A rapid solvent extraction method for the detection of perfluorinated alternatives in soil and sediment

Abstract

The present invention discloses a rapid solvent extraction detection method for perfluorinated substitutes in soil and sediments, comprising the following steps: collecting soil or sediment samples, removing foreign matter, drying, grinding, and sieving, mixing the obtained sample powder with diatomaceous earth, placing it in an extraction pool with a glass fiber filter membrane, and adding an isotope-labeled compound as an extraction internal standard in the extraction pool, and then covering the extraction pool with a metal cover and tightening it; placing the extraction pool in a pressurized fluid extractor, using an extractant for pressurized extraction, then collecting the extract, rotary evaporating it to near dryness, re-dissolving it with a solvent, adding an injection internal standard, and obtaining a solution to be tested; finally, using a liquid chromatography-mass spectrometry determination method to perform qualitative and quantitative determination of perfluorinated substitutes. This method uses acetonitrile and methyl tert-butyl ether as extraction solvents, has the advantages of relatively simple and quick pretreatment process, short time consumption, strong sample processing stability, and reduces the error caused by the manual extraction process.

Description

Technical Field

[0001] The invention belongs to the technical field of environmental monitoring, and in particular relates to a rapid solvent extraction detection method for perfluorinated substitutes in soil and sediment. Background Art

[0002] Perfluorinated and polyfluorinated compounds are mainly used in food packaging, non-stick pan coatings, outdoor clothing, furniture, foam fire extinguishers, coatings and electroplating industries, and play a wide range of indispensable roles. There are 4,730 perfluorinated compounds used in the market, which have the advantages of strong carbon-fluorine bonds, acid and alkali resistance, low surface tension, hydrophobic and oleophobic properties. Studies have found that these traditional perfluorinated and polyfluorinated compounds have multiple toxicities such as liver toxicity, immunotoxicity, developmental toxicity, endocrine disruption and potential carcinogenicity, and their toxicity has a very long incubation period, which will pose a serious threat to the ecological environment and human health. New PFOS substitutes-6:2 Cl-PFAES and 6:2 FTS have gradually appeared on the market. In the electroplating industry, F-53B is widely used instead of PFOS as a chromic acid inhibitor. The current annual output of F-53B is about more than 10 tons, and the annual demand is still rising. The full market replacement of 6:2 FTS needs to be studied and verified. As a substitute for PFOS, OBS is a powdered anionic fluorocarbon surfactant that is white or slightly yellow in color, easily absorbs moisture in the air, and is resistant to strong acids and alkalis. Et-PFOA is mainly used as a lubricant and surfactant. It has a low friction coefficient and high chemical stability and is commonly used in lubricating oils, brake fluids, rust inhibitors, and certain adhesives. PFOSA is mainly used to synthesize fluorosurfactants by introducing other groups onto nitrogen atoms. PFOSA can have adverse effects on aquatic organisms and can cause neurotoxicity.

[0003] In the prior art, the pretreatment extraction technology for the detection of perfluorinated and polyfluorinated compounds in soil mainly adopts oscillation extraction or solvent leaching extraction, and then uses WAX solid phase extraction cartridges for purification. This type of method has the disadvantages of complicated pretreatment process, high extraction time cost, high purification cartridge price, etc. For example, patent number CN105467026B "A method for detecting perfluorinated compounds in soil and sediments" discloses that the extraction of perfluorinated compounds in soil and sediments adopts segmented multiple extractions. The first segment is subjected to oscillation, standing, and ultrasonic extraction in a water bath. The supernatant is collected by extraction and centrifugation and placed in a collection container, and the lower layer of residue is retained in a centrifuge tube; an extractant is added to the residue in the second centrifuge tube, and an auxiliary reagent is added to adjust the pH of the solution to 3.0-5.8, and the solution is oscillated, allowed to stand, ultrasonically extracted in a water bath, and centrifuged to collect the supernatant and place it in a collection container, and the lower layer of residue is retained in a centrifuge tube; the supernatants after the two stages of extraction are combined, and the supernatant is separated and purified by a WAX solid phase extraction column; the entire pretreatment process is very complicated and time-consuming, with high extraction time cost and high purification column price.

[0004] The present invention develops a method for extracting perfluorinated substitutes from freeze-dried soil and sediments using a pressurized fluid extractor (ASE), collecting the extracted extract, concentrating it to near dryness by rotary evaporation, dissolving it with 2 mL of extraction solvent, passing it through a 0.45 μm polypropylene needle filter, blowing it to 1 mL with nitrogen, and finally quantitatively determining it by the internal standard method of a high performance liquid chromatography-triple quadrupole mass spectrometer. The pretreatment process of the method of the present invention is relatively simple and fast, short in time, and has strong sample processing stability, reduces the error caused by the manual extraction process, has high accuracy and reliable precision, and can be applied to the screening and monitoring of perfluorinated substitutes in environmental soils and sediments. Summary of the invention

[0005] In view of the above-mentioned technical problems existing in the prior art, the purpose of the present application is to provide a rapid solvent extraction detection method for perfluorinated substitutes in soil and sediment.

