A method for rapid extraction of pesticides in water based on confined liquid film

Abstract

This invention relates to the field of sample pretreatment technology, and in particular to a rapid extraction method for pesticides in water based on a confined liquid membrane. The method includes the following steps: preparing a composite substrate membrane comprising carbon nanofibers / carbon fibers and carbon nanofibers / carbon spheres; injecting ethanol as a confining solvent through the composite substrate membrane until droplets form beneath the membrane, thus completing the construction of the confined liquid membrane; passing a water sample containing the target pesticide through the confined liquid membrane at a set flow rate; using a desorption solvent at a set flow rate through the confined liquid membrane to elute the extracted target pesticide; collecting the eluent and performing quantitative analysis. This invention, through its ingenious confined liquid membrane design, successfully achieves rapid simultaneous extraction of pesticides with a wide polarity range and multiple categories from water while ensuring high extraction efficiency and good reproducibility.

Description

Technical Field

[0001] This invention relates to the field of sample pretreatment technology, and in particular to a rapid extraction method for pesticides in water based on a confined liquid membrane. Background Technology

[0002] Pesticides are widely used in crop cultivation to control pests and diseases. They are diverse and can be classified according to their chemical structure into organophosphates, organochlorines, pyrethroids, carbamates, and organic heterocyclic compounds. After application, pesticides may enter water bodies through surface runoff and groundwater infiltration. Pesticide residues in the aquatic environment pose a serious threat to ecosystems and human health due to their persistence and potential toxicity. Therefore, developing a pretreatment method capable of simultaneously and rapidly extracting multiple types of pesticides is of great significance for water environment monitoring and food safety.

[0003] Currently, pretreatment technologies for pesticide extraction in water mainly include solid-phase extraction, aqueous two-phase extraction, and liquid-phase nanoextraction. These methods all have certain limitations in practical applications. Specifically, solid-phase extraction: its principle is based on the selective adsorption of the target analyte by the adsorbent, and it can usually only extract pesticides with a specific chemical structure, making it difficult to achieve broad-spectrum extraction. Although the adsorption of specific polar substances can be enhanced by modifying the functional groups on the surface of the adsorbent, this method generally suffers from long extraction times, poor adsorbent repeatability, and cumbersome operation. Aqueous two-phase extraction: this method forms a two-phase system through salting out, utilizing the difference in pesticide distribution between the two phases to achieve separation. However, its synthesis conditions are complex, salt concentration needs precise control, costs are high, and the source of certain ionic liquids is limited, restricting its widespread application in practical detection. Liquid-phase nanoextraction: the liquid-phase nanoextraction technology developed in recent years utilizes the confinement effect of carbon nanomaterials, forming a high specific surface area liquid-phase extraction interface by adding a confining solvent to its surface, thereby improving extraction efficiency. There are many choices of confining solvents, they are easy to change, and the mass transfer rate is fast. However, existing studies mostly use a single nonpolar solvent (such as n-hexane) as the confinement medium. While this method shows good extraction efficiency for hydrophobic pesticides, it has low extraction efficiency for highly polar pesticides (such as some organophosphates and carbamates), making it difficult to achieve truly "broad-spectrum" extraction. Furthermore, existing methods still lack systematic optimization in terms of material structure design and solvent polarity adaptation, resulting in a difficulty in balancing extraction speed, recovery rate, and applicability.

[0004] Therefore, there is an urgent need to develop a rapid extraction method for pesticides in water that is broad-spectrum, highly efficient, and easy to operate, in order to meet the detection needs of pesticide residues of multiple categories and a wide range of polarities. Summary of the Invention

[0005] The purpose of this invention is to address the problems existing in the prior art by providing a rapid extraction method for pesticides in water based on a confined liquid membrane. Through a clever confined liquid membrane design, the rapid and simultaneous extraction of pesticides with a wide polarity range and multiple categories in water is successfully achieved while ensuring high extraction efficiency and good reproducibility.

