A method for automated extraction of polybrominated organic pollutants from sediment samples

Abstract

The application provides a kind of automated extraction of polybrominated organic pollutants in sediment sample method, comprising the following steps: step 1: collecting sediment sample, wrapping with aluminum foil, low temperature frozen preservation;Step 2: freeze-drying machine is used to freeze-dry sample, then impurity is removed by screening with metal screen;Step 3: the parameter and process setting of the automatic sample pretreatment system built in laboratory are carried out;Step 4: the pretreated sediment is mixed with diatomite, then loaded into stainless steel extraction tank, filter membrane is placed at the bottom of tank body, placed in sample extraction position of accelerated solvent extraction instrument, the sample is extracted, and sediment extraction liquid is obtained;Step 5: every extraction is completed, the obtained extraction liquid is automatically transferred to full-automatic gel purification quantitative concentration system instrument by mechanical arm, and concentrated and dissolved again, then submitted to gel permeation chromatography by instrument sampling needle;Step 6: after the extraction liquid is concentrated, gel permeation chromatography elution purification is used;Step 7: the concentrated liquid after gel permeation chromatography purification is introduced into concentrator through internal pipeline, concentrated by two modes of reduced pressure and heating, finally transferred to brown sample vial by sampling needle, and the extraction liquid of sample is obtained.The purpose of the application is to provide a kind of efficient and rapid extraction method of brominated organic pollutants in sediment, which has less manual operation, shortens the time of sample pretreatment, improves the extraction efficiency, and provides convenience for subsequent compound analysis and identification.

Description

TECHNICAL FIELD

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

[0002] Polybrominated organic compounds (such as tetrabromobisphenol A, 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 biological accumulation and toxicity, these compounds have become a class of pollutants that have potential hazards to the environment and health, and have been detected in various environmental media. As an important sink of brominated organic pollutants, river sediment not only serves as a major reservoir for these harmful substances, but also provides a long-term deposition environment for their diffusion and accumulation in water bodies. Therefore, river sediment has become an important medium for studying the distribution and environmental behavior of brominated organic pollutants.

[0003] At present, although the study of brominated organic compounds in sediment has been increasingly concerned, the existing extraction methods (such as Soxhlet extraction, solid-phase extraction, ultrasonic extraction, microwave-assisted extraction) still have many problems, such as long time-consuming, large amount of solvent used, complicated operation and low extraction efficiency, which seriously limits the subsequent compound detection and analysis, and also limits the universality and economy of its application in large-scale sample processing. Therefore, developing a rapid and efficient extraction method not only helps to improve the accuracy and reliability of detection, but also provides solid technical support for 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 risk of brominated organic compounds in the environment. SUMMARY

[0004] In view of the long extraction time, large solvent consumption and low extraction efficiency of the existing methods in extracting brominated organic pollutants, the purpose of the present application is to provide an efficient and rapid extraction method for extracting brominated organic pollutants in sediment, which requires less manual operation, shortens the sample pretreatment time, improves the extraction efficiency and provides convenience for subsequent compound analysis and identification.

[0005] To solve the above technical problems, the technical solution adopted by the present application is as follows:

[0006] A method for automatically extracting polybrominated organic pollutants in bottom sediment samples, comprising the following steps:

[0007] Step 1: Collect the bottom sediment sample, wrap it with aluminum foil and store it at low temperature for freezing;

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

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

[0010] The automated sample pretreatment system comprises an accelerated solvent extraction instrument (ASE), a concentration instrument, a full-automatic gel purification quantitative concentration system instrument, a mechanical arm, and an intelligent processing terminal; the full-automatic gel purification quantitative concentration system instrument comprises a sample injection needle, a concentration cavity, and a gel permeation chromatography (GPC) module; the intelligent processing terminal is used to receive the automatic processing flow and control the automated sample pretreatment system to complete the automatic operation of sample extraction, enrichment, purification, concentration, and constant volume according to the automatic processing flow;