[0006] The technical solution adopted by the present invention is as follows:

[0007] A rapid solvent extraction method for detecting perfluorinated substitutes in soil and sediments comprises the following steps:

[0008] S1 Sample collection and pretreatment: Collect soil or sediment samples, store them in a refrigerator, remove foreign matter from the samples in the laboratory, dry them, grind them, and sieve them to obtain sample powder;

[0009] S2 Sample analysis: Mix the sample powder with diatomaceous earth, put it into an extraction cell with a glass fiber filter membrane, add isotope-labeled compounds as extraction internal standards into the extraction cell, and then cover the extraction cell with a metal cover and tighten it; put the extraction cell into a pressurized fluid extractor, use an extractant for pressurized extraction, then collect the extract, evaporate it to near dryness, re-dissolve it with a solvent, add the injection internal standard (the injection internal standard is mainly to determine the stability of the instrument, ignoring the error caused by the fixed volume of the solvent), and obtain the solution to be tested;

[0010] S3 Chromatographic Analysis: Finally, liquid chromatography-mass spectrometry was used for qualitative and quantitative determination of perfluorinated substitutes.

[0011] Furthermore, in step S1, the foreign matter includes branches, leaves and stones in the sample, and the sample is dried by natural air drying or freeze drying, and the mesh size of the sieve is 60-100 meshes.

[0012] Furthermore, the perfluorinated substitute is one or more of 6:2Cl-PFAES, 6:2FTS, OBS, Et-PFOA, and PFOSA, and the isotope-labeled compound includes 13 C 4PFOS and / or 13 C 4 PFOA, 13 C 4 PFOA is a perfluorinated substitute for Et-PFOA and is used as an extracted internal standard for detection. 13 C 4 PFOS is the extracted internal standard used for the detection of perfluorinated substitutes 6:2Cl-PFAES, 6:2FTS, OBS, and PFOSA.

[0013] Furthermore, in step S2, the pressurized extraction conditions are: extraction pressure 1500 psi, static extraction time 5 min, extraction temperature 60-70°C; solvent flushing volume is 60% of the extraction cell volume; nitrogen purge time 60 s, static cycle number 2 times.

[0014] Furthermore, the solvent used for redissolution in step S2 is acetonitrile or methanol.

[0015] Further, in step S3, the liquid chromatography conditions are as follows: chromatographic column: Shim-pack GIST-HP C18 chromatographic column, particle size of 3 μm, column length of 100 mm, inner diameter of 2.1 mm; methanol and 2 mmol / L ammonium acetate aqueous solution are used as mobile phase A and mobile phase B, respectively, and the elution degree is as follows: 0-5 min, 30%-65% A; 5-9 min, 65%-95% A; 9-11 min, 95% A; 11.1-12 min, 30% A.

[0016] Furthermore, in step S3, the mass spectrometry conditions are: electrospray ESI ion source, negative ion mode; monitoring mode: multiple reaction monitoring; capillary voltage 3000 V; vacuum interface temperature 300 ° C; heating block temperature 400 ° C; nebulizing gas flow rate 3.0 L / min; drying gas flow rate 10 L / min; heating gas flow rate 10 L / min; collision gas flow rate 0.25 ml / min.

[0017] Further, the internal standard injected in step S2 is 13 C 2 -PFOA.

[0018] Furthermore, the extractant in step S2 is one or more mixed solvents of methanol, acetonitrile, and methyl tert-butyl ether, preferably methanol-methyl tert-butyl ether in a volume ratio of 1:1 or acetonitrile-methyl tert-butyl ether in a volume ratio of 1:1.

[0019] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are:

[0020] In the present invention, by comparing and studying the pretreatment extraction conditions of soil and sediment samples, a method for determining the contents of five perfluorinated substitutes in soil and sediment by rapid solvent extraction-ultra-performance liquid chromatography-tandem mass spectrometry is established. The results show that the detection limit of the method determined by the method is 0.14 μg / kg~0.23 μg / kg, the recovery ranges of the actual spiked samples of soil and sediment are 63.6%~110% and 73.1%~100%, respectively, and the relative standard deviations are 3.5%~7.7% and 3.8%~8.2%, respectively. The method has the advantages of relatively simple and fast pretreatment process, short time consumption, strong sample processing stability, reduction of errors caused by artificial extraction process, high accuracy and reliable precision, and can be applied to the screening and monitoring of perfluorinated substitutes in environmental soil and sediments.

