A medium-pressure injection valve group for gel purification chromatography and its operation method

Abstract

The present invention provides a medium-pressure injection valve group for gel purification chromatography and an operation method thereof, wherein the injection valve group comprises three two-position three-way medium-pressure injection valves connected in series in sequence, wherein one interface of the first medium-pressure injection valve is connected to the second medium-pressure injection valve, and the remaining two interfaces are respectively a sample quantitative loop interface and a syringe injection pump interface, two interfaces of the second medium-pressure injection valve are respectively connected to the first medium-pressure injection valve and the third medium-pressure injection valve, and the remaining one interface is a medium-pressure plunger infusion pump interface; one interface of the third medium-pressure injection valve is connected to the second medium-pressure injection valve, and the remaining two interfaces are respectively a gel purification chromatography column interface and an injection needle interface. The present invention can realize the automatic injection process of instruments in the pressure range of 1 MPa to 10 MPa through the independently designed and developed medium-pressure injection valve group, and solves the problems of insufficient pressure of low-pressure injection valves, poor dirt resistance and salt resistance of high-pressure injection valves, and insufficient flow of small diameters.

Description

Technical Field

[0001] The invention relates to an experimental and automated analytical instrument and liquid automatic processing equipment in the biochemical field, and in particular to a medium-pressure injection valve group for gel purification chromatography. Background Art

[0002] With the development of the demand for high throughput of instrument automation, the automatic injection of biochemical instruments has become a necessary step to achieve automation and high throughput, and various automatic sample injectors have emerged. The core component required for the realization of the automatic injection function is the flow path switching valve, which can switch the sample to the main flow path to complete the injection process. Therefore, many foreign-funded enterprises specializing in the production of flow path switching valves have also emerged. For example, Valco, VICI, and IDEX in the United States, especially the 7725i and 3725i high-pressure valves, as well as a wide variety of low-pressure valves. It has almost become the standard injection valve for liquid chromatography and other analytical instruments around the world.

[0003] Among them, the low-pressure injection valve is suitable for instruments and equipment with a flow pressure below 1 MPa, such as conventional solid phase extraction instruments and other pre-treatment instruments. There are many imported and domestic products, and there is a lot of room for choice. The advantages are: 1) Low price. Mature products are 2000-5000 yuan / piece. 2) There are both domestic and imported brands, and there is a lot of room for choice. For example, Germany's Baodi Fluid, the United States VICI, the United States IDEX, China Kentuo and Beiang Fluid, etc. The disadvantages are: 1) Poor salt and dirt resistance. The stator and rotor are sealed by high-precision surface fitting, which requires the cleanliness of the sample, and salt-containing samples will also damage the sealing surface. 2) The failure rate is relatively high. Because it involves high-precision stator and rotor processing, assembly and reducer structure, and the samples of the pre-treatment instrument are relatively dirty, the possibility of failure is increased, affecting the reliability of the instrument.

[0004] Among them, the high-pressure injection valve is suitable for instruments and equipment above 20 MPa, such as liquid chromatography and ultra-high performance liquid chromatography and other analytical instruments. There are only imported brands of mature commercial products, such as VICI and IDEX in the United States, and there is no mature domestic product at present. The advantages are: 1) High pressure resistance, suitable for analytical instruments related to high-pressure fluids, and irreplaceable. For example, the pressure resistance of the 3725i injection valve of VICI and IDEX in the United States is 20 MPa, and the 7725i injection valve will not leak even at 42 MPa. The disadvantages are: 1) Poor salt and dirt resistance. The stator and rotor are sealed by a more high-precision surface fitting, which requires higher cleanliness of the sample, and salt-containing samples will also cause great damage to the sealing surface. 2) The failure rate is higher than that of the low-pressure injection valve. Because it involves more high-precision stator and rotor processing, assembly and reducer structure, and the samples of the pre-treatment instrument are relatively dirty, the possibility of failure is increased, which further affects the reliability of the instrument. 3) The internal liquid path of the injection valve is small, which is not suitable for sample pre-treatment instruments. In order to achieve ultra-high pressure, the internal liquid path diameter is very small, and the dirt resistance and flow rate are limited. 4) Expensive, foreign monopoly. Imports are basically American VICI and American IDEX brands. For example, the price of 3725i injection valve is nearly 8,000 yuan per piece.

