Solvent dispersion strategy-based surface enhanced Raman scattering (SERS) micro-plastic detection method

Abstract

The invention discloses a surface enhanced Raman scattering (SERS) micro-plastic detection method based on a solvent dispersion strategy, which comprises the following steps: filtering and enriching a liquid containing a sample to be detected by adopting a centrifugation and suction filtration mode or a mode of adopting a Raman substrate with a filtering function, dissolving the filtered sample to be detected by using an organic solvent; heating to completely volatilize the organic solvent, performing Raman detection on the to-be-detected sample to obtain Raman signal intensity, substituting the obtained Raman signal intensity into a known relationship between the sample concentration and the Raman signal intensity, and finally obtaining the actual concentration of the to-be-detected sample. According to the method, the micro-plastic is dissolved and dispersed in the organic solvent, and then the micro-plastic is subjected to Raman detection, so that the problems of low loading efficiency and low detection sensitivity of a sample to be detected are effectively solved. The method is convenient to operate, the structure of the micro-plastic cannot be damaged, the sample enrichment, dispersion and detection efficiency is effectively improved, meanwhile, the signal intensity is enhanced, background interference is reduced, repeatability is improved, the method has wide applicability, and the micro-plastic Raman detection is more efficient and faster.

Description

Technical Field

[0001] The present invention relates to the technical field of microplastic detection, and in particular to a surface enhanced Raman scattering (SERS) microplastic detection method based on a solvent dispersion strategy. Background Art

[0002] Once released into the nature, plastics are easily degraded to form microplastics and nanoplastics. The main sources include: decomposition of plastic waste, washing clothes, car tire wear, use and disposal of plastic products, as well as microplastic particles in cosmetics and plastic particles in industrial wastewater. Microplastics are widely present in the environment and may have serious impacts on the environment and the health of organisms. After entering water, soil and air, microplastics are ingested by organisms and may enter human food through the food chain, posing potential risks to human health. Microplastics will also affect the balance of water and soil ecosystems, biodiversity and ecological functions. Toxic and harmful substances may be adsorbed on the surface of microplastics. When microplastics are ingested by organisms, these chemicals may be released and cause poisoning to organisms. Microplastics accumulate in the environment for a long time and become a persistent organic pollutant, causing long-term pollution to the environment. On this basis, the detection of microplastics is of great significance for the subsequent response and treatment of microplastics.

[0003] There are many defects in the existing methods for detecting microplastics. For example, microscopic observation can only observe the morphology and size, but cannot determine the chemical composition. It can only distinguish the size and shape of microplastics when it is confirmed to be microplastic particles; infrared spectroscopy requires sample pretreatment and is not sensitive enough for low-concentration samples; thermogravimetric analysis cannot provide specific particle information and has limited applicability; flow cytometry requires labeling reagents and high-cost equipment and may be interfered with; mass spectrometry has low sensitivity and requires high-resolution instruments; traditional filtration combined with microscopy can only detect larger particles, and has limited effect on small-sized and low-concentration samples. Therefore, it is necessary to further develop and improve existing methods to improve the accuracy and reliability of microplastic detection.

[0004] Raman spectroscopy is a non-destructive detection method that can quickly identify the chemical composition of microplastic particles. Raman detection technology has significant advantages over other methods. By measuring the Raman spectrum of microplastic particles in the sample, its type and structure can be determined. Raman scattering changes the frequency of the scattered light, producing a wavelength different from the incident light. This difference is called Raman shift. The size of the Raman shift can provide structural information such as chemical bonds and functional groups contained in the substance to be tested. Based on this characteristic of Raman spectroscopy, Raman spectroscopy is called the "fingerprint" of the substance. Surface-enhanced Raman spectroscopy combined with the surface enhancement effect of nanomaterials can improve the sensitivity and accuracy of microplastic detection. Combining surface-enhanced Raman technology with microplastic detection can achieve rapid and accurate identification and quantitative analysis of microplastics.

