Sample introduction system

Abstract

A sample introduction system (102) is connected to a gas chromatograph mass spectrometer (101) provided with: a mass spectrometry unit (5); a first pump (1) that exhausts gas inside the mass spectrometry unit (5); and a second pump (2) that discharges the gas discharged from the first pump (1). The sample introduction system (102) is provided with: an introduction device (7) that is connected to the mass spectrometry unit (5) and directly introduces a sample (S) to the mass spectrometry unit (5); and a restriction unit (3) that is disposed in a connection path between the second pump (2) and the introduction device (7) and that limits the flow rate of the gas flowing from the introduction device (7) to the second pump (2). The gas inside the introduction device (7) is discharged by the second pump (2). The flow path resistance of the restriction unit (3) is set so that the back pressure of the first pump (1) becomes the flow rate of the gas that does not exceed the prescribed back pressure when the pressure inside the introduction device (7) becomes equal to the atmospheric pressure.

Description

Sample Introduction System

[0001] The present invention relates to a sample introduction system, and more particularly to a technique for sharing a vacuum pump.

[0002] In analyses using gas chromatograph mass spectrometers, not only are samples analyzed via a gas chromatograph, but direct sample introduction methods are also used, in which samples are directly introduced into an ion source for analysis. For example, as disclosed in Japanese Patent Laid-Open Publication No. 2021-103133 (Patent Document 1), in direct sample introduction methods, a probe with a sample injected or coated at its tip is introduced into a mass spectrometer, and the probe is heated to vaporize the sample. The vaporized sample is ionized and analyzed by the mass spectrometer.

[0003] In the direct sample introduction method, if a sample from the atmosphere is directly introduced into an ion source maintained at a high vacuum, a large amount of gas will flow into the mass spectrometer. The gas molecules that flow into the mass spectrometer collide with ions originating from the sample, bending the ion trajectory or destroying the ions. This can result in insufficient measurement accuracy in the mass spectrometer. Furthermore, a large amount of oxygen can shorten the life of the filament that lights during ionization. Therefore, to prevent a large amount of gas from flowing into the mass spectrometer, the sample is depressurized in an intermediate region of the direct sample introduction device before being introduced into the ion source. In other words, a direct sample introduction device requires a mechanism for depressurizing the inside of the device.

[0004] The gas chromatograph mass spectrometer includes a main pump for achieving a high vacuum inside the apparatus, and an auxiliary pump for maintaining the back pressure of the main pump to be smaller than the maximum exhaust port pressure of the main pump.

[0005] Japanese Patent Application Laid-Open No. 2021-103133

[0006] When connecting a direct sample introduction device to a gas chromatograph mass spectrometer, a separate vacuum pump must be prepared to reduce the pressure in the intermediate region, which can increase the cost for users.

[0007] On the other hand, instead of providing a vacuum pump, it is possible to configure the gas chromatograph mass spectrometer so that the auxiliary vacuum pump is connected not only to the main pump but also to the intermediate region. In other words, it is possible to configure the auxiliary vacuum pump to also serve to depressurize the intermediate region. However, in such a configuration, the pressure in the intermediate region increases when a sample is introduced, and the back pressure of the main pump exceeds the maximum outlet pressure of the main pump, which may cause the main pump to malfunction.

[0008] The present disclosure has been made in view of the above circumstances, and its purpose is to provide a technique for reducing the cost of introducing a direct sample introduction device.

[0009] A sample introduction system according to a first aspect of the present disclosure is a sample introduction system connected to a gas chromatograph mass spectrometer having a mass analysis section, a first pump that exhausts gas inside the mass analysis section, and a second pump that exhausts gas exhausted from the first pump, and further comprising: an introduction device connected to the mass analysis section and that directly introduces a sample into the mass analysis section; and a restriction section disposed in a connection path between the second pump and the introduction device and that restricts the flow rate of gas flowing from the introduction device to the second pump, wherein the gas inside the introduction device is exhausted by the second pump, and the flow path resistance of the restriction section is set so that the gas flow rate does not exceed a predetermined back pressure when the pressure inside the introduction device becomes equal to atmospheric pressure.

[0010] A sample introduction system according to a second aspect of the present disclosure is a sample introduction system connected to a gas chromatograph mass spectrometer having a mass analysis section, a first pump that exhausts gas inside the mass analysis section, and a second pump that exhausts gas exhausted from the first pump, and includes an introduction device connected to the mass analysis section and that directly introduces a sample into the mass analysis section, and an intermediate chamber arranged in the connection path between the second pump and the introduction device, and the resistance of the flow path between the second pump and the intermediate chamber is greater than the resistance of the flow path between the introduction device and the intermediate chamber.

