS priority screening and feature identification; UPLC-MS / MS is used to perform quantitative analysis of the test solution to obtain quantitative data of PFAS in the test solution. The present invention combines three screening technologies: targeted screening, suspected screening and non-targeted screening, to achieve comprehensive, rapid and accurate screening and quantification of perfluorinated compounds in water, regardless of the presence or absence of standard control.

[0065] The technical solutions in the present invention will be described clearly and completely below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0066] The present invention uses the following reagents and materials:

[0067] 26 standard substances: perfluorobutanecarboxylic acid (PFBA), perfluoropentanecarboxylic acid (PFPeA), perfluorobutanesulfonic acid (PFBS), perfluorohexanecarboxylic acid (PFHxA), perfluoropentanesulfonic acid (PFPeS), perfluorobutanesulfonamide (FBSA), 2,3,3,3-trifluoro-2-(1,1,2,2,3,3-trifluoropropane)-propane acid perfluoro(2-methyl-3-oxahexanoic acid) (HFPO-DA (GenX)), perfluoroheptanecarboxylic acid (PFHpA), 4.8-dioxa-3H-perfluorononanoic acid (DONA), perfluorohexanesulfonic acid (PFHxS), perfluorooctanecarboxylic acid (PFOA), perfluoroheptanesulfonic acid (PFHpS), 6:2 fluorotelomer sulfonic acid (6:2FT SA), perfluorononanecarboxylic acid (PFNA), perfluorooctane sulfonic acid (PFOS), 6:2 chlorinated polyfluoroalkyl ether sulfonate (F-53B (6 / 2)), perfluorononane sulfonic acid (PFNS), perfluorodecane carboxylic acid (PFDA), perfluoroundecane carboxylic acid (PFUdA), perfluorodecane sulfonic acid (PFDS), 8:2 chlorinated polyfluoroalkyl ether sulfonate (F-53B (8 / 2)), perfluorododecane carboxylic acid (PFDoA), perfluorotridecane carboxylic acid (PFTrDA), perfluorotetradecane carboxylic acid (PFTeDA), perfluorohexadecane carboxylic acid (PFHxDA), perfluorooctadecane carboxylic acid (PFOdA, HPLC grade, Dr. Ehrenstorfer, Germany), and 13 mixed internal standards ( 13 C4-PFBA, 13 C5-PFPeA, 13 C5-PFHxA, 13 C4-PFHpA, 13 C8-PFOA, 13 C9-PFNA, 13 C6-PFDA, 13 C7-PFUdA, 13 C2-PFDoA, 13 C2-PFTeDA, 13 C3-PFBS, 13 C3-PFHxS and 13 C8-PFOS, TRC, Canada); methanol and acetonitrile (HPLC grade, Fisher Scientific, USA); ammonium formate (HPLC grade, ROE Scientific, USA).

[0068] Instruments and equipment used in the embodiments of the present invention: UPLC-Q-Orbitrap analysis using Thermo Fisher QExactive TM Combined quadrupole Orbitrap TMMass spectrometer, data acquisition and processing used TraceFinder5.1 and Compound Discover3.3 software; UPLC-TQ-MS analysis used UPLC-AB Sciex Triple Quad 5500MS system, which consists of TripleQuad 5500 mass spectrometer (AB Sciex, USA) and Exion UPLC system (AB Sciex, USA), and used SCIEXAnaylst software for data acquisition and processing; ultrapure water device (Millipore, USA).

[0069] Preparation of PFAS standard solution in the embodiment of the present invention: Accurately pipette 100 μL of the above 26 standard substances into a 1.5 mL injection bottle, dilute to 1 mL with methanol, and obtain a 100 μg / L standard solution containing 26 PFAS. Accurately pipette 100 μL of 100 μg / L PFAS standard solution into a 1.5 mL injection bottle, dilute to 1 mL with methanol, and configure it into a 10 μg / L mixed standard solution. Before use, use methanol-water (1:3, v / v) solution to configure a mixed standard solution of 0.1 μg / L, 0.2 μg / L, 1 μg / L, 5 μg / L, 10 μg / L, 20 μg / L, and 100 μg / L, and add an internal standard (200 μg / L, 25 μL, final concentration 5 μg / L).