[0005] Existing Raman detection technology faces many challenges in the detection of microplastics in the marine environment. First, the concentration of microplastics in the ocean is usually very low, with only a few to hundreds of microplastic particles per cubic meter of water, which makes it more difficult to detect and identify microplastics. In addition, there are many organic and inorganic particles in seawater, which may produce Raman signals similar to microplastics, causing background interference and reducing the accuracy and reliability of detection. Microplastic particles range in size from nanometers to millimeters, and particles of different sizes may require different detection methods and parameters. In addition, the shapes of microplastic particles are also diverse, including flakes, spheres, fibers, etc., and particles of different shapes may affect the generation and detection of Raman signals. The collection and preparation of marine samples are crucial for Raman detection of microplastics, but there are many other components in marine samples, such as salts, algae, etc., and the samples need to be properly processed to effectively detect microplastics. The steps are relatively complicated. For example, density filtration operations are required in the separation and extraction methods of microplastics, making the detection more cumbersome, the sample loading efficiency is low, and the efficiency of detection is greatly reduced. Finally, there is currently a lack of standardized methods and standard samples for Raman detection of microplastics in the marine environment, making it difficult to compare and verify the results of different laboratories.

[0006] Therefore, it is necessary to provide a detection method for microplastics that can enhance Raman scattering to solve the problems of low loading efficiency of samples to be tested and low detection sensitivity. Summary of the invention

[0007] The present invention provides a surface enhanced Raman scattering (SERS) microplastic detection method based on a solvent dispersion strategy to solve the above problems.

[0008] In order to achieve the above object, the technical solution of the present invention is:

[0009] A surface enhanced Raman scattering (SERS) microplastic detection method based on a solvent dispersion strategy comprises the following steps:

[0010] After filtering and enriching the liquid containing the sample to be tested by centrifugation and suction filtration or by using a Raman substrate with a filtering function, the sample to be tested obtained after filtration is dissolved using an organic solvent. After the organic solvent is completely evaporated by heating, a Raman spectrometer is used to perform Raman detection on the sample to be tested after the organic solvent dissolution treatment to obtain Raman signal intensity and Raman spectrum. The type of the sample to be tested is determined by comparing the obtained Raman spectrum with the Raman spectrum corresponding to a known substance, and the obtained Raman signal intensity is brought into the relationship between the known sample concentration and the Raman signal intensity, and finally the actual concentration of the sample to be tested is obtained.

[0011] Furthermore, when the filtration and enrichment adopt the centrifugation and suction filtration, after the filtered sample is dissolved by an organic solvent, a mixed solution of the sample and the organic solvent is dripped onto the surface of the Raman substrate, and then the Raman substrate is heated to completely volatilize the organic solvent thereon, and finally Raman detection is performed;

[0012] When the filtration and enrichment adopts a Raman substrate with a filtering function, a liquid containing the sample to be tested is first dripped onto the detection area on the Raman substrate for filtration and enrichment, and then an organic solvent is dripped into the detection area on the Raman substrate to dissolve the sample to be tested, and then the Raman substrate is heated to completely volatilize the organic solvent thereon, and finally Raman detection is performed.

[0013] Furthermore, the organic solvent is toluene; it can also be xylene, acetone and other organic solvents;

[0014] Furthermore, in the mixed solution of the organic solvent and the liquid containing the sample to be tested, the concentration of the sample to be tested is not less than 10 -11 mg / ml.

[0015] Furthermore, the sample to be tested is microplastic.

[0016] Furthermore, the Raman substrate with filtering function is a paper-based Raman substrate based on in-situ silver reduction.

[0017] Furthermore, the specific method of heating is: placing the Raman substrate on a hot plate and heating it at a temperature of 50° C.-80° C. for 3 minutes.

[0018] Furthermore, the liquid containing the sample to be tested is a seawater sample containing microplastics.

[0019] The beneficial effects of the present invention are:

[0020] The present invention discloses a surface enhanced Raman scattering (SERS) microplastic detection method based on a solvent dispersion strategy, which first dissolves and disperses microplastics in an organic solvent, and then performs Raman detection on them, effectively solving the problems of low loading efficiency of the sample to be tested and low detection sensitivity. The pre-treatment method of the method is simple, easy to operate, and will not damage the microplastic structure. The method of dissolving microplastics with solvents for Raman detection effectively improves sample enrichment, dispersion and detection efficiency, while enhancing signal strength, reducing background interference, and improving repeatability. It has a wide range of applicability, making Raman detection of microplastics more efficient and quick. 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 This is a flow chart of the surface enhanced Raman scattering (SERS) microplastic detection method based on the solvent dispersion strategy disclosed in the present invention;

[0023] Figure 2 Schematic diagram of the surface enhanced Raman scattering (SERS) microplastic detection method based on solvent dispersion strategy Figure 1 (Use centrifugation and filtration to enrich the sample);