[0006] To achieve the above objectives, the present invention provides a rapid extraction method for pesticides in water based on a confined liquid membrane, comprising the following steps:

[0007] S1. Providing a confined liquid membrane: A composite substrate membrane comprising carbon nanofibers / carbon fibers and carbon nanofibers / carbon spheres is prepared: A carbon fiber substrate is calcined, acidified, and immersed in a catalyst solution, then reacted with acetylene-containing gas to grow carbon nanofibers on the surface of the carbon fiber substrate, yielding carbon nanofibers / carbon fibers; A carbon sphere substrate is immersed in a catalyst solution, then reacted with acetylene-containing gas to grow carbon nanofibers on the surface of the carbon sphere substrate, yielding carbon nanofibers / carbon spheres; Carbon nanofibers / carbon fibers and carbon nanofibers / carbon spheres are arranged alternately to obtain a composite substrate membrane; Ethanol is injected as a confining solvent and passed through the composite substrate membrane until droplets form beneath the membrane, completing the construction of the confined liquid membrane;

[0008] S2. Pass the water sample containing the target pesticide through the confined liquid membrane at a set flow rate;

[0009] S3. Use a desorption solvent at a set flow rate through a confined liquid membrane to elute the extracted target pesticide;

[0010] S4. Collect the desorption solution and perform quantitative analysis.

[0011] Preferably, in the composite substrate membrane described in S1, carbon nanofibers / carbon fibers and carbon nanofibers / carbon spheres are filled in an alternating manner; wherein, the alternating arrangement is achieved by repeatedly containing a basic filling unit comprising one layer of carbon nanofibers / carbon fibers and one layer of carbon nanofibers / carbon spheres.

[0012] Preferably, in the composite substrate membrane described in S1, the unit area filling amount of carbon nanofibers / carbon fibers is 3-20 mg / cm². 2 The carbon nanofiber / carbon sphere filler content per unit area is 3-25 mg / cm³. 2 .

[0013] Preferably, in S2, the flow rate is 250-1000 μL / min.

[0014] Preferably, in S2, the flow rate is 750 μL / min.

[0015] Preferably, in S3, the desorption solvent is selected from one or more of methanol, ethanol, dichloromethane, ethyl acetate, and n-hexane.

[0016] Preferably, in S3, the desorption solvent is dichloromethane.

[0017] Preferably, in S3, the flow rate is 0.5-2.0 mL / min.

[0018] Preferably, in S3, the flow rate is 1.0 mL / min.

[0019] Preferably, in S2, the target pesticide includes at least one of organophosphate pesticides, organochlorine pesticides, pyrethroid pesticides, carbamate pesticides, and organoheterocyclic pesticides.

[0020] The beneficial effects of this invention are as follows:

[0021] (1) This invention constructs a composite substrate membrane filled with alternating layers of carbon nanofibers / carbon fibers (CNFs / CFs) and carbon nanofibers / carbon spheres (CNFs / CμS), and uses ethanol as the confining solvent to form a stable liquid-film interface under the confinement effect of the substrate membrane. This confined ethanol system can simultaneously provide hydrogen bonding and van der Waals forces, thereby achieving efficient simultaneous extraction of various pesticides ranging from strongly hydrophilic to strongly hydrophobic. This method successfully covers 21 pesticides in five major classes, including organophosphates, organochlorines, pyrethroids, carbamates, and organic heterocyclic compounds, significantly expanding the range of pesticides detectable by a single method and effectively solving the shortcomings of existing technologies in terms of the broad spectrum of target analytes.

[0022] (2) By optimizing the structure and operating parameters of the confined liquid membrane, this invention optimizes the membrane extraction flow rate of water samples to 750 μL / min and the desorption flow rate to 1.0 mL / min, achieving rapid enrichment and elution of pesticides in water. The entire extraction-desorption process can be completed within minutes, greatly shortening the sample pretreatment time, increasing analytical throughput, and meeting the urgent needs for rapid detection in fields such as environmental monitoring and food safety.

