A mobile phase configuration device

Abstract

The utility model discloses a kind of mobile phase configuration devices, belong to liquid chromatography analysis technical field.The device includes at least one water phase pumping pipeline, at least one organic phase pumping pipeline, an additive pumping pipeline and system control unit.The water phase and organic phase pumping pipeline are sequentially provided with positive displacement pump, pressure gauge, flowmeter and automatic emptying device;The additive pumping pipeline is provided with switchable injection pump assembly, and is connected in parallel with the water phase and organic phase pumping pipeline by multiple multi-channel switching valve respectively.System control unit is connected with each component signal, and is coordinately controlled.The utility model is switched by multiple parallel connection and valve design, realizes the online, fast, accurate configuration and automatic emptying of multiple-component mobile phase, effectively improves configuration efficiency, precision and cleanliness.

Description

Technical Field

[0001] This utility model relates to the field of liquid chromatography analysis technology, specifically to a mobile phase preparation device for instruments such as high performance liquid chromatography (HPLC). Background Technology

[0002] In liquid chromatography analysis, the precise preparation of the mobile phase is crucial for ensuring the accuracy and reproducibility of analytical results. Currently, the mainstream method for preparing mobile phases in laboratories still relies on manual operation, where researchers measure out the aqueous phase, organic phase, and various additives according to proportions and manually mix them thoroughly in a container. This method is not only time-consuming and labor-intensive, but also inefficient, and it is difficult to guarantee the accuracy and consistency of each preparation. Human error is particularly significant when there are many types of mobile phases to be prepared or when the volume is small.

[0003] To improve automation levels, some automatic mobile phase configuration or replenishment devices have emerged on the market. For example, Chinese utility model patent CN220188435U discloses an "automatic mobile phase replacement device for liquid chromatographs". This device, by setting up a configuration container, a storage container, and a mobile phase container, and utilizing the linkage between a liquid level sensor and a microcontroller, realizes the automatic configuration and replenishment of the mobile phase, reducing manual intervention to a certain extent.

[0004] However, analysis reveals the following significant shortcomings in existing technical solutions: Insufficient configuration efficiency and flexibility: Existing devices mostly adopt a batch configuration mode of "mixing in a centralized configuration container first, then transferring to a storage container." This mode has a long process, slow configuration speed, and makes it difficult to achieve rapid and continuous mobile phase supply, failing to meet the "ready-to-use, rapid output" requirements of high-throughput laboratories. Its structure is complex, involving multiple large containers, and occupies a large area.

[0005] Accuracy and reliability need improvement: For the pumping of trace additives (such as trifluoroacetic acid), existing technologies are generally not specifically optimized, making it difficult to achieve a wide range of accurate pumping at both microliter and milliliter levels, affecting the formulation accuracy of low-concentration additives. At the same time, the pipeline lacks effective online monitoring and safety protection mechanisms, making it impossible to detect and respond quickly to faults such as blockages in real time, posing a risk of equipment damage.

[0006] There are risks of cross-contamination and reagent residue: After each configuration, residual reagents in the pipelines may volatilize or cause cross-contamination in subsequent configurations, especially additives with strong adsorption properties. Existing equipment lacks a targeted and efficient pipeline evacuation and cleaning mechanism, affecting the purity of switching between different mobile phases.

[0007] Therefore, there is an urgent need in the field for an integrated mobile phase configuration device that can achieve high-speed, high-precision, and high-reliability configuration and effectively avoid cross-contamination, in order to overcome the above-mentioned deficiencies of the prior art. Utility Model Content

[0008] To solve at least one of the above-mentioned technical problems, the present invention provides a mobile phase preparation device, comprising: At least one organic phase pumping pipeline, one end of which is connected to an organic phase storage tank and the other end of which is connected to an outlet, is used to transport the organic phase to the outlet. At least one aqueous phase pumping pipeline, one end of which is connected to an external pressurized water supply source and the other end of which is connected to an outlet, is used to transport the aqueous phase to the outlet. At least one additive pumping pipeline, one end of which is connected to an additive storage tank, and the other end of which is connected to multiple multi-channel switching valves. The pipeline is connected in parallel with the organic phase pumping pipeline and the aqueous phase pumping pipeline through the multiple multi-channel switching valves, respectively, to deliver the additive to the outlet. Both the organic phase pumping pipeline and the aqueous phase pumping pipeline are equipped with a volumetric pump, a pressure gauge, a flow meter, and an automatic evacuation device in sequence along the conveying direction. The additive pumping pipeline is also equipped with a switchable injection pump assembly.