[0024] Figure 3 Schematic diagram of the surface enhanced Raman scattering (SERS) microplastic detection method based on solvent dispersion strategy Figure 2 (Enrichment of samples using filtered Raman substrate);

[0025] Figure 4 Raman spectra of polystyrene particles detected by surface-enhanced Raman scattering microplastic detection method based on solvent dispersion strategy;

[0026] Figure 5 Raman spectrum of 10 mg / mL polystyrene sample detected by surface-enhanced Raman scattering microplastic detection method based on solvent dispersion strategy;

[0027] Figure 6 The surface enhanced Raman scattering microplastic detection method based on solvent dispersion strategy detects different concentration gradients (10 -5 mg / ml~10 -10 mg / ml) of polystyrene / xylene solution;

[0028] Figure 7 The surface enhanced Raman scattering microplastic detection method based on solvent dispersion strategy detects 1-10 -10 Raman spectrum of the polystyrene sample with a concentration of mg / mL. DETAILED DESCRIPTION

[0029] 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.

[0030] Principles involved in the present invention:

[0031] Compared with traditional microplastic detection, the method of dispersing microplastics with organic solvents used in this method can solve the problems of weak low-concentration signals and large background interference in the detection of microplastics in the marine environment. The microplastics can be fully dispersed through the organic solvent dissolution strategy and then attached to the surface of the Raman enhanced substrate and between the hotspots, increasing their interaction with the laser, thereby enhancing the intensity of the Raman signal, which helps to improve the sensitivity and accuracy of the detection. In addition, there are a large number of background interferents in environmental samples, such as organic and inorganic impurities. The use of organic solvents to dissolve microplastics can separate them from environmental samples, thereby reducing the impact of background signals on Raman detection results; and the present invention effectively dissolves microplastic particles of different sizes and shapes through organic solvents, so that the microplastic samples can be more evenly dispersed in the organic solvent, so that the distribution of microplastics between different samples on the Raman substrate (detection chip) is more consistent. At the same time, this method can simplify the sample processing process and be used together with a standardized mixture of microplastic particles to improve the reliability and comparability of the detection method. In addition, this method uses filter paper as a Raman substrate, which has a filtering effect on microplastic particles, further enhancing the Raman detection signal of the object to be detected. The flowcharts of the two microplastic detection methods used in the present invention are as follows: Figure 1 shown.

[0032] Example

[0033] Embodiment 1:

[0034] like Figure 2 The present embodiment shows a surface enhanced Raman scattering (SERS) microplastic detection method based on a solvent dispersion strategy. First, the liquid sample containing microplastics is centrifuged or filtered to enrich the microplastics in the liquid. Then, an organic solvent with good solubility is added to the enriched microplastic sample to dissolve and disperse it. Then, the dispersed microplastic sample is loaded onto the surface of the SERS substrate. Finally, after the organic solvent is completely volatilized, the SERS substrate is subjected to Raman detection to achieve high-sensitivity identification and detection of microplastics. The specific steps are as follows:

[0035] First, we need to collect 1L of seawater sample for microplastic detection, and then centrifuge and filter the 1L sample repeatedly to obtain 0.1g of microplastic sample. Figure 2 (A) is the sampling step, and (B) is the centrifugal filtration step;

[0036] Then, 0.1 g of the enriched microplastic samples were placed in beakers respectively. Under ventilation conditions, 10 ml of toluene solution was added to each beaker to dissolve them. Figure 2 (C) is a dissolution step, in which the dissolution of the microplastics can be accelerated by ultrasonically heating the sample. In this embodiment, the sample is heated at 40°C and ultrasonically heated for 10 minutes. The specific ultrasonic heating parameters can be adjusted according to actual needs.