[0021] 1. In the present invention, the comparative test results of the pretreatment method with other methods, such as the shaking table oscillation pretreatment method and the ultrasonic extraction pretreatment method, show that the rapid solvent extraction method extracts the perfluorinated compounds in the soil sample better than the other two pretreatment methods, and has a good addition recovery rate;

[0022] 2. In the present invention, acetonitrile and methyl tert-butyl ether are used as extraction solvents, which have a better recovery rate for perfluorinated substitutes compared with methanol solvent extraction. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is the comparison result of the effects of different extraction solvents in ultrasonic extraction pretreatment method;

[0024] Figure 2 It is the comparison result of the effects of different extraction solvents in the oscillation extraction pretreatment method;

[0025] Figure 3 It is the comparison result of the effects of different extraction solvents in the rapid solvent extraction method;

[0026] Figure 4 This is the test result of the spiked recoveries of different perfluorinated substitutes under three pretreatment methods: ultrasonic extraction, oscillation extraction and rapid solvent extraction when methanol is selected as the extractant. DETAILED DESCRIPTION

[0027] The present invention will be further described below in conjunction with specific embodiments, but the protection scope of the present invention is not limited thereto.

[0028] Example 1: A rapid solvent extraction detection method for perfluorinated substitutes in soil and sediments, comprising the following steps:

[0029] S1. Sample collection: Soil samples should be collected and stored in accordance with the relevant requirements of HJ / T 166, and water sediment samples should be collected in accordance with the relevant requirements of HJ 494. After the samples are collected, they should be placed in polypropylene sampling bottles, refrigerated, sealed, and kept away from light at a temperature below 4°C, and the extraction should be completed within 28 days; the extract should be refrigerated, sealed, and kept away from light at a temperature below 4°C, and the analysis should be completed within 30 days. It is also necessary to prevent new contaminants from entering the container and contaminating the bottle mouth, causing the sample to deteriorate. The sample storage area in the laboratory should be free of organic interference.

[0030] S2. Sample preparation: The collected samples are transported and stored in a frozen blue ice incubator, and then transported to the laboratory by logistics. Foreign matter in the samples, such as branches, leaves, and stones, is removed, and the samples are dried by natural air drying. After the samples are dried, they are ground, homogenized, and sieved through a 60-mesh sample sieve to obtain sample powder.

[0031] S3. Sample analysis: Weigh about 10.0 g of sample powder and mix it with diatomaceous earth in a mass ratio of 1:2, put it into an extraction cell with a glass fiber filter membrane, and add 50.0 μL of the extraction internal standard containing 0.200 mg / L 13 C 4 PFOS and 0.200mg / L 13 C 4 The mixture of PFOA, then cover the extraction cell with a metal cap and tighten it; place the extraction cell in a pressurized fluid extractor, use the extractant for pressurized extraction, after the extraction is completed, collect the extract, transfer it to a rotating bottle, rotate and evaporate it until it is almost dry, add 2 mL of acetonitrile to shake the rotating bottle, pass the sample through a 0.45 μm polypropylene needle filter, blow nitrogen to make the volume 1 mL, add 50.0 μL of the injection internal standard 0.200 mg / L 13 C 2 -PFOA, detected by ultra-high performance liquid chromatography tandem mass spectrometry.

[0032] Among them, in order to reduce the background value, the use of chromatographic pipelines and utensils made of polytetrafluoroethylene should be avoided during the experiment. The chromatographic pipeline used in this experiment is a polypropylene plastic tube specially used for the determination of perfluorinated compounds, and the sample vial is a polypropylene plastic bottle.

[0033] S31. Pressurized fluid extraction conditions: extraction pressure 1500 psi, static extraction time 5 min, extraction temperature 70°C; solvent flushing volume is 60% of the extraction cell volume; nitrogen purge time 60 s, static cycle number 2 times.

[0034] S32. Liquid chromatography conditions are as follows: chromatographic column: Shim-pack GIST-HP C18 chromatographic column, particle size 3 μm, column length 100 mm, inner diameter 2.1 mm; delay column: Shim-pack GIST-HP, C18-AQ chromatographic column, particle size 3 μm, column length 50 mm, inner diameter 2.1 mm. Methanol and 2 mmol / L ammonium acetate aqueous solution were used as mobile phase A and mobile phase B, respectively. Column temperature 35 °C; injection volume 5.0 μl; flow rate 0.3 ml / min; gradient elution program see Table 1.

[0035]

[0036] S33, mass spectrometry conditions are: electrospray ESI ion source, negative ion mode; monitoring mode: multiple reaction monitoring (MRM); capillary voltage 3000 V; vacuum interface temperature 300 ℃; heating block temperature 400 ℃; nebulizer gas flow 3.0 L / min; drying gas flow 10 L / min; heating gas flow 10 L / min; collision gas flow 0.25 ml / min; collision gas flow 0.25 ml / min. Specific conditions are shown in Table 2.

[0037]

[0038] S4. Under the experimental conditions of step S3, obtain the linear regression equations and correlation coefficients of the five perfluorinated substitutes, and determine the method detection limits of the five perfluorinated substitutes;

[0039] S41. Purchase commercially available standard solutions of 6:2Cl-PFAES (F-53B) with a concentration of 50 μg / mL, 6:2FTS with a concentration of 100 μg / mL, pure OBS with a purity of 97%, pure Et-PFOA with a purity of 97%, and pure PFOSA with a purity of 95%. The above five perfluorinated substitutes were dissolved and diluted in acetonitrile to prepare a perfluorinated substitute standard solution with a concentration of 0.200 mg / L.

