Detection method and application of PE micro-plastic in lipid-containing organic matrix

Abstract

The invention belongs to the technical field of detection, and particularly relates to a method for detecting PE micro-plastic in a lipid-containing organic matrix and application. Comprising the following steps: (1) mixing a PE standard substance with a solvent to prepare a standard working solution; sequentially cleaning and extracting a to-be-detected sample, and extracting PE in the to-be-detected sample to obtain a to-be-detected sample solution; and (2) evaporating the standard solution and the to-be-detected solution in the step (1) to remove the solvent, and then carrying out thermal cracking-gas chromatography-mass spectrometry detection analysis to complete the detection of the PE micro-plastic in the lipid-containing organic matrix. The detection method provided by the invention can be used for detecting the PE micro-plastic in the lipid-containing organic matrix, accurate qualitative and quantitative analysis of the PE micro-plastic in the lipid-containing organic matrix can be realized through a thermal cracking-gas chromatography-mass spectrometry combined detection method, and the method is stable and good in repeatability.

Description

Technical Field

[0001] This invention belongs to the field of detection technology, and more specifically relates to a method and application for detecting PE microplastics in a lipid-containing organic matrix. Background Technology

[0002] Microplastics, as an emerging global pollutant, are widely present in water bodies, soil, and organisms, and their potential risks to ecosystems and human health are receiving increasing attention. Accurate detection of microplastics in environmental and biological samples is a prerequisite for assessing their pollution levels and ecotoxicological effects.

[0003] Currently, the main detection technologies for microplastics include morphological observation-based spectroscopic methods (such as Fourier transform infrared spectroscopy and Raman spectroscopy). While Fourier transform infrared spectroscopy and Raman spectroscopy can provide fingerprint information of polymers and allow for morphological observation, their signals are severely interfered with when the sample matrix is ​​complex, the particle size is extremely small, or the surface is covered by organic matter, leading to reduced recognition rates or even failure. Some related technologies disclose the use of pyrolysis-gas chromatography-mass spectrometry (PCMS) to detect microplastics in soil or water.

[0004] However, applying pyrolysis-gas chromatography-mass spectrometry (PCC-MS) to detect microplastics in complex biomatrices containing lipids faces significant challenges due to matrix interference. These samples are rich in organic components such as lipids and proteins, and their pyrolysis behavior can severely mask or interfere with the characteristic signals of the target microplastics. Therefore, there is an urgent need to develop a novel method that can effectively overcome interference from complex biomatrices, particularly lipids, and achieve accurate quantitative and qualitative detection of PE microplastics. Summary of the Invention

[0005] To address the matrix interference challenge encountered in the prior art when detecting PE microplastics in lipid-containing organic matrices, the first aspect of the present invention provides a method for detecting PE microplastics in lipid-containing organic matrices, comprising the following steps: (1) Mix the PE standard with the solvent to prepare a standard working solution; wash and extract the sample to be tested in sequence to extract the PE from the sample to be tested and obtain the sample solution to be tested; (2) After removing the solvent from the standard solution and the test solution mentioned in step (1), perform thermal pyrolysis-gas chromatography-mass spectrometry for detection and analysis to complete the detection of PE microplastics in lipid-containing organic matrix; Optionally, in the pyrolysis-gas chromatography-mass spectrometry (GC-MS) detection, the pyrolysis is performed in single-click mode, and the pyrolysis temperature is 400℃~550℃. As an example, the pyrolysis temperature can be 400℃, 420℃, 440℃, 460℃, 480℃, 500℃, 510℃, 530℃, 550℃, etc., or any value within the above range; no further limitation is made here.