[0037] The microplastic / toluene solution was dripped onto the prepared Raman substrate (paper-based Raman chip). Figure 2 (D) is the step of loading the sample on the chip. The Raman chip loaded with microplastics is then heated by ventilation. The specific conditions are heating at 80°C for 5 minutes to allow the organic solvent to completely evaporate before Raman detection. Figure 2 Middle (E) is a Raman detection step, in which the Raman signal intensity and Raman spectrum are obtained by Raman detection, and the obtained Raman signal intensity is brought into the standard curve of known sample concentration and Raman signal intensity to finally obtain the actual concentration of the sample to be tested; the obtained Raman spectrum of microplastics is compared and analyzed with the standard Raman spectrum of plastics or the type of specific plastic is obtained by decoupling technology;

[0038] Currently, only a few noble metals and transition metals have Raman effect, but the enhancement effect of transition metals is slightly inferior to that of noble metals. For noble metals, there are many ways to make them serve as Raman substrates, such as using the properties of some bifunctional molecules to adsorb metal nanoparticles to make them self-assemble into a tightly packed metal nanoparticle layer; or using different elements to react under certain conditions to in-situ reduce metal nanoparticles, which can also make the solid substrate carrier and the metal nanoparticles have good adhesion, thus obtaining a substrate with Raman effect;

[0039] The Raman substrate in this embodiment uses a Raman detection substrate based on in-situ silver reduction of a paper-based chip, and the specific design method is as follows:

[0040] 1) Printing a paper base (filter paper) of a specific shape by a printer, wherein the paper base has four Raman detection windows of equal size and arranged in the center;

[0041] 2) At each Raman detection window position on the upper surface of the paper base, 20 μL of silver nano suspension (8 mM) is dripped and filtered to deposit the metal silver particles on the filter paper (paper base). The nanocellulose and silver nanoparticles are mixed and filtered to better combine the silver nanoparticles with the filter paper base. At the same time, the rough structure of the filter paper can also make the silver nanoparticles more closely combined with it. The aqueous solution and common organic solvents in the Raman detection area have good wettability. The organic solvent evaporates in the detection area to achieve enrichment and loading of the detection object in the detection area, thereby achieving SERS high-sensitivity detection;

[0042] 3) The filtered chip is dried at 40° C. for 3 min. After it is completely dried, the Raman detection substrate for in-situ silver reduction of the paper-based chip is prepared;

[0043] The selection of organic solvents includes the following conditions:

[0044] 1) It has good volatility and will not cause signal interference to subsequent detection after volatilization;

[0045] 2) It has good properties of dissolving microplastics, which is beneficial to the dissolution of target detection substances and the aggregation and concentration of detection substances in the Raman detection area;

[0046] 3) The physical properties are stable, which is conducive to the long-term storage of the solution.

[0047] Embodiment 2:

[0048] like Figure 3 The present embodiment provides a surface-enhanced Raman scattering (SERS) microplastic detection method based on a solvent dispersion strategy: first, a paper-based Raman substrate with a filtering function is used to enrich microplastics, and then an organic solvent with good solubility is loaded onto the surface of the Raman substrate to dissolve and disperse the enriched microplastic samples, and finally, after the organic solvent evaporates, the Raman substrate is subjected to Raman detection to achieve high-sensitivity identification and detection of microplastics. The surface-enhanced Raman microplastic detection method based on a solvent dispersion strategy described in this embodiment can effectively achieve rapid, portable, low-cost, and high-sensitivity detection of microplastic samples. The specific steps of the detection are:

[0049] like Figure 3 As shown in (A), firstly, a seawater sample for detecting microplastics is sampled, and the sample is dripped onto a paper-based Raman substrate (chip) for filtration and enrichment, and finally a paper-based Raman chip enriched with microplastic samples is obtained. The filtration and enrichment steps are as follows: Figure 3 (F)

[0050] like Figure 3 (G) As shown in FIG. 1 , a proper amount of organic solvent is directly added to the microplastic sample (detection area) on the paper-based Raman chip to dissolve it (ensuring that the concentration of the sample to be tested is not less than 10-10 mg / ml), the microplastics are dispersed on a paper-based Raman chip, and the paper-based Raman chip loaded with microplastic particles dispersed with an organic solvent is appropriately heated to allow the organic solvent to completely evaporate and not interfere with subsequent detection; Figure 3 As shown in (H), a Raman spectrometer is used to detect the Raman detection area where the sample is dropped and the organic solvent has completely evaporated to obtain the Raman signal intensity. The obtained Raman signal intensity is substituted into the standard curve of known sample concentration and Raman signal intensity to finally obtain the actual concentration of the sample to be tested.

[0051] The paper-based Raman chip in this embodiment uses a Raman detection substrate based on in-situ silver reduction of a paper-based chip, and the specific design method is the same as that of Example 1. The paper-based Raman chip is a paper-based chip with nanocellulose reduced silver, and the target molecules or particles to be measured can be embedded between the silver nanoparticles by dropping a solution, thereby improving the hot spot density and detection sensitivity of the Raman detection substrate.