[0040] Buy 13 C 4 -PFOA and 13 C 4 -PFOS mixed standard stock solution, both concentrations are 2.00 mg / L, diluted with acetonitrile to prepare the extraction internal standard working solution with both concentrations of 0.200 mg / L; purchase 13 C 2 -PFOA standard stock solution concentration is 50.0 mg / L, and is prepared with acetonitrile to prepare an injection internal standard solution with a concentration of 0.200 mg / L.

[0041] S42. Use a microsyringe to pipette 50 μL, 125 μL, 250 μL, 500 μL, 1250 μL, and 2500 μL of the above-mentioned perfluorinated substitute standard working solution (concentration of 0.200 mg / L) into a 5 mL volumetric flask in sequence, add 250 μL of extraction internal standard working solution and 250 μL of injection internal standard working solution, dilute to the mark with methanol, and prepare a standard working solution series with 6 concentration points. The concentrations of the standard working solutions are 2.00 µg / L, 5.00 µg / L, 10.0 µg / L, 20.0 µg / L, 50.0 µg / L, and 100 µg / L, respectively.

[0042] S43, according to the instrument reference conditions S32-S33, use liquid chromatography-mass spectrometry to detect, obtain liquid chromatograms under different concentrations of standard working solutions, use the target concentration as the horizontal axis, and the product of the liquid chromatography peak area ratio of the target to the corresponding extracted internal standard and the corresponding extracted internal standard concentration as the vertical axis to establish a standard curve, see Table 3. Among them, 13 C 4 PFOA is a perfluorinated substitute for Et-PFOA and is used as an extracted internal standard for detection. 13 C 4 PFOS is the extracted internal standard used for the detection of perfluorinated substitutes 6:2Cl-PFAES, 6:2FTS, OBS, and PFOSA.

[0043]

[0044] S44. Determination of detection limit and lower limit of determination: Determine the detection limit of the method according to the "Technical Guidelines for the Formulation and Revision of Environmental Testing and Analysis Methods Standards HJ168-2020", repeat the whole process and measure in parallel 7 times, and calculate the standard deviation S. The calculation formula of the detection limit is: MDL=t (n-1,0.99) *S, the lower limit of determination is 4 times the detection limit;

[0045] Wherein, MDL—method detection limit;

[0046] t—t distribution with n-1 degrees of freedom and 99% confidence level is 3.143;

[0047] S—standard deviation of n parallel determinations;

[0048] n—number of parallel measurements of samples;

[0049] Specific operation experiment of detection limit of 5 kinds of perfluorinated substitutes: Take 50 μL of 100 μg / L perfluorinated substitute standard working solution and add it to the mixture of dry soil sample powder and diatomaceous earth. The mass of dry soil sample powder is 10 g, and the mass ratio of sample powder to diatomaceous earth is 1:2. According to the above operation, 7 parallel samples are prepared, and the extraction is carried out according to the method of step S3 and the detection is carried out on the machine. The extraction agent is methyl tert-butyl ether and acetonitrile in a volume ratio of 1:1. The detection limit of the method is calculated according to the test results. The detection limit is based on 10.0 g dry soil sample and 1.0 mL concentrated volume. The measurement results are shown in Table 4 below.

[0050]

[0051] According to the HJ168-2020 standard, the ratio of the measured average value to the detection limit meets the standard requirements, as follows.

[0052]

[0053] S5. Under the experimental conditions of step S3, the blank sample after spiked was tested for precision and accuracy: diatomaceous earth was used to make blank samples, and 5 kinds of perfluorinated substitute standard working solutions with a concentration of 100μg / L were used for spiked experiments. 0.1 mL, 0.5 mL, and 0.9 mL of the standard mixed solution were taken, and the spiked amounts were 10ng, 50ng, and 90ng, respectively. Six parallel samples were prepared for each concentration. Extraction was performed according to the method of step S3 and the machine was tested. The extractant was methyl tert-butyl ether and acetonitrile in a volume ratio of 1:1. The mean, standard deviation, relative standard deviation, and relative error were calculated to evaluate the precision and accuracy of the blank after spiked. The results are listed in Tables 6-8 below.

[0054]

[0055]

[0056]

[0057] Conclusion: In this experiment, six repeated measurements were performed on blank spiked samples of five perfluorinated substitutes with spiked amounts of 10 ng, 50 ng and 90 ng. The obtained laboratory relative standard deviation was 4.2%~16%, and the relative error range was -36%~18%.

