Method for automatically extracting polybrominated organic pollutants in bottom mud sample

Abstract

The invention provides a method for automatically extracting polybrominated organic pollutants in a bottom mud sample, which comprises the following steps: step 1, collecting the bottom mud sample, wrapping the bottom mud sample with an aluminum foil, and performing low-temperature cryopreservation; 2, freeze-drying the sample by using a freeze-drying machine, and then sieving by using a metal sieve to remove impurities; step 3, performing parameter and process setting on an automatic sample pretreatment system built in a laboratory; 4, mixing the pretreated bottom mud with diatomite, filling the mixture into a stainless steel extraction pool, placing a filter membrane at the bottom of the pool body, placing the pool body into a sample extraction position of an accelerated solvent extraction instrument, and extracting a sample to obtain a bottom mud extracting solution; step 5, each time one sample is extracted, the obtained extracting solution is automatically transferred to a full-automatic gel purification quantitative concentration system instrument by a mechanical arm to be concentrated and dissolved, and then is transferred and submitted to a gel permeation chromatography by a sample injection needle of the instrument; step 6, concentrating the extracting solution, and eluting and purifying by using gel permeation chromatography; and 7, introducing the concentrated solution purified by the gel permeation chromatography into a concentrator through an internal pipeline, concentrating in two modes of pressure reduction and heating, and finally transferring the concentrated solution into a brown small sample injection bottle through a sample injection needle to obtain an extracting solution of the sample. The invention aims to provide a method for efficiently and quickly extracting brominated organic pollutants in bottom mud, manual operation is less, the sample pretreatment time is shortened, the extraction efficiency is improved, and convenience is provided for subsequent compound analysis and identification.

Description

Technical Field

[0001] The present invention relates to the technical field of environmental organic pollutant analysis and detection, and in particular to a method for automatically extracting polybrominated organic pollutants from sediment samples. Background Art

[0002] Polybrominated organic compounds (such as tetrabromobisphenol A and polybrominated diphenyl ethers) play an important role in human industrial activities and are widely used in industrial fields such as flame retardants, electronic products, pesticides, etc. Due to their difficulty in degradation, easy bioaccumulation and toxicity, these compounds have become a class of pollutants that are potentially harmful to the environment and health, and have been detected in a variety of environmental media. As an important sink for brominated organic pollutants, river sediments are not only the main storage reservoir for these harmful substances, but also provide a long-term sedimentation environment for their diffusion and accumulation in water bodies. Therefore, river sediments have become an important medium for studying the distribution and environmental behavior of brominated organic pollutants.

[0003] At present, although the research on brominated organic compounds in sediments has received increasing attention, the existing extraction methods (such as Soxhlet extraction, solid phase extraction, ultrasonic extraction, and microwave-assisted extraction) still have many problems, such as long time consumption, large amount of solvent usage, cumbersome operation, and low extraction efficiency, which seriously limit the subsequent compound detection and analysis, and also limit the extensiveness and economy of its application in large-scale sample processing. Therefore, the development of a fast and efficient extraction method will not only help improve the accuracy and reliability of detection, but also provide solid technical support for a better understanding of the types, distribution, and occurrence forms of brominated organic pollutants in the environment, which is of great significance for assessing the ecological risks of brominated organic compounds in the environment. Summary of the invention

[0004] In view of the shortcomings of existing methods in extracting brominated organic pollutants, such as long extraction time, large solvent consumption and low extraction efficiency, the purpose of the present invention is to provide a method for extracting brominated organic pollutants in sediment with high efficiency and rapidity, which reduces manual operation, shortens the time for sample pretreatment, improves the extraction efficiency and facilitates subsequent compound analysis and identification.

