A high-throughput fully automatic liquid-liquid counter-current microextraction system

Abstract

The application belongs to the field of microfluidic chemical analysis and separation technology, and particularly relates to a high-throughput full-automatic liquid-liquid countercurrent microextraction system, which comprises a plurality of countercurrent microextraction combinations, each of which comprises a suction filtration unit, a countercurrent microextraction unit and a fluid power unit; the plurality of countercurrent microextraction units realize multi-channel synchronous extraction, the suction filtration unit integrates filtration and negative pressure circulation to complete sample pretreatment, and the fluid power unit is composed of a suction pump, a plurality of peristaltic pumps and a plurality of capillary connectors to form a full-automatic flow path, so that the extraction process is unattended throughout the whole process. The application realizes mass transfer enhancement through the reverse staggered flow of the heavy phase downward and the light phase dropwise upward in the extraction tube, has the advantages of high-throughput, high automation, high extraction efficiency, compact structure, good reproducibility and the like, and is suitable for efficient enrichment and separation of trace components in complex samples such as food, environment, medicine and biological detection.

Description

Technical Field

[0001] This invention belongs to the field of microfluidic chemical analysis and separation technology, specifically involving a high-throughput fully automated liquid-liquid countercurrent microextraction system. Utilizing a specific microchannel structure design and fluid control mechanism, it achieves efficient, continuous, and multi-stage liquid-liquid countercurrent separation. It is suitable for applications such as pharmaceutical engineering, biomedical testing, food safety analysis, and environmental monitoring that require precise enrichment, high-purity analysis, and continuous preparation of trace components in complex sample matrices. Background Technology

[0002] Liquid-liquid extraction is one of the most fundamental and important separation and purification methods in the fields of chemistry, biology, and medicine. In recent years, with the rapid development of micro / nano fabrication and microfluidic technologies, microextraction has attracted widespread attention as a novel separation method combining microfluidics with solvent extraction. Microextraction significantly improves mass transfer efficiency by miniaturizing equipment and utilizing micron-sized channels to achieve efficient contact between two-phase fluids. The main advantages of microextraction compared to traditional extraction techniques include: 1. Enhanced mass transfer: Microchannels have short mass transfer distances and the fluid inside the channels has a large specific surface area, which can effectively accelerate the transfer of target substances between two objects; 2. Solvent saving: Significantly reduces solvent consumption, in line with the principles of green chemistry; 3. High safety and easy control: Small operating volume, low reagent consumption, and easy to achieve integrated and automated control.

[0003] Current microextraction operation modes and their limitations: In liquid-liquid extraction, mass transfer efficiency and extraction rate are key indicators for evaluating separation performance. To achieve high extraction rates and high separation degrees, the limitations imposed by traditional thermodynamic equilibrium must be overcome, and transport length and interfacial area are the core factors determining mass transfer efficiency. Shortening the transport path and significantly increasing the interfacial area between the two phases can effectively accelerate the migration of solutes between the two phases, thereby improving the extraction rate.

[0004] The flow pattern within the microextraction unit is also a key parameter affecting extraction performance. In existing technologies, most research focuses on co-current extraction modes, where both phases flow in the same direction. The mass transfer process in these modes is limited by instantaneous liquid-liquid equilibrium, making it difficult to achieve the theoretical maximum extraction efficiency in a single stage, thus failing to meet the demands of efficient separation processes. In contrast, countercurrent microextraction, by causing the two phases to flow in opposite directions, can form an equivalent multi-stage mass transfer structure within the unit, thereby overcoming equilibrium limitations and significantly improving the extraction rate.

[0005] Current countercurrent microextraction is mainly achieved in two forms: multistage countercurrent microextraction and continuous countercurrent microextraction. Multistage countercurrent microextraction uses multiple mass transfer units connected in series to achieve a stepwise extraction effect, but it requires additional pumps, valves, and connecting components, resulting in a complex system structure, high operating costs, and difficulty in miniaturizing and integrating the equipment, thus limiting its application in portable or compact systems. Although continuous countercurrent microextraction can achieve two-phase countercurrent operation within a single microchannel, the two-phase flow rates are usually low to maintain interface stability, leading to mass transfer relying on inefficient diffusion mechanisms. Furthermore, the limited mass transfer interface area, excessively long channels, and potential interface fluctuations can all cause countercurrent interruption or interface breakage, significantly affecting the stability and controllability of the extraction process. Summary of the Invention

[0006] To address the aforementioned technical problems, this invention provides a high-throughput fully automated liquid-liquid countercurrent microextraction system, which realizes a high-throughput, fully automated liquid-liquid countercurrent microextraction process. This provides a novel solution for the precise analysis and high-purity preparation of trace components in complex samples and can be widely applied in applications such as pharmaceutical engineering, biomedical testing, food, and environment, where precise analysis and high-purity preparation of trace components in complex samples are required.