[0011] According to the present disclosure, a technique for reducing the cost of introducing a direct sample introduction device is provided.

[0012] 1 is a diagram showing the overall configuration of an analysis system; FIG. 2 is a diagram showing an example of the configuration of a restriction unit; FIG. 3 is a diagram showing a state in which a probe is introduced into an analysis device in an analysis system; FIG. 4 is a diagram showing the configuration of an analysis system connected to a conventional sample introduction system; FIG. 5 is a diagram showing the lower limit value of an intermediate chamber; FIG. 6 is a diagram showing the upper limit value of an intermediate chamber; FIG. 7 is a diagram showing the time change in the inlet pressure of a rotary pump when an intermediate region at atmospheric pressure is connected to an intermediate chamber that is sufficiently depressurized; and FIG. 8 is a diagram showing the time change in the inlet pressure of a rotary pump when an intermediate chamber at atmospheric pressure is connected to the rotary pump.

[0013] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present disclosure will be described in detail with reference to the accompanying drawings. In the drawings, the same or corresponding parts are designated by the same reference numerals and the description thereof will not be repeated.

[0014] 1 is a schematic diagram of an analysis system according to one embodiment. The analysis system 100 includes a gas chromatograph mass spectrometer 101 and a sample introduction system 102. The analysis system 100 ionizes atoms or molecules in an introduced sample and analyzes the mass-to-charge ratios and abundances of the ions.

[0015] The gas chromatograph mass spectrometer 101 includes a turbomolecular pump 1, a rotary pump 2, and an analyzer 5. The gas chromatograph mass spectrometer 101 ionizes components in a sample, separates the ions according to their mass, and detects each of the ions.

[0016] The turbomolecular pump 1 is connected to the analyzer 5, evacuates gas from the analyzer 5, and maintains a high vacuum inside the analyzer 5. The turbomolecular pump is sometimes referred to as a main pump. In this embodiment, the gas chromatograph mass spectrometer 101 is equipped with the turbomolecular pump 1 to reduce the pressure inside the analyzer 5, but the type of pump is not limited to a turbomolecular pump as long as it is capable of reducing the pressure inside the analyzer 5.

[0017] The rotary pump 2 is connected to the turbomolecular pump 1 and exhausts the gas exhausted by the turbomolecular pump 1. The rotary pump 2 is sometimes called an auxiliary pump. In this embodiment, the gas chromatograph mass spectrometer 101 is provided with the rotary pump 2 to reduce the back pressure of the turbomolecular pump 1, but the type of pump is not limited to a rotary pump as long as it is possible to reduce the back pressure of the turbomolecular pump 1 to a predetermined back pressure.

[0018] The predetermined back pressure is a back pressure that is low enough for the turbomolecular pump 1 to operate efficiently. The predetermined back pressure is sometimes referred to as the maximum exhaust port pressure. A turbomolecular pump has rotating turbine blades and fixed stator blades. A turbomolecular pump exhausts gas by rotating the turbine blades at high speed, repelling gas molecules and causing the gas molecules to collide with the stator blades. If the gas molecules repelled by the turbine blades collide with other gas molecules before colliding with the stator blades, the exhaust efficiency may decrease. Therefore, a maximum exhaust port pressure, which is the maximum back pressure at which a turbomolecular pump operates efficiently, is set. Note that the maximum exhaust port pressure varies depending on the type of turbomolecular pump, but is, for example, 600 Pa.

[0019] The analyzer 5 is, for example, a quadrupole mass spectrometer including an ionization chamber 51, an ion guide 53, a partition electrode 54, a mass filter 55, and an ion detector 56. The analyzer 5 can ionize and analyze substances contained in an introduced sample. The analyzer 5 is not limited to a quadrupole mass spectrometer. The analyzer 5 is connected to a gas chromatograph (GC) (not shown) and can also analyze a sample introduced from the GC into the ionization chamber 51 of the analyzer 5. In FIG. 1 , the direction in which the probe P moves when introduced into the gas chromatograph mass spectrometer 101 is defined as the X-axis direction. The direction in which ions pass through the analyzer 5 is defined as the Z-axis direction, and the direction perpendicular to the XZ plane is defined as the Y-axis direction.

[0020] The sample introduction system 102 includes a restriction section 3, an intermediate chamber 4, a valve 6, and an introduction device 7. A user can directly introduce a probe P, to which a sample S has been injected or applied, into the analysis device 5 via the sample introduction system 102 without going through a GC. The sample S to be measured may be either a liquid or a solid.

[0021] The valve 6 includes an outer frame 61 and a rotary valve 62 having a through-hole 63 therein. The rotary valve 62 is rotatable relative to the outer frame 61 around a predetermined axis parallel to the Y axis. The analysis device 5 is connected to an introduction device 7 of the sample introduction system 102 via the valve 6.