[0005] Among them, the medium-pressure injection valve is suitable for instruments and equipment with pressures between 1 MPa and 10 MPa, such as analytical instruments such as gel purification preparative chromatography, with working pressures in the range of 1 MPa to 10 MPa. Currently, there is no suitable injection valve, and only the expensive 3725i high-pressure injection valve (about 30 MPa) can be used, which can only be used reluctantly. However, the 3725i high-pressure injection valve cannot maximize the efficiency of gel purification preparative chromatography, and has a high failure rate due to poor resistance to dirt, which needs to be solved urgently.

[0006] In view of this, in order to provide gel purification chromatography with a suitable medium-pressure injection valve, and in order to have a medium-pressure injection valve with high resistance to dirt and salt and a large internal diameter, the inventor, based on research and development in related fields, in order to fill the technical gap in medium-pressure injection valves in pretreatment fields such as medium-pressure gel purification preparative chromatography, has continuously tested and improved, and thus the patent of the present invention was produced. Summary of the invention

[0007] In order to solve the above problems and achieve good use effect and economic benefits, the present invention specially invents a medium-pressure injection valve group for gel purification chromatography and an operation method thereof, wherein the medium-pressure injection valve group comprises three medium-pressure injection valves, and the three medium-pressure injection valves are connected by liquid pipelines and stainless steel joints, and the medium-pressure injection valve comprises a stepper motor, a positioning optical coupler and a two-position three-way valve head. The stepper motor and the positioning optical coupler can drive the two-position three-way valve head to rotate, thereby switching the flow direction of the liquid. The medium-pressure injection valve group is then connected to the main flow path of the medium-pressure gel purification chromatography, and the automatic loading process of the medium-pressure gel purification chromatography can be realized in conjunction with the software and the underlying circuit system.

[0008] To achieve the above object, the present invention provides a medium-pressure injection valve group for gel purification chromatography, characterized in that it comprises three medium-pressure injection valves connected in series, and the medium-pressure injection valves are all two-position three-way valves; wherein:

[0009] Among the three interfaces of the first medium-pressure injection valve, one interface is connected to the second medium-pressure injection valve, and the remaining two interfaces are respectively a sample quantitative loop interface and a syringe injection pump interface, wherein the sample quantitative loop interface is used to connect to a sample quantitative loop, and the syringe injection pump interface is used to connect to a syringe injection pump;

[0010] Among the three interfaces of the second medium-pressure injection valve, two interfaces are respectively connected to the first medium-pressure injection valve and the third medium-pressure injection valve, and the remaining interface is a medium-pressure plunger infusion pump interface, which is used to connect to a first liquid container through the medium-pressure plunger infusion pump, and the first liquid container can be used to hold a mobile phase liquid;

[0011] Among the three interfaces of the third medium-pressure injection valve, one interface is connected to the second medium-pressure injection valve, and the remaining two interfaces are respectively a gel purification chromatographic column interface and an injection needle interface. The gel purification chromatographic column interface is used to connect to a gel purification chromatographic column, and the injection needle interface can allow an injection needle to be inserted to form a connection.

[0012] The medium-pressure injection valve group for gel purification chromatography, wherein: the injection needle is connected to the sample quantitative loop, the injection needle can be selectively inserted into a second liquid container to absorb the sample solution contained in the second liquid container, and the injection needle can also be selectively in a non-inserted state.

