Pollution-free liquid drop transfer device and method for continuous instillation micro-extraction

Abstract

The invention belongs to the technical field of analytical chemical sample pretreatment and on-line analysis, and particularly relates to a pollution-free liquid drop transfer device and method for continuous instillation microextraction, the device comprises a liquid drop forming unit and a liquid drop collecting unit, the liquid drop forming unit comprises a collecting pipe, and the collecting pipe is connected with the liquid drop forming unit. One end of the collecting pipe extends into the extraction head to reach the liquid suction port, the other end of the collecting pipe penetrates through the sealing head, the sealing head penetrates through one end of the vacuum pipe, the other end of the vacuum pipe penetrates through the second peristaltic pump, the inner wall of the collecting pipe is coated with an inert layer, and the inert layer is made of a chemical inert material. The inner wall of the collecting pipe is coated with the inert layer, and the inert layer is made of a chemical inert material, so that extraction liquid drops only make contact with the inert layer in the transfer process, pollution-free inert transmission is achieved, contact with polymer materials such as a pump pipe is thoroughly avoided, and the memory effect and background pollution are eliminated.

Description

Technical Field

[0001] This invention belongs to the field of analytical chemistry sample pretreatment and online analysis technology, and specifically relates to a pollution-free droplet transfer device and method for continuous drip microextraction. Background Technology

[0002] In fields such as materials pyrolysis behavior research, tobacco science, and food flavor analysis, dynamic analysis of volatile components released by materials during programmed temperature rise is crucial. Traditional escape gas analysis methods, such as online coupling with mass spectrometry or infrared spectroscopy, are insufficient for the resolution of trace and complex components and cannot achieve time-resolved offline in-depth analysis. In contrast, thermogravimetric analyzers can precisely control the temperature program and record mass changes.

[0003] Droplet microextraction is a highly efficient miniaturized sample pretreatment technique. Currently, droplet transfer methods mostly use syringes for direct extraction or peristaltic pump tubing for transfer. These methods are prone to problems such as sample contact with polymer tubing leading to adsorption or leaching contamination, slow transfer speed, complex negative pressure control, and interference with the subsequent droplet formation environment. As a result, these methods cannot meet the requirements of continuous, online, and high temporal resolution sampling. Summary of the Invention

[0004] The present invention addresses the above-mentioned problems by providing a pollution-free droplet transfer device and method for continuous drip microextraction.

[0005] To achieve the above objectives, the present invention employs the following technical solution: A pollution-free droplet transfer device and method for continuous drip microextraction, comprising a droplet forming unit and a droplet collecting unit: The droplet forming unit includes a storage bottle containing an extractant. One end of a replenishment tube extends into the storage bottle, and the other end of the replenishment tube passes through a first peristaltic pump and extends into an extraction head inside the extraction chamber. The extraction head is located at the top of the extraction chamber, and a suction port is provided at the bottom of the extraction head. Extracted droplets overflow from the suction port. Droplet optical monitoring modules are provided on both sides of the extracted droplets. Carrier gas inlets are provided on the left and right sides at the bottom of the extraction chamber, and a carrier gas outlet is provided at the upper right side of the extraction chamber. The droplet forming unit includes a collection tube, one end of which extends into the extraction head to the suction port, and the other end of which passes through a sealing head. One end of a vacuum tube passes through the sealing head, and the other end of the vacuum tube passes through a second peristaltic pump. The sealing head is fixedly mounted on a lifting mechanism, which is used to move the sealing head up and down. The lifting mechanism is mounted on a fixed frame, and a sample bottle is placed below the sealing head. The sealing head is used to seal the mouth of the sample bottle.

[0006] Furthermore, the droplet optical monitoring module includes a transmitting optical fiber and a receiving optical fiber arranged opposite to each other, used to monitor the size of the extracted droplets and feed it back to the controller. The controller is used to control the start and stop of the first peristaltic pump to maintain a constant volume of the extracted droplets.

[0007] Furthermore, the droplet collection unit also includes a conveyor belt for sequentially transporting multiple sample vials to a collection station below the sealing head.

[0008] Furthermore, the conveyor belt is provided with a fixing position, which is used to clamp and fix the sample bottle to prevent the sample bottle from moving with it when the sealing head rises and detaches.

[0009] Furthermore, an inert layer is coated on the inner wall of the collection tube. The inert layer is made of a chemically inert material, so that the extract droplets only come into contact with the inert layer during the transfer process, achieving pollution-free inert transport.

