Automatic sample injection device, gas chromatograph, and gas chromatography analysis system

Abstract

An automatic sample injection device (4) that comprises: a syringe (18) that aspirates and dispenses a sample via a needle (24) that is provided at the tip thereof; and a travel mechanism (20) for moving the syringe (18). The automatic sample injection device (4) injects the sample into a gas chromatograph (2) by moving the syringe (18) and inserting the needle into a sample vaporization chamber (12) of the gas chromatograph (2). The automatic sample injection device (4) comprises a control unit (30) that: controls the operation of the travel mechanism (20); and executes transmission control which changes the travel speed of the syringe (18) during travel such that the travel speed of the needle (24) is the highest when passing through an area closes to the sample vaporization chamber (12), out of the travel speeds of the needle (24) as the tip of the needle (24) passes through a septum (16) sealing an injection port (14) that connects to the sample vaporization chamber (12).

Description

[Technical field]

[0001] The present invention relates to an automatic sample injection device, a gas chromatograph, and a gas chromatography analysis system. [Background technology]

[0002] A gas chromatograph is configured to vaporize a sample in a sample vaporization chamber, then transport the sample to a separation column by a carrier gas to separate each component in the sample, and detect each separated component by a detector. The sample vaporization chamber is provided with an injection port sealed by a septum, and the sample is injected into the sample vaporization chamber by piercing the septum with a needle at the tip of a syringe that has collected the sample (see Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2016 / 132439 Summary of the Invention [Problem to be solved by the invention]

[0004] If the syringe needle remains in the sample vaporizer for a long time, the sample in the needle that should not be injected into the sample vaporizer leaks into the sample vaporizer due to the heat of the sample vaporizer, causing so-called discrimination. For this reason, a measure may be taken to insert and remove the needle into and from the injection port leading to the sample vaporizer at high speed when injecting a sample into the sample vaporizer. However, simply increasing the speed at which the needle penetrates the septum places a high load on the needle and septum, which can cause the needle to break or accelerate deterioration of the septum.

[0005] The septum that seals the sample vaporizer is intended to keep the sample vaporizer airtight, and so it must be replaced when it deteriorates, and so durability is a requirement. Septa come in a variety of types, including high durability, high heat resistance, and low bleed (low plasticizer) types, and the type of septum can be selected according to the purpose. However, there are often trade-offs between the characteristics of the septum material, such as high durability septa having low heat resistance, and there is a problem in that durability and heat resistance must be sacrificed in order to reduce discrimination.

[0006] The present invention has been made in view of the above problems, and has an object to reduce discrimination while also satisfying other required performance. [Means for solving the problem]

[0007] The automatic sample injection device according to the present invention is an automatic sample injection device that includes a syringe that aspirates and dispenses a sample via a needle at its tip, and a movement mechanism for moving the syringe, and that moves the syringe to insert the needle into a sample vaporization chamber of a gas chromatograph to inject a sample into the gas chromatograph. The automatic sample injection device includes a control unit that controls the operation of the movement mechanism and executes speed change control that changes the movement speed of the syringe midway so that the movement speed of the needle when the tip of the needle passes through a septum sealing an injection port leading to the sample vaporization chamber is the highest when the tip of the needle passes through a region closest to the sample vaporization chamber.

[0008] The gas chromatograph according to the present invention has an injection port sealed by a septum that can be penetrated by a needle provided at the tip of a syringe, and is equipped with a sample vaporization chamber for vaporizing a sample injected through the injection port, a separation column for separating the sample vaporized in the sample vaporization chamber into components, and a detector for detecting each component separated in the separation column. In the gas chromatograph, the septum includes a first layer and a second layer laminated in the needle penetration direction at the position where the needle penetrates, the first layer faces the sample vaporization chamber, and the first layer and the second layer are formed of materials having different properties.