[0009] The system control unit is connected to the positive displacement pump, pressure gauge, flow meter, automatic evacuation device, injection pump assembly, and multi-channel switching valve.

[0010] In some implementations, the multi-channel switching valve includes a common outlet and two inlets; wherein the common outlet is connected via a pipeline to the pipeline between the automatic evacuation device and the outlet, the first inlet is connected via a pipeline to the outlet end of the injection pump assembly, and the second inlet is connected via a pipeline to the pipeline between the flow meter and the automatic evacuation device.

[0011] In some implementations, the automatic venting device includes an air pump, a solenoid two-way valve, and a solenoid three-way valve connected in sequence via pipelines. The solenoid three-way valve connects the pipelines containing the air pump and the solenoid two-way valve in parallel to the organic phase pumping pipeline and the aqueous phase pumping pipeline. The solenoid three-way valve includes a normally open inlet, a normally open outlet, and a normally closed outlet. The normally closed outlet is connected to the solenoid two-way valve via a pipeline.

[0012] In some implementations, the multi-channel switching valve also includes a third inlet, which is connected via a pipeline between the air pump and the solenoid two-way valve.

[0013] In some implementations, the switchable injection pump assembly includes a small-volume injection pump and a large-volume injection pump, the small-volume injection pump having a rated capacity of 250 μL and the large-volume injection pump having a rated capacity of 2.5 mL. The inlets of the small-volume injection pump and the large-volume injection pump are respectively connected to an additive storage tank, and the outlets of the small-volume injection pump and the large-volume injection pump are respectively connected to a first inlet. The system control unit is respectively connected to the small-volume injection pump and the large-volume injection pump via signal connection.

[0014] In some implementations, the system control unit includes a pump selection switch circuit configured to receive a volume signal representing the volume of additive pumped and output a drive signal to a small-volume syringe pump or a large-volume syringe pump based on the volume signal. The pump selection switch circuit is configured to output a drive signal to the large-volume syringe pump when the volume value represented by the volume signal is greater than 0.5 mL, and to output a drive signal to the small-volume syringe pump when the volume value represented by the volume signal is less than or equal to 0.5 mL.

[0015] In some implementations, the automatic evacuation device is configured to perform the following evacuation modes: The system control unit signals control the solenoid three-way valves on the organic phase pumping pipeline and / or the aqueous phase pumping pipeline to connect their normally open outlet and normally closed outlet, while closing the normally open inlet and starting the air pump and solenoid two-way valve to discharge the liquid in the corresponding pipeline from the outlet. The system control unit signals the electromagnetic three-way valve corresponding to the additive pump pipeline to close its normally open outlet. At the same time, it signals the multi-channel switching valve to connect its third inlet to the common outlet and starts the air pump connected to the third inlet of the multi-channel switching valve to empty the liquid in the pipeline between the multi-channel switching valve and the liquid outlet.

[0016] In some implementation schemes, a first branch is provided between the external pressurized water supply source and the positive displacement pump, on which a back pressure valve and a waste liquid port are installed in sequence. The back pressure valve is a purely mechanical back pressure valve with a preset opening pressure of 0.3 MPa.

[0017] In some implementations, the positive displacement pump is a diaphragm pump, using a PTFE diaphragm, and the external pressurized water supply source is an ultrapure water system.

[0018] In some implementations, the system control unit is configured to perform an automatic emergency stop function based on pressure gauge readings.

[0019] All materials used in this utility model are existing materials and do not involve new materials; all processes and methods used are existing technologies and do not involve new processes and methods.

[0020] Compared with the prior art, the beneficial effects of this utility model are reflected in: 1. Through the design of multiple parallel pumping pipelines, combined with multi-channel switching valves, the synchronous or sequential precise pumping of aqueous phase, organic phase and additives is realized, and the mixture is directly mixed online and then output. This eliminates the need for intermediate configuration and transfer containers, greatly shortens the process, has extremely high configuration efficiency, and has a compact structure.