[0007] The present invention is implemented as follows: a high-throughput fully automated liquid-liquid countercurrent microextraction system includes several countercurrent microextraction assemblies. Each countercurrent microextraction assembly includes a filtration unit, a countercurrent microextraction unit, and a fluid power unit. The filtration unit includes a filter cup and a vacuum bottle. The liquid outlet at the lower end of the filter cup is connected to the liquid inlet at the upper end of the vacuum bottle. The countercurrent microextraction unit includes an extraction tube and an upper connector and a lower connector sealed on the extraction tube. The fluid power unit includes a vacuum pump, multiple peristaltic pumps, and multiple capillary connectors. The air inlet of the vacuum pump is connected to the air outlet of the vacuum bottle via a tubing. The liquid inlet of the vacuum bottle is connected to the liquid outlet of the filter cup via a flexible tube. The vacuum bottle is connected to the fifth and sixth peristaltic pumps via a T-connector and a flexible tube. The other port of the fifth peristaltic pump is connected to the water outlet connector via a flexible tube, and the water outlet connector is installed directly above the filter cup. The other port of the sixth peristaltic pump is connected to the lower connector. The fourth capillary connector is connected to the lower connector of the extraction tube. The third capillary connector is connected to the upper connector, and the end of the third capillary connector is located in the light phase layer of the two extraction phases. One end of the first peristaltic pump is connected to the third capillary connector, and the other end is connected to the fourth capillary connector. The first capillary connector is connected to the upper connector, and the end of the first capillary connector is located below the interface between the two extraction phases. One end of the fourth peristaltic pump is connected to the first capillary connector, and the other end is connected to the lower connector.

[0008] Preferably, the fluid power unit further includes a second capillary connector, a third peristaltic pump, and a liquid collection cup. The second capillary connector is connected to the upper connector, and the interface between the two liquid phases is located 1-2 mm below the second capillary connector. One end of the third peristaltic pump is connected to the liquid collection cup, and the other end is connected to the second capillary connector.

[0009] Further preferably, the fluid power unit also includes a second peristaltic pump and a waste liquid cup, with one end of the second peristaltic pump connected to the lower connector and the other end connected to the waste liquid cup.

[0010] Preferably, the inner diameter of the fourth capillary connector is 0.3-0.9 mm.

[0011] Preferably, the upper connector is provided with an exhaust port.

[0012] Preferably, the countercurrent microextraction system further includes a body and a backplate unit. The backplate of the backplate unit is vertically fixed to the body. All the filtration units of the countercurrent microextraction assembly are installed in a row on the body, and one countercurrent microextraction unit is installed on the backplate at the corresponding position of each filtration unit.

[0013] Further preferably, the countercurrent microextraction unit also includes two mounting bases. The inner side of the mounting base is a semi-circular groove that matches the outer diameter of the extraction tube. The inner wall of the groove is provided with an elastic buffer pad. The upper and lower ends of the extraction tube are respectively clamped in the groove of one mounting base. The two ends of the mounting base are fixed to the back plate. All the extraction tubes of the countercurrent microextraction assembly are arrayed and mounted on the back plate.

[0014] In a further preferred embodiment, the filtration unit also includes a vacuum bottle mounting plate, which has a plurality of mounting holes, and each vacuum bottle is disposed in a corresponding mounting hole.

[0015] Preferably, the bottom of the filter cup is provided with a filter membrane mounting groove, and a filter membrane with a pore size of 0.22 μm is installed in the filter membrane mounting groove.