[0005] In order to solve the above technical problems, the technical solution adopted in this application is:

[0006] A method for automatically extracting polybrominated organic pollutants from sediment samples comprises the following steps:

[0007] Step 1: Collect sediment samples, wrap them in aluminum foil, and store them at low temperatures;

[0008] Step 2: Freeze-dry the sample using a freeze dryer and then sieve it with a metal sieve to remove impurities;

[0009] Step 3: Building an automated sample pretreatment system and setting up an automated processing flow of the automated sample pretreatment system; wherein:

[0010] The automated sample pretreatment system includes an accelerated solvent extractor (ASE), a concentrator, a fully automated gel purification quantitative concentration system instrument, a robotic arm, and an intelligent processing terminal; the fully automated gel purification quantitative concentration system instrument includes an injection needle, a concentration chamber, and a gel permeation chromatography (GPC) module; the intelligent processing terminal is used to receive an automated processing flow and control the automated sample pretreatment system according to the automated processing flow to complete automated operations of sample extraction, enrichment, purification, concentration, and volume determination;

[0011] Step 4: Mix the sediment sample in step 2 with diatomaceous earth, and then load it into the stainless steel extraction tank of the accelerated solvent extractor, place a filter membrane at the bottom of the extraction tank, put it into the sample extraction position of the accelerated solvent extractor, extract the sample, and obtain a sediment extract;

[0012] Step 5: After each sediment extract of step 4 is extracted, the extract is automatically transferred to the heating platform of the concentrator by the robotic arm, and then the robotic arm automatically transfers the sample bottle of the extract to the fully automatic gel purification quantitative concentration system instrument, and the sampling needle of the fully automatic gel purification quantitative concentration system instrument draws the extract and transfers it to the concentration chamber for quantitative concentration, and then the sampling needle transfers it to the gel permeation chromatography module for elution and purification;

[0013] Step 6: The concentrated solution purified by the gel permeation chromatography module is introduced into the concentrator through the internal pipeline, concentrated by two modes of decompression and heating, and finally transferred to a brown injection vial by an injection needle to obtain the final sample extract.

[0014] Preferably, the extraction parameters of the accelerated solvent extractor are set as follows: extraction pressure is 10 MPa; extraction temperature is 100°C; extraction time is 300s; extraction cycle number is 3 times; heating time is 300s; each solvent elution volume is 60%; and solvent collection time is 90s.

[0015] Preferably, in step 4, the mass of the sludge is 5 g, the mass of the diatomaceous earth is 6 g, the volume of the sample pool is 22 mL, the extraction solvent is a mixed solvent of dichloromethane and acetone, the volume ratio is 1:1, and the amount of solvent used is about 50 mL.

[0016] Preferably, the elution solvent of the gel permeation chromatography module is a mixed solvent of ethyl acetate and cyclohexane in a volume ratio of 1:1, and the elution flow rate is 5 min / mL.

[0017] Preferably, the concentrated volume-fixing solvent in step 6 is methanol, and the volume-fixing volume is 1 mL.

[0018] Preferably, the method further comprises detecting and analyzing the sample extract using a liquid chromatography-high resolution mass spectrometer (LC-HRMS), wherein the liquid chromatography mobile phase in the liquid chromatography-high resolution mass spectrometer is pure water and methanol, and 1 mM / L ammonium acetate is added as a mobile phase additive, and the liquid phase elution procedure is as follows: the initial ratio of the aqueous phase to the organic phase is 80:20 (v:v); gradually changes to 60:40 (v:v) within 3 minutes, gradually changes to 50:50 (v:v) within 8 minutes, and gradually changes to 30:40 (v:v) within 12 minutes. :70 (v:v); gradually changed to 20:80 (v:v) within 15min and maintained for 3min; gradually changed to 100% organic phase within 19min and maintained for 2min; then restored to the initial ratio of 80:20 (v:v) within 0.1min and maintained for 3.9min; the detection conditions were negative ion full scan mode, and the ion source parameters were set as follows: sheath gas was 35psi; auxiliary gas was 10psi; backblowing gas was 0; spray voltage was 3.3KV; ion transfer tube temperature was 320℃; heating temperature was 350℃.

[0019] Compared with the prior art, the beneficial technical effects of this application are:

[0020] An efficient and rapid automated extraction method for polybrominated organic pollutants in sediment has been established: the extraction method used in the present invention is rapid, efficient, and concise, and can extract 24 samples at a time, while greatly reducing the time and process of manual operation. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0022] Figure 1 : Schematic diagram of the self-built automated sample pretreatment system.