[0023] (3) The extraction recovery rates of 21 pesticides in water by this invention ranged from 51.62% to 116.71%, and the relative standard deviations (RSDs) were all no higher than 13.49%. This indicates that the method not only has good extraction capabilities for various pesticides, but also has stable operation and high reproducibility, and can provide stable and reliable samples for subsequent instrumental analysis, ensuring the accuracy of the detection results.

[0024] (4) The preparation process of the core materials used in this invention is mature, and ethanol and desorption solvent are common and inexpensive reagents. The whole method only requires manual pushing of the membrane with a syringe, without the need for large pretreatment equipment. The device is small and the operation process is simple. It has low requirements for the professional skills of the operators. It is not only suitable for routine laboratory analysis, but also convenient for on-site sampling and rapid detection. It is conducive to its widespread use in grassroots testing units and actual monitoring scenarios.

[0025] (5) With its broad spectrum, speed, efficiency and reliability, this method can effectively address the challenge of simultaneous detection of multiple types of pesticide residues in the water environment, and provides a powerful sample pretreatment tool for monitoring water quality in agricultural production areas, assessing drinking water safety and tracing pesticide residues in food. Attached Figure Description

[0026] Figure 1 This is a schematic diagram illustrating the effect of the type of confining solvent on the extraction efficiency in this invention;

[0027] Figure 2 This is a schematic diagram illustrating the effect of the flow rate of the water sample containing the target pesticide on the extraction efficiency.

[0028] Figure 3 This is a schematic diagram illustrating the effect of the type of desorption solvent on the extraction efficiency of this invention;

[0029] Figure 4 This is a schematic diagram illustrating the effect of the desorption solvent flow rate on the extraction efficiency of this invention;

[0030] Figure 5 This is a schematic diagram illustrating the effect of the membrane filling method of the present invention on the extraction efficiency. Detailed Implementation

[0031] This invention provides a rapid extraction method for pesticides in water based on a confined liquid membrane, comprising the following steps:

[0032] S1. Providing a confined liquid membrane: A composite substrate membrane comprising carbon nanofibers / carbon fibers and carbon nanofibers / carbon spheres is prepared: A carbon fiber substrate is calcined, acidified, and immersed in a catalyst solution, then reacted with acetylene-containing gas to grow carbon nanofibers on the surface of the carbon fiber substrate, yielding carbon nanofibers / carbon fibers; A carbon sphere substrate is immersed in a catalyst solution, then reacted with acetylene-containing gas to grow carbon nanofibers on the surface of the carbon sphere substrate, yielding carbon nanofibers / carbon spheres; Carbon nanofibers / carbon fibers and carbon nanofibers / carbon spheres are arranged alternately to obtain a composite substrate membrane; Ethanol is injected as a confining solvent and passed through the composite substrate membrane until droplets form beneath the membrane, completing the construction of the confined liquid membrane;

[0033] S2. Pass the water sample containing the target pesticide through the confined liquid membrane at a set flow rate;

[0034] S3. Use a desorption solvent at a set flow rate through a confined liquid membrane to elute the extracted target pesticide;

[0035] S4. Collect the desorption solution and perform quantitative analysis.

[0036] In this invention, in the composite substrate membrane described in S1, carbon nanofibers / carbon fibers (labeled CNFs / CFs) and carbon nanofibers / carbon spheres (labeled CNFs / CμS) are filled in an alternating arrangement; wherein, the alternating arrangement is achieved by repeatedly containing a basic filling unit comprising one layer of carbon nanofibers / carbon fibers and one layer of carbon nanofibers / carbon spheres.

[0037] F represents a layer of CNFs / CFs, and B represents a layer of CNFs / CμS. The basic filling unit consisting of a layer of carbon nanofibers / carbon fibers and a layer of carbon nanofibers / carbon spheres refers to: one layer of F and one layer of B, forming a two-layer structure with F on top and B on the bottom (F / B) or B on top and F on the bottom (B / F).