[0006] The inventors' in-depth research revealed that for the detection of PE microplastics in lipid-containing organic matrices, traditional pyrolysis-gas chromatography-mass spectrometry (PCMS-MS) methods suffer from decreased accuracy due to interference from lipid components. Specifically, because the initial thermal decomposition temperature of PE (approximately 400°C) significantly overlaps with the complete decomposition temperature of fats in the organic matrix (approximately 500°C), the traditional "double-click mode" cannot find an intermediate temperature point where lipids completely decompose without any PE decomposition. If the first-step temperature is set too low, lipid removal is incomplete, resulting in severe background interference; conversely, increasing the first-step temperature to improve lipid removal efficiency inevitably leads to premature pyrolysis and loss of some PE, resulting in significantly lower and distorted detection results. The method provided by this invention, using a single-click mode with pyrolysis and controlling the pyrolysis temperature between 400°C and 550°C, along with precise cleaning of the sample with an organic solvent before analysis, enables precise qualitative and quantitative analysis of PE microplastics in lipid-containing organic matrices. The method is stable and highly accurate.

[0007] It should be noted that lipid-containing organic matrices refer to test samples containing fat. Examples include biological tissues (such as fish, mussels, liver, and human diseased tissues) or blood, oily food residues, and biological sludge from wastewater treatment.

[0008] In some implementable embodiments, the method for preparing the standard working solution includes: Accurately weigh 0.05 g of PE standard into a 20 mL glass sample bottle, add 20 g of p-xylene, and heat at 150 °C to dissolve, to obtain standard working solution 1; Take 0.20 g of standard working solution 1 into a 20 mL glass sample bottle, add 20 g of p-xylene, and heat at 150 °C to dissolve, to obtain standard working solution 2; Take 0.05 g of standard working solution 1 into a 20 mL glass sample bottle, add 20 g of p-xylene, and heat at 150 °C to dissolve, to obtain standard working solution 3.

[0009] In some feasible embodiments, the cleaning is performed using an organic solvent; the organic solvent includes one or more of C5-C8 aliphatic hydrocarbons, halogenated C1-C2 hydrocarbons, and C2-C4 alcohol solvents.

[0010] Further optionally, the organic solvent includes at least one selected from n-hexane, n-heptane, cyclohexane, petroleum ether, ethanol, acetonitrile, dichloromethane, chloroform, carbon tetrachloride, diethyl ether, methyl tert-butyl ether, tetrahydrofuran, ethyl acetate, acetone, methanol, or isopropanol.

[0011] Further optionally, the organic solvent includes n-hexane and ethanol.

[0012] In some feasible methods, the cleaning includes a first cleaning and a second cleaning, which together form a cleaning cycle; the cleaning cycle is repeated until the sample to be tested is free of oil stains. Typically, the cleaning cycle includes 1 cycle, 2 cycles, 3 cycles, 4 cycles, etc.; usually, 3 cleaning cycles are sufficient to remove oil stains from the sample to be tested.

[0013] Optionally, the cleaning temperature for both the first and second cleaning is 40-70°C. For example, the temperature can be 40°C, 50°C, 60°C, 70°C, etc., or any value within the above range; no further limitation is made here.

[0014] Optionally, the cleaning time for both the first and second cleaning is 5 to 15 minutes. As an example, the time can be 5 minutes, 8 minutes, 10 minutes, 12 minutes, 15 minutes, etc., or any value within the above range, without further limitation.

[0015] Further optionally, the organic solvent used for the first cleaning is n-hexane; and the organic solvent used for the second cleaning is ethanol.

[0016] This invention employs a stepwise cyclic cleaning method, first using n-hexane and then ethanol, which achieves unexpectedly superior results compared to conventional single-stage cleaning with mixed solvents. The inventors speculate that the nonpolar n-hexane efficiently and specifically removes the predominantly neutral triglycerides from the lipid-containing organic matrix of the sample, while the polar ethanol effectively removes interfering substances such as phospholipids and cholesterol. The stepwise operation avoids interference between molecules of different polarities in the mixed solvent, allowing each solvent to exert its maximum solubility. Simultaneously, the stepwise removal of the oil-loaded waste liquid effectively prevents the redeposition of contaminants. After treatment with the stepwise cyclic cleaning method provided by this invention, the background of the sample is significantly reduced in thermal decomposition-gas chromatography-mass spectrometry (TCMS) analysis, and the signal-to-noise ratio of the target microplastic characteristic peaks is significantly improved, further enhancing the repeatability of the detection method provided by this invention.

