A method for detecting short-chain / ultra-short-chain PFAS in various environmental media in the surface water-groundwater interaction system

Abstract

This invention discloses a method for detecting short-chain and ultra-short-chain PFAS in various environmental media within the surface water-groundwater interaction system. The method comprises the following steps: sample pretreatment; solid-phase extraction of the resulting sample to obtain a sample; and analysis of the sample using liquid chromatography-mass spectrometry to determine the PFAS content. This method offers a wide detection range, high recovery, ease of operation, high sensitivity, and a low detection limit, making it suitable for the analysis of trace amounts of PFAS in environmental samples.

Description

Technical Field

[0001] The present invention belongs to the field of analytical technology, and specifically relates to a method for detecting short-chain / ultra-short-chain PFAS in various environmental media in a surface water-groundwater interaction system. Background Art

[0002] Perfluoroalkyl and polyfluoroalkyl substances (PFAS) are a broad class of man-made chemicals characterized by partial or complete replacement of hydrogen atoms on the carbon chain by fluorine atoms, forming an extremely stable carbon-fluorine bond. Due to its hydrophobicity and stability, PFAS has been used in many industries. Currently, PFAS have been detected to varying degrees in surface water, groundwater, tap water, soil, sediments and sewage sludge, even in the inaccessible Arctic region, and in the tissues and blood of various organisms. Humans can be exposed to PFAS through drinking water, dust, food, and contact with contaminated soil or sediment. PFAS is bioaccumulative and can be transmitted and amplified in the food chain. It is difficult to decompose and can therefore accumulate in the human body and remain for a long time.

[0003] At present, countries around the world have developed PFAS detection methods, but most detection targets focus on long-chain PFAS (PFAS with a carbon chain greater than or equal to 8). The quantitative detection of short-chain PFAS and even ultra-short-chain PFAS (short-chain PFAS: carbon chain between 4-7, ultra-short-chain PFAS: carbon chain between 1-3) is still in its infancy and has many shortcomings, such as a small scope of application and low sensitivity. At the same time, the complex and diverse environmental media of the surface water-groundwater interaction system further increases the difficulty of PFAS detection.

[0004] With the explicit ban on the production and use of long-chain PFAS such as perfluorooctanoic acid and perfluorooctane sulfonic acid, the use of short-chain / ultra-short-chain PFAS alternatives has increased significantly. Because of their physical and chemical properties, they are more easily spread and diffuse in the environment, are potentially toxic to organisms, and are difficult to remove through traditional water treatment technologies. Therefore, it is necessary to strengthen the supervision and detection of short-chain and ultra-short-chain PFAS. Therefore, how to efficiently and accurately detect the content of short-chain / ultra-short-chain PFAS in various environmental media in the surface water-groundwater interaction system is one of the difficulties in PFAS detection technology at this stage. Summary of the Invention

[0005] The purpose of the present invention is to provide an efficient detection method for short-chain / ultra-short-chain PFAS in various environmental media in the surface water-groundwater interaction system. This method has the advantages of simple operation, wide detection range, high recovery rate, high sensitivity and low detection limit, and is suitable for the analysis of trace PFAS in complex environmental medium samples.

[0006] In the present invention, the surface water-groundwater interaction system refers to the water quantity and water quality exchange process between surface water bodies (such as rivers, lakes, wetlands, etc.) and groundwater.

[0007] In the present invention, the environmental medium in the surface water-groundwater interaction system refers to the interaction carrier or medium between substances such as soil, rock, and sediment. They play an important role in the transmission and transformation of water flow, material changes, and water quality changes.

[0008] In order to achieve the above object, the technical solution adopted by the present invention is as follows:

[0009] The present invention provides a method for detecting short-chain / ultra-short-chain PFAS in various environmental media in the surface water-groundwater interaction system, comprising the following steps:

[0010] S1, pre-treating the sample;

[0011] S2, extracting the sample obtained in step S1 to obtain a sample for loading;

[0012] S3. Detect the sample obtained in step S2 and calculate the PFAS content;

[0013] The PFAS are short-chain or ultra-short-chain perfluoroalkyl and polyfluoroalkyl substances;

[0014] The short-chain PFAS refers to PFAS with a carbon chain between 4 and 7.