[0013] The medium-pressure injection valve group for gel purification chromatography, wherein the three medium-pressure injection valves can be switched between the following two connection states:

[0014] Connectivity state 1: the first medium-pressure injection valve is not connected to the second medium-pressure injection valve, the sample quantitative loop interface on the first medium-pressure injection valve is connected to the syringe injection pump interface, and the medium-pressure plunger infusion pump interface on the second medium-pressure injection valve is connected to the gel purification chromatographic column interface on the third medium-pressure injection valve;

[0015] Connectivity state two: the sample quantitative loop interface on the first medium-pressure injection valve is connected to the medium-pressure plunger infusion pump interface on the second medium-pressure injection valve, the second medium-pressure injection valve is not connected to the third medium-pressure injection valve, and the gel purification chromatographic column interface on the third medium-pressure injection valve is connected to the injection needle interface.

[0016] The medium-pressure injection valve group for gel purification chromatography, wherein: each of the medium-pressure injection valves has a stepper motor, a positioning optical coupler, a coupling, a two-position three-way valve head fixing seat and a two-position three-way valve head, the two-position three-way valve head is installed on the two-position three-way valve head fixing seat, the stepper motor is connected to the two-position three-way valve head through a coupling, and can drive the two-position three-way valve head to rotate and switch between two working positions, a positioning optical coupler is provided on one side of the coupling, which is used to position the two working positions of the two-position three-way valve head; hollow screws are provided on the three interfaces of the two-position three-way valve head for connection with corresponding pipelines in the form of threaded and blade ring connections.

[0017] The medium-pressure injection valve group for gel purification chromatography, wherein: the maximum pressure resistance of the two-position three-way valve head is 10 MPa.

[0018] The medium-pressure injection valve group for gel purification chromatography, wherein: the sample quantitative ring adopts a volume specification of 10 ml, has an outer diameter of 1 / 8 inch, an inner diameter of 1 / 16 inch, and is made of polyetheretherketone, Teflon or stainless steel.

[0019] The medium-pressure injection valve group for gel purification chromatography, wherein: the interior of the injection needle interface adopts a FFKM perfluororubber O-ring structure.

[0020] The medium-pressure injection valve group for gel purification chromatography, wherein: the injection needle is made of a stainless steel tube with an outer diameter of 1 / 8 inch and an inner diameter of 1 mm.

[0021] An operating method of a medium-pressure injection valve group for gel purification chromatography, characterized in that: it has the above-mentioned medium-pressure injection valve group for gel purification chromatography, the medium-pressure plunger infusion pump interface is connected to the liquid outlet pipeline of the medium-pressure plunger infusion pump, the gel purification chromatography column interface is connected to the liquid inlet pipeline of the gel purification chromatography column, the sample quantitative loop interface is connected to one end of the sample quantitative loop, the other end of the sample quantitative loop is connected to the injection needle, the injection needle is selected to be empty or inserted into a second liquid container containing a sample solution or inserted into the injection needle interface, and the syringe injection pump interface is connected to the syringe injection pump; the operating method comprises:

[0022] Sample liquid quantitative absorption process: the medium-pressure injection valve group for gel purification chromatography is in the connected state one, the injection needle is inserted into a second liquid container containing a sample solution, and the chromatographic mobile phase liquid in the first liquid container, under the power provided by the medium-pressure plunger infusion pump, flows through the medium-pressure plunger infusion pump interface and the gel purification chromatography column interface in sequence and enters the gel purification chromatography column; the sample liquid in the second liquid container, under the suction power provided by the syringe injection pump, flows through the injection needle and the sample quantitative loop in sequence and is temporarily stored in the sample quantitative loop;

[0023] Complete injection process of sample liquid: the medium-pressure injection valve group for gel purification chromatography is switched to the second connection state, the injection needle is inserted into the injection needle interface, and the chromatographic mobile phase liquid in the first liquid container, under the power provided by the medium-pressure plunger infusion pump, flows through the medium-pressure plunger infusion pump interface, the sample quantitative loop interface, the sample quantitative loop, the injection needle, the injection needle interface, the gel purification chromatography column interface and flows to the gel purification chromatography column; the sample liquid in the sample quantitative loop, along with the chromatographic mobile phase liquid in the first liquid container, flows through the injection needle, the injection needle interface, the gel purification chromatography column interface in sequence, enters the gel purification chromatography column, and starts the gel purification chromatography separation process;