[0038] In this invention, in the composite base membrane described in S1, regardless of the filling method, the carbon fiber filling amount per unit area is 3-20 mg / cm². 2 The unit area filling amount of carbon nanofibers / carbon spheres is 3-25 mg / cm³. 2 .

[0039] In this invention, the flow rate in S2 is 250-1000 μL / min; preferably 750 μL / min.

[0040] In this invention, in step S3, the desorption solvent is selected from one or more of methanol, ethanol, dichloromethane, ethyl acetate, and n-hexane; preferably dichloromethane.

[0041] In this invention, the flow rate in S3 is 0.5-2.0 mL / min; preferably 1.0 mL / min.

[0042] In this invention, in S2, the target pesticide includes at least one of organophosphorus pesticides, organochlorine pesticides, pyrethroid pesticides, carbamate pesticides, and organoheterocyclic pesticides.

[0043] In this invention, in S2, the LogP range of the target pesticide covers 0.75 to 6.91. P represents the partition coefficient, which refers to the concentration ratio of the compound when it reaches equilibrium in two immiscible solvents (oil phase and aqueous phase). The LogP range covered by this invention extends from 0.75 to 6.91, meaning that the method is applicable to a wide range of pesticides from strongly hydrophilic to strongly lipophilic, demonstrating a very broad polarity adaptability.

[0044] The present invention will be further described below with reference to the accompanying drawings and embodiments. Unless otherwise defined, the technical or scientific terms used in this invention should be understood in their ordinary sense by those skilled in the art. The features mentioned above or in the specific examples mentioned in this invention can be combined arbitrarily, and these specific embodiments are only used to illustrate the invention and are not intended to limit the scope of the invention.

[0045] Example 1

[0046] This embodiment provides a rapid extraction method for pesticides in water based on a confined liquid membrane, comprising the following steps:

[0047] Carbon fiber substrates (labeled CFs) were calcined at 450°C for 30 min, then placed in 250 mL of acetone and extracted by Soxhlet extraction for 12 h to obtain treated fibers. Next, the treated fibers were immersed in a mixture of 63% nitric acid solution and 98% sulfuric acid solution (volume ratio of 1:3) for 12 h. After immersion, the fibers were washed with deionized water until neutral and dried at 80°C to obtain acidified carbon fiber substrates. The substrates were then immersed in a catalyst solution prepared by tetraethyl orthosilicate, P123, water, ethanol, hydrogen chloride, and nickel nitrate in a molar ratio of 1:0.0103:9.36:21.4:0.04:0.47 for 12 h. After immersion, the substrates were removed and rinsed with the catalyst solution to ensure complete dispersion and uniform adhesion of the catalyst on the surface. The substrates were then air-dried and calcined at 450°C for 30 min to remove P123, yielding a substrate containing the catalyst. The substrate containing the catalyst was placed in a tube furnace. Nitrogen gas was first introduced at room temperature (flow rate 150 cc / min), and then the temperature was increased to 600°C at a rate of 5°C / min and maintained at that temperature for 60 min. Subsequently, hydrogen gas was introduced (25 cc / min) for 30 min, and then acetylene gas was introduced simultaneously (35 cc / min) to continue the reaction for another 30 min. After the reaction was completed, the introduction of hydrogen and acetylene gas was stopped, and interwoven carbon nanofibers (labeled CNFs) were grown on the surface of the CFs, thus obtaining carbon nanofibers / carbon fibers (labeled CNFs / CFs).

