Automatic sampler

Abstract

To secure sealability between an injection port and a needle in a state where a tip part of the needle is pressed against a seal part in the injection port.SOLUTION: This device is provided with a needle holding part 5 for holding a needle 4 for sucking and discharging a fluid through the tip, a needle unit 3 for moving the needle holding part 5 in the horizontal direction while moving it in the vertical direction, and an injection port 12. When the needle 4 is lowered to a predetermined height from above the opening 36 of the injection port at the time of sample injection, the distal end portion of the needle 4 is pressed against the seal portion 40, so that the needle 4 is fluidly connected to the flow path 38 in a liquid-tight manner.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to an autosampler used in a chromatograph such as a liquid chromatograph, a supercritical fluid chromatograph, or an ion chromatograph. [Background technology]

[0002] In an autosampler for a liquid chromatograph, a supercritical fluid chromatograph, or an ion chromatograph, an injection port is fluidly connected to one port of an injection valve, and when injecting a sample, the tip of a needle that has aspirated the sample from a sample container is inserted into the injection port to fluidly connect the needle to the injection port (see Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2020 / 121430 Summary of the Invention [Problem to be solved by the invention]

[0004] A seal is provided inside the opening on the top surface of the injection port. When fluidly connecting a needle to the injection port, the needle is inserted into the injection port so that the tip of the needle presses against the seal, ensuring a seal at the connection between the needle and the injection port. While the needle is fluidly connected to the injection port, the tip of the needle presses against the seal by continuously driving the motor that moves the needle up and down, pushing the needle downward. Therefore, even when the needle is fluidly connected to the injection port and its operation is stopped, power must be continuously supplied to the motor that moves the needle up and down. If the power supply to the motor is stopped, for example, by accidentally turning off the main power of the autosampler while the needle is fluidly connected to the injection port, the force of the tip of the needle pressing against the seal will be lost. As a result, the seal between the needle and the injection port will be lost, and the liquid inside the needle may leak.

[0005] Mechanisms for moving the needle up and down include ball bearing systems and belt pulley systems. Belt pulley systems have the advantage of being able to move the needle up and down at higher speeds than ball bearing systems. However, belt pulley systems are less susceptible to forces other than the driving force of the motor acting on the needle than ball bearing systems. Therefore, if the power supply to the motor is lost while the needle is fluidly connected to the injection port, the needle is likely to be pushed back upward by the pressure of the fluid in the flow path and the repulsive force of the seal of the injection port, which can easily cause the above-mentioned liquid leakage.

[0006] The present invention has been made in consideration of the above-mentioned problems, and aims to ensure sealing between the injection port and the needle without continuously supplying power to the motor that moves the needle up and down while the tip of the needle is pressed against the seal portion inside the injection port. [Means for solving the problem]

[0007] The autosampler according to the present invention is an autosampler for injecting a sample into a mobile phase flowing toward a separation column in a chromatograph, the autosampler comprising: a needle unit having a needle holding part for holding a needle that sucks and discharges a fluid through a tip thereof, the needle unit moving in a horizontal direction while moving the needle holding part in a vertical direction; an injection port having an internal flow path to which the needle is fluidically connected when the sample is injected, an opening communicating with the flow path provided on an upper surface, a seal portion provided inside the opening against which the outer circumferential surface of the tip of the needle is pressed when the needle descends from above the opening to a predetermined height, and the tip of the needle is pressed against the seal portion to fluidly connect the needle to the flow path in a liquid-tight manner; and a magnetic portion that applies a magnetic force in a direction that presses down the needle holding portion when at least the outer peripheral surface of the needle is pressed against the seal portion inside the injection port. [Effects of the Invention]

[0008] The autosampler of the present invention is equipped with a magnetic section that applies a magnetic force in a direction that presses down the needle holding section when the outer surface of the needle is pressed against the seal section inside the injection port.Therefore, sealing between the injection port and the needle is ensured even if power is not continuously supplied to the motor that moves the needle up and down when the tip of the needle is pressed against the seal section inside the injection port. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a schematic diagram showing an example of an autosampler. [Figure 2] FIG. 10 is a diagram showing an example of the configuration of a magnetic unit, illustrating the state before the tip of a needle is inserted into an injection port. [Figure 3] FIG. 10 is a diagram showing an example of the configuration of a magnetic unit, illustrating the state when the tip of a needle is inserted into an injection port. [Figure 4] 10A and 10B are diagrams illustrating another example of the configuration of the magnetic part. DETAILED DESCRIPTION OF THE INVENTION

[0010] An embodiment of an autosampler according to the present invention will be described below with reference to the drawings. While the following description will be given taking an autosampler used in a liquid chromatograph as an example, the present invention can also be applied to autosamplers used in supercritical fluid chromatographs and ion chromatographs.