[0009] A gas chromatography analysis system according to the present invention includes the above-mentioned automatic sample injection device and the above-mentioned gas chromatograph. Effect of the Invention

[0010] According to the automatic sample injection device of the present invention, the moving speed of the tip of the needle when passing through the septum is the highest when passing through the area in the septum closest to the sample vaporization chamber, so that the time for which the needle is inserted into the sample vaporization chamber can be shortened and the time for which the needle receives heat from the sample vaporization chamber can be shortened. This can reduce discrimination. The moving speed of the tip of the needle when passing through an area away from the sample vaporization chamber is lower than when passing through the area closest to the sample vaporization chamber, so damage to the area away from the sample vaporization chamber caused by the passage of the needle is reduced. This can reduce discrimination and extend the life of the septum.

[0011] According to the gas chromatograph of the present invention, the septum sealing the injection port leading to the sample vaporization chamber includes a first layer and a second layer laminated in the needle penetration direction at the needle penetration position, and the material of the first layer facing the sample vaporization chamber is formed of a material with different properties from that of the second layer, so that the septum can have two properties. For example, if a septum is used in which the first layer facing the sample vaporization chamber is formed of a material with high heat resistance and the second layer is formed of a material with excellent durability, the injection port leading to the sample vaporization chamber can be sealed by the septum that has both heat resistance and durability. If the septum can be made highly durable, the moving speed of the needle when passing through the septum can be increased, so that the time during which the needle is inserted into the sample vaporization chamber can be shortened, and discrimination can also be reduced.

[0012] The gas chromatography analysis system of the present invention is equipped with the above-mentioned automatic sample injection device and the above-mentioned gas chromatograph, and the synergistic effect of these two components reduces discrimination while providing the septum with desired characteristics such as high durability, high heat resistance, and low plasticizer content. [Brief description of the drawings]

[0013] [Figure 1] FIG. 1 is a schematic diagram showing an embodiment of a gas chromatography analysis system. [Diagram 2] FIG. 2 is a cross-sectional view of an injection port portion leading to a sample vaporization chamber, showing an example of the structure of a septum of the gas chromatograph in the embodiment. [Diagram 3] FIG. 11 is a cross-sectional view showing a state in which a needle penetrates an upper layer portion of a septum in the embodiment. [Figure 4] FIG. 11 is a cross-sectional view showing a state in which a needle penetrates a lower layer portion of a septum in the embodiment. [Diagram 5] 4 is a flowchart showing an example of an operation during sample injection in the embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An automatic sample injection device, a gas chromatograph, and a gas chromatography analysis system according to an embodiment of the present invention will now be described with reference to the drawings.

[0015] 1, the gas chromatography analysis system 1 includes a gas chromatograph 2 and an automatic sample injection device 4. The automatic sample injection device 4 is disposed on the gas chromatograph 2 and is used to inject a sample into a sample vaporization chamber 12 of the gas chromatograph 2.

[0016] The gas chromatograph 2 comprises a sample vaporization unit 6, a separation column 8, and a detector 10. The sample vaporization chamber 12 is provided inside the sample vaporization unit 6. An injection port 14 leading to the sample vaporization chamber 12 is provided on the top surface of the sample vaporization unit 6, and the injection port 14 is sealed by a septum 16 made of an elastic material such as silicone resin. One end of the separation column 8 is connected to the outlet of the sample vaporization chamber 12, and the other end of the separation column 8 is connected to the detector 10.

[0017] The sample injected into sample vaporization chamber 12 by automatic sample injection device 4 is vaporized in sample vaporization chamber 12 and transported to separation column 8 by carrier gas supplied into sample vaporization chamber 12, where the components are separated. Each component separated in separation column 8 is introduced into detector 10 and detected.

[0018] The automatic sample injection device 4 includes a syringe 18 , a moving mechanism 20 , a turret 22 , and a control unit 30 .

[0019] The syringe 18 is disposed directly above the injection port 14 of the sample vaporization unit 6 of the gas chromatograph 2. The syringe 18 has a needle 24 extending vertically downward at its tip, and a piston 26 slides inside the syringe 18 to suck in and eject a fluid through the needle 24. The moving mechanism 20 is configured to move up and down along a vertical axis 28 while holding the syringe 18, and is also configured to move the piston 26 relative to the syringe 18. The turret 22 is a movable table on which a vial V containing a sample is placed, and can move the vial V containing the sample to be injected into the gas chromatograph 2 to a position directly below the syringe 18. The operations of the moving mechanism 20 and the turret 22 are controlled by a control unit 30. The control unit 30 can be realized by an electronic circuit board equipped with a CPU (central processing unit) and the like.