[0024] Cleaning process: the medium-pressure injection valve group used for gel purification chromatography is switched to connected state 1, the injection needle is empty, and the chromatographic mobile phase liquid in the first liquid container, under the power provided by the medium-pressure plunger infusion pump, flows through the medium-pressure plunger infusion pump interface and the gel purification chromatography column interface in sequence and enters the gel purification chromatography column; under the liquid pushing power provided by the syringe injection pump, the chromatographic mobile phase liquid in the syringe injection pump flows through the syringe injection pump interface, the sample quantitative loop interface, the sample quantitative loop and the injection needle in sequence to complete the cleaning of the injection needle and the sample quantitative loop.

[0025] Compared with the prior art, the present invention has the following advantages:

[0026] 1. The medium-pressure injection valve group independently designed and developed by the present invention fills the technical gap of medium-pressure injection valves in gel purification chromatography injection devices, and can realize the automatic injection process of instruments in the pressure range of 1 MPa to 10 MPa. It solves the problem that low-pressure injection valves cannot be used due to insufficient pressure, and solves the problems of poor dirt resistance, poor salt resistance, small diameter and insufficient flow of high-pressure injection valves.

[0027] 2. The present invention can avoid the problems of poor dirt resistance and salt resistance caused by high-precision processing and assembly of the stator and rotor of a traditional rotary valve by using a medium-pressure injection valve including a two-position three-way valve head.

[0028] 3. The medium-pressure injection valve group independently designed and developed by the present invention can solve the problems of rising costs and incompatible performance caused by the use of high-pressure injection valves.

[0029] 4. The circuit and mechanical technical difficulty of the present invention is very small, the reliability is higher, it is easier to implement and popularize, and the subsequent maintenance cost is reduced through three simple medium-pressure injection valves. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1A , Figure 1B The overall stereogram of the medium-pressure injection valve assembly of the present invention and the stereogram without the outer shell are shown;

[0031] Figure 2A , Figure 2B It is a stereoscopic diagram and a stereoscopic exploded diagram of a single medium-pressure injection valve of the present invention;

[0032] Figure 3A , Figure 3B A schematic diagram of the working process of the medium-pressure injection valve group of the present invention;

[0033] Figure 4A , Figure 4B It is a schematic diagram of the working principle of the medium-pressure injection valve of the present invention.

[0034] Explanation of the accompanying drawings: 1-housing; 2-medium-pressure injection valve; 3-medium-pressure plunger infusion pump interface; 4-gel purification chromatographic column interface; 5-sample quantitative loop interface; 6-syringe injection pump interface; 7-injection needle interface; 8-medium-pressure plunger infusion pump; 9-first liquid container; 10-gel purification chromatographic column; 11-sample quantitative loop; 12-syringe injection pump; 13-second liquid container; 14-liquid pipeline; 15-stepping motor; 16-positioning optical coupler; 17-coupling 1; 18-two-position three-way valve head fixing seat; 19-two-position three-way valve head; 20-hollow screw; 21-injection needle. DETAILED DESCRIPTION

[0035] The present invention is further described below with reference to the accompanying drawings.