[0011] The autosampler 2 includes a needle unit 3, a sample loop 6, an injection valve 8, a syringe pump 10, an injection port 12, a magnetic unit 17, and a control unit 18.

[0012] The needle unit 3 is a unit that includes a needle holding part 5 that holds the needle 4, and moves the needle holding part 5 vertically and the needle unit itself horizontally, thereby moving the needle 4 three-dimensionally. The needle 4 has a tip and a base end, and is used to aspirate a sample from the tip. The needle holding part 5 holds the needle 4 with the tip of the needle 4 facing vertically downward.

[0013] One end of a sample loop 6 is fluidly connected to the base end of the needle 4. The sample loop 6 is a flow path for holding the sample sucked in from the tip of the needle 4, and the other end opposite the needle 4 is fluidly connected to one port (1) of the injection valve 8.

[0014] The injection valve 8 is used to switch the flow path configuration, and in this embodiment, a 6-port valve is used. In addition to the sample loop 6, each port of the injection valve 8 is connected to a syringe pump 10, a pipe 14 leading to the injection port 12, a drain flow path 16, a mobile phase supply flow path 19, and an analysis flow path 22. The mobile phase supply flow path 19 is a flow path for supplying a mobile phase by a liquid delivery pump 20. The analysis flow path 22 is a flow path in which a separation column 24 and a detector 26 are provided. The injection valve 8 can be switched between two states: a sampling state (a state in which ports (1)-(2), (3)-(4), and (5)-(6) are connected together) in which the mobile phase supply flow path 19 is directly connected to the analysis flow path 22 and the syringe pump 10 is connected to the needle 4 via the sample loop 6; and an injection state (a state in which ports (1)-(6), (2)-(3), and (4)-(5) are connected together as shown in FIG. 1) in which the sample loop 6 and the needle 4 are interposed between the mobile phase supply flow path 19 and the analysis flow path 22.

[0015] Syringe pump 10 is provided so as to be in fluid communication with needle 4 via sample loop 6 through injection valve 8, and is used to aspirate a sample through needle 4. When aspirating a sample from a sample container through needle 4, injection valve 8 is set to a sampling state, and syringe pump 10 is connected to needle 4 via sample loop 6.

[0016] Injection port 12 is fluidly connected to one port (4) of injection valve 8 via piping 14, and is used to introduce the sample aspirated from the tip of needle 4 and held in sample loop 6 into analysis flow path 22. When injecting the sample aspirated from the tip of needle 4, the tip of needle 4 is inserted into injection port 12, as shown in Figure 1, and injection valve 8 is set to the injection state. As a result, the sample held in sample loop 6 is introduced into analysis flow path 22 by the mobile phase supplied through mobile phase supply flow path 19.

[0017] The magnetic part 17 is a mechanism provided to apply a magnetic force to the needle holding part 5 in a direction that presses the needle downward when at least the tip of the needle 4 is inserted into the injection port 12 .

[0018] The control unit 18 controls the operations of the needle unit 3, the injection valve 8, and the syringe pump 10. The control unit 18 can be realized by an electronic circuit including a CPU (Central Processing Unit) and the like.

[0019] An example of the configuration of the magnetic part 17 will be described with reference to FIGS.

[0020] First, we will explain the injection port 12. The injection port 12 has a flow path 38 inside that fluidly connects the needle 4 when injecting a sample, and has an opening 36 on the top surface that leads to the flow path 38. The flow path 38 leads to the piping 14. A tapered seal portion 40 is provided inside the opening 36, with the inner surface sloping so that the inner diameter becomes smaller as it goes downward.