[0020] After sucking the sample into the syringe 18, the automatic sample injection device 4 lowers the syringe 18 toward the injection port 14 while ensuring that the turret 22 is not directly below the syringe 18, and causes the needle 24 to pierce the septum 16. Then, with the tip of the needle 24 inserted into the sample vaporization chamber 12, the sample is discharged into the syringe 18, thereby injecting the sample into the sample vaporization chamber 12.

[0021] As shown in FIG. 2, the septum 16 sealing the injection port 14 is made of a first material 16a and a second material 16b. At the position of the septum 16 where the needle 24 penetrates, a layer (first layer) made of the first material 16a and a layer (second layer) made of the second material 16b are laminated. The layer made of the first material 16a faces the sample vaporization chamber 12. The thickness of the layer made of the second material 16b that does not face the sample vaporization chamber 12 is greater than the thickness of the layer made of the first material 16a. In addition, the portion of the septum 16 that contacts the housing (metal) of the sample vaporization unit 6 is made of the first material 16a, and the portion made of the second material 16b is not made to contact the housing of the sample vaporization unit 6.

[0022] The first material 16a and the second material 16b constituting the septum 16 can be selected according to the analytical conditions and purpose. For example, a material having high heat resistance (for example, heat resistance temperature 450° C.) can be used as the first material 16a exposed to high temperatures, and a material having higher durability than the first material 16a or a material having a higher plasticizer content than the first material 16a can be used as the second material 16b. Since heat from the sample vaporization chamber 12 is not easily transmitted to the second material 16b not facing the sample vaporization chamber 12, the second material 16b does not require high heat resistance. Therefore, a material having high durability can be used as the second material 16b. In other words, since the durability of the septum 16 can be ensured by the layer made of the second material 16b, a material having properties other than durability can be used as the first material 16a.

[0023] By configuring the septum 16 as described above, a highly durable septum that can be used under high temperature conditions (e.g., 400° C. or higher) can be realized. If the septum 16 has high durability, the moving speed of the needle 24 when passing through the septum 16 can be increased, and thus discrimination can be reduced.

[0024] In this embodiment, two layers, a first layer made of a first material 16a and a second layer made of a second material 16b, are formed at the position of the septum 16 where the needle 24 passes, but the present invention is not limited to this, and three or more layers may be formed at the position of the septum 16 where the needle 24 passes.

[0025] In addition, the control unit 30 of the automatic sample injection device 4 performs variable control of the movement speed of the syringe 18 so that the movement speed of the needle 24 while the tip of the needle 24 is passing through the septum 16 is the highest when the needle 24 passes through the area of ​​the septum 16 closest to the sample vaporization chamber 12.

[0026] In the variable speed control of the movement speed of the syringe 18, the movement speed v2 (see FIG. 4) of the needle 24 when the tip of the needle 24 passes through the area of ​​the septum 16 closest to the sample vaporization chamber 12 is higher than the movement speed v1 (see FIG. 3) of the needle 24 when the tip of the needle 24 enters the septum 16. In other words, when the tip of the needle 24 passes through the upper area of ​​the septum 16 away from the sample vaporization chamber 12, the needle 24 is moved at a relatively slow speed, and when the tip of the needle 24 passes through the lower area of ​​the septum 16 close to the sample vaporization chamber 12, the needle 24 is moved at a high speed.

[0027] By controlling the moving speed of the needle 24 while passing through the septum 16 as described above, it is possible to reduce the damage to the upper layer region of the septum 16 caused by the passage of the needle 24, while shortening the time that the needle 24 stays in the region close to the sample vaporization chamber 12, thereby reducing discrimination. This variable speed control may be performed both when the needle 24 penetrates the septum 16 and when the needle 24 is pulled out from the septum 16, or may be performed only in one of these cases. For example, the variable speed control may be performed only when the needle 24 penetrates the septum 16, and the moving speed of the needle 24 when the needle 24 is pulled out from the septum 16 may be kept constant.