[0022] When the valve 6 is closed, the user cannot insert the probe P into the analysis device 5. When the valve 6 is opened, the user can insert the probe P into the analysis device 5. When the valve 6 is opened, the gas inside the introduction device 7 flows into the analysis device 5, which is in a high vacuum. Note that the valve 6 is not limited to one including the rotary valve 62 described above, and may be configured in any way as long as it allows the probe P to pass through when open and prevents gas from passing between the analysis device 5 and the introduction device 7 when closed.

[0023] The introduction device 7 is connected to the rotary pump 2 so that the gas inside the introduction device 7 can be exhausted by the rotary pump 2 of the gas chromatograph mass spectrometer 101. The introduction device 7 is also connected to the analysis device 5 via a valve 6 so that the probe P can be introduced into the ionization chamber 51 of the analysis device 5.

[0024] The introduction device 7 includes an exhaust chamber 71, a seal member 73, and a valve 74. By introducing the sample S directly into the ionization chamber 51 via the introduction device 7, the analysis device 5 can analyze the sample S without going through a GC. The exhaust chamber 71 has an intermediate region 72 extending in the X direction in FIG. 1 . The seal member 73 improves the airtightness of the intermediate region 72 when the probe P is inserted. The seal member 73 is, for example, an O-ring. By opening the valve 74, the intermediate region 72 and the rotary pump 2 are connected, and the pressure in the intermediate region 72 is reduced.

[0025] The restrictor 3 is provided between the rotary pump 2 and the intermediate chamber 4, and restricts the flow rate of gas flowing from the introducing device 7 into the rotary pump 2. In order to restrict the flow rate of gas passing through, the restrictor 3 has a predetermined flow path resistance, which will be described later. The greater the value of the flow path resistance of the restrictor 3, the smaller the flow rate of gas passing through the restrictor 3 per unit time. The structure of the restrictor 3 is not limited as long as it can achieve the predetermined flow path resistance.

[0026] FIG. 2 shows an example of the structure of the restriction section 3. The area surrounded by the dashed line corresponds to the restriction section 3. In (A), the restriction section 3 is a structure in which the flow path resistance is increased by using a pipe that is thinner than the pipes before and after it. In (B), the flow path resistance is increased by lengthening the length of the pipe of the restriction section 3, and for example, a capillary tube is used. Note that in (B), the flow path resistance can be further increased by making the pipe of the restriction section 3 thinner than the pipes before and after it. In (C), the flow path resistance is increased by providing an orifice in the pipe as the restriction section 3. The flow rate of the gas is narrowed by the orifice, thereby increasing the flow path resistance. Note that the structure shown in FIG. 2 is an example of the restriction section 3, and the structure of the restriction section 3 is not limited to that shown in FIG. 2.

[0027] The intermediate chamber 4 is a housing having a space of a predetermined capacity, which is provided in the flow path that communicates between the restriction unit 3 and the introduction device 7. The gas inside the intermediate chamber 4 is exhausted by the rotary pump 2 connected via the restriction unit 3. The intermediate chamber 4 improves the efficiency of decompression inside the introduction device 7. When the pressure inside the intermediate chamber 4 is low, the pressure inside the introduction device 7 can be quickly reduced by opening the valve 74. The predetermined capacity of the intermediate chamber 4 will be described later.

[0028] [Method of Introducing a Probe and Method of Measuring a Sample] Fig. 3 shows a state in which a probe P is introduced into the analysis device 5 in the analysis system 100. A method of introducing the probe P into the analysis device 5 and a method of measuring a sample S in the analysis system 100 will be described with reference to Fig. 3 and Fig. 1, which shows a state in which the probe P is not introduced into the analysis device 5.

[0029] 1, when the rotation angle of the rotary valve 62 causes the direction of the through-hole 63 to deviate from the X direction and the connection path between the analyzer 5 and the introduction device 7 is blocked, the valve 6 is closed. When the valve 6 is closed, the analyzer 5 and the introduction device 7 are disconnected, and the user cannot introduce the probe P into the analyzer 5.

[0030] On the other hand, as shown in FIG. 3 , when the rotation angle of the rotary valve 62 is such that the direction of the through-hole 63 coincides with the X direction, the valve 6 is in an open state, and the user can insert the probe P from the introduction device 7 into the ionization chamber 51 via the through-hole 63.

[0031] A sample S injected or applied to the tip of a probe P is introduced into an ionization chamber 51. Ions generated in the ionization chamber 51 are guided by an ion guide 53, pass through a partition electrode 54, and are introduced into a mass filter 55. Ions having a mass-to-charge ratio corresponding to the voltage applied to the mass filter 55 pass through the mass filter 55 and are detected by an ion detector 56.