[0021] 3, when the needle 4 is fluidly connected to the injection port 12, the needle holding portion 5 is lowered to a predetermined height with the needle 4 positioned directly above the opening 36 of the injection port 12, whereby the outer circumferential surface of the tip of the needle 4 is pressed against the inner circumferential surface of the seal portion 40. By pressing the outer circumferential surface of the tip of the needle 4 against the inner circumferential surface of the seal portion 40, the needle 4 and the flow path 38 are fluidly connected in a liquid-tight manner.

[0022] The magnetic force section 17 is a mechanism that assists in pressing the tip of the needle 4 against the seal section 40 when fluidly connecting the needle 4 to the injection port 12, and can include a magnet 28 and a metal member 30. In this example, the magnet 28 is fixed to the housing 32 of the autosampler 2 via an attachment member 34, and the metal member 30 is attached to the needle holder 5 of the needle unit 3 and moves up and down together with the needle holder 5.

[0023] Magnet 28 is positioned below metal member 30 attached to needle holder 5 when needle 4 is located directly above opening 36 of injection port 12. The height of magnet 28 is designed so that, as shown in Figure 3, when needle holder 5 is lowered to a predetermined height at which the tip of needle 4 is pressed against seal portion 40 inside injection port 12, metal plate 30 comes close enough to magnet 28 that the magnetic force of magnet 28 can fully act on metal plate 30.

[0024] With the above configuration, when the needle holder 5 descends to a predetermined height at which the tip of the needle 4 presses against the seal portion 40 in the injection port 12, the magnetic force of the magnet 28 attracts the metal member 30 to the magnetic force 28, thereby exerting a downward force on the needle holder 5. As a result, even if power is not supplied to a motor (not shown) that moves the needle holder 5 up and down, a force pressing the tip of the needle 4 against the seal portion 40 is ensured, thereby ensuring a seal between the needle 4 and the flow path 38. Conversely, by providing the magnetic unit 17, the supply of power to the motor that moves the needle holder 5 up and down can be stopped while the needle 4 is fluidly connected to the injection port 12, thereby enabling power saving. In other words, the control unit 18 that controls the operation of the needle unit 5 can be configured to stop the supply of power to the motor that moves the needle holder 5 up and down while the needle 4 is fluidly connected to the injection port 12.

[0025] The height of magnet 28 may be designed so that metal plate 30 comes into contact with magnet 28 when needle holding unit 5 is lowered to a predetermined height, but it is more preferable to design the height so that a small gap (e.g., 0.1 to 5 mm) exists between magnet 28 and metal plate 30 when needle holding unit 5 is lowered to the predetermined height. This eliminates the contact sound between magnet 28 and metal plate 30 when fluidly connecting needle 4 to injection port 12, preventing noise caused by magnetic unit 17 and preventing malfunctions caused by impact when magnet 28 and metal plate 30 come into contact.

[0026] Furthermore, in the above example, the magnet 28 is provided independently of the needle unit 3, and the metal member 30 is provided on the needle unit 3 and linked to the up and down movement of the needle holding portion 5. However, conversely, the magnet 28 may be provided on the needle unit 3 and linked to the up and down movement of the needle holding portion 5, and the metal member 30 may be provided independently of the needle unit 3.

[0027] In the above example, one of the magnet 28 and the metal member 30 of the magnetic force section 17 is provided independently of the needle unit 3, and the other is provided in the needle unit 3. However, as long as it does not impede access of the needle 4 to a sample container or the like, it is also possible to provide both the magnet 28 and the metal member 30 in the needle unit 3, as shown in the example of Figure 4. In the example of Figure 4, the metal member 30 is attached to the needle holding section 5, and the magnet 28 is independent from the needle holding section 5. However, the magnet 28 may be attached to the needle holding section 5, and the metal member 30 may be independent from the needle holding section 5.

[0028] The above-described examples are merely examples of embodiments of the autosampler according to the present invention. The embodiments of the autosampler according to the present invention are as follows.

[0029] One embodiment of the autosampler of the present invention is an autosampler for injecting a sample into a mobile phase flowing toward a separation column in a chromatograph, the autosampler comprising: a needle unit having a needle holding part for holding a needle that sucks and discharges a fluid through a tip thereof, the needle unit moving in a horizontal direction while moving the needle holding part in a vertical direction; an injection port having an internal flow path to which the needle is fluidically connected when the sample is injected, an opening communicating with the flow path provided on an upper surface, a seal portion provided inside the opening against which the outer circumferential surface of the tip of the needle is pressed when the needle descends from above the opening to a predetermined height, and the tip of the needle is pressed against the seal portion to fluidly connect the needle to the flow path in a liquid-tight manner; and a magnetic portion that applies a magnetic force in a direction that presses down the needle holding portion when at least the outer peripheral surface of the needle is pressed against the seal portion inside the injection port.