[0015] The ultra-short-chain PFAS refers to PFAS with a carbon chain between 1 and 3.

[0016] Specifically, the short-chain / ultra-short-chain PFAS include: PFBA, PFPeA, PFHpA, PFBS, PFPeS, PFHxS, PFHpS, 4:2FTS, HFPO-DA, TFA, PFEtS, MPFBA, MPFPeA, MPFHxA, MPFHpA, MPFBS, MPFHxS, MPFOS, and M4:2FTS.

[0017] The sample is a sample in a surface water-groundwater interaction system.

[0018] The extraction is solid phase extraction.

[0019] The detection method is liquid chromatography-mass spectrometry technology.

[0020] In the present invention, in step S1, the sample is a water sample or a sediment sample.

[0021] The water body is groundwater, such as a spring leak, an underground river, or surface water, such as a river.

[0022] The sediment is soil or river bottom sediment.

[0023] In the present invention, the sample is a water sample, and the pretreatment of the sample is carried out according to the following operations: filtering the water sample, adding a PFAS internal standard, and adjusting the pH value to 6-8; wherein, the pore size of the filter membrane used for the filtration is 0.22 μm, which can remove suspended matter and impurities in the water and prevent clogging of the instrument pipeline.

[0024] The amount of the PFAS internal standard added is: 10 ng of internal standard per 1 L of water sample.

[0025] In the present invention, the sample is a water sample, and the extraction column used in the extraction is an Oasis@WAX extraction column.

[0026] The sample is a water sample, and the eluent used for the extraction is 0.1% ammonia water-methanol.

[0027] In one embodiment of the present invention, the extraction of the water sample is carried out according to the following operation: the Oasis@WAX extraction column is activated with 0.1% ammonia-methanol, methanol and ultrapure water in sequence, the water sample is passed through the extraction column, and the extraction column is eluted with ammonium acetate solution and ultrapure water; the extraction column is dried under negative pressure, and then the extraction column is eluted with methanol and 0.1% ammonia-methanol in sequence at a flow rate of 1 ml / min to 3 ml / min, the eluate is collected in a centrifuge tube, blown almost dry with nitrogen, and made up to volume with methanol-water solution.

[0028] In the present invention, the sample is sediment, and the sample pretreatment is performed according to the following operations: homogenizing the sediment sample, adding a PFAS internal standard, ultrasonically extracting, centrifuging, collecting the supernatant, and concentrating; wherein the homogenization treatment makes the sample particle size ≥100 mesh; the amount of the PFAS internal standard added is: 1 ng of the internal standard is added to 1 g of the sediment sample;

[0029] The conditions of the ultrasonic extraction are: 25° C., 40 KHz.

[0030] Preferably, the extractant used in the ultrasonic extraction is a methanol solution containing 100 mM ammonium acetate. Studies have found that ammonium acetate can enhance the interaction between the hydrophilic part of PFAS and water, thereby desorbing PFAS from the soil surface or particles.

[0031] The centrifugal conditions are as follows: centrifugation on a shaker at 25°C and 5000 r / min;

[0032] The concentration conditions are as follows: at 40° C. and under nitrogen protection, the liquid volume is concentrated to 2 mL.

[0033] The centrifugal conditions were as follows: centrifugation on a shaker at 25° C. and 5000 r / min for 10 min.

[0034] The concentration conditions are as follows: concentrating the sample volume to 2 mL at 40° C. under high-purity nitrogen.

[0035] In the present invention, the sample is sediment, and the extraction column used in the extraction is a graphitized carbon solid phase extraction column.

[0036] In the present invention, the sample is sediment, and the eluent used in the extraction is methanol.