[0048] A carbon sphere substrate (labeled CμS) was immersed in a catalyst solution for 12 h. The catalyst solution was prepared by mixing tetraethyl orthosilicate, P123, water, ethanol, hydrogen chloride, and nickel nitrate in a molar ratio of 1:0.0103:9.36:21.4:0.04:0.47. After immersion, the substrate was removed and rinsed with the catalyst solution to ensure complete dispersion and uniform adhesion of the catalyst on its surface. The substrate was then air-dried and calcined at 450 °C for 30 min to remove P123, yielding a substrate containing the catalyst. The catalyst-containing substrate was placed in a tube furnace. Nitrogen gas was first introduced at room temperature (flow rate 150 cc / min), and then the temperature was increased to 600 °C at a rate of 5 °C / min and maintained at this temperature for 60 min. Subsequently, hydrogen gas (25 cc / min) was introduced for 30 min, followed by simultaneous introduction of acetylene gas (35 cc / min) for another 30 min of reaction. After the reaction is complete, the flow of hydrogen and acetylene gas is stopped, and interwoven carbon nanofibers (labeled CNFs) are grown on the CμS surface, thus obtaining carbon nanofibers / carbon spheres (labeled CNFs / CμS).

[0049] CNFs / CFs and CNFs / CμS were stacked in an alternating (F / B) / (F / B) / (F / B) / (F / B) pattern on a 0.22 μm thick nylon-66 membrane, with a carbon nanofiber / carbon fiber filler content of 9 mg / cm³. 2 The carbon nanofiber / carbon sphere packing density is 22 mg / cm². 2 A composite base membrane was obtained. Ethanol was drawn up using a syringe and injected as a confining solvent through the composite base membrane until a droplet formed beneath the membrane (one drop flowed out), thus obtaining a confined liquid membrane. 1 mL of water containing the target pesticide was taken and passed through the confined liquid membrane at a set flow rate (750 μL / min). Then, 1 mL of dichloromethane was taken as the desorption solvent and passed through the confined liquid membrane at a set flow rate (1.0 mL / min) to elute the extracted target pesticide. The eluent was collected and quantitatively analyzed.

[0050] Example 2

[0051] This embodiment provides a rapid extraction method for pesticides in water based on a confined liquid membrane. The difference from Embodiment 1 is that the flow rate of the water sample containing the target pesticide is modified to 250 μL / min.

[0052] Example 3

[0053] This embodiment provides a rapid extraction method for pesticides in water based on a confined liquid membrane. The difference from Embodiment 1 is that the flow rate of the water sample containing the target pesticide is modified to 500 μL / min.

[0054] Example 4

[0055] This embodiment provides a rapid extraction method for pesticides in water based on a confined liquid membrane. The difference from Embodiment 1 is that the flow rate of the water sample containing the target pesticide is modified to 1000 μL / min.

[0056] Example 5

[0057] This embodiment provides a rapid extraction method for pesticides in water based on a confined liquid membrane, which differs from Embodiment 1 in that the desorption solvent is changed to n-hexane.

[0058] Example 6

[0059] This embodiment provides a rapid extraction method for pesticides in water based on a confined liquid membrane, which differs from Embodiment 1 in that the desorption solvent is changed to ethyl acetate.

[0060] Example 7

[0061] This embodiment provides a rapid extraction method for pesticides in water based on a confined liquid membrane, which differs from Embodiment 1 in that the flow rate of the desorption solvent is modified to 0.5 mL / min.

[0062] Example 8

[0063] This embodiment provides a rapid extraction method for pesticides in water based on a confined liquid membrane, which differs from Embodiment 1 in that the flow rate of the desorption solvent is modified to 1.5 mL / min.

[0064] Comparative Example 1

[0065] This comparative example provides a rapid extraction method for pesticides in water based on a confined liquid membrane, which differs from Example 1 in that the confining solvent is changed to n-hexane.

[0066] Comparative Example 2

[0067] This comparative example provides a rapid extraction method for pesticides in water based on a confined liquid membrane. The difference from Example 1 is that it does not use alternating CNFs / CFs and CNFs / CμS stacks; instead, a single layer of CNFs / CFs is simply laid flat on a 0.22 μm thick nylon-66 membrane (with a packing density of 9 mg / cm³). 2 ).

[0068] Comparative Example 3

[0069] This comparative example provides a rapid extraction method for pesticides in water based on a confined liquid membrane. The difference from Example 1 is that it does not use alternating CNFs / CFs and CNFs / CμS stacked structures; instead, a single layer of CNFs / CμS is simply laid flat on a 0.22 μm thick nylon-66 membrane (with a packing density of 22 mg / cm³). 2 ).