[0032] Comparative Example A gas chromatograph mass spectrometer is equipped with a turbomolecular pump to achieve a high vacuum inside the mass spectrometer. A turbomolecular pump cannot achieve the desired performance unless its back pressure is less than the maximum exhaust port pressure. Therefore, a gas chromatograph mass spectrometer is equipped with a rotary pump to reduce the back pressure of the turbomolecular pump to less than the maximum exhaust port pressure. As shown in FIG. 1 , for example, a gas chromatograph mass spectrometer 101 is equipped with a turbomolecular pump 1 and a rotary pump 2.

[0033] When analyzing a sample without using a gas chromatograph, a device for directly introducing a sample into the ion source of a gas chromatograph mass spectrometer is connected. Figure 4 shows a schematic configuration of an analysis system 100B in which a conventional sample introduction system 102B is connected to a gas chromatograph mass spectrometer 101. By using the sample introduction system 102B, the sample can be introduced directly into the ion source. This makes it possible to analyze, using a mass spectrometer, low-volatility compounds and thermally unstable compounds that are difficult to analyze using a gas chromatograph.

[0034] The sample introduction system 102B includes an introduction device 7 and a rotary pump 8. The rotary pump 8 is connected to the introduction device 7 so that the pressure inside the introduction device 7 can be reduced. When using the introduction device 7, if the sample S, which is at atmospheric pressure, is introduced directly into the ionization chamber 51, the pressure inside the analysis device 5 may increase, resulting in a decrease in analytical accuracy. Therefore, the sample S is reduced in pressure inside the introduction device 7 before being introduced into the ionization chamber 51. The rotary pump 8 is a component necessary for reducing the pressure inside the sample S.

[0035] That is, when connecting the introduction device 7 to the gas chromatograph mass spectrometer 101, the user needs to separately prepare the rotary pump 8. For the user, the cost of introducing a sample introduction system may increase.

[0036] On the other hand, it is also possible to use the rotary pump 2 provided in the analytical device 5 as a pump used to reduce the pressure inside the introduction device 7. However, if the pressure inside the introduction device 7 becomes atmospheric when the sample S is introduced, the amount of gas flowing into the rotary pump 2 per unit time increases, and the back pressure of the turbomolecular pump 1 may exceed the maximum exhaust port pressure. As a result, the pressure inside the analytical device 5 increases, and sufficient measurement accuracy may not be obtained.

[0037] For example, matrix-assisted laser desorption / ionization mass spectrometry and X-ray fluorescence spectrometry also involve a process of introducing a sample from atmospheric pressure into a high vacuum. Some of these instruments share a backing pump and a decompression pump at the sample introduction section. This pump sharing is achieved by temporarily closing a valve on the exhaust side of the turbomolecular pump to prevent back pressure buildup. On the other hand, in gas chromatograph mass spectrometry, carrier gas constantly flows into the high vacuum region. Therefore, the turbomolecular pump constantly exhausts carrier gas, and if a valve on the exhaust side of the turbomolecular pump is attached and closed, the back pressure of the turbomolecular pump will increase. Therefore, it is difficult to share a pump in a gas chromatograph mass spectrometry instrument using the method implemented in instruments such as matrix-assisted laser desorption / ionization mass spectrometry and X-ray fluorescence spectrometry.

[0038] [Features of the Sample Introduction System According to the Embodiment] Therefore, the sample introduction system 102 according to the present embodiment includes a restriction unit 3 in addition to the introduction device 7. In the analysis system 100, the intermediate region 72 and the rotary pump 2 included in the gas chromatograph mass spectrometer 101 are connected via the restriction unit 3 having a predetermined flow path resistance. The predetermined flow path resistance makes it possible to limit the amount of gas flowing into the rotary pump 2 from the intermediate region 72 per unit time, and even when the intermediate region 72 is at atmospheric pressure, the back pressure of the turbomolecular pump 1 can be prevented from exceeding the maximum outlet pressure. With this configuration, the rotary pump 2 and rotary pump 8 in FIG. 4 can be shared, and there is no need to provide a separate rotary pump for depressurizing the introduction device 7 when connecting the sample introduction system 102 to the gas chromatograph mass spectrometer 101.

[0039] Furthermore, the sample introduction system 102 includes an intermediate chamber 4 having a predetermined volume between the restriction section 3 and the intermediate region 72. Without the intermediate chamber 4 having a predetermined volume, the flow path resistance of the restriction section 3 would require time to depressurize the intermediate region 72, which could result in a longer measurement time than with conventional configurations. On the other hand, by providing the intermediate chamber 4 and depressurizing its interior beforehand, it is possible to quickly depressurize the intermediate region 72 after sample introduction while maintaining the back pressure of the turbomolecular pump 1 at or below the maximum exhaust port pressure. The inclusion of the intermediate chamber 4 improves the efficiency of depressurizing the intermediate region 72 and shortens the measurement time.