[0036] like Figure 1A , Figure 1B , Figure 3A , Figure 3B , Figure 4A , Figure 4B As shown, the present invention provides a medium-pressure injection valve group for gel purification chromatography, comprising three medium-pressure injection valves 2 connected in series, which are used for switching liquid flow paths, and the medium-pressure injection valves 2 are two-position three-way medium-pressure valves with a maximum pressure resistance of 10 MPa; wherein:

[0037] Among the three interfaces of the first medium-pressure injection valve 2, one interface is connected to the second medium-pressure injection valve, and the remaining two interfaces are respectively a sample quantitative loop interface 5 and a syringe injection pump interface 6, wherein the sample quantitative loop interface 5 is used to connect to a sample quantitative loop 11, and the syringe injection pump interface 6 is used to connect to a syringe injection pump 12;

[0038] Among the three interfaces of the second medium-pressure injection valve 2, two of them are respectively connected to the first medium-pressure injection valve and the third medium-pressure injection valve, and the remaining interface is a medium-pressure plunger infusion pump interface 3, which is used to connect to a first liquid container 9 through a medium-pressure plunger infusion pump 8, and the first liquid container 9 can be used to hold a mobile phase liquid;

[0039] Among the three interfaces of the third medium-pressure injection valve 2, one interface is connected to the second medium-pressure injection valve, and the remaining two interfaces are respectively a gel purification chromatographic column interface 4 and an injection needle interface 7, wherein the gel purification chromatographic column interface 4 is used to connect to a gel purification chromatographic column 10, and the injection needle interface 7 is used for an injection needle 21 to be inserted to form a connection;

[0040] The injection needle 21 is connected to the sample quantitative loop 11. The injection needle 21 can be selectively inserted into a second liquid container 13 to absorb the sample solution contained in the second liquid container 13. The injection needle 21 can also be in a non-inserted state to backwash and clean the injection needle 21.

[0041] The three medium-pressure injection valves 2 can switch the connection state at the same time to form two different flow paths:

[0042] In the connected state 1, the first medium-pressure injection valve 2 is not connected to the second medium-pressure injection valve 2, the sample quantitative loop interface 5 is connected to the syringe injection pump interface 6, and the medium-pressure plunger infusion pump interface 3 on the second medium-pressure injection valve 2 is connected to the gel purification chromatographic column interface 4 on the third medium-pressure injection valve 2;

[0043] In the second connection state, the sample quantitative loop interface 5 on the first medium-pressure injection valve 2 is connected with the medium-pressure plunger infusion pump interface 3 on the second medium-pressure injection valve 2, the second medium-pressure injection valve 2 is not connected with the third medium-pressure injection valve 2, and the gel purification chromatographic column interface 4 on the third medium-pressure injection valve 2 is connected with the injection needle interface 7.

[0044] In order to facilitate switching of the connection status of the three medium-pressure injection valves 2, as shown in FIG. Figure 1A , Figure 1B , Figure 2A , Figure 2B As shown, each of the medium-pressure injection valves 2 has a stepper motor 15, a positioning optical coupler 16, a coupling 17, a two-position three-way valve head fixing seat 18 and a two-position three-way valve head 19, wherein the two-position three-way valve head 19 is installed on the two-position three-way valve head fixing seat 18, and the stepper motor 15 is connected to the two-position three-way valve head 19 through the coupling 17, and can drive the two-position three-way valve head 19 to rotate and switch between two working positions, and a positioning optical coupler 16 is provided on one side of the coupling 17 for positioning the two working positions of the two-position three-way valve head 19; hollow screws 20 are provided on the three interfaces of the two-position three-way valve head 19, which can be connected to the corresponding pipeline in the form of threaded and blade ring connections.

[0045] In the medium-pressure injection valve 2, the stepper motor 15 adopts a 42 or 57 fixed-axis stepper motor, which can realize clockwise and counterclockwise rotation.

[0046] In the medium-pressure injection valve 2, the positioning optical coupler 16 adopts a photoelectric sensor to detect whether the medium-pressure injection valve 2 has successfully switched the flow path.

[0047] In the medium-pressure injection valve 2, the two-position three-way valve head 19 has a maximum pressure resistance of 10 MPa and a spherical valve design is adopted inside.

[0048] Finally, the three medium-pressure injection valves 2 are integrated and covered by the shell 1, leaving only the medium-pressure plunger infusion pump interface 3, the gel purification column interface 4, the sample quantitative loop interface 5, the syringe injection pump interface 6, and the injection needle interface 7 exposed, thus completing the assembly of the medium-pressure injection valve group.