[0016] Compared with the prior art, the advantages of the present invention are as follows: 1) High throughput and automation: Array-type countercurrent microextraction can simultaneously complete the extraction of multi-channel samples; the fluid power unit fully automates the fluid transport, requiring no manual intervention and significantly improving extraction efficiency; 2) High-efficiency extraction: The tiny droplets formed by the capillary liquid increase the liquid-liquid two-phase contact area, and the countercurrent flow of the two liquids increases the liquid-liquid two-phase contact time, which enhances the mass transfer efficiency and significantly improves the extraction recovery rate and reproducibility. 3) Structural integration: Each unit is integrated with the body and backplate unit through standardized interfaces, resulting in a compact structure, convenient operation, low manufacturing cost, and compatibility with laboratory automation platforms. Attached Figure Description

[0017] Figure 1 This is an overall structural diagram of the high-throughput fully automated liquid-liquid countercurrent microextraction system provided in an embodiment of the present invention; Figure 2 This is a structural diagram of the countercurrent microextraction unit in the high-throughput fully automated liquid-liquid countercurrent microextraction system provided in this embodiment of the invention; Figure 3 This is a structural diagram of the filtration unit in the high-throughput fully automated liquid-liquid countercurrent microextraction system provided in an embodiment of the present invention; Figure 4 This is a diagram of the backplate structure in the high-throughput fully automated liquid-liquid countercurrent microextraction system provided in this embodiment of the invention. Figure 5 This is a schematic diagram illustrating the working principle of the high-throughput fully automated liquid-liquid countercurrent microextraction system provided in this embodiment of the invention. The components are: 1-body, 2-countercurrent microextraction unit, 201-upper connector, 202-mounting base, 203-extraction tube, 204-lower connector, 3-vacuum filtration unit, 301-filter cup, 302-vacuum bottle mounting plate, 303-vacuum bottle, 4-back plate unit, 401-back plate, 5-fluid power unit, 501-vacuum pump, 502-outlet connector, 503-first peristaltic pump, 504-liquid collection cup, 505-waste liquid cup, 506-exhaust port, 507-extraction liquid, 508-liquid to be extracted, 509-first capillary connector, 510-second capillary connector, 511-third capillary connector, 512-fourth capillary connector, 513-second peristaltic pump, 514-third peristaltic pump, 515-fourth peristaltic pump, 516-fifth peristaltic pump, 517-sixth peristaltic pump. Detailed Implementation

[0018] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are for illustrative purposes only and are not intended to limit the invention.

[0019] This invention proposes a novel high-throughput fully automated liquid-liquid countercurrent microextraction system. Through a unique microchannel structure design, this system enables stable countercurrent mass transfer without additional complex components, allowing the two phases to operate under inertial and gravitational forces in a microscale environment, prioritizing these forces over viscosity and interfacial tension. The combined array design generates a large number of continuous microdroplets per unit time, significantly improving mass transfer and extraction efficiency. This results in high-throughput liquid-liquid microextraction. The device not only achieves multi-stage countercurrent extraction within a single structure, resulting in high mass transfer efficiency and significantly reduced solvent consumption, but also boasts high integrability and miniaturization, supporting parallel operation of multiple units and simultaneous execution of multiple extraction processes to maximize equipment utilization. Furthermore, the device allows for flexible adjustment of key parameters such as flow rate, phase ratio, and channel cross-sectional structure to further optimize extraction efficiency and separation performance according to different separation requirements.

[0020] refer to Figures 1-5 This embodiment provides a high-throughput fully automated liquid-liquid countercurrent microextraction system, including several countercurrent microextraction combinations. Each countercurrent microextraction combination includes a filtration unit 3, a countercurrent microextraction unit 2, and a fluid power unit 5. The filtration unit 3 includes a filter cup 301 and a vacuum bottle 303. The liquid outlet at the lower end of the filter cup 301 is connected to the liquid inlet at the upper end of the vacuum bottle 303. The countercurrent microextraction unit 2 includes an extraction tube 203 and an upper connector 201 and a lower connector 204 sealed and installed on the extraction tube 203. The upper connector 201 and the lower connector 204 are each provided with stepped holes adapted to the two ends of the extraction tube 203 at the ends connected to the extraction tube 203. Fluororubber sealing rings are embedded in the stepped holes. The two ends of the extraction tube 203 are respectively inserted into the stepped holes of the upper connector 201 and the lower connector 204. Liquid tightness is achieved through the sealing rings to prevent liquid leakage during the extraction process. The fluid power unit 5 includes a vacuum pump 501, multiple peristaltic pumps, and multiple capillary connectors. The air inlet of the vacuum pump 501 is connected to the air outlet of the vacuum bottle 303 by an air pipe. The liquid inlet of the vacuum bottle 303 is connected to the liquid outlet of the filter cup 301 by a flexible hose. The vacuum bottle 303 is connected to the fifth peristaltic pump 516 and the sixth peristaltic pump 517 via a T-connector and a flexible hose. Another port of the fifth peristaltic pump 516 is connected to the water outlet connector 502 by a flexible hose, and the water outlet connector 502 is installed directly above the filter cup 301. Another connector of the sixth peristaltic pump 517 is connected to the lower connector 204. The fourth capillary connector 512... The third capillary connector 511 is connected to the upper connector 201 and the end of the third capillary connector 511 is located in the light phase layer of the two extraction phases. One end of the first peristaltic pump 503 is connected to the third capillary connector 511 and the other end is connected to the fourth capillary connector 512. The first capillary connector 509 is connected to the upper connector 201 and the end of the first capillary connector 509 is located below the interface between the two extraction phases. One end of the fourth peristaltic pump 515 is connected to the first capillary connector 509 and the other end is connected to the lower connector 204.