[0037] In one embodiment of the present invention, the solid phase extraction of the sediment sample is carried out according to the following operation: the extraction column is activated with methanol, the sediment sample is loaded into a small column, and methanol is used to elute at a flow rate of 1 ml / min to 3 ml / min. The eluate is collected in a centrifuge tube, blown almost dry with nitrogen, and fixed to volume with 30 wt% methanol aqueous solution.

[0038] In the present invention, in step S3, the detection conditions of the liquid chromatography-mass spectrometry technique are as follows:

[0039] Liquid chromatography conditions:

[0040] Chromatographic column: ACQUITY UPLC BEH C18 column, 1.7 μm, 2.1 mm × 50 mm;

[0041] Mobile phase: Phase A is 0.005 mol / L ammonium acetate aqueous solution, phase B is methanol;

[0042] Flow rate: 0.3 ml / min;

[0043] Injection volume: 10 μL;

[0044] Column temperature: 40°C;

[0045] Mobile phase gradient elution program Table 1.

[0046] Table 1 Mobile phase gradient elution program

[0047]

[0048] Mass spectrometry conditions:

[0049] Table 2 Mass spectrometry conditions of perfluorinated compounds and their internal standards

[0050]

[0051] In the present invention, the calculation of the PFAS content is performed according to the following operation:

[0052] (1) The standard curve was established as follows: the PFAS standard solution was diluted with 30 wt% methanol aqueous solution to prepare a series of standard solutions of 0, 0.1, 0.2, 0.5, 1, 2, 5, 10, 20, 50, 100, and 200 μg / L, and the standard curve was drawn;

[0053] Table 3 Standard curve

[0054] Compound Standard curve <![CDATA[R 2 ]]> PFBA y=0.07625x+0.00262 0.99817 PFPeA y=0.07389x+0.00452 0.99270 PFH y=0.11757x+0.00447 0.99476 PFHpA y=0.10859x+0.00331 0.98889 PFBS y=0.09042x+7.75552e-5 0.99627 PFPeS y=0.01872x+2.18032e-5 0.99649 PFHx y=0.08653x+3.51707e-4 0.99726 PFH y=0.09577x+6.68881e-4 0.99821 4:2FTS y=0.16103x+2.42461e-4 0.99730 HFPO-DA y=0.00201x+2.03359e-4 0.99493 TFA y=0.25141x+7.68555e-4 0.99037 PFS y=0.30955x+6.87965e-5 0.99756

[0055] (2) The PFAS content is calculated according to the following operation: the ratio of the peak area of ​​each target substance to be measured in the sample to the peak area of ​​its corresponding internal standard is substituted into the standard curve to obtain the injection mass concentration of each target substance to be measured; the injection mass concentration is then substituted into the following formula to calculate the mass concentration of the target substance to be measured in the sample, and the measurement result is expressed as the arithmetic mean of parallel measurements.

[0056] The calculation formula for the PFAS content is as follows:

[0057]

[0058] in:

[0059] ρ—mass concentration of each target substance in the sample, ng / L;

[0060] ρ1—injection mass concentration, μg / L;

[0061] V1—final fixed volume of the sample, ml;

[0062] V—sampling volume, L.

[0063] Compared with the prior art, the present invention has the following beneficial effects:

[0064] This method uses solid-phase extraction and liquid chromatography-mass spectrometry technology to achieve quantitative analysis of different short-chain and ultra-short-chain PFAS in a variety of environmental media, solving the problem of insufficient sensitivity of existing detection methods in detecting short-chain / ultra-short-chain PFAS. It can effectively detect 12 PFAS (10 of which are short-chain and 2 are ultra-short-chain), with recovery rates between 70% and 140%. BRIEF DESCRIPTION OF THE DRAWINGS

[0065] Figure 1 These are the sampling points for surface water and groundwater in Example 1. DETAILED DESCRIPTION

[0066] The present invention will be further described below with reference to specific examples, but the present invention is not limited to the following examples.