[0049] When in use, the medium-pressure plunger infusion pump interface 3 is connected to the liquid outlet pipeline of the medium-pressure plunger infusion pump 8, the gel purification chromatographic column interface 4 is connected to the liquid inlet pipeline of the gel purification chromatographic column 10, the sample quantitative ring interface 5 is connected to one end of the sample quantitative ring 11, and the other end of the sample quantitative ring 11 is connected to the injection needle 21, and the injection needle 21 can be selected to be empty or inserted into the second liquid container 13 or inserted into the injection needle interface 7 (the injection needle 21 can be operated manually or by an automatic injector), and the syringe injection pump interface 6 is connected to the syringe injection pump 12; the flow path between the above-mentioned components is marked with a liquid pipeline 14 in the accompanying drawings, and the liquid pipeline 14 is preferably made of chemically resistant stainless steel with an outer diameter of 1.6 mm and an inner diameter of 0.8 mm or PEEK polyetheretherketone material.

[0050] The sample quantitative ring 11 has a volume specification of 10 ml, an outer diameter of 1 / 8 inch, an inner diameter of 1 / 16 inch, and is made of polyetheretherketone, Teflon or stainless steel.

[0051] The inside of the injection needle interface 7 adopts a FFKM perfluororubber O-ring structure for sealing the injection needle 21 .

[0052] The injection needle 21 is made of a stainless steel tube with an outer diameter of 1 / 8 inch and an inner diameter of 1 mm.

[0053] Next, combine Figure 3A , Figure 3B , Figure 4A , Figure 4B The three working steps of the present invention are explained in detail.

[0054] Step 1: If Figure 3A , 4A As shown, the present invention is in the first connected state. The chromatographic mobile phase liquid in the first liquid container 9, under the power provided by the medium-pressure plunger infusion pump 8, sequentially flows through the medium-pressure plunger infusion pump interface 3 and the gel purification chromatographic column interface 4 into the gel purification chromatographic column 10. At the same time, the sample liquid in the second liquid container 13, under the liquid suction power provided by the syringe injection pump 12, sequentially flows through the injection needle 21 and the sample quantitative loop 11, and finally the sample is temporarily stored in the sample quantitative loop 11. This sample liquid quantitative suction process ends.

[0055] Step 2: If Figure 3B , 4BAs shown, the present invention switches to the second connection state, and the injection needle 21 is inserted into the injection needle interface 7 with the participation of a manual or automatic sampler. At this time, the chromatographic mobile phase liquid in the first liquid container 9, under the power provided by the medium-pressure plunger infusion pump 8, flows through the medium-pressure plunger infusion pump interface 3, the sample quantitative loop interface 5, the sample quantitative loop 11, the injection needle 21, the injection needle interface 7, the gel purification chromatographic column interface 4 and flows to the gel purification chromatographic column 10. In this process, the sample liquid in the sample quantitative loop 11, along with the chromatographic mobile phase liquid in the first liquid container 9, flows through the injection needle 21, the injection needle interface 7, the gel purification chromatographic column interface 4, and finally enters the gel purification chromatographic column 10, and the gel purification chromatographic separation process begins. This sample liquid complete injection process ends.

[0056] Step 3: If Figure 3A As shown, the present invention switches to the connected state 1. After the injection is completed, the chromatographic mobile phase liquid in the first liquid container 9, under the power provided by the medium-pressure plunger infusion pump 8, flows through the medium-pressure plunger infusion pump interface 3 and the gel purification chromatographic column interface 4 in sequence and enters the gel purification chromatographic column 10. At the same time, under the liquid pushing power provided by the syringe injection pump 12, the chromatographic mobile phase liquid in the syringe injection pump 12 flows through the syringe injection pump interface 6, the sample quantitative loop interface 5, the sample quantitative loop 11, and the injection needle 21 in sequence, and finally completes the cleaning of the inner and outer walls of the injection needle 21. This cleaning process of the injection needle 21 and the sample quantitative loop 11 is completed, and the next sample liquid quantitative absorption process is prepared.