[0023] Figure 2 : Instrumental parameters for the accelerated solvent extraction method.

[0024] Figure 3 : Flow chart of the experiment applied for the present invention.

[0025] Figure 4 : Absolute recoveries and matrix effect results of 15 polybrominated organic compound pretreatment methods of the present invention. DETAILED DESCRIPTION

[0026] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0027] In combination with 2-4 of the present application, a method for extracting brominated organic pollutants from a sediment sample of the present application comprises the following steps:

[0028] Step 1: Collect sediment samples, wrap them in aluminum foil, and store them at low temperature.

[0029] Step 2: Freeze-dry the sample using a freeze dryer and then sieve it through a metal sieve to remove impurities.

[0030] Step 3: Set parameters and processes for the automated sample pretreatment system built in the laboratory, which is part of the fully automatic biological evaluation and chemical analysis all-in-one machine (patent number CN 110333364 A).

[0031] Step 4: Mix the pretreated sediment with diatomaceous earth, and then load it into a stainless steel extraction tank. Place a filter membrane at the bottom of the tank, and put it into the sample extraction position of the accelerated solvent extraction (ASE). Extract the sample to obtain a sediment extract.

[0032] Step 5: After each sample is extracted, the obtained extract is automatically transferred by the robotic arm to the fully automatic gel purification quantitative concentration system instrument for concentration and dissolution, and then transferred by the instrument injection needle to the gel permeation chromatography (GPC).

[0033] Step 6: After the extract is concentrated, it is purified by GPC elution.

[0034] Step 7: The concentrated liquid after GPC purification is introduced into the concentrator through the internal pipeline, concentrated by two modes of decompression and heating, and finally transferred to the brown injection vial by the injection needle to obtain the sample extract.

[0035] In a specific embodiment of the present application, Figure 1 As shown, the automated sample pretreatment system includes an accelerated solvent extractor (ASE) 1, a concentrator 2, a fully automatic gel purification quantitative concentration system instrument 3, a robotic arm 4 and a computer workstation 5. The fully automatic gel purification quantitative concentration system instrument 3 includes a sample injection needle 6, a concentration chamber 7 and a gel permeation chromatography (GPC) module 8. The pretreatment system integrates the accelerated solvent extractor 1, the robotic arm 4 and the fully automatic gel purification quantitative concentration system instrument 3, and the computer workstation 5 performs instrument control and method editing to complete the automated operation of the sample from extraction, enrichment, purification to concentration and volume setting. The accelerated solvent extractor 1 independently performs instrument operation and method editing, and the operation and method editing of the robotic arm 4 and the fully automatic gel purification quantitative concentration system instrument 3 are controlled by the computer workstation 5. The specific operation process is: the accelerated solvent extractor 1 extracts the sample loaded into the extraction pool, and then the robotic arm 4 automatically transfers the sample bottle of the extract to the heating table of the concentrator 2, and then the robotic arm 4 transfers the sample bottle of the extract to the sample position of the fully automatic gel purification quantitative concentration system instrument 3, and the fully automatic gel purification quantitative concentration system instrument 3 completes the enrichment, purification, concentration and volume determination operations on the sample, and the entire process is completed by instrument automation.

[0036] Furthermore, in step 3, the extraction parameters of the accelerated solvent extractor are set as follows: extraction pressure is 10 MPa; extraction temperature is 100° C.; extraction time is 300 s; extraction cycle number is 3 times; heating time is 300 s; each solvent elution volume is 60%; solvent collection time is 90 s;

[0037] Furthermore, in step 4, the mass of the bottom mud is 5 g, the mass of the diatomaceous earth is 6 g, and the volume specification of the sample pool is 22 mL. The extraction solvent is a mixed solvent of dichloromethane and acetone, and the volume ratio is 1:1. The amount of solvent used is about 50 mL.

[0038] Furthermore, in step 6, the elution solvent is a mixed solvent of ethyl acetate and cyclohexane in a volume ratio of 1:1, and the elution flow rate is 5 min / mL.