[0040] [Flow path resistance of restricting section] The restricting section 3 restricts the amount of gas per unit time flowing from the intermediate region 72 of the introducing device 7 into the rotary pump 2. The greater the value of the flow path resistance of the restricting section 3, the smaller the amount of gas per unit time flowing from the intermediate region 72 into the rotary pump 2. The condition for the value of the flow path resistance of the restricting section 3 to be greater than a predetermined value is that the back pressure of the turbomolecular pump 1 does not exceed the maximum exhaust port pressure when the intermediate region 72 becomes atmospheric pressure.

[0041] On the other hand, if the flow path resistance of the restrictor 3 is large, it takes time to reduce the pressure in the intermediate region 72, and it takes a long time before the probe P can be introduced into the ionization chamber 51. As a result, the measurement time for the sample S becomes long, which may be inconvenient for the user. For example, if it is necessary to measure a predetermined number of samples in a predetermined period of time, it is preferable that the measurement time be short.

[0042] Therefore, it is preferable that the flow path resistance value of the restricting portion 3 be a small value that satisfies the above-mentioned conditions.

[0043] The preferred value of the flow path resistance of the restriction unit 3 varies depending on the configuration conditions of the analysis system 100. The configuration conditions include, for example, the performance of the turbomolecular pump 1 and the rotary pump 2, the internal volume of the introduction device 7, and the flow path resistance of the flow paths other than the restriction unit 3.

[0044] Here, the back pressure of the turbo molecular pump 1 is N (Pa), the atmospheric pressure is W (Pa), and the conductance C (m ３ / s), the gas flow rate Q (Pa m ３ / s), the following equation (1) holds:

[0045] Q = C × (W-N) (1) Also, the exhaust speed of the rotary pump 2 is S (m ３ / s), the following equation (2) is established for the back pressure N of the turbo molecular pump 1.

[0046] N=Q / S (2) When equation (1) is substituted into equation (2) and the back pressure N of the turbomolecular pump 1 is solved, the following equation (3) is established.

[0047] N={C / (S+C)}×W (3) When the maximum exhaust port pressure of the turbo molecular pump 1 is P, the following equation (4) must be satisfied.

[0048] P>N (4) When equation (3) is substituted into equation (4) and the conductance C of the flow path resistance of the restricting portion 3 is solved, the following equation (5) is established.

[0049] C<S×W / (P−W) (5) Therefore, it can be said that the limiting portion 3 has a conductance C that satisfies the formula (5).

[0050] [Volume of Intermediate Chamber] The intermediate chamber 4 is provided to improve the efficiency of depressurizing the intermediate region 72. Specifically, the intermediate chamber 4, which has been depressurized in advance, is connected to the intermediate region 72, which has a high pressure, so that the gas in the intermediate region 72 flows into the intermediate chamber 4, and the intermediate region 72 is depressurized.

[0051] After the pressure in the intermediate region 72 has been sufficiently reduced to a predetermined pressure or less, the sample S placed in the intermediate region 72 can be introduced into the ionization chamber 51. Therefore, the time required to reduce the pressure in the intermediate region 72 corresponds to the time required to introduce the probe P into the ionization chamber 51 after the probe P has been introduced into the intermediate region 72, and users prefer that this time be short.

[0052] It is preferable that the volume of the intermediate chamber 4 is sufficiently reduced in pressure so that when the valve 74 is opened, the intermediate region 72, which is at atmospheric pressure, becomes below a predetermined pressure and the sample S can be quickly introduced into the ionization chamber 51.

[0053] The predetermined pressure is, for example, the pressure in the intermediate region 72 at which the valve 6 can be opened. Whether the valve 6 can be opened is determined, for example, by the pressure difference between the inlet and outlet of the valve 6. Some existing devices are provided with a fail-safe stopper that prevents the valve 6 from opening depending on the pressure in the intermediate region 72. In this case, the predetermined pressure is the pressure at which the stopper is released and the valve 6 can be opened. The predetermined pressure can vary depending on the conditions constituting the analytical system 100. The conditions constituting the analytical system 100 are, for example, the performance of the turbomolecular pump 1, the performance of the rotary pump 2, the type of analytical device 5, and the diameter of the pipe through which the gas flows and the material constituting the pipe.

[0054] Next, the volume of the intermediate chamber 4 and the time required for the intermediate region 72 to reach a predetermined pressure will be described. In Fig. 5, line L1 shows the relationship between the time required for the pressure in the intermediate region 72 to be reduced to a predetermined pressure (required time) and the volume of the intermediate chamber 4. The required time is set to 0 when the valve 74 is opened and the sufficiently reduced pressure intermediate chamber 4 communicates with the intermediate region 72 at atmospheric pressure.