[0057] The advantages of the present invention are:

[0058] The invention fills the technical gap of medium-pressure injection valves in gel purification chromatography injection devices through the independently designed and developed medium-pressure injection valve group, and can realize the automatic injection process of instruments in the pressure range of 1 MPa to 10 MPa. It solves the problem that low-pressure injection valves cannot be used due to insufficient pressure, and solves the problems of poor dirt resistance, poor salt resistance, small diameter and insufficient flow of high-pressure injection valves.

[0059] The invention can avoid the problems of poor dirt resistance and poor salt resistance caused by high-precision machining and assembly of the stator and rotor of a traditional rotary valve by using a medium-pressure injection valve comprising a two-position three-way valve head.

[0060] The invention can solve the problems of cost increase and performance mismatch caused by using high-pressure injection valves through the independently designed and developed medium-pressure injection valve group.

[0061] The circuit and mechanical technical difficulties of the present invention are very small, the reliability is higher, and it is easier to realize and popularize. The subsequent maintenance cost is reduced by three simple medium-pressure injection valves designed and manufactured independently.

[0062] The above description of the present invention is illustrative rather than restrictive. Those skilled in the art will appreciate that many modifications, changes or equivalents may be made within the spirit and scope defined in the claims, but they will all fall within the scope of protection of the present invention.

Claims

1. A medium pressure injection valve group for gel purification chromatography, characterized in that: It includes three medium-pressure injection valves connected in series, each of which is a two-position three-way valve; wherein: Among the three interfaces of the first medium-pressure injection valve, one interface is connected to the second medium-pressure injection valve, and the remaining two interfaces are respectively a sample quantitative loop interface and a syringe injection pump interface, wherein the sample quantitative loop interface is used to connect to a sample quantitative loop, and the syringe injection pump interface is used to connect to a syringe injection pump; Among the three interfaces of the second medium-pressure injection valve, two interfaces are respectively connected to the first medium-pressure injection valve and the third medium-pressure injection valve, and the remaining interface is a medium-pressure plunger infusion pump interface, which is used to connect to a first liquid container through the medium-pressure plunger infusion pump, and the first liquid container can be used to hold a mobile phase liquid; Among the three interfaces of the third medium-pressure injection valve, one interface is connected to the second medium-pressure injection valve, and the remaining two interfaces are respectively a gel purification chromatographic column interface and an injection needle interface, wherein the gel purification chromatographic column interface is used to connect to a gel purification chromatographic column, and the injection needle interface can be inserted with an injection needle to form a connection; Among them, each of the medium-pressure injection valves has a stepper motor, a positioning optical coupler, a coupling, a two-position three-way valve head fixing seat and a two-position three-way valve head. The two-position three-way valve head is installed on the two-position three-way valve head fixing seat. The stepper motor is connected to the two-position three-way valve head through a coupling, and can drive the two-position three-way valve head to rotate and switch between two working positions. A positioning optical coupler is provided on one side of the coupling for positioning the two working positions of the two-position three-way valve head.

2. The medium-pressure injection valve group for gel purification chromatography according to claim 1, characterized in that: The injection needle is connected to the sample quantitative loop. The injection needle can be selectively inserted into a second liquid container to absorb the sample solution contained in the second liquid container. The injection needle can also be selectively in a non-inserted state.

3. The medium-pressure injection valve group for gel purification chromatography according to claim 1, characterized in that: The three medium-pressure injection valves can be switched between the following two connection states: Connectivity state 1: the first medium-pressure injection valve is not connected to the second medium-pressure injection valve, the sample quantitative loop interface on the first medium-pressure injection valve is connected to the syringe injection pump interface, and the medium-pressure plunger infusion pump interface on the second medium-pressure injection valve is connected to the gel purification chromatographic column interface on the third medium-pressure injection valve; Connectivity state two: the sample quantitative loop interface on the first medium-pressure injection valve is connected to the medium-pressure plunger infusion pump interface on the second medium-pressure injection valve, the second medium-pressure injection valve is not connected to the third medium-pressure injection valve, and the gel purification chromatographic column interface on the third medium-pressure injection valve is connected to the injection needle interface.