[0058] S6. Under the experimental conditions of step S3, the precision and correctness test of the spiked soil and sediment samples was carried out: the actual soil and sediment samples were used to make matrix samples, and the soil sample G-1-1-1 of project HJ230111 was used for detection, and the results of 5 perfluorinated substitutes were not detected; the sediment sample G-1-1-1 of the Hangzhou Bay area (Fuyang section) was used for detection, and the results of 5 perfluorinated substitutes were not detected. Use 100μg / L 5 kinds of perfluorinated substitute standard working solutions for the spike experiment, take 0.1 mL and 0.5 mL of the standard working solution, and the spike amount is 10ng and 50ng respectively. Prepare 6 parallel samples for each concentration. Extraction was carried out according to the method of step S3 and the machine was tested. The extraction agent was methyl tert-butyl ether and acetonitrile in a volume ratio of 1:1. The average value, standard deviation, relative standard deviation, and spike recovery rate were calculated to evaluate the precision and correctness of the actual sample after spike. The results of soil and sediment sample spike are listed in Tables 9 and 10.

[0059]

[0060]

[0061] Conclusion: This experiment conducted 6 repeated determinations of 5 kinds of perfluorinated substitutes spiked in soil samples with a spike amount of 10 ng, and the relative standard deviation of soil samples was 3.5% to 7.7%, and the spike recovery range was 63.6% to 110%; the experiment conducted 6 repeated determinations of 5 kinds of perfluorinated substitutes spiked in sediment samples with a spike amount of 50 ng, and the relative standard deviation of sediment samples was 3.8% to 8.2%, and the spike recovery range was 73.1% to 100%. The results of soil and sediment sample spikes showed that the detection method has good precision and accuracy.

[0062] Example 2. This example uses ultrasonic extraction pretreatment to extract perfluorinated substitutes from soil and sediments. Specifically: methanol / acetonitrile solvent is used to ultrasonically extract air-dried or freeze-dried soil and sediment samples. After ultrasonic extraction, the extract is centrifuged, and the supernatant is extracted and passed through a 0.45 μm polypropylene needle filter and transferred to another 50 mL centrifuge tube. The above extraction steps are repeated twice, and the extracted supernatants are combined and nitrogen blown to near dryness. After redissolution, the solution is transferred to an injection vial, and then quantitatively determined by high performance liquid chromatography-triple quadrupole mass spectrometry internal standard method. The liquid chromatography and mass spectrometry analysis parameters are the same as those in Example 1 of the present invention.

[0063] The specific steps of ultrasonic extraction pretreatment method are:

[0064] S1. Mix and homogenize the air-dried and ground soil sample that has passed through a 60-mesh sieve. The sample volume should be at least 250 g. The five perfluorinated substitutes in the soil were not detected in the analysis before the experiment. Weigh 10.0 g of the soil sample, add 50 μL of the perfluorinated substitute standard working solution with a concentration of 100 μg / L, mix the soil sample, put it into a conical flask, add 30 mL of methanol or acetonitrile solvent, and mix it with a vortex instrument.

[0065] S2. Put the bottle cap into the ultrasonic instrument (power 1500W) for the first ultrasonic extraction for 20 min. Transfer the ultrasonicated sample into a centrifuge tube and spin at 8000 r·min -1 Centrifuge for 6 min. After completion, filter the supernatant and put it into a clean conical flask.

[0066] S3. Add 30 mL of methanol or acetonitrile to the centrifuge tube containing the soil sample and place it in an ultrasonic device (power 1500 W) for a second extraction for 20 min. After completion, centrifuge and combine the two supernatants.

[0067] S4. Set the parameters of the rotary evaporator to -310 Pa, 50°C, and rotary evaporate to near dryness.

[0068] S5. Dissolve with 2 mL of methanol, purify with WAX solid phase extraction column, and activate with 5 mL of 2% ammonia-methanol solution, 5 mL of methanol and 5 mL of pure water. During the activation process, ensure that the filler in the solid phase extraction column is not exposed to the air. After loading the sample at a flow rate of 3 mL / min to 5 mL / min, elute the solid phase extraction column with 8 ml of 0.025 mol / L ammonium acetate buffer and discard the eluent. Dry the extraction column with the vacuum pump of the solid phase extraction device for 10 min to remove the residual water in the extraction column. Elute the solid phase extraction column with 8 mL of methanol at a flow rate of 1 ml / min to 3 ml / min, and discard the eluent. Elute the solid phase extraction column with 8 mL of 2% ammonia-methanol mixed solution at a flow rate of 1 mL / min to 3 mL / min, and collect the eluent and sample.

[0069] S6. Use a nitrogen blower to concentrate the eluate to near dryness and dilute to 1 mL with methanol / acetonitrile. Filter through a 0.22 μm polypropylene syringe filter, mix well and test.

[0070] S7. Sample analysis and determination were performed according to the liquid chromatography and mass spectrometry parameter conditions of Example 1. When methanol or ethanol was used as the extractant, the test results of the spiked recovery rates of different perfluorinated substitutes were shown in Figure 1 .