[0010] The aforementioned method for continuous drip microextraction with a pollution-free droplet transfer includes the following steps: S1, Droplet Formation and Extraction: The controller starts the first peristaltic pump to deliver the extractant to the end of the extraction head to form extraction droplets; the transmitting and receiving optical fibers monitor and are linked with the first peristaltic pump to maintain the stability of the droplet volume; the carrier gas is introduced into the extraction chamber and purges the extraction droplets, and the extraction droplets extract the components in the carrier gas at normal pressure. When the preset extraction time is reached, the extraction of the droplets is completed. S2, Droplet Transfer: The controller controls the first peristaltic pump to stop working and controls the elevator to move the sealing head down, sealing the designated sample bottle to form a closed transfer chamber. The vacuum tube and the second peristaltic pump connected to it apply negative pressure to the chamber, and under the action of negative pressure, the extracted droplets are transferred to the sample bottle through the collection tube. S3, System Reset: After the extracted droplets are transferred, the controller controls the second peristaltic pump to stop working to remove the negative pressure, and controls the elevator to move the sealing head upward to release the seal on the sample bottle. Subsequently, the conveyor belt moves to transport the next empty sample bottle to the collection station, and a new extraction droplet is formed at the end of the extraction head to prepare for the next extraction.

[0011] Furthermore, the second peristaltic pump in S2 applies negative pressure for 1 to 5 seconds to achieve rapid transfer of the extract droplets.

[0012] Furthermore, the carrier gas is a gas containing pyrolysis products of the sample, generated by the thermogravimetric analyzer during programmed temperature rise.

[0013] Furthermore, the preset extraction time in S1 is 40-60 seconds.

[0014] Compared with the prior art, the present invention has the following advantages: This invention uses an inert layer coated on the inner wall of the collection tube. The inert layer is made of a chemically inert material, which ensures that the extract droplets only come into contact with the inert layer during the transfer process. This achieves pollution-free inert transport, completely avoids contact with polymer materials such as pump tubes, and eliminates memory effect and background contamination.

[0015] This invention employs a lifting mechanism to lower the sealing head, creating a temporary sealed transfer chamber between the sealing head, sample vial, and collection tube. A second peristaltic pump applies negative pressure to this chamber, drawing the extracted droplets into the sample vial through the collection tube. Once the droplet transfer is complete, the controller moves the lifting mechanism to raise the sealing head, releasing the seal and activating the first peristaltic pump. Simultaneously, atmospheric pressure is restored for new droplet extraction. This mechanical, instantaneous on / off (millisecond-level) structure physically isolates the extraction (atmospheric pressure) and transfer (instantaneous negative pressure) stages, ensuring their independence and continuity. This invention minimizes interference with the continuous extraction process, increases the droplet transfer speed, reduces sample evaporation loss, and maintains sample authenticity. Furthermore, it features a compact structure, low failure rate, and easy online integration with thermogravimetric analyzers, gas chromatograph-mass spectrometers, etc., resulting in a high degree of automation. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the present invention.

[0017] In the diagram, 1 is the extractant, 2 is the storage bottle, 3 is the replenishment tube, 4 is the first peristaltic pump, 5 is the extraction head, 6 is the suction port, 7 is the carrier gas inlet, 8 is the transmitting optical fiber, 9 is the extraction chamber, 10 is the receiving optical fiber, 11 is the carrier gas exhaust port, 12 is the collection tube, 13 is the sealing head, 14 is the sample bottle, 15 is the conveyor belt, 16 is the fixing frame, 17 is the elevator, 18 is the vacuum tube, 19 is the second peristaltic pump, and 20 is the fixing position. Detailed Implementation

[0018] To further illustrate the technical solution of the present invention, the present invention will be further described below through embodiments.