[0021] The extraction reaction process in a countercurrent microextraction assembly within the high-throughput fully automated liquid-liquid countercurrent microextraction system provided in this embodiment is as follows: 1. Preliminary preparation: Add heavy phase A and light phase B to filter cup 301. Heavy phase A contains target compound C. The purpose is to extract target compound C from heavy phase A using light phase B through this system. 2. Start vacuum filtration: The vacuum pump 501 starts to pump air, creating negative pressure in the vacuum bottle 303, which draws the liquid in the filter cup 301 into the vacuum bottle 303. Solid substances / impurities remain in the filter cup 301, preventing solid substances / impurities from entering the extraction tube 203 and clogging the capillary joints during the extraction process. 3. Repeated filtration: After all the liquid has been filtered into the vacuum bottle 303, start the fifth peristaltic pump 516 to pump the liquid in the vacuum bottle 303 back into the filter cup 301. Repeat this operation several times to thoroughly filter solid substances / impurities. 4. Stratification: Start the sixth peristaltic pump 517 to pump all the mixed liquid into the extraction tube 203. The mixed liquid will naturally separate into layers in the extraction tube 203—light phase B is on the upper layer and heavy phase A is on the lower layer. 5. Interleaved Flow Extraction: The fourth peristaltic pump 515 is activated, causing the heavy phase A to flow out from below the extraction tube 203 and into the first capillary connector 509, achieving a downward flow of the heavy phase A. Simultaneously, the first peristaltic pump 503 is activated, causing the light phase B to flow out from the third capillary connector 511 and into the fourth capillary connector 512. The flowing light phase B enters the milk in droplets and floats to the upper layer. During this process, the interleaved state of the heavy phase A flowing downward and the light phase B floating upward can accelerate the extraction of the target substance C in the heavy phase by the light phase B until all the target substance C is extracted into the light phase B. The heavy phase and the light phase B containing the target substance C are then separated, completing this extraction process.

[0022] During the extraction process, multiple countercurrent microextraction combinations work together to achieve multi-channel, high-throughput extraction.

[0023] In the above extraction process, when the light phase B extracts the target substance C from the heavy phase A, if the heavy phase A is a mixture, to avoid the light phase B extracting substances that are not the target substance C during the extraction process, or even producing precipitation that clogs the capillary joints, the interfering substances in the heavy phase B can be extracted first by adding a substance to the filter cup 301 and repeatedly filtering to remove the mixture. Then, the mixed liquid is introduced into the extraction tube 203 for the extraction of the target substance. For example, when the heavy phase A is milk and the light phase B is acetonitrile, the purpose is to extract pesticide or veterinary drug residues (such as aniline, isoprocarb, etc.) from the milk using acetonitrile. However, since milk contains a large amount of protein, if the protein is not precipitated in the filter cup 301 first, the acetonitrile will slowly extract some of the protein in the extraction tube 203, causing precipitation in the extraction tube 203. Therefore, milk, acetonitrile, and salt are added to the filter cup 301 beforehand. The salt precipitates the protein in the milk. During repeated filtration, the protein precipitate remains in the filter cup 301, and the remaining mixed liquid enters the extraction tube 203 for extraction.

[0024] To facilitate the separation of the light phase B containing the target compound C after extraction, as an improvement to the technical solution, the fluid power unit 5 further includes a second capillary connector 510, a third peristaltic pump 514, and a collection cup 504. The second capillary connector 510 is connected to the upper connector 201, and the interface between the two liquid phases is located 1-2 mm below the second capillary connector 510. One end of the third peristaltic pump 514 is connected to the collection cup 504, and the other end is connected to the second capillary connector 510.