[0011] Step 4: mix the bottom mud sample in step 2 with diatomite, and then load the mixture into a stainless steel extraction cell of the accelerated solvent extraction instrument, place a filter membrane at the bottom of the cell body, and place the cell in a sample extraction position of the accelerated solvent extraction instrument to extract the sample, thereby obtaining a bottom mud extract;

[0012] Step 5: after the extraction of the bottom mud extract in step 4 is completed, the extract is automatically transferred by the mechanical arm to a heating table of the concentration instrument, and then the extract sample bottle is automatically transferred by the mechanical arm to the full-automatic gel purification quantitative concentration system instrument, the extract is sucked by the sample injection needle of the full-automatic gel purification quantitative concentration system instrument and transferred to the concentration cavity for quantitative concentration, and then the extract is transferred by the sample injection needle to the gel permeation chromatography module for elution and purification;

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

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

[0015] Preferably, in step 4, the mass of the bottom mud is 5 g, the mass of the diatomite is 6 g, the volume specification of the sample cell is 22 mL, the extraction solvent is a mixed solvent of dichloromethane and acetone with a volume ratio of 1:1, and the solvent usage amount is about 50 mL.

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

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

[0018] Preferably, the sample extract is further detected and analyzed by using a liquid chromatography-high resolution mass spectrometer (LC-HRMS), and 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 program is as follows: the initial water phase and organic phase ratio is 80:20 (v:v); gradually changed to 60:40 (v:v) within 3 min, gradually changed to 50:50 (v:v) within 8 min, gradually changed to 30:70 (v:v) within 12 min; gradually changed to 20:80 (v:v) within 15 min, kept for 3 min; gradually changed to 100% organic phase within 19 min and kept for 2 min; then returned to the initial ratio of 80:20 (v:v) within 0.1 min, and kept for 3.9 min; the detection condition is negative ion full scan mode, and the ion source parameter is set as: sheath gas is 35 psi; auxiliary gas is 10 psi; backflush gas is 0; spray voltage is 3.3 KV; ion transmission tube temperature is 320 DEG C; heating temperature is 350 DEG C.

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

[0020] An automatic extraction method of multi-bromine organic pollutants in sediment is established: the extraction method used in the present application is rapid, efficient and simple, and can extract 24 samples at a time, while greatly reducing the time and process of manual operation. BRIEF DESCRIPTION OF DRAWINGS

[0021] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed to be used in the embodiments or the prior art description will be briefly introduced below. Obviously, the drawings in the following description are some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without creative labor.

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

[0023] Figure 2 : Instrument parameters of the accelerated solvent extraction method.

[0024] Figure 3 : Flowchart of the experimental process of the present application.

[0025] Figure 4 Absolute recovery rate and matrix effect results of 15 kinds of polybrominated organic matter pretreatment method of the application. DETAILED DESCRIPTION

[0026] In order to make the purpose, technical scheme and advantages of the embodiments of the present application clearer, the technical scheme in the embodiments of the present application will be described clearly and completely below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0027] In conjunction with the present application 2-4, a method for extracting brominated organic pollutants in a bottom sediment sample according to the present application comprises the following steps:

[0028] Step 1: Collect the bottom sediment sample, wrap it with aluminum foil, and store it at low temperature for freezing.

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

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

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

[0032] Step 5: After each sample is extracted, the obtained extract is automatically transferred by a mechanical arm to a full-automatic gel purification and quantitative concentration system instrument for concentration and solvent conversion, and then transferred by an instrument sampling needle to a gel permeation chromatography (GPC) for submission.

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

[0034] Step 7: The concentrated solution after GPC purification is introduced into a concentrator through an internal pipeline, and is concentrated by reducing pressure and heating. Finally, it is transferred by a sampling needle to a brown sample vial to obtain the extract of the sample.