[0052] Example 3: Detection of polystyrene

[0053] The detection steps are as follows:

[0054] S1: Take 0.1g of polystyrene sample, add 10ml of toluene organic solvent to completely dissolve the polystyrene, and prepare a 10mg / mL polystyrene microplastic solution;

[0055] S2: preparing a paper-based chip in-situ silver-reduced Raman detection substrate, the method is the same as the steps in Example 1;

[0056] S3: adding the polystyrene microplastic solution prepared in S1 to S2, placing the Raman substrate on a heating plate and heating it until the toluene thereon is completely volatilized, so that the toluene does not interfere with subsequent detection, and the sample to be tested is embedded in the gaps between the nanoparticles of the Raman detection substrate;

[0057] S4: A Raman spectrometer is used to detect the Raman detection area where the sample is dropped and the toluene has been completely volatilized. The Raman spectrum excitation wavelength used is 785nm, the integration time used for detection is 20s, and the excitation intensity used is 7mW. The Raman spectrum of polystyrene is as follows: Figure 5 As shown (the horizontal axis in the figure is Raman shift, and the vertical axis is Raman detection intensity);

[0058] S5: After the detection is completed, the obtained Raman spectrum is analyzed, and the Raman characteristic peaks of the sample to be tested are Figure 4 The Raman characteristic peaks of the polystyrene standard are compared and found to be consistent, so the sample to be tested is determined to be polystyrene; the specific components of the sample to be tested can also be analyzed according to the decoupling method to determine the type of the sample to be tested;

[0059] S6: Under the same conditions, polystyrene solutions with known concentrations are prepared in a gradient, for example, the concentrations of polystyrene in the polystyrene / toluene solution are 10 -5 mg / ml, 10 -6 mg / ml, 10 -7 mg / ml, 10 -8 mg / ml, 10 -9 mg / ml, 10 - 10 Repeat the above steps S2-S4 and finally perform Raman detection to obtain the complete spectrum data of polystyrene microplastics with full gradient concentrations. Figure 6 As shown in the figure (the horizontal axis is Raman shift, and the vertical axis is Raman detection intensity), the spectral data corresponding to the polystyrene to be tested obtained in step S5 is Figure 6 The spectral data is compared with that of the polystyrene solution with known concentration, and the Raman spectral intensity corresponding to the polystyrene solution is obtained by combining the Raman spectral intensity (i.e., the obtained Raman signal intensity is brought into the relationship between the known sample concentration and the Raman signal intensity), so as to obtain the actual content of the measured polystyrene sample.

[0060] Embodiment 4:

[0061] Weigh 0.1g of polystyrene and place it in 11 beakers. Add 10ml of toluene solution to each beaker to prepare a polystyrene solution with a concentration of 10mg / ml. Then take 1ml from the solution and add 9ml of toluene to prepare a polystyrene solution with a concentration of 1mg / ml. Repeat the above steps to make a gradient dilution until the concentration is 10. -1 mg / ml, 10 -2 mg / ml, 10 -3 mg / ml, 10 -4 mg / ml, 10 -5 mg / ml, 10 -6 mg / ml, 10 -7 mg / ml, 10 -8 mg / ml, 10 -9 mg / ml, 10 - 10 The polystyrene / toluene solution was added dropwise onto the in-situ silver-reduced paper-based Raman chip to complete loading. The Raman chip was then heated at 80°C for 5 minutes to completely evaporate the toluene. After the toluene in which the polystyrene was dissolved evaporated, the signal of the sample was collected with an integration power of 30 mW, an integration time of 3000 ms, and a sampling frequency of 5 times to obtain the Raman spectrum of the polystyrene.