[0021] 2. For additives, an innovative switchable dual injection pump assembly (250μL and 2.5mL) is adopted, which is intelligently switched by the system control unit according to the volume requirements, perfectly balancing the pumping needs of microliter and milliliter levels, and ensuring the accuracy of additive preparation from low to high concentrations.

[0022] 3. A unique automatic evacuation device and its working mode were designed. After each pumping task, the residual liquid in the main pipeline and additive pipeline can be purged by an air pump, which effectively prevents reagent evaporation, ensures the accuracy of analysis results, and avoids cross-contamination.

[0023] 4. Pressure gauges and flow meters are integrated into each main line, enabling online monitoring and calibration of flow rate and velocity. The system control unit can monitor pressure anomalies in real time and execute automatic emergency shutdown. Simultaneously, an independent overpressure protection mechanism is provided for the purely mechanical back pressure valve of the ultrapure water system, providing dual protection and greatly improving the stability and safety of equipment operation. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the structure and connection relationship of the mobile phase configuration device provided in Embodiment 1 of this utility model.

[0025] Figure 2 for Figure 1 A partially enlarged schematic diagram of the electromagnetic three-way valve and multi-channel switching valve of the mobile phase configuration device described herein.

[0026] Figure reference numerals: 500 - outlet, 600 - external pressurized water supply, 110 - first positive displacement pump, 120 - first pressure gauge, 130 - first flow meter, 710 - back pressure valve, 720 - waste outlet, 210 - methanol storage tank, 220 - second positive displacement pump, 230 - second pressure gauge, 240 - second flow meter, 310 - acetonitrile storage tank, 320 - third positive displacement pump, 330 - third pressure gauge, 340 - third flow meter, 410 - additive storage tank, 420 - switchable injection pump assembly, 421 - small capacity injection pump, 422 - large capacity injection pump, A - first multi-channel switching valve, A1 - first inlet, A2 - second inlet, A3 - third inlet, A4 - common outlet, B - second multi-channel switching valve, B1 - first inlet, B2 - third... Two inlets, B3-Third inlet, B4-Common outlet, C-Third multi-channel switching valve, C1-First inlet, C2-Second inlet, C3-Third inlet, C4-Common outlet, 140-First automatic venting device, 141-First air pump, 142-First solenoid two-way valve, D-First solenoid three-way valve, D1-Normally open inlet, D2-Normally open outlet, D3-Normally closed outlet, 250-Second automatic venting device, 251-Second air pump, 252-Second solenoid two-way valve, E-Second solenoid three-way valve, E1-Normally open inlet, E2-Normally open outlet, E3-Normally closed outlet, 350-Third automatic venting device, 351-Third air pump, 352-Third solenoid two-way valve, F-Third solenoid three-way valve, F1-Normally open inlet, F2-Normally open outlet, F3-Normally closed outlet. Detailed Implementation

[0027] In order to make the technical means, inventive features, objectives and effects of the utility model easy to understand, the utility model is further described in conjunction with specific illustrations, but the utility model is not limited to the following embodiments.

[0028] It should be noted that the structures, proportions, sizes, etc., shown in the accompanying drawings of this specification are only used to complement the content disclosed in the specification for those skilled in the art to understand and read, and are not intended to limit the conditions under which this utility model can be implemented. Therefore, they have no substantial technical significance. Any modifications to the structure, changes in the proportional relationships, or adjustments to the size, without affecting the effects and purposes that this utility model can produce, should still fall within the scope of the technical content disclosed in this utility model.

[0029] Terms such as “comprising” and “including” indicate that, in addition to the components that are directly and explicitly stated in the specification and claims, the technical solution of this utility model does not exclude the presence of other components that are not directly or explicitly stated.

[0030] This utility model provides a mobile phase preparation device and offers the following technical solution, which will be described in detail below with reference to the accompanying drawings: Example 1 The specific embodiments of this utility model will be described in detail below with reference to the accompanying drawings. The core concept of this utility model is that the additive pumping pipeline can be flexibly connected in parallel with any organic phase or aqueous phase pumping pipeline through multiple parallel multi-channel switching valves, thereby realizing the precise mixing and delivery of additives with different main reagents. The organic phase or aqueous phase is used to flush trace amounts of additives to the outlet, reducing the loss of additives in the pipeline.