[0025] After all the target substance C has been extracted into the light phase B, the third peristaltic pump 514 is started to draw all of the light phase B into the collection cup 504. Since the second capillary connector 510 is located slightly above the liquid surface of the light phase B and the heavy phase A, the third peristaltic pump 514 can basically pump all of the light phase B into the collection cup 504.

[0026] To further separate the heavy phase A from the extraction tube 203, as an improvement to the technical solution, the fluid power unit 5 also includes a second peristaltic pump 513 and a waste liquid cup 505. One end of the second peristaltic pump 513 is connected to the lower connector 204, and the other end is connected to the waste liquid cup 505.

[0027] After extraction is complete, start the second peristaltic pump 513 to draw all the milk into the waste liquid cup 505, thus completing the extraction reaction.

[0028] To ensure that the light phase B flows countercurrently with the heavy phase A as tiny droplets during countercurrent extraction, as an improvement to the technical solution, the inner diameter of the fourth capillary connector 512 is 0.3-0.9 mm.

[0029] All of the above components and connecting pipes are chemically resistant. Figure 4 The diagram shown is of the back structure of back panel 401. The bottom is the air pump, and the five above it are the distribution of the first to fifth peristaltic pumps. The specific positions are subject to the appropriate pipeline connections.

[0030] In order to remove the gas in the extraction tube 203 during the extraction process, as an improvement, an exhaust port 506 is provided on the upper connector 201.

[0031] To integrate the filtration unit 3, countercurrent microextraction unit 2, and fluid power unit 5 in all countercurrent microextraction assemblies into a single device product, as an improvement to the technical solution, the countercurrent microextraction system further includes a body 1 and a backplate unit 4. The backplate 401 of the backplate unit 4 is vertically fixed to the body 1. All the filtration units 3 of the countercurrent microextraction assemblies are installed in a row on the body 1, and one countercurrent microextraction unit 2 is installed on the backplate 401 at the corresponding position of each filtration unit 3.

[0032] As a specific installation method of the extraction tube 203 on the back plate 401, the countercurrent microextraction unit 2 also includes two mounting seats 202. The inner side of the mounting seat 202 is a semi-circular groove that matches the outer diameter of the extraction tube 203. The inner wall of the groove is provided with an elastic buffer pad. The upper end and lower end of the extraction tube 203 are respectively clamped in the groove of one mounting seat 202. The two ends of the mounting seat 202 are fixed to the back plate 401. All the extraction tubes 203 of the countercurrent microextraction assembly are installed in an array on the back plate 401.

[0033] To facilitate the installation of each vacuum bottle 303 on the body 1, as an improvement to the technical solution, the filtration unit 3 also includes a vacuum bottle mounting plate 302. The vacuum bottle mounting plate 302 is processed by sheet metal bending process, and is made of 304 stainless steel. It is flat in shape and has several mounting holes. The vacuum bottle 303 is funnel-shaped, and each vacuum bottle 303 is set in the corresponding mounting hole.

[0034] Preferably, the bottom of the filter cup 301 is provided with a filter membrane mounting groove, and a filter membrane with a pore size of 0.22μm is installed in the filter membrane mounting groove.

[0035] To make the equipment look neat and tidy, a pipeline storage cavity is provided inside the body 1 to organize the connecting conduits between the filtration unit 3 and the countercurrent microextraction unit 2.

[0036] The extraction speed of this system is more than 20 times that of traditional separatory funnels. The recovery rate of traditional separatory funnels is between 60% and 85% per extraction, while the recovery rate of this system can reach between 98% and 102%.

[0037] In summary, the high-throughput fully automated liquid-liquid countercurrent microextraction system provided by this invention, through the synergistic design of scale-scale hydrodynamic characteristics and a unique countercurrent channel structure, successfully achieves efficient and stable multi-stage countercurrent extraction in a compact, low-energy micro-device. It realizes unattended operation of the entire process from filtration to circulation extraction to countercurrent extraction to automatic stratification, collection, and waste discharge, breaking through the bottlenecks of existing microextraction technologies in terms of mass transfer efficiency, equipment integration, and interface stability, and has significant innovation and engineering applicability.