[0071] Depend on Figure 1It can be seen that in the ultrasonic extraction pretreatment method, acetonitrile extraction has a significant effect on perfluorosulfonic acid compounds, acetonitrile extraction has almost no effect on Et-PFOA, and the methanol extraction spike recovery rate is better than acetonitrile.

[0072] Example 3. This example uses an oscillation extraction pretreatment method to extract perfluorinated substitutes from soil and sediments. Specifically: methanol / acetonitrile solvent shaker oscillation extraction air-dried or freeze-dried soil and sediment samples, after oscillation extraction, transfer to a centrifuge tube for centrifugation, filter the supernatant and transfer to a clean conical flask, repeat the above extraction steps for the remaining soil sample, combine the two supernatants and rotary evaporate to near dryness, dissolve with methanol / acetonitrile, pass through a solid phase extraction column, purify liquid nitrogen and blow and concentrate, then transfer to an injection vial to a fixed volume, and then quantitatively determine by the internal standard method of a high-performance liquid chromatography-triple quadrupole mass spectrometer. The liquid chromatography and mass spectrometry analysis parameters are the same as those in Example 1 of the present invention.

[0073] The specific steps of the oscillation extraction pretreatment method are:

[0074] S1. Take the soil sample ground through a 60-mesh sieve in Example 2 above, weigh 10.0 g of the soil sample, add 50 μL of a 100 μg / L perfluorinated substitute standard working solution, mix the soil sample, put it into a conical flask, add 30 mL of methanol or acetonitrile solvent, and mix it using a vortex instrument.

[0075] S2, cover the bottle with a stopper and place it in a shaking incubator at 200 r.min -1 The first extraction was carried out under shaking conditions for 30 min. The shaken samples were transferred into centrifuge tubes and centrifuged at 6000 r·min. -1 Centrifuge for 6 min. After centrifugation, filter the supernatant and put it into a clean conical flask.

[0076] S3. Add 30 mL of methanol or acetonitrile to the centrifuge tube containing the soil sample and place it on a shaking table at 200 r.min. -1 The second extraction was carried out under shaking for 30 min, and then centrifuged and the two supernatants were combined.

[0077] S4. Set the parameters of the rotary evaporator to -310 Pa, 50°C, and rotary evaporate to near dryness.

[0078] S5. Dissolve with 2 mL of methanol, purify with WAX solid phase extraction column, and activate with 5 mL of 2% ammonia-methanol solution, 5 mL of methanol and 5 mL of pure water. During the activation process, ensure that the filler in the solid phase extraction column is not exposed to the air. After loading the sample at a flow rate of 3 mL / min to 5 mL / min, elute the solid phase extraction column with 8 ml of 0.025 mol / L ammonium acetate buffer and discard the eluent. Dry the extraction column with the vacuum pump of the solid phase extraction device for 10 min to remove the residual water in the extraction column. Elute the solid phase extraction column with 8 mL of methanol at a flow rate of 1 ml / min to 3 ml / min, and discard the eluent. Elute the solid phase extraction column with 8 mL of 2% ammonia-methanol mixed solution at a flow rate of 1 mL / min to 3 mL / min, and collect the eluent and sample.

[0079] S6. Use a nitrogen blower to concentrate the eluate to near dryness and dilute to 1 mL with methanol / acetonitrile. Filter through a 0.22 μm polypropylene syringe filter, mix well and test.

[0080] S7. Sample analysis and determination were performed according to the liquid chromatography and mass spectrometry parameter conditions of Example 1. When methanol or ethanol was used as the extractant, the test results of the spiked recovery rates of different perfluorinated substitutes were shown in Figure 2 .

[0081] Depend on Figure 2 It can be seen that acetonitrile extraction in the oscillation extraction pretreatment method has obvious effects on 6:2Cl-PFAES, 6:2FTS, OBS, and PFOSA. The recovery rate of Et-PFOA by acetonitrile extraction is less than 20%, and the recovery rate of methanol extraction is better than that of acetonitrile. The recovery rate of oscillation extraction is higher than that of ultrasonic extraction.

[0082] Example 4. This example uses a rapid solvent extraction method to extract perfluorinated substitutes from soil and sediments. Specifically: a pressurized fluid extractor is used to extract air-dried or freeze-dried soil and sediment samples using methanol / acetonitrile solvents. After two extractions with ASE, the samples are transferred to a rotary concentrator bottle and evaporated to near dryness, dissolved with methanol / acetonitrile, filtered through a 0.22 μm polypropylene needle filter, and then the volume is fixed to 1 mL. The samples are then quantitatively determined by the internal standard method of a high performance liquid chromatography-triple quadrupole mass spectrometer. The liquid chromatography and mass spectrometry analysis parameters are the same as those of Example 1 of the present invention.

[0083] The specific steps of the rapid solvent extraction method are:

[0084] S1. Take the soil sample ground through a 60-mesh sieve in the above-mentioned Example 2, weigh 10.0 g of the soil sample, add 50 μL of a 100 μg / L perfluorinated substitute standard working solution, mix the soil sample, add diatomaceous earth to mix, and then put it into a rapid solvent extraction cell for pressurized extraction. The extraction solvents are methanol, acetonitrile, methyl tert-butyl ether, or a mixed solvent thereof.