[0035] In a specific embodiment of the present application, asFigure 1 As shown in the figure, the automatic sample pretreatment system comprises an accelerated solvent extraction instrument (ASE) 1, a concentration instrument 2, a full-automatic gel purification quantitative concentration system instrument 3, a mechanical arm 4 and a computer workstation 5. The full-automatic gel purification quantitative concentration system instrument 3 comprises a sample injection needle 6, a concentration cavity 7 and a gel permeation chromatography (GPC) module 8. The pretreatment system integrates the accelerated solvent extraction instrument 1, the mechanical arm 4 and the full-automatic gel purification quantitative concentration system instrument 3, and completes the automatic operation of the sample from extraction, enrichment and purification to concentration and constant volume by instrument control and method editing of the computer workstation 5. The accelerated solvent extraction instrument 1 independently performs instrument operation and method editing, and the operation and method editing of the mechanical arm 4 and the full-automatic gel purification quantitative concentration system instrument 3 are controlled by the computer workstation 5. The specific operation process is as follows: the accelerated solvent extraction instrument 1 extracts the sample filled in the extraction cell, then the mechanical arm 4 automatically transfers the sample bottle of the extracted liquid to the heating table of the concentration instrument 2, and then the mechanical arm 4 transfers the sample bottle of the extracted liquid to the sample site of the full-automatic gel purification quantitative concentration system instrument 3, and the full-automatic gel purification quantitative concentration system instrument 3 completes the enrichment, purification, concentration and constant volume operation of the sample. The whole process is automatically completed by the instrument.

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

[0037] Further, the mass of the bottom mud in step 4 is 5 g, the mass of the diatomite is 6 g, and the sample cell volume specification is 22 mL. The extraction solvent is a mixed solvent of dichloromethane and acetone with a volume ratio of 1:1. The solvent usage amount is about 50 mL.

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

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

[0040] Further, step 8 is included, which is detecting and analyzing the sample extraction solution by using a liquid chromatography-high resolution mass spectrometer. The instrument in step 8 is liquid chromatography-high resolution mass spectrometer (LC-HRMS), and the mobile phase of liquid chromatography is pure water and methanol, and 1 mM / L ammonium acetate is added as a mobile phase additive, wherein the liquid elution program is as follows: the initial ratio of water phase and organic phase is 80:20; gradually changes to 60:40 within 3 min, gradually changes to 50:50 within 8 min, gradually changes to 30:70 within 12 min; gradually changes to 20:80 within 15 min, and maintains for 3 min; gradually changes to 100% organic phase within 19 min and maintains for 2 min; then returns to the initial ratio (80:20) within 0.1 min and maintains for 3.9 min.

[0041] Further, the detection condition in step 8 is negative ion full scan mode. The ion source parameter settings are as follows: 1) sheath gas: 35 psi; 2) auxiliary gas: 10 psi; 3) sweep gas: 0; 4) spray voltage: 3.3 KV; 5) capillary temperature: 320℃; 6) heater temperature: 350℃.

[0042] The application will be further described below in combination with examples:

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

[0044] In this example, by adding 15 kinds of polybrominated organic compound standards to the sample, an automatic method for extraction and pretreatment of polybrominated organic compounds is established. The basic information of the 15 kinds of polybrominated organic compound standards is shown in Table 1:

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

[0046]

[0047]

[0048] The specific experimental steps are as follows:

[0049] Step one, the collected river sediment samples are wrapped with aluminum foil and placed in a-20℃ refrigerator for frozen storage, and then freeze-dried for 7 days using a freeze-drying machine, and the samples are sieved using a 60-mesh metal sieve.

[0050] Step two, set the parameters of the accelerated solvent extraction instrument, including: extraction pressure is 10 MPa; extraction temperature is 100℃; extraction time is 300s; extraction cycle number is 3 times; heating time is 300s; each solvent leaching volume is 60%; collection solvent time is 90s;

[0051] Step three, extract the sample using the accelerated solvent extraction instrument, specifically: mix 5g of the sediment sample obtained in step one with 6g of diatomite, add 22mL of stainless steel extraction cell, add copper rod to remove sulfur, set three identical parallel samples, numbered A1, A2, A3, add 25ng of 15 kinds of polybrominated organic compounds to the sample numbered A2 before extraction for absolute recovery rate and matrix effect correction. Dichloromethane and acetone mixed solvent (1:1, v:v) is used as the extraction solvent.