[0017] In some feasible embodiments, the extraction employs an extractant; the extractant includes at least one selected from toluene, ethanol, o-xylene, m-xylene, p-xylene, acetone, acetonitrile, or methanol. Further optionally, the extractant is p-xylene or o-xylene.

[0018] Optionally, the extractant is p-xylene; the ratio of the sample to be tested and p-xylene is 1g:(10~40)mL. As an example, the ratio can be 1g:10mL, 1g:20mL, 1g:30mL, 1g:40mL, etc., or any value within the above range. No further limitation is made here.

[0019] It should be noted that the ratio of the sample to be tested and p-xylene described in this application is the ratio of a single extraction.

[0020] In some feasible embodiments, the extraction step includes: adding an extractant to the cleaned sample to be tested, extracting at 120~180℃ for 5-15 min, collecting the extractant, repeating the extraction 2~5 times, combining the extractants from each extraction, and using them to extract PE from the sample to be tested.

[0021] In some feasible embodiments, the gas chromatography in the pyrolysis-gas chromatography-mass spectrometry detection meets at least one of the following conditions: (1) The chromatographic column includes an SH-I-5Sil MS column; the column length is 15~60m, the inner diameter is 0.25mm, and the film thickness is 0.1~1μm; (2) The gas chromatography adopts a split injection mode with a split ratio of (3~6):1; (3) The column flow rate is 0.5~2 mL / min (4) The injection port temperature is 300~350℃; (5) The carrier gas is helium with a linear velocity of 36.1 cm / sec.

[0022] Further optionally, the gas chromatography in the pyrolysis-gas chromatography-mass spectrometry detection meets the following conditions: (1) The chromatographic column includes an SH-I-5Sil MS column; the column length is 15~60m, the inner diameter is 0.25mm, and the film thickness is 0.1~1μm; (2) The gas chromatography adopts a split injection mode with a split ratio of (3~6):1; (3) The column flow rate is 0.5~2 mL / min (4) The injection port temperature is 300~350℃; (5) The carrier gas is helium with a linear velocity of 36.1 cm / sec.

[0023] Furthermore, in the pyrolysis-gas chromatography-mass spectrometry (PCMS) detection, the gas chromatography meets the following conditions: (1) The chromatographic column includes an SH-I-5Sil MS column; the column has a length of 30m, an inner diameter of 0.25mm, and a film thickness of 0.25μm; (2) The gas chromatograph uses a split injection mode with a split ratio of 5:1; (3) The column flow rate is 1 mL / min (4) The injection port temperature is 320℃; (5) The carrier gas is helium with a linear velocity of 36.1 cm / sec.

[0024] In some feasible embodiments, the pyrolysis detected by the pyrolysis-gas chromatography-mass spectrometry (GC-MS) meets at least one of the following conditions: (1) The carrier gas is helium; (2) The temperature of the pyrolyzer-gas chromatograph interface is 280~320℃; (3) The pyrolysis time is 10~15s.

[0025] Further optionally, the thermal decomposition in the thermal decomposition-gas chromatography-mass spectrometry detection meets the following conditions: (1) The carrier gas is helium; (2) The temperature of the pyrolyzer-gas chromatograph interface is 280~320℃; (3) The pyrolysis time is 10~15s.

[0026] Furthermore, the thermal decomposition in the thermal decomposition-gas chromatography-mass spectrometry detection meets the following conditions: (1) The carrier gas is helium; (2) The temperature of the pyrolyzer-gas chromatograph interface is 300℃; (3) The pyrolysis time is 12s.

[0027] In some feasible embodiments, the mass spectrometric solution detected by the pyrolysis-gas chromatography-mass spectrometry (PCMS) meets at least one of the following conditions: (1) Full scan acquisition mode; (2) The scanning time is 10~30 min; (3) The ionization energy is 50~80 eV; (4) The scanning range is 29~600 m / z; (5) The ion source is EI; positive ion mode; (6) The ion source temperature is 200~250℃; (7) The gas chromatography-mass spectrometry interface temperature is 300~330℃.

