Selective separation of polybrominated diphenyl ethers from soil extracts using 13X molecular sieves
By using 13X molecular sieve as solid-phase extraction adsorbent, the problems of complex operations and matrix interference during the extraction and purification of polybrominated diphenyl ethers in the soil are solved, and the accurate determination and purification of polybrominated diphenyl ethers are achieved, reducing costs and time, and environmentally friendly.
Patent Information
- Application Number
- CN202111117246.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2021-09-23
- Publication Date
- 2024-12-06
- Estimated Expiration
- 2041-09-23
AI Technical Summary
The prior art has problems such as complex operation, long time consumption and large matrix interference in the extraction and purification of polybrominated diphenyl ethers in soil, making it difficult to achieve accurate measurement.
Using 13X molecular sieve as solid-phase extraction adsorbent, polybrominated diphenyl ether is extracted by Soxhlet extraction or pressurized solvent extraction, and purified by glass solid-phase extraction column and specific solvents, including filling, activation, loading, rinsing and elution Steps: Purification is performed using the selective adsorption characteristics of the 13X molecular sieve.
The selective separation and purification of polybrominated diphenyl ethers in the soil is achieved, the matrix effect is reduced, the accuracy of the measurement is ensured, time and labor costs are saved, and environmentally friendly.
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Abstract
Description
Technical Field
[0001] The present invention belongs to the technical field of extraction and purification of organic pollutants in environmental samples, and particularly relates to a method for selectively separating polybrominated diphenyl ethers in soil extracts based on 13X molecular sieve as a solid phase extraction adsorbent. Background Art
[0002] Polybrominated diphenyl ethers (PBDEs) are among the most widely used brominated flame retardants, widely used in electronics, building materials, furniture, foams, textiles, and automotive parts. Common commercial mixtures include pentabromodiphenyl ether, octabromodiphenyl ether, and decabromodiphenyl ether. Commercial pentabromodiphenyl ether and octabromodiphenyl ether were officially listed as persistent organic pollutants (POPs) under the Stockholm Convention by the United Nations Environment Programme in May 2009. Decabromodiphenyl ether was also added to the Stockholm Convention's controlled list as a POP in 2017. PBDEs are toxic, bioaccumulative, extremely stable, and persistent, making them a major challenge in environmental pollution control. Due to their strong lipophilicity, adsorption, and volatility, PBDEs easily accumulate in environmental media such as soil and in organisms. Soil not only serves as a sink for PBDEs but can also act as a source for secondary releases. PBDE contamination in soil can easily lead to the accumulation of PBDEs in plants and animals, and spread to other environmental media through water leaching, soil erosion, and surface runoff. They are then taken up by organisms in various ways, passed down the food chain, and ingested by humans, posing a threat to human health. Soil is a mixture of minerals and organic matter, with minerals being the main component and organic matter accounting for only 1-10%. It is reported that the content of polybrominated diphenyl ethers in soil is mostly at the ng / g concentration level. [1-3] Therefore, in order to achieve accurate determination of polybrominated diphenyl ethers in soil, the purification process is crucial. To this end, multilayer silica gel columns have been reported in the literature. [4] and gel purification chromatography (GPC) columns [5-7] Although it can effectively remove macromolecules such as pigments and lipids and reduce matrix interference, it has problems such as complex operation, large amount of organic solvents, and long time consumption.