[0055] 5, if the volume of the intermediate chamber 4 is small, it takes time for the pressure in the intermediate region 72 to be reduced to the predetermined pressure. This is because the pressure in the intermediate region 72 is not reduced to the predetermined pressure when the valve 74 is opened, and the pressure is reduced by the rotary pump 2. If the volume of the intermediate chamber 4 is equal to or larger than the volume D, the pressure in the intermediate region 72 quickly drops below the predetermined pressure after the valve 74 is opened. In other words, after the valve 74 is opened, the valve 6 can be quickly opened and the sample S can be measured.

[0056] If the time required for the pressure in the intermediate region 72 to decrease to a predetermined pressure is t1, which is acceptable to the user, then the volume of the intermediate chamber 4 is preferably E or greater. Furthermore, if the volume of the intermediate chamber 4 is D or greater, the pressure in the intermediate region 72 will quickly decrease to or below the predetermined pressure after the valve 74 is opened. In other words, if the volume of the intermediate chamber 4 is D or greater, the pressure in the intermediate region 72 will quickly decrease to or below the predetermined pressure after the valve 74 is opened, so that the sample S can be measured quickly after the probe P is inserted. Note that t1 is, for example, one minute.

[0057] The volumes D and E may vary depending on the conditions for configuring the analytical system 100. The conditions for configuring the analytical system 100 include, for example, the performance of the turbomolecular pump 1, the performance of the rotary pump 2, the diameter of the pipe through which the gas flows and the material that configures it, the volume of the intermediate region 72, and the value of the flow path resistance between the introducing device 7 and the intermediate chamber 4.

[0058] Next, the volume of the intermediate chamber 4 and the time required for the intermediate chamber 4 to be depressurized will be described. After the probe P is introduced into the ionization chamber 51, the valve 74 is closed, and the intermediate chamber 4 is depressurized by the rotary pump 2 to depressurize the next sample. After the intermediate chamber 4 has been sufficiently depressurized, the probe P into which the sample S for the next measurement has been injected or applied is introduced, and the valve 74 is opened.

[0059] 6, a line L2 shows the relationship between the time (required time) required for the internal pressure of the intermediate chamber 4 to be reduced to a level at which the valve 74 can be opened and the volume of the intermediate chamber 4. The required time is set to 0 at the time when the valve 74 is closed.

[0060] As shown in Figure 6, the larger the intermediate chamber 4, the longer the time required to reduce the pressure. This time can be expressed as the time it takes to analyze one sample and then the next, and a long time is inconvenient for the user. For example, if a predetermined number of samples need to be measured within a predetermined period of time, a shorter time is preferable.

[0061] If the time required for the internal pressure of the intermediate chamber 4 to be reduced to a level that allows the valve 74 to be opened is t2, the volume of the intermediate chamber 4 is preferably equal to or less than the volume F. Note that t2 is, for example, 10 minutes.

[0062] 6, the graph shown in FIG. 5 is indicated by line L1. As shown in FIG. 6, the volume of the intermediate chamber 4 is preferably equal to or greater than E and equal to or less than F, which satisfies the condition shown in region R. Furthermore, from the viewpoint that the user can introduce the sample S into the intermediate region 72 and quickly introduce the sample S into the ionization chamber 51, the volume of the intermediate chamber 4 is more preferably equal to or greater than D and equal to or less than F. Note that when the volume of the intermediate chamber 4 is equal to or greater than E but less than D, after the sample S is introduced into the intermediate region 72, time is required to depressurize the intermediate region 72 depending on the volume of the intermediate chamber 4.

[0063] [Example] An example will be described below in which the volume of the intermediate chamber 4 is examined when a specific analytical system 100 is used. In the analytical system 100, the volume of the intermediate region 72 is 3.1 cm ３ In addition, it is assumed that t1 in the example of FIG. 5 is 0 seconds.

[0064] 7 shows the change over time in the intake port pressure of the rotary pump 2 when the intermediate region 72, which is at atmospheric pressure, is connected to the intermediate chamber 4, which is sufficiently decompressed. Fig. 7 shows the intake port pressure of the rotary pump 2 when the volume of the intermediate chamber 4 relative to the intermediate region 72 is changed, with "9 times," "13 times," and "34 times" indicating that the volume of the intermediate chamber 4 is "9 times," "13 times," and "34 times," respectively, relative to the intermediate region 72. This pressure change indirectly indicates the change in the internal pressure of the intermediate region 72.