4. The medium-pressure injection valve assembly for gel purification chromatography according to claim 1, characterized in that: The maximum pressure resistance of the two-position three-way valve head is 10 MPa.

5. The medium-pressure injection valve group for gel purification chromatography according to claim 1, characterized in that: The sample quantitative ring adopts a volume specification of 10 ml, an outer diameter of 1 / 8 inch, an inner diameter of 1 / 16 inch, and is made of polyetheretherketone, Teflon or stainless steel.

6. The medium-pressure injection valve assembly for gel purification chromatography according to claim 1, characterized in that: The interior of the injection needle interface adopts a FFKM perfluororubber O-ring structure.

7. The medium-pressure injection valve assembly for gel purification chromatography according to claim 1, characterized in that: The injection needle is made of a stainless steel tube with an outer diameter of 1 / 8 inch and an inner diameter of 1 mm.

8. A method for operating a medium-pressure injection valve group for gel purification chromatography, characterized in that: A medium-pressure injection valve group for gel purification chromatography as claimed in claim 1, wherein the medium-pressure plunger infusion pump interface is connected to the liquid outlet pipeline of the medium-pressure plunger infusion pump, the gel purification chromatography column interface is connected to the liquid inlet pipeline of the gel purification chromatography column, the sample quantitative loop interface is connected to one end of the sample quantitative loop, and the other end of the sample quantitative loop is connected to the injection needle, the injection needle is selected to be empty or inserted into a second liquid container containing a sample solution or inserted into the injection needle interface, and the syringe injection pump interface is connected to the syringe injection pump; the operation method comprises: Sample liquid quantitative absorption process: the medium-pressure injection valve group for gel purification chromatography is in the connected state one, the injection needle is inserted into a second liquid container containing a sample solution, and the chromatographic mobile phase liquid in the first liquid container, under the power provided by the medium-pressure plunger infusion pump, flows through the medium-pressure plunger infusion pump interface and the gel purification chromatography column interface in sequence and enters the gel purification chromatography column; the sample liquid in the second liquid container, under the suction power provided by the syringe injection pump, flows through the injection needle and the sample quantitative loop in sequence and is temporarily stored in the sample quantitative loop; Complete injection process of sample liquid: the medium-pressure injection valve group for gel purification chromatography is switched to the second connection state, the injection needle is inserted into the injection needle interface, and the chromatographic mobile phase liquid in the first liquid container, under the power provided by the medium-pressure plunger infusion pump, flows through the medium-pressure plunger infusion pump interface, the sample quantitative loop interface, the sample quantitative loop, the injection needle, the injection needle interface, the gel purification chromatography column interface and flows to the gel purification chromatography column; the sample liquid in the sample quantitative loop, along with the chromatographic mobile phase liquid in the first liquid container, flows through the injection needle, the injection needle interface, the gel purification chromatography column interface in sequence, enters the gel purification chromatography column, and starts the gel purification chromatography separation process; Cleaning process: the medium-pressure injection valve group used for gel purification chromatography is switched to connected state 1, the injection needle is empty, and the chromatographic mobile phase liquid in the first liquid container, under the power provided by the medium-pressure plunger infusion pump, flows through the medium-pressure plunger infusion pump interface and the gel purification chromatography column interface in sequence and enters the gel purification chromatography column; under the liquid pushing power provided by the syringe injection pump, the chromatographic mobile phase liquid in the syringe injection pump flows through the syringe injection pump interface, the sample quantitative loop interface, the sample quantitative loop and the injection needle in sequence to complete the cleaning of the injection needle and the sample quantitative loop.

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