[0052] Step four, use the full-automatic gel purification and quantitative concentration system instrument to enrich, purify, concentrate and transfer the extract obtained in step three, specifically: the extract is transferred to the instrument concentration cavity by the instrument sampling needle using vacuum negative pressure for reduced pressure distillation, and then dissolved with ethyl acetate and cyclohexane mixed solvent (1:1, v:v), then sampled into the gel permeation chromatography (GPC) for purification, using ethyl acetate and cyclohexane mixed solvent (1:1, v:v) for elution, the eluent flow rate is 5mL / min, collect the eluent of 25-85mL to the concentration cavity for reduced pressure distillation, after the eluent is concentrated to dryness, use 1mL of methanol to constant volume and transfer to a brown sample vial, then add 25ng of 15 kinds of polybrominated organic compound mixed standard to the sample numbered A3.

[0053] Step five, prepare the mixed standard solution of polybrominated organic compounds with concentration gradient of 0.01, 0.025, 0.05, 0.1, 0.25, 0.5, 1, 2.5, 5, 10, 25, 50, 100 ng / mL, and detect and analyze the sample obtained in step four and the standard solution with concentration gradient by liquid chromatography-high resolution mass spectrometry (LC-QE). The mobile phase of liquid chromatography is ultrapure water and methanol, and 1 mM ammonium acetate is added as an additive. The elution gradient of the mobile phase is as follows: the initial ratio of water phase and organic phase is 80:20; gradually changes to 60:40 within 3 min, to 50:50 within 8 min, to 30:70 within 12 min, to 20:80 within 15 min, and maintains for 3 min; gradually changes to 100% organic phase within 19 min and maintains for 2 min; then returns to the initial ratio (80:20) within 0.1 min and maintains for 3.9 min. The injection volume is 1 μL, the column oven temperature is 40°C, and the flow rate of the mobile phase is 0.3 mL / min. The mass spectrometry detection mode is negative ion full scan mode, and the ion source parameters are as follows: 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; and 6) heater temperature: 350°C.

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

[0055] Step seven, determination of absolute recovery rate and matrix effect: calculate the absolute recovery rate according to formula (1), and calculate 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] wherein R represents the recovery rate, C A1 represents the concentration of 15 kinds of polybrominated organic compounds in the sediment sample, C A2 represents the concentration of polybrominated organic compounds in the spiked sample before treatment, C A3 represents the concentration of 15 kinds of polybrominated organic compounds in the spiked sample after treatment, E represents the matrix effect, C STD represents the theoretical concentration of 15 kinds of polybrominated organic compounds added.

[0059] Table 2. Recovery rate and matrix effect of 15 kinds of polybrominated organic compounds

[0060]

[0061]

[0062] In this example, the absolute recovery rate of 15 kinds of polybrominated organic compounds is between 45% and 80%. The matrix effect is between 93% and 180%.

[0063] Example 2:

[0064] In this example, sediment samples from e-waste dismantling areas in Taizhou, Zhejiang and Guiyu, Guangdong were collected, and a total of 12 sediment samples were obtained. The sample pretreatment operation and instrument analysis and detection steps were the same as in Example 1, except that no brominated organic compound 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. Concentration of polybrominated organic compounds in the sample

[0066]

[0067]

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

[0069] In this example, a total of 24 kinds of polybrominated organic pollutants were detected in the 12 sediment samples from the two areas of Taizhou, Zhejiang and Guiyu, Guangdong, and rapid and efficient extraction and analysis of polybrominated organic pollutants in sediment were achieved.

[0070] The results of the above examples collectively show that the extraction method of polybrominated organic pollutants in sediment involved in the present application is rapid and efficient, can widely analyze various brominated organic pollutants in the sample, and has a wide application prospect.