[0067] Unless otherwise specified, the experimental methods used in the following examples are conventional methods.

[0068] Unless otherwise specified, the reagents, materials, instruments, etc. used in the following examples can be obtained from commercial sources.

[0069] Example 1: Detection of PFAS in Water

[0070] Here are the steps:

[0071] (1) All surface water and groundwater samples were filtered through a 0.22 μm filter membrane to remove suspended solids and impurities in the water to prevent impurities from entering the instrument and clogging the pipes. 10 ng of PFAS internal standard was added. The addition of the internal standard was used to correct the recovery rate and matrix effect in the subsequent quantitative analysis to ensure the accuracy of the quantification.

[0072] in:

[0073] Groundwater samples: GW-2, GW-6, and GW-9 were collected from spring outcrops and underground rivers in the Hongfeng Lake area of ​​Guiyang City, Guizhou Province, respectively.

[0074] Surface water samples: SW-1, SW-2, SW-3, SW-4, SW-7, SW-9, SW-13, and SW-16 were collected from the confluence of Hongfeng Lake and its tributaries in Guiyang City, Guizhou Province, respectively.

[0075] (2) The pH of the water sample was adjusted to 6-8 using acetic acid or ammonia. The Oasis@WAX extraction column was activated with 5 mL of 0.1% ammonia-methanol, 7 mL of methanol, and 10 mL of ultrapure water, respectively, to fully expose the active sites on the column surface and enhance its adsorption capacity. The water sample was passed through the extraction column at a flow rate of 8 mL / min, capturing and concentrating the PFAS on the column, enabling more sensitive detection of these target substances.

[0076] The column was rinsed with 5 ml of 25 mmol / L ammonium acetate solution and 12 ml of ultrapure water to remove impurities and other water-soluble components other than PFAS, and the eluent was discarded. The column was dried under negative pressure for 10 minutes, and then eluted with 5 ml of methanol and 7 ml of 0.1% ammonia-methanol at a flow rate of 1 ml / min to 3 ml / min. The PFAS was eluted from the column into the eluent. The eluent was collected in a centrifuge tube, blown nearly dry with liquid nitrogen, and then diluted to 1 ml with a 30 wt% methanol-water solution for subsequent liquid chromatography-mass spectrometry analysis.

[0077] (3) Test and results:

[0078] The detection conditions and calculation formula are the same as above.

[0079] Table 4 PFAS concentrations in groundwater (GW) and surface water (SW) (ng / L)

[0080] target GW-2 GW-6 GW-9 SW-1 SW-2 SW-3 SW-4 SW-7 SW-9 SW-13 SW-16 PFBA 0.514 2.538 0.268 2.039 2.571 0.723 0.634 0.536 0.824 0.825 1.721 PFPeA 0.308 0.9 0.062 1.357 1.959 1.258 0.106 0.211 0.126 0.028 0.26 PFH 1.127 2.939 1.123 2.359 1.269 1.219 1.213 0.483 1.023 0.976 1.369 PFHpA 0.136 0.653 0.027 0.517 1.635 0.758 0.648 0.077 0.111 0.152 0.682 PFBS 0.11 0.366 0.323 8.683 0.637 0.293 0.47 0.865 0.673 0.173 1.003 PFPeS 0.383 0.152 0.524 0.129 0.286 0.124 0.34 0.174 0.169 0.247 0.082 PFHx 0.089 0.064 0.186 0.115 0.109 0.063 0.664 0.263 0.348 0.201 0.054 PFH 0.285 0.061 0.826 0.073 0.139 0.103 0.384 0.402 1.196 0.428 0.148 4:2FTS ND ND ND ND ND ND ND ND ND ND ND HFPO-DA 0.226 0.152 0.093 1.571 1.407 1.345 0.468 2.911 0.406 1.873 1.871 TFA 2.576 0.507 2.594 0.898 0.85 0.262 0.696 1.008 0.274 0.382 0.91 PFS 0.004 0.009 0.007 0.003 0.014 0.007 0.007 0.009 0.014 0.011 0.004