[0070] Example 1

[0071] A method for rapid screening and targeted quantification of PFAS in factory water, the steps are:

[0072] (1) The PFAS standard solution was analyzed by UPLC-Q-Orbitrap, and the parameters of the self-built secondary fragment screening process for per- and polyfluoroalkyl compounds were optimized as shown in Table 1; the mass spectrometry conditions and chromatographic conditions of the UPLC-Q-Orbitrap were optimized. The mass spectrometry conditions were as follows: the Q Exactive MS instrument used electrospray ionization (ESI -) mode ionization, mass range: 70-1000 m / z; sheath gas flow: 60; auxiliary gas flow: 25; scan gas flow: 2; spray voltage (kV): 3.6; capillary temperature: 300°C; S-lens RF level: 50; auxiliary gas heater temperature: 370°C. Full scan MS parameters: resolution, 70,000 (up to 140,000); AGC target value, 1e6; maximum IT, 100 ms; spectrum data type, center point. MS2 parameters related to secondary data: resolution, 17,500; AGC target, 1e5; maximum IT, 50 ms; number of cycles, 20; TopN, 20; isolation window, 1.5 m / z; fixed first mass, 50.0 m / z; (N)CE, optimized according to PFAS secondary fragment response, and included in the InclusionList priority acquisition (see Table 2, total ion current TIC graph see Figure 1 ), and obtain a high-resolution PFAS secondary screening mass spectrometry database; the chromatographic conditions are shown in Table 3;

[0073] Table 1 Optimization of parameters for self-built PFAS secondary fragment screening process

[0074]

[0075] Table 2 Self-built secondary fragment screening (N) CE optimization of perfluorinated and polyfluorinated alkyl compounds

[0076]

[0077]

[0078] Table 3 Chromatographic conditions

[0079]

[0080] (2) Use Waters Oasis WAX solid phase extraction column (6cc, 150mg) to perform solid phase extraction on the factory water to extract PFAS in the water sample and obtain the test solution;

[0081] The specific operation of the solid phase extraction is shown in Table 4:

[0082] Table 4 Specific operation steps and process of solid phase extraction

[0083]

[0084] (3) Analyze the test solution obtained in step (2) using ultra-high performance liquid chromatography-quadrupole-electrostatic field orbital trap high-resolution mass spectrometry to obtain mass spectrum data of the test solution; perform targeted screening on the mass spectrum data of the test solution according to the self-built high-resolution PFAS secondary screening mass spectrum database obtained in step (1) to obtain targeted screening results; screen the mass spectrum data of the test solution according to the accurate charge-to-mass ratio, isotope ion peaks and fragment ions of the integrated known PFAS mass spectrum database to obtain suspected screening results; perform characteristic peak screening and identification on the mass spectrum data of the test solution according to the carbon-fluorine mass ratio characteristics of PFAS to obtain non-targeted screening results. Figure 2 and Figure 3 Targeted screening conditions include: accurate charge-to-mass ratio (m / z) mass deviation range of ±0.001Da; retention time (RT) window threshold of 20sec; isotope ion distribution signal matching fitting threshold of 75%, mass deviation range of ±0.002Da; mass spectrometry signal intensity deviation of 25%; suspected PFAS mass spectrometry databases include: 34 perfluorinated substances database in NIST, 61 PFAS screening database in MoNA, 57 perfluorinated substances database in MzCloud and Duke One or more of the 48,646 fluorinated substances in specLibrary; non-targeted screening includes: after extracting characteristic peaks from the mass spectrometry data of the test solution, PFAS priority screening is performed based on Python code, and the carbon mass defect-carbon mass ratio filtering range is -0.5 to 0.5; the Kendrick mass defect (KMD) homologous sequences are CF2 and CF2O, and the screening range is 0 to 0.15 and 0.85 to 1; the mass deviation range is ±0.002Da to analyze potential PFAS characteristics and screen perfluorinated compounds with confidence levels 2b to 3b. After extracting characteristic peaks and PFAS priority screening from the mass spectrometry data of the test solution, Compound Discoverer 3.3 software is used to predict the PFAS molecular formula, and the element formula is preset as C 1-20 , H 0-20 , F 2-40 , O 2-6 , N 0-4 , P 0-2 , S 0-2 , Cl 0-2 and I 0-2 ; The ring and double bond equivalence (RDBE) range is set to 1.5 to 10.5.

[0085] (4) The PFAS standard solution obtained in step (1) was analyzed by UPLC-MS / MS. The mass spectrometry conditions and chromatographic conditions were the same as those in step (1). The MRM quantitative parameter optimization results were shown in Table 6.