[0070] Experimental Example 1

[0071] To systematically evaluate the extraction performance of the method of this invention, high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS / MS) and gas chromatography-mass spectrometry (GC-MS) were used to analyze the eluents after extraction and desorption in Examples 1-8 and Comparative Examples 1-3. HPLC-MS / MS analysis was performed using an Agilent 1260 HPLC system coupled with an Agilent 6420 triple quadrupole mass spectrometer (QqQ-MS); GC-MS analysis was performed using a gas chromatography system coupled with a mass spectrometer (GC 2010-QPMS2010). The extraction efficiency of each example and comparative example was systematically evaluated through quantitative analysis of the target pesticide in the samples.

[0072] A matrix spiked recovery experiment was conducted by adding a known concentration of the target pesticide compound standard to an environmental water sample (tap water) matrix, using the extraction recovery rate as the core indicator for evaluating extraction efficiency. The extraction recovery rate was calculated as: (peak area of ​​the target compound measured after extraction and desorption using the example or comparative method / peak area measured by direct injection of the same concentration standard) × 100%. A graph with this extraction recovery rate on the x-axis was obtained. Figure 1 Plotting the extraction recovery rate on the ordinate yields... Figures 3-5 ; Figure 2 This is a box plot showing the effect of flow rate on recovery rate. The boxes in the plot represent the data range between the first quartile and the third quartile, and the error bars represent the minimum and maximum values. The box plot shows the central tendency and distribution of the data, which helps to select the optimal flow rate conditions.

[0073] Specifically, by analyzing Example 1 and Comparative Example 1, a schematic diagram illustrating the effect of the type of confining solvent on the extraction efficiency was obtained, as shown below. Figure 1 As shown in the diagram. Analysis of Examples 1-4 yielded a schematic diagram illustrating the effect of water sample flow rate containing the target pesticide on extraction efficiency. Figure 2 As shown in the diagram. Analysis of Examples 1 and 5-6 yielded a schematic diagram illustrating the effect of the type of desorption solvent on the extraction efficiency. Figure 3 As shown in the diagram. Analysis of Examples 1 and 7-8 yielded a schematic diagram illustrating the effect of desorption solvent flow rate on extraction efficiency, as shown in the diagram. Figure 4 As shown in the diagram. Analysis of Example 1 and Comparative Examples 2-3 yielded a schematic diagram illustrating the effect of membrane packing method on extraction efficiency, as shown in the diagram. Figure 5 As shown. From Figure 1The results show that the ethanol-confined system significantly outperforms the hexane-confined system in extracting highly polar pesticides. For example, for the highly polar pesticide dimethoate, the extraction recovery rate in the ethanol-confined system reaches 100.98% (RSD of 3.48%), twice that of the hexane system. This result verifies the crucial contribution of hydrogen bonding provided by the hydroxyl groups in the ethanol molecule to the extraction of hydrophilic pesticides. Simultaneously, ethanol can also effectively extract hydrophobic pesticides through van der Waals forces, demonstrating its ability to cover a wide range of polarities. This confirms that choosing ethanol as the confining solvent is one of the core innovations in achieving broad-spectrum extraction. Figure 1-4 It can be seen that this method exhibits the best extraction efficiency when the confining solvent is ethanol, the flow rate of the water sample containing the target pesticide is 750 μL / min, the desorption solvent is dichloromethane, and the desorption solvent flow rate is 1.0 mL / min. Figure 5 It can be seen that the composite substrate membrane using alternating stacks of CNFs / CFs and CNFs / CμS (Example 1) exhibits higher overall extraction recoveries for various pesticides than Comparative Example 2 (CNFs / CFs only) and Comparative Example 3 (CNFs / CμS only), which use only a single material. Especially for pesticides with a wide polarity range, the alternating stacking structure allows the confined ethanol to exhibit more balanced and stable extraction performance. This indicates that the two materials may form complementary mass transfer channels in their alternating arrangement, not only enhancing the stability of the confined liquid membrane but also regulating the arrangement and interfacial properties of the confined solvent at the nanoscale, thereby further expanding its affinity range for pesticides of different polarities and supporting the broad-spectrum nature of the method at the liquid membrane structure level.