[0085] S2. Set the parameters of the pressurized fluid extractor: extraction temperature 70°C; extraction pressure 1500 psi; static extraction time 5 min; flushing volume 60% of the extraction pool solvent; nitrogen purge time 60 s, cyclic extraction times 2 times. Collect and combine the two extracts after extraction.

[0086] S3. Transfer the solvent to a rotary concentrator bottle, set the rotary evaporator parameters to -310 Pa, 50°C, and rotary evaporate until nearly dry.

[0087] S4. Add 2 mL of acetonitrile to dissolve and shake the rotating bottle. Pass the sample through a 0.22 μm polypropylene needle filter, blow nitrogen to make the volume up to 1 mL, mix well and then test.

[0088] S6. Sample analysis and determination were performed according to the liquid chromatography and mass spectrometry parameter conditions of Example 1. When the extractant was methanol, acetonitrile, methyl tert-butyl ether, methanol-methyl tert-butyl ether with a volume ratio of 1:1, and acetonitrile-methyl tert-butyl ether with a volume ratio of 1:1, the test results of the spiked recovery rates of different perfluorinated substitutes were shown in Figure 3 .

[0089] Depend on Figure 3 It can be seen that in the rapid solvent extraction method, acetonitrile showed a good extraction effect for the selected perfluorinated substitutes, with the spiked recovery rate ranging from 70.4% to 82.4%. Methanol as an extractant has obvious advantages over acetonitrile, with the spiked recovery rate ranging from 79.5% to 92.7%. The spiked recovery rates of various extraction solvents are in the following order: acetonitrile + methyl tert-butyl ether > methanol + methyl tert-butyl ether > methanol > methyl tert-butyl ether > acetonitrile.

[0090] Depend on Figure 1-Figure 3 It can be concluded that the recovery rate when methanol is selected as the extraction solvent is significantly higher than when acetonitrile is used as the extraction solvent. Figure 1-3 The experimental results show that when methanol is selected as the extractant, the detection results of the spiked recoveries of different perfluorinated substitutes under three pretreatment methods, namely ultrasonic extraction, oscillation extraction and rapid solvent extraction, are shown in Figure 4 . Figure 4 It can be seen that the rapid solvent extraction method can extract perfluorinated substitutes from soil samples better than the other two pretreatment methods. The five perfluorinated substitutes selected in this experiment have good added recovery rates.

[0091] Example 5: A city in Zhejiang is an industrial cluster for chemical, electroplating, fire protection and other industries. The five perfluorinated substitutes in this study will be produced in large quantities and used as raw materials. Therefore, the present invention establishes a rapid solvent extraction detection method for perfluorinated substitutes in soil and sediments, which is very meaningful for finding out the residual distribution and source analysis of perfluorinated substitutes in the soil and river sediments around the investigated enterprises. The specific experimental steps are as follows:

[0092] S1. Sample collection: Use hand drill and shovel equipment to collect soil samples from the above area at 50 cm. During the collection process, remove the 0~20 cm sample, branches, debris and other interferences. Use a shovel to collect about 250 g of soil samples and put them into a polypropylene plastic bottle; Use a stainless steel grab bucket to collect soil samples 1m near the water sampling point 2 Sediment samples were collected from the range and placed in polypropylene plastic containers.

[0093] S2. Sample preparation: The collected samples are placed in a frozen blue ice incubator for transportation and storage, and then transported to the laboratory by flow transport. Foreign matter in the samples, such as branches, leaves, and stones, is removed, and the samples are dried by natural air drying or freeze drying. After the samples are dried, they are ground, homogenized, and sieved through a 60-mesh sample sieve.

[0094] S3. Sample analysis: Weigh about 10.0 g of the ground dry sample and mix it with diatomaceous earth in a mass ratio of 1:2, and place it in a rapid solvent extraction cell equipped with a glass fiber filter membrane.

[0095] S4. Set the parameters of the pressurized fluid extractor: extraction temperature 70°C; extraction pressure 1500 psi; static extraction time 5 min; flushing volume 60% of the extraction pool solvent; nitrogen purge time 60 s, cyclic extraction times 2 times. Collect and combine the two extracts after extraction.

[0096] S5. Add 50.0 μL of the internal standard containing 0.200 mg / L into the extraction cell. 13 C 4 PFOS and 0.200 mg / L 13 C 4 PFOA mixture, then cover the extraction pool with a metal cap and tighten it; place the extraction pool in a pressurized fluid extractor and use an extractant for pressurized extraction. The extractant is acetonitrile: methyl tert-butyl ether (volume ratio is 1:1). After the extraction is completed, the extract is collected and transferred to a rotating bottle. After rotating and evaporating until nearly dry, 2 mL of acetonitrile solution is added to shake the rotating bottle. The sample is passed through a 0.45 μm polypropylene needle filter, and the volume is adjusted to 1 mL with nitrogen blowing. 50.0 μL of the injection internal standard 0.200 mg / L is added. 13 C 2-PFOA, detected by ultra-high performance liquid chromatography tandem mass spectrometry. Samples were injected and analyzed according to the liquid chromatography and mass spectrometry parameter conditions of Example 1. The test results are shown in Tables 11 and 12.