[0062] At the same time, the polystyrene concentration was 10 -11 mg / ml, 10-12 mg / ml polystyrene / toluene solution was used as a comparison for Raman detection;

[0063] Test results such as Figure 7 As shown, Figure 7 (a) is the SERS detection of CNF-Ag substrate to polystyrene solutions with different concentrations (the horizontal axis is Raman shift, and the vertical axis is Raman detection intensity). Figure 7 (b) is 1139 cm -1 The logarithmic relationship between the SERS peak intensity and the polystyrene solution concentration (the horizontal axis in the figure is the lg function of the concentration, and the vertical axis is the Raman signal intensity); Figure 7 In (a), it can be seen that the polystyrene sample solution is between 1 mg / ml and 10 -10 The SERS signal is obvious in the concentration range of 10 mg / ml. As the polystyrene solution is diluted, the concentration decreases and the intensity of SERS detection also decreases. -11 mg / ml~10 -12 When the concentration was 0.1 mg / ml, the SERS signal dropped significantly to a low point and even approached a straight line. It can be determined that the detection limit of this method for polystyrene microplastics is as high as 10 -10 mg / ml, it has a high sensitivity in microplastic detection. At the same time, when the microplastic sample is loaded into the chip, the time from loading to solvent evaporation to obtaining the test result can be controlled within 10 minutes. Therefore, this detection method can realize rapid detection of microplastics.

[0064] In summary, the detection limit of the detection method disclosed in the present invention for detecting microplastics is as high as 10 -10 mg / ml, it has a high sensitivity in microplastic detection. At the same time, when the microplastic sample is loaded into the chip, the time from loading to solvent volatilization and then to the detection result is controlled within 10 minutes, and the detection is fast and efficient. The pre-treatment method of this method is simple, easy to operate, and will not damage the microplastic structure. The method of dissolving microplastics with solvents for Raman detection effectively improves sample enrichment, dispersion and detection efficiency, while enhancing signal intensity, reducing background interference, and improving repeatability (the ability to obtain uniform results). It has a wide range of applicability, making Raman detection of microplastics more efficient and quick.

[0065] 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 replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A surface enhanced Raman scattering (SERS) microplastic detection method based on solvent dispersion strategy, characterized in that: Includes steps: After filtering and enriching the liquid containing the sample to be tested by centrifugation and suction filtration or by using a Raman substrate with a filtering function, the sample to be tested obtained after filtration is dissolved using an organic solvent. After the organic solvent is completely evaporated by heating, a Raman spectrometer is used to perform Raman detection on the sample to be tested after the organic solvent dissolution treatment to obtain Raman signal intensity and Raman spectrum. The type of the sample to be tested is determined by comparing the obtained Raman spectrum with the Raman spectrum corresponding to a known substance, and the obtained Raman signal intensity is brought into the relationship between the known sample concentration and the Raman signal intensity, and finally the actual concentration of the sample to be tested is obtained.

2. The surface enhanced Raman scattering (SERS) microplastic detection method based on solvent dispersion strategy according to claim 1, characterized in that: When the filtration and enrichment adopt the centrifugation and suction filtration method, after dissolving the filtered sample with an organic solvent, a mixed solution of the sample and the organic solvent is dripped onto the surface of the Raman substrate, and then the Raman substrate is heated to completely volatilize the organic solvent thereon, and finally Raman detection is performed; When the filtration and enrichment adopts a Raman substrate with a filtering function, a liquid containing the sample to be tested is first dripped onto the detection area on the Raman substrate for filtration and enrichment, and then an organic solvent is dripped into the detection area on the Raman substrate to dissolve the sample to be tested, and then the Raman substrate is heated to completely volatilize the organic solvent thereon, and finally Raman detection is performed.

3. The surface enhanced Raman scattering (SERS) microplastic detection method based on solvent dispersion strategy according to claim 1, characterized in that: The organic solvent is toluene.

4. The surface enhanced Raman scattering (SERS) microplastic detection method based on solvent dispersion strategy according to claim 1, characterized in that: In the mixed solution of the organic solvent and the liquid containing the sample to be tested, the concentration of the sample to be tested is not less than 10 -10 mg / ml.

5. The surface enhanced Raman scattering (SERS) microplastic detection method based on solvent dispersion strategy according to claim 1, characterized in that: The sample to be tested is microplastic.

6. The surface enhanced Raman scattering (SERS) microplastic detection method based on solvent dispersion strategy according to claim 1, characterized in that: The Raman substrate with filtering function is a paper-based Raman substrate based on in-situ silver reduction.

7. The surface enhanced Raman scattering (SERS) microplastic detection method based on solvent dispersion strategy according to claim 2, characterized in that: The specific heating method is: placing the Raman substrate on a hot plate and heating it at a temperature of 50° C.-80° C. for 3 minutes.

8. The surface enhanced Raman scattering (SERS) microplastic detection method based on solvent dispersion strategy according to claim 1, characterized in that: The liquid containing the sample to be tested is a seawater sample containing microplastics.

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