[0039] Furthermore, in step 7, the constant volume solvent is methanol, and the constant volume is 1 mL.

[0040] Furthermore, it also includes step 8: using a liquid chromatography-high resolution mass spectrometer to detect and analyze the sample extract. The instrument in step 8 is a liquid chromatography-high resolution mass spectrometer (LC-HRMS), the liquid chromatography mobile phase is pure water and methanol, and 1mM / L ammonium acetate is added as a mobile phase additive, wherein the liquid phase elution procedure is as follows: the initial water phase and organic phase ratio is 80:20; gradually changes to 60:40 within 3 minutes, gradually changes to 50:50 within 8 minutes, and gradually changes to 30:70 within 12 minutes; gradually changes to 20:80 within 15 minutes, and keeps for 3 minutes; gradually changes to 100% organic phase within 19 minutes and keeps for 2 minutes; then returns to the initial ratio (80:20) in 0.1 minutes and keeps for 3.9 minutes.

[0041] Furthermore, the detection conditions in step 8 are: negative ion full scan mode (Full scan). The ion source parameters are set as follows: 1) sheath gas: 35psi; 2) aux gas: 10psi; 3) sweep gas: 0; 4) spray voltage: 3.3KV; 5) capillary temperature: 320°C; 6) heater temperature: 350°C.

[0042] The present application is further described below in conjunction with embodiments:

[0043] Example 1: Extraction and analysis of 15 polybrominated organic compounds.

[0044] In this example, 15 polybrominated organic compound standards were added to the sample to establish an automated method for the extraction and pretreatment of polybrominated organic compounds. The basic information of the 15 polybrominated organic compound standards is shown in Table 1:

[0045] Table 1. Structural formula, detection mode and ion mass number of 15 bromides

[0046]

[0047]

[0048] The specific experimental steps are as follows:

[0049] Step 1: Wrap the collected river sediment samples with aluminum foil and place them in a -20°C refrigerator for freezing. After freeze-drying them in a freeze dryer for 7 days, sieve the samples with a 60-mesh metal sieve.

[0050] Step 2, setting the instrument parameters of the accelerated solvent extractor, including: extraction pressure of 10 MPa; extraction temperature of 100°C; extraction time of 300 s; extraction cycle number of 3 times; heating time of 300 s; each solvent elution volume of 60%; solvent collection time of 90 s;

[0051] Step 3: Extract the sample using an accelerated solvent extractor, specifically: Mix 5g of the sediment sample obtained in step 1 with 6g of diatomaceous earth, add it to a 22mL stainless steel extraction pool, add a copper rod to the pool for sulfur removal, set up three identical parallel samples, numbered A1, A2, and A3, and add 25ng of 15 polybrominated organic compounds to the sample numbered A2 before extraction for correction of absolute recovery and matrix effect. A mixed solvent of dichloromethane and acetone (1:1, v:v) was used as the extraction solvent.

[0052] Step 4: The extract obtained in step 3 is enriched, purified, concentrated, and dissolved using a fully automatic gel purification and quantitative concentration system instrument. Specifically, the extract is transferred from the instrument injection needle to the instrument concentration chamber by vacuum negative pressure for reduced pressure distillation, and redissolved using a mixed solvent of ethyl acetate and cyclohexane (1:1, v:v), and then injected into gel permeation chromatography (GPC) by the instrument injection needle for purification, and eluted using a mixed solvent of ethyl acetate and cyclohexane (1:1, v:v). The eluent flow rate is 5 mL / min, and the 25-85 mL of eluent is collected and distilled in the concentration chamber under reduced pressure. After the eluent is concentrated to dryness, it is fixed to volume with 1 mL of methanol and transferred to a brown injection vial, and then 25 ng of 15 polybrominated organic mixed standards are added to the sample numbered A3.