[0003] Zeolite molecular sieves are a type of porous aluminosilicate material with a complete skeleton structure and a uniform pore structure. They can be divided into microporous molecular sieves (d < 2nm), medium-pore molecular sieves (2nm ≤ d ≤ 50nm) and large-pore molecular sieves (d ≥ 50nm) according to the pore size. For molecular sieves with the same skeleton structure, they can be divided into X-type molecular sieves (2.2 ≤ Si / Al ≤ 3) and Y-type molecular sieves (Si / Al ≥ 3) according to the different silicon-aluminum ratios. The application of zeolite molecular sieves is mainly reflected in two aspects: (1) selective adsorption based on the size of the pores inside the crystal, usually used for the separation of organic matter in the gas phase; (2) widely used in catalytic cracking, hydrocracking and oil refining. X molecular sieve is a zeolite molecular sieve with a low silicon-aluminum ratio. Because it is easy to synthesize, has a large surface area, good hydrophilicity, and has good ion exchange and adsorption properties, it has been widely used in drying and separation. For example, X molecular sieve is often used to adsorb heavy metal ions in industrial wastewater and exhaust emissions from automobiles, but there have been no reports on its use in the purification of persistent organic pollutants in the environment. [8][9] . Summary of the Invention
[0004] The purpose of the present invention is to establish a purification method for selectively separating polybrominated diphenyl ethers in soil extracts using 13X molecular sieve as a solid phase extraction adsorbent.
[0005] To achieve the above object, the technical solution adopted by the present invention is: a method for purifying polybrominated diphenyl ethers in soil, comprising the following steps:
[0006] 1. Extraction and concentration
[0007] Soxhlet or pressurized solvent extraction was used to extract polybrominated diphenyl ethers from soil, using either n-hexane, dichloromethane, acetone, or a mixture thereof. The extract was concentrated by rotary evaporation or nitrogen purge and then replaced with a specific solvent, which was n-hexane, pentane, or petroleum ether.
[0008] 2. Purification
[0009] (1) Filling the solid phase extraction column: Select a glass solid phase extraction column, and the volume ratio of the sample solvent to the solid phase extraction column should not be higher than 2:3; install the fiber sieve plate into the glass solid phase extraction column, and fill anhydrous sodium sulfate, 13X molecular sieve and anhydrous sodium sulfate from bottom to top, and finally use the fiber sieve plate to compact; the mass ratio of the upper layer of anhydrous sodium sulfate to the 13X molecular sieve, and the mass ratio of the upper and lower layers of anhydrous sodium sulfate should not be less than 1.
[0010] (2) Activation: Activate the solid phase extraction column using a specific solvent that is more than 1 times the volume of the solid phase extraction column;
[0011] (3) Sampling: Add the concentrated soil extract to the solid phase extraction column, wash the round-bottom flask with 1-2 mL of n-hexane, combine and load the sample, and discard the effluent;
[0012] (4) Elution: Use n-hexane for elution; the ratio of eluent to 13X molecular sieve should not exceed 5 mL:1 g; discard the eluent;
[0013] (5) Elution: Use a mixed solution of dichloromethane and a specific solvent for elution; the volume ratio of dichloromethane to the specific solvent is not greater than 2:15, and the ratio of the eluent to the 13X molecular sieve is not less than 20 mL:1 g; collect the eluent in a glass centrifuge tube;
[0014] (6) Concentration: The eluate was dried by nitrogen gas and reconstituted with a suitable solvent for testing.
[0015] Beneficial Effects of the Invention The present invention uses 13X molecular sieve as a solid phase extraction adsorbent to remove macromolecules such as lipids and pigments in the soil. On the one hand, it greatly reduces the matrix effect of the soil and ensures the accuracy of the polybrominated diphenyl ether determination; on the other hand, it saves time and labor costs and is more environmentally friendly. BRIEF DESCRIPTION OF THE DRAWINGS
[0016] Figure 1 is the elution curve of polybrominated diphenyl ether on 13X molecular sieve;
[0017] Figure 2 This is the gel permeation chromatogram of the soil extract before and after purification by 13X molecular sieve solid phase extraction;
[0018] Figure 3 This is the gel chromatogram of the soil sample extract before 13X molecular sieve solid phase extraction purification. DETAILED DESCRIPTION
[0019] The present invention will be further described in detail below with reference to the accompanying drawings.
[0020] The 27 isomers of polybrominated diphenyl ethers contained in the polybrominated diphenyl ether mixed standard BDE-MXE are divided into three groups according to their concentration: BDE-3, 7, 15, 17, 28, 47, 49, 66, 71, 77, 85, 99, 100, 119, 126 (1 μg / mL); BDE-138, 153, 154, 156, 183, 184, 191, 196, 197 (2 μg / mL); BDE-206, 207, 209 (5 μg / mL).