[0081] Table 5 Recovery rate and RSD of PFAS in water samples

[0082] target Recovery rate / % RSD PFBA 93.51 6.45％ PFPeA 78.93 12.51％ PFH 120.67 12.33％ PFHpA 123.07 16.36％ PFBS 99.16 5.08％ PFPeS 135.53 16.76％ PFHx 89.67 15.85％ PFH 83.81 17.33％ 4:2FTS 100.19 11.46％ HFPO-DA 104.64 16.86％ TFA 126.54 15.49％ PFS 97.45 7.41％

[0083] As can be seen from the above table, the method provided by the present invention can effectively detect 12 PFAS in water (including 10 short-chain and 2 ultra-short-chain), with relatively high sensitivity (RSD 5.08%-17.33%) and recovery rates between 70% and 140%.

[0084] Example 2: Detection of PFAS in Sediments

[0085] Here are the steps:

[0086] (1) The soil sample was thoroughly mixed and dried, large fragments were manually picked out, and the sample was ground through a 100-mesh sieve for thorough homogenization. 2 g of soil sample was weighed and placed in a 15 mL centrifuge tube. 2 ng of PFAS internal standard was added, followed by 5 mL of methanol, shaken for 1 min, and then ultrasonically extracted for 30 min. Ultrasonic waves generate high-frequency vibrations, destroying soil particles, increasing the contact surface between the target and the solvent, and promoting the extraction of the compound. The sample was centrifuged on a shaker at 25 ° C and 5000 r / min for 10 min to precipitate the soil sample, and the supernatant was transferred to a new 15 mL centrifuge tube. 5 mL of methanol solution was added and the above extraction steps were repeated twice. The recovery rate of the target was improved by multiple extractions. The supernatant was concentrated to reduce the solvent volume, enrich the target, and facilitate subsequent analysis. The obtained supernatant (about 15 ml) was concentrated to about 2 ml under high-purity nitrogen at 40 ° C to remove excess solvent, reduce target loss, and make the sample more concentrated.

[0087] The soil samples were collected from the bottom mud and sediment at the surface water sampling point described in Example 1.

[0088] (2) Purification was performed using a PestiCarb (graphitized carbon solid phase extraction column, 500 mg / 6 mL) column. The graphitized carbon column has a high adsorption capacity and can effectively remove interfering substances while maintaining good retention of the target compound on the column, thus preventing target loss. First, 2 ml of methanol was passed through the extraction column three times for activation. The concentrate was loaded into the column and rinsed three times with 1 ml of methanol. The collected solution was blown to near dryness under high-purity nitrogen gas and then diluted to 1 ml with methanol-water solution for analysis.

[0089] (3) Test and results:

[0090] The detection conditions and calculation formula are the same as above.

[0091] Table 6 PFAS recovery and RSD in sediment

[0092] target Recovery rate / % RSD PFBA 110.98 7.58％ PFPeA 103.84 10.14％ PFH 139.04 16.30％ PFHpA 92.61 17.60％ PFBS 111.22 8.54％ PFPeS 130.73 12.70％ PFHx 107.32 14.28％ PFH 108.91 15.25％ 4:2FTS 113.63 7.29％ HFPO-DA 99.69 14.71％ TFA 116.10 13.91％ PFS 111.03 15.67％

[0093] As can be seen from the above table, the method provided by the present invention can effectively detect 12 PFAS in sediments (including 10 short-chain and 2 ultra-short-chain), with relatively high sensitivity (RSD 7.29%-17.60%) and recovery rates between 90-140%.