[0053] Step 5: prepare a concentration gradient solution of a mixed standard of polybrominated organic compounds, the concentration gradient is 0.01, 0.025, 0.05, 0.1, 0.25, 0.5, 1, 2.5, 5, 10, 25, 50, 100 ng / mL, and use liquid chromatography-high resolution mass spectrometry (LC-QE) to detect and analyze the sample and standard concentration gradient solution obtained in step 4. The liquid chromatography mobile phase is ultrapure water and methanol, and 1 mM ammonium acetate is added as an additive. The mobile phase elution gradient is as follows: the initial ratio of aqueous phase to organic phase is 80:20; gradually change to 60:40 within 3 minutes, gradually change to 50:50 within 8 minutes, gradually change to 30:70 within 12 minutes; gradually change to 20:80 within 15 minutes, and keep for 3 minutes; gradually change to 100% organic phase within 19 minutes and keep for 2 minutes; then restore to the initial ratio (80:20) in 0.1 minutes and keep for 3.9 minutes. The injection volume was 1 μL, the column oven temperature was 40°C, and the mobile phase flow rate was 0.3 mL / min. The mass spectrometry detection mode was negative ion full scan mode, and the ion source parameters were: 1) sheath gas: 35 psi; 2) aux gas: 10 psi; 3) sweep gas: 0; 4) spray voltage: 3.3 KV; 5) capillary temperature: 320°C; 6) heater temperature: 350°C.

[0054] Step 6. Calculate the absolute recovery rate and matrix effect of polybrominated organic compound standards in the sediment according to the external standard method, and draw a standard curve of the gradient concentration of the polybrominated organic compound mixed standard, as shown in Table 2. The linear correlation coefficients of the obtained standard curves are all greater than 0.99.

[0055] Step 7. Determination of absolute recovery and matrix effect: Calculate the absolute recovery according to formula (1) and the matrix effect according to formula (2).

[0056] R=(C A2 -C A1 ) / (C A3 -C A1 )×100%------------------------(1)

[0057] E=(C A3 -C A1 ) / C STD ×100%---------------------------(2)

[0058] Where R represents the recovery rate, C A1Represents the concentration of 15 polybrominated organic compounds in sediment samples, C A2 represents the concentration of polybrominated organic compounds in the spiked sample before treatment, C A3 represents the concentration of 15 polybrominated organic compounds in the spiked sample after treatment, E represents the matrix effect, C represents the matrix effect, STD Represents the theoretical concentration of 15 added polybrominated organic compounds.

[0059] Table 2. Recovery rates and matrix effects of 15 polybrominated organic compounds

[0060]

[0061]

[0062] In this example, the absolute recovery rates of 15 polybrominated organic compounds were between 45% and 80%, and the matrix effect was between 93% and 180%.

[0063] Embodiment 2:

[0064] In this example, 12 sediment samples were collected from electronic waste dismantling areas in Taizhou, Zhejiang and Guiyu, Guangdong. The sample pretreatment operation and instrument analysis and detection steps were the same as in Example 1, except that no brominated organic standard was added to the sample. The extraction results of various polybrominated organic compounds in the samples of this example are shown in Table 3:

[0065] Table 3. Concentrations of polybrominated organic compounds in samples

[0066]

[0067]

[0068] (“NF” indicates that the compound was not detected in the sample.)

[0069] In this embodiment, 24 polybrominated organic pollutants were detected in 12 sediment samples from Taizhou, Zhejiang and Guiyu, Guangdong, which enables rapid and efficient extraction and analysis of polybrominated organic pollutants in sediments.

[0070] The results of the above examples comprehensively show that the method for extracting polybrominated organic pollutants from sediments involved in the present invention is rapid and efficient, can perform extensive analysis on a variety of brominated organic pollutants in samples, can identify a comprehensive range of compound types, and has broad application prospects.