[0028] An example of the sample injection operation by the automatic sample injection device 4 will be described with reference to the flow chart of FIG. 5 together with FIG.

[0029] First, a vial V containing a sample to be injected is placed directly below the syringe 18, and the sample is sucked into the syringe 18 from the tip of the needle 24 (step 101). Then, the turret 22 is not placed directly below the syringe 18, and the syringe 18 is lowered toward the injection port 14 at a first speed v1 until the height of the needle 24 reaches a predetermined height (step 102). When the height of the needle 24 reaches the predetermined height (step 103: Yes), the lowering speed of the syringe 24 is increased to a second speed v2 (>v1) (step 104), and the syringe 24 is lowered until the tip of the needle 24 reaches the predetermined injection height (step 105). When the tip of the needle 24 reaches the predetermined injection height (step 105: Yes), the sample is discharged from the syringe 18 and injected into the sample vaporization chamber 12 (step 106). When the sample injection is completed, the syringe 18 is immediately raised at a predetermined speed v3 to pull the needle 24 out of the septum 16 (step 107). This completes the sample injection into the sample vaporization chamber 12.

[0030] In the above sample injection operation, the movement speed of the syringe 18 when the needle 24 penetrates the septum 16 is changed in two stages from the first speed v1 to the second speed v2, but the present invention is not limited to this, and the descent speed of the needle 24 may be changed in more stages.

[0031] In the above-described embodiment, the laminated structure of the septum 16 described with reference to FIG. 2 and the variable speed control of the movement speed of the syringe 18 described with reference to FIG. 3 and the like are described to be performed simultaneously, but it is not essential that these are performed simultaneously in the present invention, and the present invention also includes the implementation of only one of them. However, by performing both simultaneously, a synergistic effect such as further improving the durability of the septum 16 can be obtained. For example, if a highly durable material is used as the second material 16b of the septum 16 and the variable speed control of the movement speed of the syringe 18 is performed, the tip of the needle 24 moves through the highly durable material 16b at a relatively low speed, so that the damage to the material 16b caused by the penetration of the needle 24 is reduced, and the life of the layer made of the second material 16 is further improved. On the other hand, the tip of the needle 24 passes through the layer made of the first material 16a, which is less durable than the layer made of the second material 16b, at high speed. However, the sealing performance of the septum 16 for the injection port 14 can be guaranteed by the layer made of the second material 16b, so there is no problem even if the layer made of the first material 16a is damaged by the high-speed movement of the needle 24.

[0032] The embodiment described above is merely one example of the embodiment of the automatic sample injection device, gas chromatograph, and gas chromatography analysis system according to the present invention. The embodiment of the automatic sample injection device, gas chromatograph, and gas chromatography analysis system according to the present invention is as follows.

[0033] One embodiment of the automatic sample injection device of the present invention is an automatic sample injection device that comprises a syringe that aspirates and dispenses a sample through a needle at its tip, and a moving mechanism for moving the syringe, and injects a sample into a gas chromatograph by moving the syringe and inserting the needle into the sample vaporization chamber of the gas chromatograph, and a control unit that controls the operation of the moving mechanism, and a control unit that performs speed change control to change the movement speed of the syringe midway so that the movement speed of the needle when the tip of the needle passes through a septum sealing the injection port leading to the sample vaporization chamber is the highest when the needle passes through the area closest to the sample vaporization chamber.

[0034] In the embodiment described above, the control unit can be configured to execute the variable speed control when the needle penetrates the septum and is inserted into the sample vaporization chamber.