[0031] See Figure 1 The mobile phase preparation device provided in this embodiment mainly includes an aqueous phase pumping pipeline, two organic phase pumping pipelines, an additive pumping pipeline, and a system control unit. The ends of all pipelines eventually converge and connect to a common outlet 500.

[0032] Aqueous phase pumping pipeline: Its starting end is connected to an external pressurized water supply source via a pipeline, which in this example is a commercially available ultrapure water system 600. Along the delivery direction, a first positive displacement pump 110, a first pressure gauge 120, a first flow meter 130 and a first automatic evacuation device 140 are installed sequentially on the pipeline.

[0033] A first branch line is also provided on the pipeline between the ultrapure water system 600 and the first positive displacement pump 110. A purely mechanical back pressure valve 710 and a waste liquid port 720 are installed sequentially on this first branch line. The back pressure valve 710 has a preset opening pressure of 0.3 MPa. When the pipeline pressure abnormally exceeds this value, the valve automatically opens to release pressure, protecting the ultrapure water system 600 from damage.

[0034] The first positive displacement pump 110 is preferably a diaphragm pump using a PTFE diaphragm sheet, which has both corrosion resistance and high flow rate pumping capacity.

[0035] The organic phase pumping pipeline includes methanol and acetonitrile pipelines, specifically: Methanol pipeline: Its starting end is connected to methanol storage tank 210. Along the conveying direction, a second positive displacement pump 220 (also a PTFE diaphragm pump), a second pressure gauge 230, a second flow meter 240, and a second automatic evacuation device 250 are installed sequentially on the pipeline.

[0036] Acetonitrile pipeline: Its starting end is connected to acetonitrile storage tank 310. Along the conveying direction, a third positive displacement pump 320 (also a PTFE diaphragm pump), a third pressure gauge 330, a third flow meter 340 and a third automatic evacuation device 350 are installed sequentially on this pipeline.

[0037] Additive pumping line: Its starting end is connected to trifluoroacetic acid (TFA) storage tank 410. This line is characterized by a switchable injection pump assembly 420.

[0038] The switchable syringe pump assembly 420 includes a small-volume syringe pump 421 with a rated capacity of 250 μL and a large-volume syringe pump 422 with a rated capacity of 2.5 mL. The inlet ends of the two syringe pumps are connected to the TFA storage tank 410 via branch lines, and their outlet ends are connected in parallel to three multi-channel switching valves via three lines.

[0039] See Figure 2 The additive pumping pipeline is connected in parallel with three main pipelines (specifically: the aqueous phase pumping pipeline, the methanol pipeline, and the acetonitrile pipeline) via three independent multi-channel switching valves. These three valves are: The first multi-channel switching valve A has its first inlet A1 connected to the common outlet pipeline of the injection pump assembly 420 via a pipeline; its second inlet A2 connected to the water phase pipeline between the first flow meter 130 and the first automatic evacuation device 140 via a pipeline; its third inlet A3 connected via a pipeline; and its common outlet A4 connected via a pipeline.

[0040] The second multi-channel switching valve B has its first inlet B1 connected to the common outlet pipeline of the injection pump assembly 420 via a pipeline; its second inlet B2 connected to the methanol pipeline between the second flow meter 240 and the second automatic venting device 250 via a pipeline; its third inlet B3 connected via a pipeline; and its common outlet B4 connected via a pipeline.

[0041] The third multi-channel switching valve C has its first inlet C1 connected to the common outlet pipeline of the injection pump assembly 420 via a pipeline; its second inlet C2 connected to the acetonitrile pipeline between the third flow meter 340 and the third automatic venting device 350 via a pipeline; its third inlet C3 connected via a pipeline; and its common outlet C4 connected via a pipeline.

[0042] The common outlets (A4, B4, C4) of all multi-channel switching valves are connected via pipelines to the pipelines between the automatic venting devices (140, 250, 350) and the outlet 500 of their respective main lines.