[0074] Therefore, the present invention adopts the above-mentioned method for rapid extraction of pesticides in water based on confined liquid membrane. Through ingenious confined liquid membrane design, it successfully achieves rapid and simultaneous extraction of pesticides with a wide polarity range and multiple categories in water while ensuring high extraction efficiency and good reproducibility. It has good application prospects and social benefits.

[0075] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the technical solutions of the present invention, and these modifications or equivalent substitutions cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A method for rapid extraction of pesticides from water based on confined liquid membranes, characterized in that, Includes the following steps: S1. Providing a confined liquid membrane: Preparing a composite substrate membrane comprising carbon nanofibers / carbon fibers and carbon nanofibers / carbon spheres: After calcination, acidification, and immersion in a catalyst solution, a gas containing acetylene is introduced to react and grow carbon nanofibers on the surface of the carbon fiber substrate, resulting in carbon nanofibers / carbon fibers; after immersion in a catalyst solution, a gas containing acetylene is introduced to react and grow carbon nanofibers on the surface of the carbon sphere substrate, resulting in carbon nanofibers / carbon spheres; carbon nanofibers / carbon fibers and carbon nanofibers / carbon spheres are arranged alternately to obtain a composite substrate membrane; ethanol is injected as a confining solvent and passed through the composite substrate membrane until droplets form under the membrane, completing the construction of the confined liquid membrane; S2. Pass the water sample containing the target pesticide through the confined liquid membrane at a set flow rate; S3. Use a desorption solvent at a set flow rate through a confined liquid membrane to elute the extracted target pesticide; S4. Collect the desorption solution and perform quantitative analysis.

2. The confined liquid film based method for rapid extraction of pesticides from water as claimed in claim 1 wherein, In the composite substrate membrane described in S1, carbon nanofibers / carbon fibers and carbon nanofibers / carbon spheres are filled in an alternating manner; wherein, the alternating arrangement is achieved by repeatedly containing a basic filling unit comprising one layer of carbon nanofibers / carbon fibers and one layer of carbon nanofibers / carbon spheres.

3. The rapid extraction method for pesticides in water based on confined liquid membranes according to claim 1, characterized in that, The filling amount of carbon nanofiber / carbon fiber per unit area in the composite base film S1 is 3-20 mg / cm 2 The filling amount of carbon nanofiber / carbon sphere per unit area is 3-25 mg / cm 2 .

4. The method for rapid extraction of pesticides in water based on confined liquid membranes according to claim 1, characterized in that, In S2, the flow rate is 250-1000 μL / min.

5. The rapid extraction method for pesticides in water based on confined liquid membranes according to claim 4, characterized in that, In S2, the flow rate is 750 μL / min.

6. The rapid extraction method for pesticides in water based on confined liquid membranes according to claim 1, characterized in that, In S3, the desorption solvent is selected from one or more of methanol, ethanol, dichloromethane, ethyl acetate, and n-hexane.

7. The rapid extraction method for pesticides in water based on confined liquid membranes according to claim 6, characterized in that, In S3, the desorption solvent is dichloromethane.

8. The method for rapid extraction of pesticides in water based on confined liquid membranes according to claim 1, characterized in that, In S3, the flow rate is 0.5-2.0 mL / min.

9. The rapid extraction method for pesticides in water based on confined liquid membranes according to claim 8, characterized in that, In S3, the flow rate is 1.0 mL / min.

10. The method for rapid extraction of pesticides in water based on a confined liquid membrane according to any one of claims 1-9, characterized in that, In S2, the target pesticide includes at least one of organophosphate pesticides, organochlorine pesticides, pyrethroid pesticides, carbamate pesticides, and organoheterocyclic pesticides.

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