[0094] Table 7 PFAS concentration in sediment (ng / L)

[0095] target S1 S2 S3 S4 S5 S6 S7 PFBA 0.014 0.036 0.041 0.076 0.109 0.126 0.08 PFPeA 0.076 0.078 0.14 0.256 0.235 0.182 0.752 PFH 0.056 0.191 0.343 0.468 0.537 0.149 1.659 PFHpA 0.075 0.126 0.159 0.484 0.265 0.341 0.141 PFBS 0.005 0.036 0.098 0.15 0.159 0.341 0.37 PFPeS 0.03 0.085 0.137 0.079 0.398 0.66 0.995 PFHx 0.012 0.064 0.026 0.0222 0.198 0.432 0.469 PFH 0.046 0.074 0.031 0.057 0.161 0.163 0.133 4:2FTS 0.009 0.008 0.081 0.211 0.083 0.487 0.26 HFPO-DA 0.503 1.994 3.77 3.21 1.481 1.588 3.255 TFA 1.051 1.431 2.749 4.33 4.322 2.209 7.013 PFS 0.001 0.005 0.009 0.048 0.045 0.233 0.046

[0096] Investigation of influencing factors

[0097] 1. Investigation of solid phase extraction column

[0098] This experiment investigated the effects of solid phase extraction columns Oasis@WAX and Oasis@HLB on the recovery of target PFAS. The steps are as follows:

[0099] Two solid-phase extraction columns were used for spike experiments, with 10 ng of target PFAS added to 1 L of ultrapure water. The experimental procedures were exactly the same except for the extraction columns. The extraction performance of the two columns was compared by calculating the recovery rate.

[0100] The detection conditions and calculation formula are the same as above.

[0101] The results are shown in the following table.

[0102] Table 8 Effects of different solid phase extraction columns on target PFAS recovery

[0103]

[0104] From the results in the above table, it can be seen that the recovery rate of short-chain and ultra-short-chain PFAS by the solid phase extraction column Oasis@WAX is significantly higher than that of the extraction column Oasis@WAX.

[0105] 2. Investigation of eluent combination

[0106] This experiment investigated the effects of different eluent combinations on the recovery of target PFAS. The steps are as follows:

[0107] Three elution reagent combinations were used: methanol-0.1% ammonia in methanol, methanol-0.1% ammonia in acetonitrile, and 0.1% ammonia in methanol-0.1% ammonia in acetonitrile. 10 ng of the target PFAS was added to 1 L of ultrapure water. The experimental procedure remained the same except for the elution reagents. 4 mL of each reagent was used for elution. The elution performance of the three elution combinations was compared by calculating recovery rates.

[0108] Table 9 Effects of different eluent combinations on target PFAS recovery

[0109]

[0110] From the results in the above table, it can be seen that the recovery rate of the target PFAS is the best when the sample is eluted using methanol-0.1% ammonia methanol combination 1, and the recovery rate of ultra-short-chain PFAS using methanol-0.1% ammonia acetonitrile combination 2 and 0.1% ammonia methanol-0.1% ammonia acetonitrile combination 3 is poor. Therefore, methanol-0.1% ammonia methanol combination 1 is selected as the elution reagent of the present invention.

[0111] 3. Detection limit and quantification limit

[0112] The methods of Example 1 and Example 2 were used to obtain the detection limits and quantification limits of the water samples and sediments, and the results are as follows.

[0113] Table 10 Detection limits and quantification limits of water samples and sediments

[0114]

[0115] In summary, from the above test results, it can be seen that the detection method provided by the present invention has the advantages of simple operation, wide detection range, high recovery rate, high sensitivity and low detection limit, and is suitable for the analysis of trace short-chain / ultra-short-chain PFAS in water and soil in surface water-groundwater interaction systems.

[0116] Although the present invention has been described in detail above using general descriptions and specific embodiments, it will be apparent to those skilled in the art that modifications and improvements may be made based on the present invention. Therefore, such modifications and improvements, which do not depart from the spirit of the present invention, are intended to be within the scope of protection claimed herein.