[0086] Table 6 Optimization of MRM quantitative parameters for PFAS

[0087]

[0088]

[0089] PFAS quantitative methodology optimization and validation:

[0090] UPLC-MS / MS analysis was performed using a mixed standard working solution of 0.1-20 μg / L. A standard curve was drawn with the injected mass concentration as the horizontal axis (x) and the quantitative ion pair peak area as the vertical axis (y). The results showed that the 26 PFAS pollutant standard solutions had a good linear relationship in the range of 0.1-20 μg / L. The signal-to-noise ratio S / N=3 was used as the limit of detection (LOD), and S / N=10 was used as the limit of quantification (LOQ).

[0091] Table 7. Standard curves, detection limits, quantification limits, spiked recoveries and relative standard deviations of 26 PFAS pollutants

[0092]

[0093]

[0094] It can be seen from Table 7 that the method provided by the present invention has high accuracy.

[0095] Application Example 1

[0096] The PFAS in the factory water was quantitatively analyzed according to the method of Example 1, specifically: 27 water samples from 12 water plants were extracted and processed according to the method of step (2) of Example 1 to obtain the test solution, and then quantitative analysis was performed according to the method of step (4) of Example 1.

[0097] The self-built high-resolution PFAS secondary screening mass spectrometry database was used to set conditions based on the accurate mass-to-charge ratio, retention time, isotope ion peak, and fragment ion: the conditions include: the mass deviation range of the accurate mass-to-charge ratio (m / z) is ±0.001Da; the retention time (RT) window threshold is 20sec; the fitting threshold of the isotope ion distribution signal matching is 75%, the mass deviation range is ±0.002Da; the intensity deviation of the mass spectrometry signal is 25%. A total of 17 perfluorinated compounds were screened, such as Figure 3 As shown, the 17 perfluorinated compounds are: PFBA, PFPeA, PFBS, PFHxA, PFPeS, FBSA, HFPO-DA, PFHpA, PFHxS, PFOA, PFHpS, 6:2FTSA, PFNA, PFOS, F-53B (6 / 2), PFDA, and PFUdA.

[0098] The PFAS mass spectrometry database (34 perfluorinated substances database in NIST, 61 PFAS screening database in MoNA, 57 perfluorinated substances database in MzCloud, and 48646 fluorinated substances database in Duke_specLibrary) was used to integrate the database using the suspected screening tool TraceFinder. Figure 2 As shown, based on the precise mass-to-charge ratio, isotope ion peaks and fragment ions, 13 perfluorinated compounds with confidence levels 1-2a were screened, including perfluorosulfonic acids (PFSAs, n=2-5, 7), perfluorocarboxylic acids (PFCAs, n=2-7) and chloropolyperfluoroether sulfonic acids (Cl-PFESAs, n=6, 8).

[0099] After extracting characteristic peaks using non-targeted screening, PFAS priority screening was performed based on Python code. The conditions included: after extracting characteristic peaks from the mass spectrometry data of the solution to be tested, PFAS priority screening was performed based on Python code, with a carbon mass defect-carbon mass ratio filtering range of -0.5 to 0.5; the Kendrick mass defect (KMD) homologous sequences were CF2 and CF2O, with a screening range of 0 to 0.15 and 0.85 to 1; the mass deviation range was ±0.002Da, and the potential PFAS characteristics were analyzed using CompoundDiscoverer 3.3 software to predict the PFAS molecular formula, and the element formula was preset as C 1-20 , H 0-20 , F 2-40 , O 2-6 , N 0-4 , P 0-2 , S 0-2 , Cl 0-2 and I 0-2 ; The range of ring and double bond equivalence (RDBE) was set to 1.5 to 10.5, and perfluorinated compounds with confidence levels of 2b to 3b were screened. Figure 2 As shown, a total of 14 perfluorinated compounds were screened, which were not included in the current standards, namely fluoroalkyl sulfonamides (FASAs, n=4,6,8), n:2 fluoroolefin sulfonic acids (n:2FTSAs, n=4,6), n:3 fluoroolefin carboxylic acids (n:3FTCAs, n=2,3,5), (n:3FTCAs, n=2,3,5), n:2 hydroxyfluorocarbon chain end sulfonic acids (OH-n:2FTSAs, n=4), unsaturated polyfluoroalkyl acids (UPFAs, n=4), n:3 fluorocarbon chain butyrates (n:3FTBs, n=2,3), and n:1:2 fluorocarbon chain butyrates (n:1:2FTBs, n=2,3).