Claims

1. A high-throughput fully automated liquid-liquid counter-current microextraction system, characterized in that, It includes several countercurrent microextraction assemblies. Each countercurrent microextraction assembly includes a filtration unit (3), a countercurrent microextraction unit (2), and a fluid power unit (5). The filtration unit (3) includes a filter cup (301) and a vacuum bottle (303). The liquid outlet at the lower end of the filter cup (301) is connected to the liquid inlet at the upper end of the vacuum bottle (303). The countercurrent microextraction unit (2) includes an extraction tube (203) and an upper connector (201) and a lower connector (204) sealed on the extraction tube (203). The fluid power unit (5) includes a vacuum pump (501), multiple peristaltic pumps, and multiple capillary connectors. The air inlet of the vacuum pump (501) is connected to the air outlet of the vacuum bottle (303) by a gas pipe. The liquid inlet of the vacuum bottle (303) is connected to the liquid outlet of the filter cup (301) by a hose. The vacuum bottle (303) is connected to the fifth peristaltic pump (516) and the sixth peristaltic pump (517) by a T-connector and a hose. Another port of the fifth peristaltic pump (516) is connected to the water outlet connector (502) by a hose, and the water outlet connector (502) is installed directly above the filter cup (301). Another connector of the sixth peristaltic pump (517) is connected to the lower connector (204). The fourth capillary connector (512) The first capillary pump (503) is connected to the lower connector (204) of the extraction tube, and the third capillary connector (511) is connected to the upper connector (201). The end of the third capillary connector (511) is located in the light phase layer of the two extraction phases. One end of the first peristaltic pump (503) is connected to the third capillary connector (511), and the other end is connected to the fourth capillary connector (512). The first capillary connector (509) is connected to the upper connector (201), and the end of the first capillary connector (509) is located below the interface of the two extraction phases. One end of the fourth peristaltic pump (515) is connected to the first capillary connector (509), and the other end is connected to the lower connector (204).

2. The high-throughput fully automated liquid-liquid countercurrent microextraction system according to claim 1, characterized in that, The fluid power unit (5) further includes a second capillary connector (510), a third peristaltic pump (514), and a liquid collection cup (504). The second capillary connector (510) is connected to the upper connector (201), and the interface between the two liquid phases is located 1-2 mm below the second capillary connector (510). One end of the third peristaltic pump (514) is connected to the liquid collection cup (504), and the other end is connected to the second capillary connector (510).

3. The high-throughput fully automated liquid-liquid countercurrent microextraction system according to claim 2, characterized in that, The fluid power unit (5) also includes a second peristaltic pump (513) and a waste liquid cup (505). One end of the second peristaltic pump (513) is connected to the lower connector (204), and the other end is connected to the waste liquid cup (505).

4. The high-throughput fully automated liquid-liquid countercurrent microextraction system according to claim 1, characterized in that, The inner diameter of the fourth capillary connector (512) is 0.3-0.9 mm.

5. The high-throughput fully automated liquid-liquid countercurrent microextraction system according to claim 1, characterized in that, An exhaust port (506) is provided on the upper connector (201).

6. The high-throughput fully automated liquid-liquid countercurrent microextraction system according to claim 1, characterized in that, The countercurrent microextraction system also includes a body (1) and a back plate unit (4). The back plate (401) of the back plate unit (4) is vertically fixed to the body (1). All the filtration units (3) of the countercurrent microextraction assembly are installed in a row on the body (1). One countercurrent microextraction unit (2) is installed on the back plate (401) at the corresponding position of each filtration unit (3).

7. The high-throughput fully automated liquid-liquid countercurrent microextraction system according to claim 6, characterized in that, The countercurrent microextraction unit (2) also includes two mounting bases (202). The inner side of the mounting base (202) is a semi-circular groove that matches the outer diameter of the extraction tube (203). The inner wall of the groove is provided with an elastic buffer pad. The upper and lower ends of the extraction tube (203) are respectively fitted into the groove of one mounting base (202). The two ends of the mounting base (202) are fixed to the back plate (401). All the extraction tubes (203) of the countercurrent microextraction assembly are arrayed on the back plate (401).

8. The high-throughput fully automated liquid-liquid countercurrent microextraction system according to claim 6, characterized in that, The filtration unit (3) also includes a vacuum bottle mounting plate (302), which has several mounting holes, and each vacuum bottle (303) is installed in the corresponding mounting hole.

9. The high-throughput fully automated liquid-liquid countercurrent microextraction system according to claim 1, characterized in that, The bottom of the filter cup (301) is provided with a filter membrane mounting groove, and a filter membrane with a pore size of 0.22μm is installed in the filter membrane mounting groove.

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