[0019] like Figure 1As shown, a pollution-free droplet transfer device for continuous drip microextraction includes a droplet forming unit and a droplet collecting unit. The droplet forming unit includes a storage bottle 2 containing an extractant 1. One end of a replenishment tube 3 extends into the storage bottle 2, and the other end of the replenishment tube 3 passes through a first peristaltic pump 4 and extends into an extraction head 5 inside an extraction chamber 9. The extraction head 5 is located at the top of the extraction chamber 9, and a suction port 6 is provided at the bottom of the extraction head 5. Extraction droplets overflow from the suction port 6. The extraction droplets are located on both sides of the suction port 6. A droplet optical monitoring module is provided, comprising a transmitting optical fiber 8 and a receiving optical fiber 10 arranged opposite each other. This module monitors the size of the extracted droplets and feeds the data back to the controller. The controller controls the start and stop of the first peristaltic pump 4 to maintain a constant volume of the extracted droplets. Carrier gas inlets 7 are located on the left and right sides of the lower part of the extraction chamber 9, and a carrier gas outlet 11 is located on the upper right side of the extraction chamber 9. The carrier gas is a gas containing pyrolysis products of the sample, generated by the thermogravimetric analyzer during programmed temperature rise. The droplet forming unit includes a collection tube 12, the inner wall of which is coated with an inert layer made of chemically inert material. This ensures that the extracted droplets only contact the inert layer during transfer, achieving contamination-free inert transport. One end of the collection tube 12 extends into the extraction head 5 to the suction port 6, and the other end passes through a sealing head 13. A vacuum tube 18 passes through the sealing head 13, and the other end of the vacuum tube 18 passes through a second peristaltic pump 19. The second peristaltic pump 19 applies pressure... The negative pressure is applied for 1 to 5 seconds to achieve rapid transfer of the extraction droplets. The sealing head 13 is fixedly mounted on the lifting platform 17, which is used to move the sealing head 13 up and down. The lifting platform 17 is mounted on the fixed frame 16. A sample bottle 14 is placed below the sealing head 13, and the sealing head 13 is used to seal the mouth of the sample bottle 14. The vacuum tube 18 is connected to the sealing head 13 and communicates with the sealed transfer chamber, and its inlet end does not extend deep into the sample bottle 14. The droplet collection unit also includes a conveyor belt 15, which is used to sequentially transport multiple sample bottles 14 to the collection station below the sealing head 13. The conveyor belt 15 is provided with a fixing position 20, which is used to clamp and fix the sample bottle 14 to prevent the sample bottle 14 from moving with the sealing head 13 when it rises and detaches. The carrier gas inlet 7 of the extraction chamber 9 of this device is connected online to the gas outlet of the thermogravimetric analyzer and the internal standard volatilization device, respectively. The thermogravimetric analyzer heats up at a programmed rate. The pyrolysis gas from the sample and the volatile gas from the internal standard solution are introduced into the device as carrier gases. The droplet transfer operation is performed once every 40 to 60 seconds under program control. In this way, a series of sample vials 14 arranged in chronological order can be obtained. The droplets in each vial correspond to the pyrolysis components in a specific temperature range. Then, offline analysis is performed using GC-MS to reconstruct a complete spectrum of the dynamic release of chemical components with temperature.

[0020] A pollution-free droplet transfer method for continuous drip microextraction is disclosed. This method is used for the online, continuous, and segmented enrichment and analysis of pyrolysis components escaping from different temperature ranges, enabling dynamic chemical characterization of the entire pyrolysis process. The method includes the following steps: S1, Droplet Formation and Extraction: The sealing head 13 is in the raised position and separated from the sample bottle 14. The controller controls the first peristaltic pump 4 to start, delivering the extractant 1 to the end of the extraction head 5 to form extraction droplets. The transmission fiber 8 and the receiving fiber 10 monitor and are linked with the first peristaltic pump 4. When the extraction droplets become smaller due to evaporation, the intensity of the transmitted light changes, and the signal is fed back to the controller. The controller controls the first peristaltic pump 4 to replenish a trace amount of extractant 1, thereby keeping the volume of the extraction droplets dynamically constant. At the same time, the carrier gas (Gas A, Gas B) enters from the carrier gas inlet 7 at the bottom of the extraction chamber 9 and blows the surface of the extraction droplets. Volatile target substances are extracted into the droplets, and the waste gas is discharged from the carrier gas exhaust port 11. The whole process is to extract the components in the carrier gas under normal pressure. When the preset extraction time of 40-60 seconds is reached, the extraction of the droplets is completed. S2, Droplet Transfer: The controller stops the first peristaltic pump 4 and controls the elevator 17 to move the sealing head 13 down to seal the designated sample bottle 14, so that a temporary sealed transfer chamber is formed between the sealing head 13, the sample bottle 14 and the collection tube 12. The vacuum tube 18 and the second peristaltic pump 19 connected to it apply negative pressure to the chamber. Under the action of negative pressure, the extraction droplets at the end of the extraction head 5 are quickly sucked into the sample bottle 14 through the suction port 6 and the collection tube 12. The process is usually completed within 1-5 seconds. S3, System Reset: After the extraction droplet transfer is completed, the controller controls the second peristaltic pump 19 to stop working to remove the negative pressure, and controls the elevator 17 to move the sealing head 13 upward to release the seal on the sample bottle 14. At this time, the negative pressure in the cavity is instantly eliminated. Subsequently, the conveyor belt 15 moves to transport the next empty sample bottle 14 to the collection station, and a new extraction droplet is formed at the end of the extraction head 5 to prepare for the next extraction. The sample bottle 14 with the collected sample can be sent by the conveyor belt 15 to the subsequent station for capping or injection analysis.

[0021] The foregoing has shown and described the main features and advantages of the present invention. It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered exemplary and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, it is intended that all variations falling within the meaning and scope of equivalents of the claims be included within the present invention.