Claims

1. A method for detecting PFAS, comprising the following steps: S1, pre-treating the sample; S2, extracting the sample obtained in step S1 to obtain a sample for loading; S3. Detect the sample obtained in step S2 and calculate the PFAS content; The PFAS are short-chain and ultra-short-chain perfluoroalkyl and polyfluoroalkyl substances; the short-chain and ultra-short-chain PFAS include: PFBA, PFPeA, PFHpA, PFBS, PFPeS, PFHxS, PFHpS, 4:2FTS, HFPO-DA, TFA and PFEtS; In step S1, the sample is a sample in a surface water-groundwater interaction system; The sample is a water sample or a sediment sample; The water body is groundwater or surface water; The sediment is soil or river bottom sediment; In step S1, the sample is a water sample, and its pretreatment is performed according to the following operations: the water sample is filtered, a PFAS internal standard is added, and the pH value is adjusted to 6-8; the pore size of the filter membrane used for the filtration is 0.22 μm; The amount of PFAS internal standard added is: 10 ng of internal standard per 1 L of water sample; The sample is a sediment sample, and its pretreatment is carried out according to the following operations: the sediment sample is homogenized, a PFAS internal standard is added, ultrasonic extraction is performed, centrifugation is performed, the supernatant is collected, and concentration is performed; The homogenization process makes the particle size of the sample ≥100 mesh; The amount of the PFAS internal standard added was: 1 ng of internal standard was added to every 1 g of sediment sample; The ultrasonic extraction conditions are: 25°C, 40KHz; the extractant is: methanol solution containing 100mM ammonium acetate; the extraction column is a graphitized carbon solid phase extraction column; the eluent is methanol; The centrifugal conditions are as follows: centrifugation on a shaker at 25°C and 5000 r / min; The concentration conditions are as follows: at 40° C. under nitrogen protection, the liquid volume is concentrated to 2 mL; In step S2, the water sample is extracted according to the following operation: the Oasis@WAX extraction column is activated with 0.1% ammonia-methanol, methanol, and ultrapure water in sequence, the water sample is passed through the extraction column, and the extraction column is eluted with ammonium acetate solution and ultrapure water; the extraction column is dried under negative pressure, and then eluted with methanol and 0.1% ammonia-methanol in sequence at a flow rate of 1 ml / min to 3 ml / min, the eluate is collected in a centrifuge tube, blown to near dryness with nitrogen, and made up to volume with methanol-water solution; The solid phase extraction of the sediment sample was performed as follows: the extraction column was activated with methanol, the sediment sample was loaded into the small column, and methanol was used to elute at a flow rate of 1 ml / min to 3 ml / min. The eluate was collected in a centrifuge tube, blown to near dryness with nitrogen, and made up to volume with a 30 wt% methanol aqueous solution; In step S3, the detection method is liquid chromatography-mass spectrometry; The conditions of the test are as follows: Liquid chromatography conditions: Chromatographic column: ACQUITY UPLC BEH C18 column, 1.7 μm, 2.1 mm × 50 mm; Mobile phase: Phase A is 0.005 mol / L ammonium acetate aqueous solution, phase B is methanol; Flow rate: 0.3 ml / min; Injection volume: 10 μL; Column temperature: 40°C; Elution procedure: Mass spectrometry conditions: 。 2. The detection method according to claim 1, wherein The PFAS content is calculated according to the following operation: (1) Establishment of standard curve: Dilute the PFAS standard solution with 30 wt% methanol aqueous solution to prepare a series of standard solutions with concentrations of 0, 0.1, 0.2, 0.5, 1, 2, 5, 10, 20, 50, 100, and 200 μg / L, and draw a standard curve; The standard curve is as follows: (2) Substitute the ratio of the peak area of ​​each target substance to its corresponding internal standard peak area into the standard curve to obtain the injection mass concentration of each target substance; then substitute the injection mass concentration into the following formula to calculate the mass concentration of the target substance in the sample; The calculation formula is as follows: in: ρ —The mass concentration of each target substance in the sample, ng / L; ρ 1—injection mass concentration, μg / L; V 1—the final volume of the sample, ml; V —Sampling volume, L.

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