[0035] One embodiment of a gas chromatograph according to the present invention is a gas chromatograph having an injection port sealed by a septum that can be penetrated by a needle provided at the tip of a syringe, and comprising a sample vaporization chamber for vaporizing a sample injected through the injection port, a separation column for separating the sample vaporized in the sample vaporization chamber into components, and a detector for detecting each component separated in the separation column, wherein the septum includes a first layer and a second layer stacked in the direction in which the needle penetrates at the position where the needle penetrates, the first layer faces the sample vaporization chamber, and the first layer and the second layer are formed from materials having different properties.

[0036] In a first aspect of one embodiment of the gas chromatograph, the material of the second layer is more durable than the material of the first layer. With this aspect, the first layer facing the sample vaporization chamber is provided with characteristics such as high heat resistance and low plasticity, while the second layer ensures durability, and the septum can be provided with two properties, high durability and high heat resistance, and high durability and low plasticity. Since the second layer of the septum has high durability, it is possible to move the needle at high speed when passing through the septum, and discrimination can also be reduced.

[0037] In a second aspect of one embodiment of the gas chromatograph, the material of the first layer has higher heat resistance than the material of the second layer. With this aspect, since the first layer facing the sample vaporization chamber has high heat resistance, it is possible to form the second layer from a highly durable material, thereby providing the septum with high durability and high heat resistance.

[0038] In a third aspect of one embodiment of the gas chromatograph, the material of the first layer has a lower plasticizer content than the material of the second layer. In gas chromatography analysis, a problem may occur in that the plasticizer contained in the septum is released from the septum by heat from the sample vaporization chamber, and is detected by a detector, thereby affecting the analysis results. In response to this, by using a material with a low plasticizer content as the material of the first layer facing the sample vaporization chamber, the amount of plasticizer released from the septum is reduced, and the plasticizer can be prevented from affecting the analysis results. On the other hand, since the second layer of the septum does not face the sample vaporization chamber, the plasticizer contained in the material of the second layer is less likely to be released from the septum, and a material with a high plasticizer content can be used as the material of the second layer.

[0039] In a fourth aspect of the embodiment of the gas chromatograph, the thickness of the second layer at the position where the needle penetrates is greater than the thickness of the first layer, so that the second layer not facing the sample vaporization chamber can maintain high durability.

[0040] One embodiment of a gas chromatography analysis system according to the present invention includes an automatic sample injection device according to the present invention and a gas chromatograph according to the present invention. [Explanation of symbols]

[0041] 1. Gas Chromatography Analysis System 2. Gas chromatograph 4 Automatic sample injection device 6 Sample injection unit 8. Separation column 10. Detector 12 Sample vaporizer 14 Inlet 16 Septum 16a First Material 16b Second Material 18 Syringe 20 Moving mechanism 22 Turret 24 Needle 26 Piston 28 Vertical Axis 30 Control section

Claims

[Claim 1] A gas chromatography analysis system comprising an automatic sample injection device and a gas chromatograph, the gas chromatograph has an injection port sealed by a septum that can be penetrated by a needle provided at the tip of a syringe, and is equipped with a sample vaporization chamber for vaporizing a sample injected through the injection port, a separation column for separating the sample vaporized in the sample vaporization chamber into components, and a detector for detecting each component separated in the separation column; the septum includes a first layer and a second layer laminated in a direction in which the needle penetrates at a position where the needle penetrates, the first layer faces the sample vaporization chamber, and the first layer and the second layer are formed of materials having properties different from each other, Comparing the first layer and the second layer, the material of the second layer is relatively more durable, and the material of the first layer is relatively more heat resistant, the thickness of the second layer at the location where the needle penetrates is greater than the thickness of the first layer; the automatic sample injection device includes a syringe that aspirates and dispenses a sample through a needle provided at the tip, and a moving mechanism for moving the syringe, and injects a sample into the gas chromatograph by moving the syringe and inserting the needle into a sample vaporization chamber of the gas chromatograph; The automatic sample injection device is a gas chromatography analysis system, and is equipped with a control unit that controls the operation of the moving mechanism and performs speed change control to change the moving speed of the needle to a speed faster than the moving speed when passing through the second layer at the timing when the tip of the needle reaches a predetermined height at which it passes through the boundary between the second layer and the first layer of the septum when the needle penetrates the septum.

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