[0022] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A pollution-free droplet transfer device and method for continuous drip microextraction, characterized in that, Includes a droplet forming unit and a droplet collecting unit: The droplet forming unit includes a storage bottle (2), in which an extractant (1) is provided. One end of a replenishment tube (3) extends into the storage bottle (2), and the other end of the replenishment tube (3) passes through a first peristaltic pump (4) and extends into an extraction head (5) in an extraction chamber (9). The extraction head (5) is located at the top of the extraction chamber (9), and a suction port (6) is provided at the bottom of the extraction head (5). Extraction droplets overflow from the suction port (6). Droplet optical monitoring modules are provided on both sides of the extraction droplets. Carrier gas inlets (7) are provided on the left and right sides of the lower part of the extraction chamber (9), and a carrier gas outlet (11) is provided on the upper right side of the extraction chamber (9). The droplet forming unit includes a collection tube (12), one end of which extends into the extraction head (5) to the suction port (6), and the other end of which passes through a sealing head (13). A vacuum tube (18) passes through the sealing head (13), and the other end of the vacuum tube (18) passes through a second peristaltic pump (19). The sealing head (13) is fixedly mounted on a lift (17), which is used to move the sealing head (13) up and down. The lift (17) is mounted on a fixed frame (16). A sample bottle (14) is provided below the sealing head (13), and the sealing head (13) is used to seal the mouth of the sample bottle (14).

2. The pollution-free droplet transfer device for continuous drip microextraction according to claim 1, characterized in that, The droplet optical monitoring module includes a transmitting optical fiber (8) and a receiving optical fiber (10) arranged opposite to each other, used to monitor the size of the extracted droplets and feed it back to the controller, which is used to control the start and stop of the first peristaltic pump (4) to maintain a constant volume of the extracted droplets.

3. The pollution-free droplet transfer device for continuous drip microextraction according to claim 2, characterized in that, The droplet collection unit also includes a conveyor belt (15) for sequentially transporting multiple sample bottles (14) to the collection station below the sealing head (13).

4. The pollution-free droplet transfer device for continuous drip microextraction according to claim 3, characterized in that, The conveyor belt (15) is provided with a fixing position (20) for clamping and fixing the sample bottle (14) to prevent the sample bottle (14) from moving with the sealing head (13) when it rises and detaches.

5. The pollution-free droplet transfer device for continuous drip microextraction according to claim 4, characterized in that, An inert layer is coated on the inner wall of the collection tube (12). The inert layer is made of chemically inert material, so that the extract droplets only come into contact with the inert layer during the transfer process, thus achieving pollution-free inert transport.

6. A pollution-free droplet transfer method for continuous drip microextraction, characterized in that, The application of the pollution-free droplet transfer device for continuous drip microextraction as described in claim 5 includes the following steps: S1, Droplet formation and extraction: The first peristaltic pump (4) is started by controlling the controller to deliver the extractant (1) to the end of the extraction head (5) to form extraction droplets; the droplet volume is maintained by monitoring and linkage with the first peristaltic pump (4) through the transmitting optical fiber (8) and receiving optical fiber (10); the carrier gas is introduced into the extraction chamber (9) and the extraction droplets are purged. The extraction droplets extract the components in the carrier gas under normal pressure. When the preset extraction time is reached, the extraction of the droplets is completed. S2, Droplet Transfer: The controller controls the first peristaltic pump (4) to stop working; and controls the elevator (17) to drive the sealing head (13) to move down, sealing the designated sample bottle (14) to form a closed transfer chamber. The vacuum tube (18) and the second peristaltic pump (19) connected to it apply negative pressure to the chamber. Under the action of negative pressure, the extracted droplets are transferred to the sample bottle (14) through the collection tube (12). S3, System Reset: After the extracted droplets are transferred, the controller controls the second peristaltic pump (19) to stop working to remove the negative pressure, and controls the elevator (17) to move the sealing head (13) upward to release the seal on the sample bottle (14). Subsequently, the conveyor belt (15) moves to transport the next empty sample bottle (14) to the collection station, and forms a new extraction droplet at the end of the extraction head (5) to prepare for the next extraction.

7. The method for pollution-free droplet transfer in continuous drip microextraction according to claim 6, characterized in that, The second peristaltic pump (19) in S2 applies negative pressure for 1-5 seconds to achieve rapid transfer of the extract droplets.

8. The method for pollution-free droplet transfer in continuous drip microextraction according to claim 6, characterized in that, The carrier gas is a gas containing pyrolysis products of the sample, generated by the thermogravimetric analyzer during programmed temperature rise.

9. A method for transferring contaminant-free droplets in continuous drip microextraction according to claim 6, characterized in that, The preset extraction time in S1 is 40-60 seconds.

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