[0021] Example 1:
[0022] (1) Weigh 1 g of 13X molecular sieve and place it into a 3 mL solid phase extraction glass column. Use fiber sieve plates to compact the upper and lower ends of the 13X molecular sieve.
[0023] (2) Activation: Use 3*3 mL of n-hexane to activate the solid phase extraction column;
[0024] (3) Sample loading: Measure 100 μL of the polybrominated diphenyl ether mixed standard sample and place it in a sample bottle. Dilute it with 900 μL of n-hexane and then load it. At the same time, wash the sample bottle with 1 mL of n-hexane and then combine and load it. Collect the loaded fraction in a glass centrifuge tube and record it as F0.
[0025] (4) Elution: Use 2*5 mL of n-hexane and 3*5 mL of dichloromethane for elution in sequence, and collect the eluted fractions in glass centrifuge tubes, which are recorded as F1-F5.
[0026] (5) Concentration: Each fraction F0-F5 was blown to near dryness with nitrogen, and then concentrated to 1 mL by adding n-hexane. The fractions were then detected by GC-MS / MS.
[0027] from Figure 1 The following conclusions can be drawn: When using 1g of molecular sieve as an adsorbent, there was no breakthrough during sample loading, and no target product was eluted using 5mL of n-hexane. Further elution with n-hexane did result in target product elution. Therefore, when using 1g of 13X molecular sieve as a solid-phase extraction adsorbent, 5mL of n-hexane is the optimal elution solvent.
[0028] Example 2:
[0029] (1) Weigh 1 g of 13X molecular sieve and load it into five 3 mL solid phase extraction glass columns. Use fiber sieve plates to compact the upper and lower ends of the 13X molecular sieve.
[0030] (2) Activation: Use 3*3mL n-hexane to activate the solid phase extraction column;
[0031] (3) Sample loading: 12 mg of corn oil was measured and diluted with 1 mL of n-hexane, and then loaded onto 5 solid phase extraction columns. At the same time, the sample bottles were washed with 1 mL of n-hexane and then combined and loaded, and the effluent was discarded.
[0032] (4) Washing: Wash five solid phase extraction columns with 5 mL of n-hexane, and discard the washing solution;
[0033] (5) Elution: 5 solid phase extraction columns were eluted with 40 mL of a dichloromethane-n-hexane mixed solvent with a volume ratio of 1:9, 2:15, 1:7, 1:6, and 1:0, respectively, and the eluents were collected;
[0034] (5) Concentration: The five eluates were blown to near dryness with nitrogen, and then concentrated to 1 mL by adding n-hexane. The eluates were then detected by GC-MS / MS.
[0035] From Table 1, it can be seen that elution with a dichloromethane-n-hexane mixed solvent with a volume ratio of no more than 2:15 can retain the oil on the solid phase extraction adsorbent.
[0036] Table 1 Effect of elution solvent ratio on elution effect of oil on 13X molecular sieve
[0037] Eluent volume ratio (dichloromethane:n-hexane) Oil elution mass percentage 1:09 0 2:15 0 1:07 36.0 1:06 38.0 1:00 47.9
[0038] Example 3:
[0039] (1) Weigh 1 g of 13X molecular sieve and place it into a 3 mL solid phase extraction glass column. Use fiber sieve plates to compact the upper and lower ends of the 13X molecular sieve.
[0040] (2) Activation: Use 3*3 mL of n-hexane to activate the solid phase extraction column;
[0041] (3) Sample loading: Measure 100 μL of 1 μg / mL polybrominated diphenyl ether mixed standard (BDE-MXE) into a sample vial, dilute with 900 μL of n-hexane, and then load the sample; at the same time, wash the sample vial with 1 mL of n-hexane, combine the sample, and discard the flow-through.
[0042] (4) Eluent: Use 5 mL of n-hexane for elution and discard the eluent;
[0043] (5) Elution: 4*10 mL of a dichloromethane-n-hexane mixed solvent with a volume ratio of 2:15 was used for elution, and the eluted solutions were collected and recorded as F6-F9.