[0028] Further optionally, the mass spectrometric solution in the thermal pyrolysis-gas chromatography-mass spectrometry detection satisfies at least one of the following conditions: (1) Full scan acquisition mode; (2) The scanning time is 10~30 min; (3) The ionization energy is 50~80 eV; (4) The scanning range is 29~600 m / z; (5) The ion source is EI; positive ion mode; (6) The ion source temperature is 200~250℃; (7) The gas chromatography-mass spectrometry interface temperature is 300~330℃.

[0029] Furthermore, the mass spectrometric solution in the thermal pyrolysis-gas chromatography-mass spectrometry detection meets the following conditions: (1) Full scan acquisition mode; (2) The scanning time is 30 minutes; (3) The ionization energy is 70 eV; (4) The scanning range is 29~600 m / z; (5) The ion source is EI; positive ion mode; (6) The ion source temperature is 230℃; (7) The gas chromatography-mass spectrometry interface temperature is 320℃.

[0030] A second aspect of the present invention provides an application of a method for detecting PE microplastics in a lipid-containing organic matrix, used to detect the content of PE microplastics in a lipid-containing organic matrix.

[0031] Compared with the prior art, the present invention has the following beneficial effects: 1. The detection method provided by this invention can be used to detect PE microplastics in lipid-containing organic matrices. The detection method uses a thermal pyrolysis-gas chromatography-mass spectrometry (PCMS) method. The thermal pyrolysis is performed in single-click mode, and the pyrolysis temperature is controlled at 400℃~550℃. In addition, the sample is precisely cleaned with organic solvent before detection and analysis. This method can achieve accurate qualitative and quantitative analysis of PE microplastics in lipid-containing organic matrices. The method is stable and highly accurate.

[0032] 2. The detection method provided by this invention uses a stepwise circulating cleaning method of first using n-hexane and then ethanol to remove the oil-loaded waste liquid stepwise, effectively preventing the redeposition of pollutants.

[0033] 3. After being processed by the stepwise cyclic cleaning method provided by the present invention, the background of the sample to be tested is significantly reduced in the detection and analysis by thermal pyrolysis-gas chromatography-mass spectrometry, and the signal-to-noise ratio of the characteristic peak of the target microplastic can be significantly improved, further enhancing the repeatability of the detection method provided by the present invention.

[0034] 4. The detection method provided by this invention can effectively analyze samples with a PE content of 0.1 μg or higher, and the analysis method is stable, reliable, and has good repeatability. Attached Figure Description

[0035] Figure 1 This is an infrared test result image of the sample to be cleaned in Example 1 of this application.

[0036] Figure 2 This is a thermogravimetric analysis (TGA) diagram of the sample to be tested in Example 1 of this application.

[0037] Figure 3 This is a thermogravimetric analysis (TGA) chart for PE.

[0038] Figure 4 The TIC chromatogram of the sample to be tested in Example 1 is shown.

[0039] Figure 5 This is an enlarged version of the TIC chromatogram of the sample to be tested in Example 1.

[0040] Figure 6 This is the EIC chromatogram (extraction ion flow chromatogram) for Example 1.

[0041] Figure 7 For sample C to be tested 10 Single rare mass spectrum.

[0042] Figure 8 For sample C to be tested 21 Single rare mass spectrum.

[0043] Figure 9 For sample C to be tested 23 Single rare mass spectrum.

[0044] Figure 10 For sample C to be tested 25 Single rare mass spectrum.

[0045] Figure 11 The TIC chromatogram is for PE standard.

[0046] Figure 12 The image shows the EIC chromatogram of the PE standard.

[0047] Figure 13 This is the TIC chromatogram of the reference standard (lard).

[0048] Figure 14 This is the EIC chromatogram of the reference standard (lard). Detailed Implementation

[0049] The technical solution of the present invention will be further illustrated below through specific embodiments. Those skilled in the art should understand that the embodiments described are merely illustrative of the present invention and should not be construed as limiting the invention in any way.