[0071] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for automatically extracting polybrominated organic pollutants from sediment samples, characterized in that: The following steps are involved: Step 1: Collect sediment samples, wrap them in aluminum foil, and store them at low temperatures; Step 2: Freeze-dry the sample using a freeze dryer and then sieve it with a metal sieve to remove impurities; Step 3: Building an automated sample pretreatment system and setting up an automated processing flow of the automated sample pretreatment system; wherein: The automated sample pretreatment system includes an accelerated solvent extractor (ASE), a concentrator, a fully automated gel purification quantitative concentration system instrument, a robotic arm, and an intelligent processing terminal; the fully automated gel purification quantitative concentration system instrument includes an injection needle, a concentration chamber, and a gel permeation chromatography (GPC) module; the intelligent processing terminal is used to receive an automated processing flow and control the automated sample pretreatment system according to the automated processing flow to complete automated operations of sample extraction, enrichment, purification, concentration, and volume determination; Step 4: Mix the sediment sample in step 2 with diatomaceous earth, and then load it into the stainless steel extraction tank of the accelerated solvent extractor, place a filter membrane at the bottom of the extraction tank, put it into the sample extraction position of the accelerated solvent extractor, extract the sample, and obtain a sediment extract; Step 5: After each sediment extract of step 4 is extracted, the extract is automatically transferred to the heating platform of the concentrator by the robotic arm, and then the robotic arm automatically transfers the sample bottle of the extract to the fully automatic gel purification quantitative concentration system instrument, and the sampling needle of the fully automatic gel purification quantitative concentration system instrument draws the extract and transfers it to the concentration chamber for quantitative concentration, and then the sampling needle transfers it to the gel permeation chromatography module for elution and purification; Step 6: The concentrated solution purified by the gel permeation chromatography module is introduced into the concentrator through the internal pipeline, concentrated by two modes of decompression and heating, and finally transferred to a brown injection vial by an injection needle to obtain the final sample extract.

2. The method for automatically extracting polybrominated organic pollutants from sediment samples according to claim 1, characterized in that: The extraction parameters of the accelerated solvent extractor are set as follows: extraction pressure of 10 MPa; extraction temperature of 100° C.; extraction time of 300 s; extraction cycle number of 3 times; heating time of 300 s; each solvent elution volume of 60%; and solvent collection time of 90 s.

3. The method for automatically extracting polybrominated organic pollutants from sediment samples according to claim 1, characterized in that: In step 4, the mass of the sludge is 5 g, the mass of the diatomaceous earth is 6 g, the volume of the sample pool is 22 mL, the extraction solvent is a mixed solvent of dichloromethane and acetone, the volume ratio is 1:1, and the amount of solvent used is about 50 mL.

4. The method for automatically extracting polybrominated organic pollutants from sediment samples according to claim 1, characterized in that: The elution solvent of the gel permeation chromatography module is a mixed solvent of ethyl acetate and cyclohexane, the volume ratio is 1:1, and the elution flow rate is 5 min / mL.

5. The method for automatically extracting polybrominated organic pollutants from sediment samples according to claim 1, characterized in that: The concentrated volume-fixing solvent in step 6 is methanol, and the volume-fixing volume is 1 mL.

6. The method for automatically extracting polybrominated organic pollutants from sediment samples according to claim 1, characterized in that: The method also includes detecting and analyzing the sample extract using a liquid chromatography-high resolution mass spectrometer (LC-HRMS), wherein the liquid chromatography mobile phase in the liquid chromatography-high resolution mass spectrometer is pure water and methanol, and 1 mM / L ammonium acetate is added as a mobile phase additive, and the liquid phase elution procedure is as follows: the initial ratio of the aqueous phase to the organic phase is 80:20 (v:v); gradually changes to 60:40 (v:v) within 3 minutes, gradually changes to 50:50 (v:v) within 8 minutes, and gradually changes to 30:7 within 12 minutes. 0 (v:v); gradually changed to 20:80 (v:v) within 15 min and maintained for 3 min; gradually changed to 100% organic phase within 19 min and maintained for 2 min; then restored to the initial ratio of 80:20 (v:v) within 0.1 min and maintained for 3.9 min; the detection conditions were negative ion full scan mode, and the ion source parameters were set as follows: sheath gas was 35 psi; auxiliary gas was 10 psi; backblowing gas was 0; spray voltage was 3.3 KV; ion transfer tube temperature was 320 °C; heating temperature was 350 °C.

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