[0100] Liquid chromatography-tandem quadrupole mass spectrometry was used to perform quantitative analysis based on the method of step (4). Figure 5As shown in the table, the perfluorinated compounds with a quantitative detection rate of PFAS greater than 50% are PFBA, PFPeA, PFBS, PFHxA, FBSA, GenX, PFHpA, PFOA, PFHpS, FTSA (6 / 2), PFNA, PFOS, F53B (6 / 2), PFDA, and PFUdA. Among them, the highest median is PFOA (5.43 ng / L), and the maximum is FTSA (6 / 2) (147.07 ng / L).

[0101] It can be seen from the above examples that the screening technology process constructed by the method provided by the present invention identified n:2 hydroxyl fluorocarbon chain terminal sulfonic acid (OH-n:2FTSAs, n=4), n:3 fluorocarbon chain butyrate (n:3FTBs, n=2,3), n:1:2 fluorocarbon chain butyrate (n:1:2FTBs, n=2,3), and unsaturated polyfluoroalkyl acids (UPFAs, n=4) in the water body to be tested in the example sample for the first time. In the absence of standard comparison, the present invention uses suspected screening combined with non-targeted screening technology to identify 27 new perfluorinated compounds; under the condition of standard comparison, the targeted quantitative method is used to detect that the concentration of the new perfluorinated compound FTSA (6 / 2) in some water bodies is relatively high. The present invention combines screening technology (targeted screening, suspected screening and non-targeted screening) with targeted quantification, and realizes rapid and accurate comprehensive analysis of perfluorinated compounds in water bodies regardless of whether there is a standard control. It can be used to identify potential high-priority pollutants in water bodies and provide technical support for environmental governance and the formulation of public health policies.

[0102] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for rapid screening and targeted quantification of PFAS in water, comprising the following steps: (1) Analyzing the PFAS standard solution using ultra-high performance liquid chromatography-quadrupole-electrostatic field orbital trap high-resolution mass spectrometry, optimizing the mass spectrometry conditions and chromatographic conditions of the ultra-high performance liquid chromatography-quadrupole-electrostatic field orbital trap high-resolution mass spectrometry, and obtaining a self-built high-resolution PFAS secondary screening mass spectrometry database; the self-built high-resolution PFAS secondary screening mass spectrometry database includes accurate charge-to-mass ratio, retention time, isotope ion peaks and fragment ions; (2) Pre-treating the water sample to obtain a test solution; the pre-treatment method is solid phase extraction, and the extraction column of the solid phase extraction is a WAX column. (3) Analyzing the test solution obtained in step (2) by ultra-high performance liquid chromatography-quadrupole-electrostatic field orbital trap high-resolution mass spectrometry to obtain mass spectrum data of the test solution, and performing targeted screening on the mass spectrum data of the test solution according to the self-built high-resolution PFAS secondary screening mass spectrum database obtained in step (1) to obtain targeted screening results; The mass spectrometry data of the solution to be tested is screened according to the accurate charge-to-mass ratio, isotope ion peaks and fragment ions of the PFAS mass spectrometry database to obtain suspected screening results; according to the carbon-fluorine mass ratio characteristics of PFAS, the mass spectrometry data of the solution to be tested is screened and identified for characteristic peaks to obtain non-targeted screening results; (4) performing quantitative analysis on the solution to be tested, including: analyzing the PFAS standard solution obtained in step (1) using liquid chromatography-tandem quadrupole mass spectrometry to obtain an MRM quantitative parameter optimization result; and then analyzing the solution to be tested using liquid chromatography-tandem quadrupole mass spectrometry based on the MRM quantitative parameter optimization result to obtain a quantitative analysis result of the solution to be tested; The pre-treatment conditions of the solution to be tested in step (3) and step (4) are the same.