[0050] Unless otherwise specified, the reagents and consumables used in the following embodiments were purchased from conventional reagent manufacturers in the art; unless otherwise specified, the experimental methods and techniques used were conventional methods and techniques in the art.

[0051] The manufacturers and models of the instruments involved in the following examples and tests are shown below:

[0052] Example 1 This embodiment provides a method for detecting PE microplastics in a lipid-containing organic matrix, the specific steps of which are as follows: (a) Preparation of standard working solution Accurately weigh 0.05 g of PE standard into a 20 mL glass sample bottle, add 20 g of p-xylene, and heat at 150 °C to dissolve, to obtain standard working solution 1; Take 0.20 g of standard working solution 1 into a 20 mL glass sample bottle, add 20 g of p-xylene, and heat at 150 °C to dissolve, to obtain standard working solution 2; Take 0.05 g of standard working solution 1 into a 20 mL glass sample bottle, add 20 g of p-xylene, and heat at 150 °C to dissolve, to obtain standard working solution 3.

[0053] The standard working solution was added dropwise to the injection crucible of the thermal pyrolysis-gas chromatography-mass spectrometry instrument using a glass dropper, and the mass of the crucible after addition was recorded as shown in Table 1. The crucible was heated at 80°C until the solvent in the crucible had completely evaporated, and then thermal pyrolysis-gas chromatography-mass spectrometry was performed for detection and analysis. The specific results are recorded in Table 1 below.

[0054] Table 1. Standard Working Solution Data Table

[0055] The standard curve equation for PE is y = 268934x - 8978.2, R0 2 =0.9983 (ii) Preparation of working solution and obtaining standard curve (1) Accurately weigh 0.5 g of the sample to be tested (healthy human blood) into a 100 mL beaker A, accurate to 0.001 g, and dry at 60 °C to constant weight.

[0056] (2) Add 30 mL of n-hexane to beaker A containing the sample to be tested, heat at 60 °C for 10 min, then discard the n-hexane. Add 30 mL of ethanol, heat at 60 °C for 10 min, then discard the ethanol. Repeat the above cleaning cycle until there are no oil stains on the surface of the sample to be tested. The above cleaning cycle is repeated a total of 3 times. The liquid after each cleaning cycle is subjected to infrared testing. The test results are shown in […]. Figure 1 .

[0057] (3) Add 10 mL of p-xylene to the cleaned sample to be tested, heat and extract at 150℃ for 10 min, collect the extractant, repeat the extraction 3 times, combine the 3 extractants in beaker B, and use them to extract PE from the sample to be tested.

[0058] (4) The extractant in beaker B is concentrated at 80 °C. The extractant is then added dropwise to the injection crucible of the thermal pyrolysis-gas chromatography-mass spectrometry instrument using a glass pipette. The concentrated extractant mass is 1.013 g, and the mass added to the injection crucible is 0.061 g. The mixture is heated at 80 °C until the solvent in the crucible has completely evaporated. Then, thermal pyrolysis-gas chromatography-mass spectrometry is performed for detection and analysis. In the thermal pyrolysis-gas chromatography-mass spectrometry detection, the thermal pyrolysis is performed in single-click mode.

[0059] (III) The instrument parameters are shown in Table 2 below: Table 2. Instrument Acquisition Parameters for Thermal Decomposition-Gas Chromatography-Mass Spectrometry

[0060] according to Figure 1 The results were used to determine the infrared characteristic peaks in the sample. The peaks were determined by the chemical bond vibrations of the core component, triglycerides (fatty acid glycerides). The test results after the first washing cycle showed a significant lipid peak (1736 cm⁻¹). -1 and 1167cm -1 This indicates that there is a certain amount of lipid interference in the sample to be tested; however, after the third washing cycle, there were no lipid peaks in the organic solvent, indicating that the lipid interference was effectively controlled by the cyclic washing method provided in this application.