[0030] In a first aspect of the above embodiment, the magnetic force unit includes a magnet and a metal member positioned above and below each other and facing each other when the needle is positioned directly above the injection port, one of the magnet and the metal member is configured to move vertically in conjunction with the needle holding unit, and the other of the magnet and the metal member is configured to be fixed at the same height regardless of the operation of the needle holding unit, and when the tip of the needle is pressed against the seal unit, the magnet and the metal member are attracted to each other by the magnetic force of the magnet.

[0031] In the first aspect, the magnet and the metal member may be arranged to be close to each other with a gap therebetween when the tip of the needle is pressed against the seal portion. This eliminates the contact noise between the magnet and the metal plate when the needle is fluidly connected to the injection port, thereby preventing noise caused by the magnetic force portion and preventing malfunctions caused by impact when the magnet and the metal plate come into contact.

[0032] In the first aspect, the one of the magnet and the metal member may be provided in the needle unit, and the other of the magnet and the metal member may be provided independently of the needle unit.

[0033] In the first aspect, both the magnet and the metal member may be provided on the needle unit.

[0034] In a second aspect of the above embodiment, the needle unit further includes a control unit for controlling operation of the needle unit, the needle unit including a motor for vertically moving the needle holder, and the control unit is configured to stop supplying power to the motor when the tip of the needle is pressed against the seal of the injection port. This second aspect can be combined with the first aspect. [Explanation of symbols]

[0035] 2 Autosampler 3 Needle Unit 4 needles 5 Needle holder 6 Sample Loop 8 Injection Valve 10 Syringe Pump 12 injection port 17 Magnetic section 18 Control Unit 19 Mobile phase supply channel 20 Liquid transfer pump 22 Analysis channel 24 Separation column 26 detector 28 Magnet 30 Metallic parts 32 Case 34 Mounting member 36 Injection port opening 38 Flow path 40 Seal part

Claims

1. 1. An autosampler for injecting a sample into a mobile phase flowing toward a separation column in a chromatograph, comprising: a needle unit having a needle holding part for holding a needle that sucks and discharges a fluid through its tip, the needle unit moving in a horizontal direction while moving the needle holding part in a vertical direction; an injection port having an internal flow path to which the needle is fluidically connected when the sample is injected, an opening communicating with the flow path provided on an upper surface, a seal portion provided inside the opening against which the outer circumferential surface of the tip of the needle is pressed when the needle descends from above the opening to a predetermined height, and the tip of the needle is pressed against the seal portion, thereby fluidly connecting the needle to the flow path in a liquid-tight manner; an autosampler comprising: a magnetic force section configured to apply a magnetic force in a direction to press down the needle holding section when at least the outer surface of the needle is pressed against the seal section in the injection port.

2. the magnetic unit includes a magnet and a metal member that are positioned vertically and face each other when the needle is located directly above the injection port, one of the magnet and the metal member is provided to move vertically in conjunction with the needle holding portion, and the other of the magnet and the metal member is provided to be fixed at the same height regardless of the movement of the needle holding portion, 2. The autosampler according to claim 1, wherein the magnet and the metal member are attracted to each other by the magnetic force of the magnet when the tip of the needle is pressed against the seal portion.

3. 3. The autosampler according to claim 2, wherein the magnet and the metal member are disposed so as to be adjacent to each other with a gap therebetween when the tip of the needle is pressed against the seal portion.

4. 3. The autosampler according to claim 2, wherein the one of the magnet and the metal member is provided in the needle unit, and the other of the magnet and the metal member is provided independently of the needle unit.

5. 3. The autosampler according to claim 2, wherein both the magnet and the metal member are provided on the needle unit.

6. a control unit for controlling the operation of the needle unit; the needle unit includes a motor for moving the needle holding portion in a vertical direction; 2. The autosampler according to claim 1, wherein the control unit is configured to stop supplying power to the motor when the tip of the needle is pressed against the seal of the injection port.

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