2. The method according to claim 1, characterized in that The self-built high-resolution PFAS secondary screening mass spectrometry database in step (1) contains 26 perfluorinated compounds, and the 26 perfluorinated compounds are: perfluorobutane carboxylic acid, perfluoropentane carboxylic acid, perfluorobutane sulfonic acid, perfluorohexane carboxylic acid, perfluoropentane sulfonic acid, perfluorobutane sulfonamide, 2,3,3,3-trifluoro-2-(1,1,2,2,3,3-trifluoropropane)-propane acid perfluoro(2-methyl-3-oxahexanoic acid), perfluoroheptane carboxylic acid, 4.8 -dioxa-3H-perfluorononanoic acid, perfluorohexane sulfonic acid, perfluorooctane carboxylic acid, perfluoroheptane sulfonic acid, 6:2 fluorotelomer sulfonic acid, perfluorononane carboxylic acid, perfluorooctane sulfonic acid, 6:2 chlorinated polyfluoroalkyl ether sulfonate, perfluorononane sulfonic acid, perfluorodecane carboxylic acid, perfluoroundecane carboxylic acid, perfluorodecane sulfonic acid, 8:2 chloropolyfluoroalkyl ether sulfonate, perfluorododecane carboxylic acid, perfluorotridecane carboxylic acid, perfluorotetradecane carboxylic acid, perfluorohexadecane carboxylic acid and perfluorooctadecane carboxylic acid.

3. The method according to claim 1, characterized in that The mass spectrometry conditions in step (1) include: collision energy of 10-46 eV; automatic gain control target of 1e6; maximum ion injection time of 100 ms; injection scan cycle number of 20; and mass-to-charge ratio isolation window of 1.5 m / z.

4. The method according to claim 1, characterized in that: The chromatographic conditions in step (1) include: a chromatographic column of X-Bridge™ BEH C18; and 0.2 mM ammonium formate-water solution and methanol as chromatographic mobile phases.

5. The method according to claim 1, characterized in that The targeted screening conditions in step (3) include: the mass deviation range of the accurate charge-to-mass ratio is ±0.001Da; the retention time window threshold is 20sec; the fitting threshold of the isotope ion distribution signal matching is 75%, and the mass deviation range is ±0.002Da; the intensity deviation of the mass spectrometry signal is 25%.

6. The method according to claim 1, characterized in that The PFAS mass spectrum database in step (3) includes one or more of: a database of 34 perfluorinated substances in NIST, a database of 61 PFAS screening in MoNA, a database of 57 perfluorinated substances in MzCloud, and a database of 48,646 fluorinated substances in Duke specLibrary.

7. The method according to claim 1, characterized in that The method for performing characteristic peak screening on the mass spectrometry data of the test solution according to the carbon-fluorine mass ratio characteristics of PFAS in step (3) includes: after extracting characteristic peaks from the mass spectrometry data of the test solution, performing PFAS priority screening based on Python code, filtering the carbon mass defect-carbon mass ratio in the range of -0.5 to 0.5; the Kendrick mass defect homologous sequences are CF2 and CF2O, and the screening range is 0 to 0.15; the mass deviation range is ±0.002Da to analyze potential PFAS characteristics, and screen perfluorinated compounds with confidence levels 2b to 3b.

8. The method according to claim 1 or 7, characterized in that: The method for performing characteristic peak screening on the mass spectrometry data of the test solution according to the carbon-fluorine mass ratio characteristics of PFAS in step (3) includes: after extracting characteristic peaks from the mass spectrometry data of the test solution, performing PFAS priority screening based on Python code, filtering the carbon mass defect-carbon mass ratio in the range of -0.5 to 0.5; the Kendrick mass defect homologous sequences are CF2 and CF2O, and the screening range is 0.85 to 1; the mass deviation range is ±0.002Da to analyze potential PFAS characteristics, and screen perfluorinated compounds with confidence levels 2b to 3b.

9. The method according to claim 1 or 7, characterized in that: In the step (3), the identification of characteristic peak screening of the mass spectrum data of the test solution according to the carbon-fluorine mass ratio characteristics of PFAS includes: after extracting characteristic peaks and PFAS priority screening from the mass spectrum data of the test solution, using Compound Discoverer 3.3 software to predict the PFAS molecular formula, and presetting the element formula as C 1-20 , H 0-20 , F 2-40 , O 2-6 , N 0-4 , P 0-2 , S 0-2 , Cl 0-2 and I 0-2 ; The ring and double bond equivalence range is set to 1.5 to 10.

5.

10. Application of the method for rapid screening and targeted quantification of PFAS in water as described in any one of claims 1 to 9 in detecting PFAS in water, wherein the water body comprises one or more of lakes, reservoirs, rivers and factory water.

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