[0065] 7, when the valve 74 is opened (time 0 seconds), the pressure in the intermediate region 72 becomes equal to or lower than a predetermined value, and the stopper of the valve 6 is released. On the other hand, although not shown, when the volume of the intermediate chamber 4 is "1 time," "5 times," or "7 times" the volume of the intermediate region 72, the stopper of the valve 6 is not released promptly even when the valve 74 is opened.

[0066] Therefore, in a given analytical system 100, the volume of the intermediate chamber 4 is preferably at least nine times the volume of the intermediate region 72.

[0067] FIG. 8 shows the time change in the intake pressure of the rotary pump 2 when the intermediate chamber 4, which is at atmospheric pressure, is connected to the rotary pump 2 after closing the valve 74 in a predetermined analytical system 100 similar to that shown in FIG. 7 . The graph shows the intake pressure of the rotary pump 2 when the volume of the intermediate chamber 4 relative to the intermediate region 72 is changed. The values ​​"5 times," "9 times," "13 times," and "34 times" indicate that the volume of the intermediate chamber 4 is "5 times," "9 times," "13 times," and "34 times," respectively, greater than that of the intermediate region 72. This pressure change indirectly indicates the change in the internal pressure of the intermediate chamber 4. The dashed line indicates a predetermined pressure of 30 Pa. When the intake pressure of the rotary pump 2 falls below the predetermined pressure, the internal pressure of the intermediate chamber 4 is reduced to a level that allows the valve 74 to be opened. Also, assume that t2 in FIG. 6 is 600 seconds.

[0068] 8, within 600 seconds from when the valve 74 is closed (time 0 second), the intake port pressure of the rotary pump 2 at volumes "5 times," "9 times," "13 times," and "34 times" the volume of the intermediate region 72 becomes approximately constant and becomes equal to or less than the predetermined pressure of 30 Pa. Although not shown, if the volume of the intermediate chamber 4 becomes larger than "34 times," the intake port pressure of the rotary pump 2 does not become a stable value or become equal to or less than 30 Pa within 600 seconds.

[0069] Therefore, in a given analytical system 100, the volume of the intermediate chamber 4 is preferably no more than 34 times the volume of the intermediate region 72.

[0070] From the above, in a given analysis system 100 , it is preferable that the volume of the intermediate chamber 4 is 9 times or more and 34 times or less the volume of the intermediate region 72 .

[0071] Furthermore, in the piping between the intermediate chamber 4 and the intermediate region 72, it is preferable that gas moves quickly from the intermediate region 72 to the intermediate chamber 4. On the other hand, in the piping between the intermediate chamber 4 and the rotary pump 2, it is preferable that the amount of gas flowing to the rotary pump 2 is limited to a certain amount or less even when the intermediate region 72 becomes atmospheric pressure. Therefore, it is preferable that the flow path resistance of the piping between the intermediate chamber 4 and the rotary pump 2, which determines the outflow amount of gas from the intermediate chamber 4 per unit time, is greater than the flow path resistance of the piping between the intermediate chamber 4 and the intermediate region 72, which determines the inflow amount of gas into the intermediate chamber 4 per unit time.

[0072] It will be appreciated by those skilled in the art that the exemplary embodiments described above are examples of the following aspects.

[0073] (Item 1) In one aspect, the sample introduction system is connected to a gas chromatograph mass spectrometer, the sample introduction system comprising a mass analysis section, a first pump that exhausts gas from inside the mass analysis section, and a second pump that exhausts gas exhausted from the first pump, and the sample introduction system comprises an introduction device connected to the mass analysis section and that directly introduces a sample into the mass analysis section, and a restriction unit that is disposed in a connection path between the second pump and the introduction device and that restricts the flow rate of gas flowing from the introduction device to the second pump, the gas inside the introduction device being exhausted by the second pump, and the flow path resistance of the restriction unit being set so that the gas flow rate does not exceed a predetermined back pressure when the pressure inside the introduction device becomes equal to atmospheric pressure.

[0074] According to the sample introduction system described in paragraph 1, an auxiliary pump provided to maintain the back pressure of the main pump of a gas chromatograph mass spectrometer evacuates the intermediate region while maintaining the back pressure of the main pump, thereby providing a technology for reducing the cost of introducing a sample introduction system.

[0075] (Item 2) In the sample introduction system described in item 1, the predetermined back pressure may be a maximum outlet pressure of the first pump.

[0076] According to the sample introduction system described in paragraph 2, an auxiliary pump provided to maintain the back pressure of the main pump of a gas chromatograph mass spectrometer evacuates the intermediate region while maintaining the back pressure of the main pump so that it does not exceed the maximum exhaust port pressure of the main pump, thereby providing a technology for reducing the cost of introducing a sample introduction system.