[0044] (6) Concentration: Each fraction F6-F9 was blown to near dryness with nitrogen, and then concentrated to 1 mL by adding n-hexane. The fractions were then detected by GC-MS / MS internal standard method.
[0045] As can be seen from Table 2, 20 mL of a dichloromethane-n-hexane mixed solvent with a volume ratio of 2:15 can effectively elute the polybrominated diphenyl ethers retained on the molecular sieve; further increasing the amount of elution solvent will not significantly improve the elution effect.
[0046]
[0047]
[0048] Example 4:
[0049] (1) Weigh 1 g of 13X molecular sieve and place it into a 3 mL solid phase extraction glass column. Use fiber sieve plates to compact the upper and lower ends of the 13X molecular sieve.
[0050] (2) Activation: Use 3*3 mL of n-hexane to activate the solid phase extraction column;
[0051] (3) Sample loading: Measure 100 μL of 1 μg / mL polybrominated diphenyl ether mixed standard into a sample vial, dilute with 900 μL of n-hexane, and then load the sample; at the same time, wash the sample vial with 1 mL of n-hexane, combine the sample, and discard the flow-through.
[0052] (4) Eluent: Use 5 mL of n-hexane for elution and discard the eluent;
[0053] (5) Elution: Sequentially use 4*10 mL of a dichloromethane-n-hexane mixed solvent with a volume ratio of 1:9 for elution, and collect the eluted solutions, which are recorded as F10-F13;
[0054] (6) Concentration: Each fraction F10-F13 was blown to near dryness with nitrogen, and then concentrated to 1 mL by adding n-hexane. The fractions were then detected by GC-MS / MS internal standard method.
[0055] As shown in Table 3, 20 mL of a 1:9 dichloromethane-n-hexane mixture effectively eluted PBDEs retained on the molecular sieve; further increasing the amount of elution solvent did not significantly improve the elution effect. Comparing Tables 2 and 3, 20 mL of a 2:15 dichloromethane-n-hexane mixture was more conducive to the selective elution of PBDEs and oils.
[0056]
[0057]
[0058] Example 5: 13X molecular sieve as a solid phase extraction adsorbent for the purification of polybrominated diphenyl ethers in soil
[0059] 1. Extraction and concentration
[0060] Weigh 5-10 g of soil, add an appropriate amount of diatomaceous earth, and grind it into quicksand. Place it in an extraction cell and use n-hexane / acetone (1:1) for pressurized fluid extraction. The static cycle time is 10 min, and the cycle is repeated 3 times. The extraction pressure is 1500 psi and the extraction temperature is 100°C. The extract is concentrated by rotary evaporation, and the solvent is replaced with n-hexane.
[0061] 2. Purification
[0062] (1) Filling the solid phase extraction column: Place the fiber frit into a 3 mL glass solid phase extraction column, and fill it with an appropriate amount of anhydrous sodium sulfate, 1 g of molecular sieve, and an appropriate amount of anhydrous sodium sulfate from bottom to top, and compact the fiber frit;
[0063] (2) Activation: Activate the solid phase extraction column with 6 mL of n-hexane;
[0064] (3) Sampling: Add the concentrated soil extract to the solid phase extraction column, wash the round-bottom flask with 1-2 mL of n-hexane, combine and load the sample, and discard the effluent;
[0065] (4) Eluent: Use 5 mL of n-hexane for elution and discard the eluent;
[0066] (5) Elution: Use 20 mL of a dichloromethane-n-hexane mixed solvent with a volume ratio of 2:15 for elution, and collect the eluate;
[0067] (6) Concentration and reconstitution: The eluate was blown dry by nitrogen and reconstituted by adding 2 mL of dichloromethane.
[0068] (7) Gel permeation chromatography was used for determination, with dichloromethane as the mobile phase, a flow rate of 5 mL / min, and an analysis time of 60 min.
[0069] from Figure 2 It can be seen that the color of the soil extract changes significantly before and after molecular sieve purification, and the pigments are effectively removed. Figure 3 It can be seen that after a simple solid phase extraction, the lipids in the soil extract can be effectively removed, and the degreasing efficiency can reach 95%.