[0043] Automatic air purging device: The first automatic venting device 140 includes a first air pump 141, a first solenoid two-way valve 142, and a first solenoid three-way valve D, which are connected in sequence via pipelines. (See the first solenoid three-way valve D for details.) Figure 2This includes a normally open inlet D1, a normally open outlet D2, and a normally closed outlet D3. The normally open inlet D1 is connected to a pipeline from the first flow meter 130, the normally open outlet D2 is connected to the liquid outlet 500, and the normally closed outlet D3 is connected to the first solenoid two-way valve 142 via a pipeline. The first solenoid three-way valve D connects the pipelines containing the first air pump 141 and the first solenoid two-way valve 142 in parallel to the water phase pumping pipeline in this manner.

[0044] The second automatic air venting device 250 includes a second air pump 251, a second solenoid two-way valve 252, and a second solenoid three-way valve E connected sequentially via pipelines. The second solenoid three-way valve E (see reference) Figure 2 This includes a normally open inlet E1, a normally open outlet E2, and a normally closed outlet E3. The normally open inlet E1 is connected to a pipeline from the second flow meter 240, the normally open outlet E2 is connected to the liquid outlet 500, and the normally closed outlet E3 is connected to the second solenoid two-way valve 252 via a pipeline. The second solenoid three-way valve E connects the pipelines containing the second air pump 251 and the second solenoid two-way valve 252 in parallel to the methanol pumping pipeline in this manner.

[0045] The third automatic venting device 350 includes a third air pump 351, a third solenoid two-way valve 352, and a third solenoid three-way valve F. (See also: [link to document]) Figure 2 This includes a normally open inlet F1, a normally open outlet F2, and a normally closed outlet F3. The normally open inlet F1 is connected to a pipeline from the third flow meter 340, the normally open outlet F2 is connected to the liquid outlet 500, and the normally closed outlet F3 is connected to the third solenoid two-way valve 352 via a pipeline. The third solenoid three-way valve F thus connects the pipelines containing the third air pump 351 and the third solenoid two-way valve 352 in parallel to the acetonitrile pump pipeline.

[0046] The third inlet of each multi-channel switching valve is connected via a pipeline to the pipeline between the air pump and the solenoid two-way valve in the corresponding automatic venting device (see...). Figure 1 , Figure 2 Specifically, the third inlet A3 of the first multi-channel switching valve A is connected to the pipeline between the first air pump 141 and the first solenoid two-way valve 142; the third inlet B3 of the second multi-channel switching valve B is connected to the pipeline between the second air pump 251 and the second solenoid two-way valve 252; and the third inlet C3 of the third multi-channel switching valve C is connected to the pipeline between the third air pump 351 and the third solenoid two-way valve 352.

[0047] System control unit: It is the core control component, and is connected to the air pumps (141, 251, 351) and solenoid valves (142, 252, 352, D, E, F) in all pumps (110, 220, 320, 421, 422), all pressure gauges (120, 230, 330), all flow meters (130, 240, 340), all automatic evacuation devices (140, 250, 350), as well as all multi-channel switching valves (A, B, C).

[0048] The working process of this utility model is as follows: Parameter Input and Calculation: The operator inputs the formula into the human-machine interface of the system control unit, for example: 92.75% ultrapure water, 3.75% methanol, 2.83% acetonitrile, 0.67% TFA, with a total configuration volume of 2L. The system control unit automatically calculates the volumes of each component: 1855mL water, 75mL methanol, 56.6mL acetonitrile, and 13.4mL TFA.

[0049] Pumping strategy formulation: The system control unit compares the volumes of water, methanol, and acetonitrile, and determines that water (1855 mL) has the largest volume. Therefore, the system decides to pump TFA out in parallel with the aqueous phase pipeline 100, and accordingly incorporates the first multi-channel switching valve A into the control sequence.

[0050] The pump selection switch circuit in the system control unit automatically determines to start the large-capacity syringe pump 422 for pumping based on the TFA volume of 13.4 mL (>0.5 mL).

[0051] The system calculates the pumping time as follows: Aqueous phase pumping time = 1855 mL / 1000 mL / min = 1.855 min; TFA pumping time = 13.4 mL / 8.5 mL / min ≈ 1.58 min. Since the TFA pumping time is shorter than the aqueous phase pumping time, the system decides to pump TFA and water simultaneously to ensure that the TFA is fully flushed by the aqueous phase in the aqueous phase pumping line to the outlet at 500°.