[0071] It should be pointed out finally that the above embodiments are only used to illustrate the technical solutions of the present application, but not to limit the same; and although the present application has been described in detail with reference to the foregoing embodiments, it should be appreciated by those skilled in the art that the technical solutions recorded in the foregoing embodiments can be modified, or some technical features thereof can be replaced equivalently; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A method for automated extraction of polybrominated organic pollutants from a sediment sample, characterized in that, The method comprises the following steps: Step 1: Collect the sediment sample, wrap it with aluminum foil, and store it in a low-temperature freezer; Step 2: Freeze-dry the sample using a freeze dryer, and then sieve it with a metal sieve to remove impurities; Step 3: Build an automated sample pretreatment system and set an automatic processing flow of the automated sample pretreatment system; wherein: The automated sample pretreatment system comprises an accelerated solvent extractor, a concentrator, a full-automatic gel purification and quantitative concentration system instrument, a mechanical arm, and an intelligent processing terminal; the full-automatic gel purification and quantitative concentration system instrument comprises a sample injection needle, a concentration cavity, and a gel permeation chromatography module; the intelligent processing terminal is used to receive the automatic processing flow and control the automated sample pretreatment system to complete the automatic operation of sample extraction, enrichment, purification, concentration, and constant volume according to the automatic processing flow; Step 4: Mix the sediment sample in step 2 with diatomite, and then load it into a stainless steel extraction cell of the accelerated solvent extractor, place a filter membrane at the bottom of the extraction cell body, and put it into a sample extraction position of the accelerated solvent extractor to extract the sample, thereby obtaining a sediment extract; Step 5: After the extraction of one sediment extract in step 4 is completed, the extract is automatically transferred to a heating table of the concentrator by the mechanical arm, and then the extract sample bottle is automatically transferred to the full-automatic gel purification and quantitative concentration system instrument by the mechanical arm, the extract is sucked and transferred to the concentration cavity by the sample injection needle of the full-automatic gel purification and quantitative concentration system instrument for quantitative concentration, and then the extract is transferred to the gel permeation chromatography module for elution and purification by the sample injection needle; Step 6: The concentrated liquid purified by the gel permeation chromatography module is introduced into a concentrator through an internal pipeline, and is concentrated through two modes of reduced pressure and heating, and finally is transferred to a brown sample injection vial by the sample injection needle, thereby obtaining the final sample extract; Further comprising detecting and analyzing the sample extract by using a liquid chromatography-high resolution mass spectrometer instrument, wherein the mobile phase of the liquid chromatography-high resolution mass spectrometer instrument is pure water and methanol, 1 mM / L ammonium acetate is added as a mobile phase additive, and the liquid elution program is as follows: the initial volume ratio of water phase to organic phase is 80:20; the volume ratio gradually changes to 60:40 within 3 min, to 50:50 within 8 min, to 30:70 within 12 min, to 20:80 within 15 min, and is kept for 3 min; the volume ratio gradually changes to 100% organic phase within 19 min and is kept for 2 min; then it is restored to the initial volume ratio of 80:20 within 0.1 min and is kept for 3.9 min; the detection condition is a negative ion full scan mode, and the ion source parameter is set as follows: the sheath gas is 35 psi; the auxiliary gas is 10 psi; the backflush gas is 0; the spray voltage is 3.3KV; the ion transmission tube temperature is 320 ℃; and the heating temperature is 350 ℃.

2. The method of claim 1, wherein the method is automated. The extraction parameter of the accelerated solvent extractor is set as follows: extraction pressure is 10 MPa; extraction temperature is 100 DEG C; extraction time is 300 s; extraction cycle number is 3; heating time is 300 s; solvent elution volume is 60% each time; and collection solvent time is 90 s.

3. The method of claim 1, wherein the method is automated. In the step 4, the mass of the bottom mud is 5 g, the mass of the diatomite is 6 g, the volume specification of the sample cell is 22 mL, the extraction solvent is a mixed solvent of dichloromethane and acetone with a volume ratio of 1:1, and the solvent usage is about 50 mL.

4. The method of claim 1, wherein the method is automated. The elution solvent of the gel permeation chromatography module is a mixed solvent of ethyl acetate and cyclohexane with a volume ratio of 1:1, and the elution flow rate is 5 min / mL.

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