[0077] (Item 3) In the sample introduction system described in item 1 or 2, when the conductance at the restriction section is C, the pumping speed of the second pump is S, the atmospheric pressure is P, and the predetermined back pressure of the first pump is W, the following formula (1) may be satisfied: C<S×W / (P−W).

[0078] According to the sample introduction system described in paragraph 3, an auxiliary pump provided to maintain the back pressure of the main pump of a gas chromatograph mass spectrometer evacuates the intermediate region while maintaining the back pressure of the main pump, thereby providing a technology for reducing the cost of introducing a sample introduction system.

[0079] (4) The sample introduction system according to the first or second aspect may further include an intermediate chamber between the restriction section and the second pump, the intermediate chamber having a volume larger than a predetermined volume.

[0080] The sample introduction system described in Section 4 provides a technique for improving the efficiency of decompression in the intermediate region and shortening the time required for measurement.

[0081] (Item 5) In the sample introduction system described in item 4, the predetermined volume may be 9 times or more and 34 times or less the internal volume of the introduction device.

[0082] The sample introduction system described in Section 5 provides a technique for improving the efficiency of decompression in the intermediate region and shortening the time required for measurement.

[0083] (Item 6) In one aspect, the sample introduction system is connected to a gas chromatograph mass spectrometer having a mass analysis section, a first pump that exhausts gas inside the mass analysis section, and a second pump that exhausts gas exhausted from the first pump, and further comprises an introduction device connected to the mass analysis section and that directly introduces a sample into the mass analysis section, and an intermediate chamber arranged in a connection path between the second pump and the introduction device, and the resistance of the flow path between the second pump and the intermediate chamber may be greater than the resistance of the flow path between the introduction device and the intermediate chamber.

[0084] According to the sample introduction system described in paragraph 6, an auxiliary pump provided to maintain the back pressure of the main pump of a gas chromatograph mass spectrometer evacuates the intermediate region while maintaining the back pressure of the main pump, thereby providing a technology for reducing the cost of introducing a sample introduction system.

[0085] The embodiments disclosed herein are intended to be combined as appropriate within the scope of any technical inconsistency. The embodiments disclosed herein should be considered to be illustrative and not restrictive in all respects. The scope of the present invention is defined by the claims, not by the description of the above-mentioned embodiments, and is intended to include all modifications within the meaning and scope of the claims.

[0086] REFERENCE SIGNS LIST 1 turbomolecular pump, 2, 8 rotary pump, 3 restriction section, 4 intermediate chamber, 5 analysis device, 6, 74 valve, 7 introduction device, 51 ionization chamber, 53 ion guide, 54 partition electrode, 55 mass filter, 56 ion detector, 61 outer frame, 62 rotary valve, 63 through hole, 71 exhaust chamber, 72 intermediate region, 73 seal member, 100, 100B analysis system, 101 gas chromatograph mass spectrometer, 102, 102B sample introduction system.

Claims

1. A sample introduction system connected to a gas chromatograph mass spectrometer comprising a mass analysis section, a first pump for exhausting gas from inside the mass analysis section, and a second pump for exhausting gas exhausted from the first pump, comprising: an introduction device connected to the mass analysis section and for directly introducing a sample into the mass analysis section; and a restriction section disposed in a connection path between the second pump and the introduction device and for restricting the flow rate of gas flowing from the introduction device to the second pump, wherein the gas inside the introduction device is exhausted by the second pump, and the flow path resistance of the restriction section is set so that the gas flow rate does not exceed a predetermined back pressure when the pressure inside the introduction device becomes equal to atmospheric pressure.

2. The sample introduction system of claim 1, wherein the predetermined back pressure is a maximum outlet pressure of the first pump.

3. A sample introduction system according to claim 1 or 2, wherein the following formula (1) is satisfied: C<S×W / (P-W)... (1), where C is the conductance at the restriction section, S is the exhaust speed of the second pump, P is the atmospheric pressure, and W is a predetermined back pressure of the first pump.

4. The sample introduction system according to claim 1 or 2, further comprising an intermediate chamber having a volume larger than a predetermined volume between the restriction portion and the second pump.

5. The sample introduction system according to claim 4, wherein the predetermined volume is 9 times or more and 34 times or less than the internal volume of the introduction device.

6. A sample introduction system connected to a gas chromatograph mass spectrometer comprising a mass analysis section, a first pump for exhausting gas inside the mass analysis section, and a second pump for exhausting gas exhausted from the first pump, the sample introduction system comprising: an introduction device connected to the mass analysis section for directly introducing a sample into the mass analysis section; and an intermediate chamber arranged in a connection path between the second pump and the introduction device, wherein the resistance of the flow path between the second pump and the intermediate chamber is greater than the resistance of the flow path between the introduction device and the intermediate chamber.

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