[0052] Perform pumping and mixing: The system control unit signals the first multi-channel switching valve A, connecting its first inlet A1 with the common outlet A4; and signals the start of the large-capacity injection pump 422, pumping TFA into the pipeline, which then flows out through the A1→A4 flow channel of the first multi-channel switching valve A and enters the aqueous phase pipeline. Note: In this embodiment, the multi-channel switching valve can only connect one flow channel at a time. For example, when A1 and A4 are connected, A2 and A3 are both closed, and the same applies to other situations, which will not be elaborated further below.

[0053] Simultaneously, the first positive displacement pump 110, the second positive displacement pump 220, and the third positive displacement pump 320 are started, pumping ultrapure water, methanol, and acetonitrile respectively. The three diaphragm pumps pump at a constant rate (e.g., 1 L / min), and the system is monitored and calibrated in real time via feedback from flow meters (130, 240, 340). Methanol and acetonitrile can be pumped in stages to match the water pumping process, achieving a more uniform mixing effect.

[0054] Pipeline cleaning: After the TFA pumping is completed, the system control unit signals the first multi-channel switching valve A to switch, connecting its second inlet A2 (connected to the aqueous phase pipeline) to the common outlet A4. Approximately 50 mL of ultrapure water is then pumped to flush out any remaining TFA in the first multi-channel switching valve A.

[0055] Automatic emptying: Main line purging: After pumping is completed and the pipeline is cleaned, the system control unit signals the solenoid three-way valves (D, E, F) on each main line to connect their normally open outlets (D2, E2, F2) with their normally closed outlets (D3, E3, F3), while simultaneously closing the normally open inlet (D1, E1, F1). Then, the air pumps (141, 251, 351) on each line are started and the solenoid two-way valves (142, 252, 352) are opened. Compressed gas blows the residual liquid in the main pumping pipeline out of the outlet 500.

[0056] Additive purging: The system control unit controls the first multi-channel switching valve A to connect its third inlet A3 with the common outlet A4. Subsequently, the first air pump 141 is started, and compressed gas enters the first multi-channel switching valve A from the third inlet A3, purging the residual TFA inside the valve and in the pipeline downstream to the outlet 500 to the outlet 500.

[0057] Safety Monitoring: Throughout the process, the system control unit continuously monitors the readings of each pressure gauge (120, 230, 330). If any pressure rises abnormally (indicating potential blockage), the system control unit will immediately execute an automatic emergency shutdown procedure, stopping all pumps and issuing an alarm.

[0058] In this utility model, "main pipeline" and "main pumping pipeline" are abbreviations for aqueous phase pumping pipeline and organic phase pumping pipeline, respectively, and "additive pipeline" is an abbreviation for additive pumping pipeline. Phrases such as "...connected to / to... and... via pipelines" and "...connected to... and... via pipelines" refer to the connection between two pipelines via a T-junction. Since these connection methods are common existing technologies and the invention does not focus on them, they are not elaborated upon.

[0059] The preferred embodiments of this utility model have been described in detail above. It should be understood that those skilled in the art can make numerous modifications and variations based on the concept of this utility model without creative effort. Therefore, all technical solutions that can be obtained by those skilled in the art based on the concept of this utility model through logical analysis, reasoning, or limited experimentation on the basis of existing technology should be within the scope of protection defined by the claims.

Claims

1. A mobile phase preparation apparatus, characterized in that, include: At least one organic phase pumping pipeline, one end of which is connected to an organic phase storage tank and the other end of which is connected to an outlet, is used to transport the organic phase to the outlet. At least one aqueous phase pumping pipeline, one end of which is connected to an external pressurized water supply source and the other end of which is connected to an outlet, is used to transport the aqueous phase to the outlet. At least one additive pumping pipeline, one end of which is connected to an additive storage tank and the other end of which is connected to multiple multi-channel switching valves, which are connected in parallel with the organic phase pumping pipeline and the aqueous phase pumping pipeline respectively through the multiple multi-channel switching valves, for transporting the additive to the outlet. Both the organic phase pumping pipeline and the aqueous phase pumping pipeline are sequentially equipped with a volumetric pump, a pressure gauge, a flow meter, and an automatic evacuation device along the conveying direction. The additive pumping pipeline is also equipped with a switchable injection pump assembly. The system control unit is connected to the positive displacement pump, the pressure gauge, the flow meter, the automatic evacuation device, the injection pump assembly, and the multi-channel switching valve, respectively.