[0097]

[0098]

[0099] As can be seen from Tables 11 and 12, the maximum value of 6:2Cl-PFAES detected in the soil of the surrounding plots of the industrial agglomeration area is 749μg / kg, and the maximum value of 6:2FTS is also 98.8μg / kg, which belongs to the electroplating industry. The two perfluorinated substitutes were detected 100%; Et-PFOA was not detected in soil and sediments. Although some samples of the other two OBS and PFOSA were also detected, the detection rate was not high. Therefore, the residual level in the soil cannot be ignored and deserves attention. Only 6:2Cl-PFAES was detected in the sediment, with a maximum value of only 0.35μg / kg. The other perfluorinated substitutes are currently below the detection limit of the method, indicating that 6:2Cl-PFAES in the soil will migrate to the river with surface runoff and atmospheric deposition. The current content of other perfluorinated substitutes is low and does not have the ability to migrate. The study found that the relative standard deviation of the parallel sample determination results was less than 10%, indicating that the detection method has good repeatability and is suitable for detecting the content of 5 perfluorinated substitutes in soil and sediments.

[0100] The contents described in this specification are merely an enumeration of implementation forms of the inventive concept, and the protection scope of the present invention should not be regarded as being limited to the specific forms described in the embodiments.

Claims

1. A rapid solvent extraction method for detecting perfluorinated substitutes in soil and sediments, characterized in that The following steps are involved: S1 Sample collection and pretreatment: Collect soil or sediment samples, store them in a refrigerator, remove foreign matter from the samples in the laboratory, dry them, grind them, and sieve them to obtain sample powder; S2 Sample analysis: Mix the sample powder with diatomaceous earth, put it into an extraction cell with a glass fiber filter membrane, add an isotope-labeled compound as an extraction internal standard into the extraction cell, and then cover the extraction cell with a metal cover and tighten it; put the extraction cell into a pressurized fluid extractor, use an extractant for pressurized extraction, then collect the extract, evaporate it to near dryness, re-dissolve it with a solvent, add the injection internal standard, and obtain a test solution; S3 Chromatographic Analysis: Finally, the qualitative and quantitative determination of perfluorinated substitutes was performed using a liquid chromatography-mass spectrometry method; The perfluorinated substitute is one or more of 6:2Cl-PFAES, 6:2FTS, OBS, and Et-PFOA, and the isotope-labeled compound includes 13 C4PFOS and / or 13 C4PFOA, 13 C4PFOA is an extracted internal standard used for detection of perfluorinated substitute Et-PFOA. 13 C4PFOS is a perfluorinated alternative to 6:2Cl-PFAES, 6:2FTS, and OBS for extraction and internal standard detection; The internal standard substance injected in step S2 is 13 C2-PFOA; The extractant is acetonitrile-methyl tert-butyl ether in a volume ratio of 1:1; In step S2, the pressurized extraction conditions are: extraction pressure 1500 psi, static extraction time 5 min, extraction temperature 60-70° C.; solvent flushing volume is 60% of the extraction cell volume; nitrogen purge time 60 s, static cycle times 2 times; In step S3, the liquid chromatography conditions are as follows: chromatographic column: Shim-pack GIST-HP C18 chromatographic column, particle size 3 μm, column length 100 mm, inner diameter 2.1 mm; methanol and 2 mmol / L ammonium acetate aqueous solution are used as mobile phase A and mobile phase B, respectively, and the elution degree is as follows: 0-5min, 30%-65%A; 5-9min, 65%-95%A; 9-11min, 95%A; 11.1-12min, 30%A; In step S3, the mass spectrometry conditions are: electrospray ESI ion source, negative ion mode; monitoring mode: multiple reaction monitoring; capillary voltage 3000 V; vacuum interface temperature 300 °C; heating block temperature 400 °C; nebulizing gas flow rate 3.0 L / min; drying gas flow rate 10 L / min; heating gas flow rate 10 L / min; collision gas flow rate 0.25 ml / min.

2. A rapid solvent extraction detection method for perfluorinated substitutes in soil and sediments as claimed in claim 1, characterized in that In step S1, the foreign matter includes branches, leaves and stones in the sample, and the sample is dried by natural air drying or freeze drying, and the mesh size of the sieve is 60-100 meshes.

3. A rapid solvent extraction detection method for perfluorinated substitutes in soil and sediments as claimed in claim 1, characterized in that The solvent used for re-dissolution in step S2 is acetonitrile or methanol.

Images