[0061] according to Figure 2 and Figure 3The data shows that the complete decomposition temperature of triglycerides, the core component of the sample, is 500℃, while the initial decomposition temperature of PE is 400℃, and the final decomposition temperature is 550℃. Based on this, the traditional double-step thermal pyrolysis mode cannot completely remove lipids at a temperature that does not trigger PE decomposition. Increasing the first-step temperature to remove interference inevitably leads to premature pyrolysis and loss of the target PE microplastics, severely affecting the accuracy and quantitative reliability of the detection. Therefore, this invention employs an optimized single-step pyrolysis mode. Through synergistic optimization of the pyrolysis temperature and chromatographic-mass spectrometry conditions, it achieves accurate identification and quantitative analysis of characteristic pyrolysis markers of microplastics in a complex lipid pyrolysis background, solving the problem of lipid interference.

[0062] Qualitative analysis results are shown in Figures 4-10 ,from Figure 4 , Figure 5 , Figure 6 It can be seen that the sample contains a typical cluster of three peaks of PE, and from... Figure 7 , Figure 8 , Figure 9 , Figure 10 It can be seen that the sample to be tested contains PE with unique C 21 C 23 C 25 Long-chain carbons elute, thus the presence of PE in the sample can be qualitatively determined. Quantitative analysis results: Based on the above standard curve and the test results, the PE content in the sample was calculated to be 0.1 μg, corresponding to a concentration of 3.32 μg / g.

[0063] To further clarify the differences between the organic matter spectra in PE and those in the test sample, lard (a reference standard) was introduced for analysis, and the results were obtained. Figure 13 and Figure 14 ; from Figures 11-14 It can be seen that there are significant differences between the TIC chromatogram of the PE standard and the lipid TIC chromatogram of the reference standard (lard). Figure 11 and Figure 12 The display shows that PE exists from C. 10- C 30+ A continuous cluster of three peaks; and from Figure 13 and Figure 14 As can be seen, lipids in lard only show a significant response at low carbon numbers, and this difference provides an important clue for us to distinguish lipids and PE in lard.

[0064] from Figure 12 As can be seen from this, the C corresponding to m / z 294 21 Monoenes, and C 21 C 23 C 25substances, and Figure 14 Such characteristic peaks do not exist in the matrix. The differences in the peak shapes of these characteristic substances help us to accurately identify and distinguish lipids from PE in complex biological matrices.

[0065] In summary, the method provided in this application has achieved sufficient removal of interferences in lipid-containing organic matrices, laying the foundation for subsequent analysis of PE microplastics in lipid-containing organic matrices.

[0066] Comparative Example 1 The specific implementation method in this example is the same as in Example 1. The difference from Example 1 is that no cleaning is performed, and the extraction operation is performed directly before FE microplastic detection.

[0067] Comparative Example 2 The specific implementation method in this example is the same as in Example 1. The difference from Example 1 is that the pyrolysis-gas chromatography-mass spectrometry coupling double-double mode is used for pyrolysis, and the first pyrolysis temperature is 300℃. The matrix interference cannot be removed by the first pyrolysis.

[0068] Comparative Example 3 The specific implementation method in this example is the same as in Example 1. The difference from Example 1 is that hexane and ethanol are mixed in a volume ratio of 1:1 before washing. The sample is washed until there are no oil stains on the surface before extraction.

[0069] Performance testing Repeatability testing: The method for detecting PE content provided in the embodiments and comparative examples of this application was repeated 10 times, and the relative standard deviation A was calculated. This was then repeated by 5 different laboratories, and the relative standard deviation B was calculated. The test results are shown in the table below:

[0070] Recovery rate test: PE standard solution was added dropwise to 0.5g of the sample to achieve a spiked concentration of 20μg / g. The sample was sonicated for 30min. After complete mixing, extraction and determination were performed according to the detection methods provided in Example 1 and Comparative Examples 1-3. The recovery rate of the target compound was obtained by subtracting the sample concentration from the spiked concentration and comparing it with the theoretical concentration. Each test method was repeated three times, and the average value was taken. The test results are shown below:

[0071] It should be noted that this application is not limited to the above-described embodiments. The above embodiments are merely examples, and any embodiments with the same structure and effect as the technical concept within the scope of this application are included in the technical scope of this application. Furthermore, various modifications that can be conceived by those skilled in the art to the embodiments, and other ways of constructing by combining some of the constituent elements of the embodiments, without departing from the spirit of this application, are also included in the scope of this application.