[0070] References
[0071] [1] Oloruntoba K, Sindiku O, Osibanjo O, et al. Polybrominated diphenylethers (PBDES) concentrations in soil and plants around municipal dumpsites in Abuja, Nigeria [J]. Environmental Pollution, 2021, 277(6): 116794.
[0072] [2] Leung AOW, Luksemburg WJ, Wong AS, et al. Spatial Distribution of Polybrominated Diphenyl Ethers and Polychlorinated Dibenzo-p-dioxins and Dibenzofurans in Soil and Combusted Residue at Guiyu,an Electronic Waste Recycling Site in Southeast China[J].Environmental Science&Technology,2007,41(8):2730-2737.
[0073] [3] Zou Mengyao, Gong Jian, Ran Yong. Distribution and environmental behavior of polybrominated diphenyl ethers (PBDEs) in soils of the Pearl River Delta Basin [J]. Journal of Ecology and Environment, 2009, 18(01): 122-127.
[0074] [4]Chakraborty P, Selvaraj S, Nakamura M, et al. PCBs and PCDD / Fs in soil from informal e-waste recycling sites and open dumpsites in India: Levels, congener profiles and health risk assessment [J]. Science of The Total Environment, 2018, 621: 930-938.
[0075] [5] Niu He, Yu Binbin, Rao Qinquan, et al. Analysis of polybrominated diphenyl ether compounds in soil by high performance liquid chromatography tandem mass spectrometry [J]. China Environmental Monitoring, 2019, 35(06): 118-123.
[0076] [6] Yu Binbin, Fang Cheng, Rao Qinquan, et al. Analysis of polybrominated biphenyls and polybrominated diphenyl ethers in soil by gas chromatography-mass spectrometry [J]. Analytical Chemistry, 2011, 39(06): 833-838.
[0077] [7] A method for detecting twelve polybrominated diphenyl ethers in soil, CN110068634B, Yang Jing, Zhao Dandan, Li Yue, Sun Pei, Luo Dongmei, Liu Min, 2020.07.17.
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[0079] [9] Peng Xiuda, Zhang Gang, Liu Hong, et al. Removal of heavy metal ions Cr from water using 13X molecular sieve 3+ [J]. Environmental Science and Technology, 2013, 36(07): 99-103+190.
Claims
1. A method for selectively separating polybrominated diphenyl ethers from soil extract using 13X molecular sieve as a solid phase extraction adsorbent, characterized in that: (1) Concentrating the soil extract and replacing it with a specific solvent; (2) Select a glass solid phase extraction column filled with 13X molecular sieve, and the volume ratio of the sample solution to the solid phase extraction column is not higher than 2:3; (3) activating the filled solid phase extraction column with a specific solvent that is more than 1 times the volume of the solid phase extraction column; (4) Using a specific solvent as eluent to remove interfering substances; the ratio of 13X molecular sieve to eluent is not less than 1g:5mL; (5) Using a mixed solution of dichloromethane and a specific solvent as an eluent to elute polybrominated diphenyl ethers; the volume ratio of dichloromethane to the specific solvent is not greater than 2:15, and the ratio of 13X molecular sieve to eluent is not greater than 1 g:20 mL; The specific solvent is selected from n-hexane, pentane and petroleum ether.
2. The selective separation method according to claim 1, characterized in that: In step (1), the soil extract solvent includes one or more of n-hexane, dichloromethane, and acetone.
3. The selective separation method according to claim 1, characterized in that: In step (2), the solid phase extraction column is filled in the order of anhydrous sodium sulfate, 13X molecular sieve and anhydrous sodium sulfate from bottom to top, and the mass ratio of the upper layer of anhydrous sodium sulfate to the 13X molecular sieve and the mass ratio of the upper and lower layers of anhydrous sodium sulfate are not less than 1.
4. The selective separation method according to claim 1, characterized in that: In step (1), the soil extract can be concentrated by rotary evaporation or nitrogen purging.