2. The mobile phase preparation apparatus according to claim 1, characterized in that, The multi-channel switching valve includes a common outlet and two inlets; wherein, the common outlet is connected to the pipeline between the automatic evacuation device and the liquid outlet via a pipeline, the first inlet is connected to the outlet end of the injection pump assembly via a pipeline, and the second inlet is connected to the pipeline between the flow meter and the automatic evacuation device via a pipeline; the number of multi-channel switching valves is equal to the sum of the number of organic phase pumping pipelines and aqueous phase pumping pipelines.

3. The mobile phase preparation apparatus according to claim 2, characterized in that, The automatic venting device includes an air pump, a solenoid two-way valve, and a solenoid three-way valve connected in sequence through pipelines. The solenoid three-way valve connects the pipelines containing the air pump and the solenoid two-way valve in parallel to the organic phase pumping pipeline and the aqueous phase pumping pipeline. The solenoid three-way valve includes a normally open inlet, a normally open outlet, and a normally closed outlet. The normally closed outlet is connected to the solenoid two-way valve through a pipeline.

4. The mobile phase preparation apparatus according to claim 3, characterized in that, The multi-channel switching valve also includes a third inlet, which is connected to the pipeline between the air pump and the solenoid two-way valve via a pipeline.

5. The mobile phase preparation apparatus according to claim 2, characterized in that, The switchable injection pump assembly includes a small-volume injection pump and a large-volume injection pump. The rated capacity of the small-volume injection pump is 250 μL, and the rated capacity of the large-volume injection pump is 2.5 mL. The inlet ends of the small-volume injection pump and the large-volume injection pump are respectively connected to the additive storage tank, and the outlets of the small-volume injection pump and the large-volume injection pump are respectively connected to the first inlet. The system control unit is signal-connected to the small-volume injection pump and the large-volume injection pump respectively.

6. The mobile phase preparation apparatus according to claim 5, characterized in that, The system control unit includes a pump selection switch circuit, which is configured to receive a volume signal representing the volume of the additive being pumped, and output a drive signal to the small-volume injection pump or the large-volume injection pump based on the volume signal. The pump selection switch circuit is configured to output the drive signal to the large-capacity syringe pump when the volume value represented by the volume signal is greater than 0.5 mL, and to output the drive signal to the small-capacity syringe pump when the volume value represented by the volume signal is less than or equal to 0.5 mL.

7. The mobile phase preparation apparatus according to claim 4, characterized in that, The automatic evacuation device is configured to perform the following evacuation modes: The system control unit signals control the electromagnetic three-way valve on the organic phase pumping pipeline and / or the aqueous phase pumping pipeline to connect its normally open outlet with its normally closed outlet, while simultaneously closing the normally open inlet, and starting the air pump and the electromagnetic two-way valve to discharge the liquid in the corresponding pipeline from the outlet. The system control unit signals control the electromagnetic three-way valve of the corresponding pipeline of the additive pumping pipeline to close its normally open outlet. At the same time, it signals control the multi-channel switching valve to connect its third inlet to the common outlet and starts the air pump connected to the third inlet of the multi-channel switching valve to empty the liquid in the pipeline between the multi-channel switching valve and the liquid outlet.

8. The mobile phase preparation apparatus according to claim 1, characterized in that, A first branch is provided between the external pressurized water supply source and the positive displacement pump, on which a back pressure valve and a waste liquid port are sequentially installed; the back pressure valve is a purely mechanical back pressure valve, and its preset opening pressure is 0.3MPa.

9. The mobile phase preparation apparatus according to claim 1, characterized in that, The positive displacement pump is a diaphragm pump, using a PTFE diaphragm, and the external pressurized water supply source is an ultrapure water machine.

10. The mobile phase preparation apparatus according to claim 1, characterized in that, The system control unit is configured to perform an automatic emergency shutdown function based on the readings of the pressure gauge.

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