Claims

1. A method for detecting PE microplastics in a lipid-containing organic matrix, characterized in that, Includes the following steps: (1) Mix the PE standard with the solvent to prepare a standard working solution; wash and extract the sample to be tested in sequence to extract the PE from the sample to be tested and obtain the sample solution to be tested; (2) After removing the solvent from the standard solution and the test solution mentioned in step (1), perform thermal pyrolysis-gas chromatography-mass spectrometry for detection and analysis to complete the detection of PE microplastics in lipid-containing organic matrix; In the thermal pyrolysis-gas chromatography-mass spectrometry (GC-MS) detection, the thermal pyrolysis is performed in single-click mode, and the pyrolysis temperature is 400℃~550℃.

2. The detection method according to claim 1, characterized in that, The cleaning process uses organic solvents; the organic solvents include one or more of C5-C8 aliphatic hydrocarbons, halogenated C1-C2 hydrocarbons, and C2-C4 alcohols. Preferably, the organic solvent includes at least one selected from n-hexane, n-heptane, cyclohexane, petroleum ether, ethanol, acetonitrile, dichloromethane, chloroform, carbon tetrachloride, diethyl ether, methyl tert-butyl ether, tetrahydrofuran, ethyl acetate, acetone, methanol, or isopropanol.

3. The detection method according to claim 2, characterized in that, The cleaning process includes a first cleaning and a second cleaning, which together form a cleaning cycle. The cleaning cycle is repeated until the sample to be tested is free of oil stains.

4. The detection method according to claim 3, characterized in that, The first cleaning and the second cleaning are each independently selected from at least one of the following conditions: (1) The cleaning temperature is 40~70℃; (2) The cleaning time is 5~15 minutes; (3) The organic solvent is n-hexane; (4) The organic solvent is ethanol.

5. The detection method according to claim 1, characterized in that, The extraction uses an extractant; the extractant includes at least one of toluene, ethanol, o-xylene, m-xylene, p-xylene, acetone, acetonitrile, or methanol.

6. The detection method according to claim 5, characterized in that, The ratio of the sample to be tested to the extractant is 1g:(10~40)mL.

7. The detection method according to claim 1, characterized in that, In the pyrolysis-gas chromatography-mass spectrometry (PCMS) detection, the gas chromatography meets at least one of the following conditions: (1) The chromatographic column includes an SH-I-5Sil MS column; the column length is 15~60m, the inner diameter is 0.25mm, and the film thickness is 0.1~1μm; (2) The gas chromatography adopts a split injection mode with a split ratio of (3~6):1; (3) The column flow rate is 0.5~2 mL / min (4) The injection port temperature is 300~350℃; (5) The carrier gas is helium with a linear velocity of 36.1 cm / sec.

8. The detection method according to claim 1, characterized in that, In the pyrolysis-gas chromatography-mass spectrometry (GC-MS) detection, the pyrolysis meets at least one of the following conditions: (1) The carrier gas is helium; (2) The temperature of the pyrolyzer-gas chromatograph interface is 280~320℃; (3) The pyrolysis time is 10~15s.

9. The detection method according to claim 1, characterized in that, The mass spectrometric solution in the thermal pyrolysis-gas chromatography-mass spectrometry detection meets at least one of the following conditions: (1) Full scan acquisition mode; (2) The scanning time is 10~30 min; (3) Ionization energy is 50~80 eV; (4) The scanning range is 29~600 m / z; (5) The ion source is EI; positive ion mode; (6) The ion source temperature is 200~250℃; (7) The gas chromatography-mass spectrometry interface temperature is 300~330℃.

10. The application of the detection method according to any one of claims 1 to 9 in detecting the content of PE microplastics in a lipid-containing organic matrix.

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