WO2025057320A1 - Sample introduction system - Google Patents

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

The present invention relates to a sample introduction system, and more specifically to a technique for sharing a vacuum pump.

In analyses using gas chromatograph mass spectrometers, in addition to methods in which the sample to be analyzed is analyzed via a gas chromatograph, a direct sample introduction method is also used in which the sample to be analyzed is directly introduced into an ion source for analysis. For example, as shown in JP 2021-103133 A (Patent Document 1), in the direct sample introduction method, a probe with a sample injected or coated on the 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.

In the direct sample introduction method, when a sample in the atmosphere is directly introduced into the ion source, which is kept at a high vacuum, a large amount of gas flows into the mass spectrometer. The gas molecules that flow into the mass spectrometer collide with the ions originating from the sample, bending the ion trajectory or destroying the ions. This can result in insufficient measurement accuracy in the mass spectrometer. Also, a large amount of oxygen can shorten the life of the filament that lights up during ionization. Therefore, in order to prevent a large amount of gas from flowing into the mass spectrometer, the sample is depressurized in an intermediate area provided in 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.

The gas chromatograph mass spectrometer is equipped with a main pump to achieve a high vacuum inside the device, and an auxiliary pump to maintain the back pressure of the main pump lower than the maximum exhaust port pressure of the main pump.

JP 2021-103133 A

When connecting a direct sample introduction device to a gas chromatograph mass spectrometer, a separate vacuum pump must be prepared to reduce pressure in the intermediate region. Therefore, the cost of introducing a direct sample introduction device may increase for users.

On the other hand, instead of preparing a vacuum pump, it is possible to configure the gas chromatograph mass spectrometer so that the vacuum pump, which is an auxiliary pump, is connected not only to the main pump but also to the intermediate region. In other words, it is possible to configure the vacuum pump, which is an auxiliary pump, to also play the role of reducing the pressure in the intermediate region. However, in such a configuration, the pressure in the intermediate region increases when the sample is introduced, and the back pressure of the main pump exceeds the maximum exhaust port pressure of the main pump, which may cause the main pump to fail to function.

This disclosure was devised in light of the above-mentioned circumstances, and its purpose is to provide technology for reducing the cost of introducing a direct sample introduction device.

The sample introduction system according to the 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 is equipped with an introduction device connected to the mass analysis section and directly introducing a sample into the mass analysis section, and a restriction section disposed in the connection path between the second pump and the introduction device and restricting the flow rate of gas flowing from the introduction device to the second pump, 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.

The sample introduction system according to the 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 directly introducing 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.

The present disclosure provides technology to reduce the cost of introducing a direct sample introduction device.

FIG. 1 is a diagram showing an overall configuration of an analysis system. FIG. 13 is a diagram illustrating an example of the configuration of a restriction unit. FIG. 2 is a diagram showing a state in which a probe is introduced into an analysis device in the analysis system. FIG. 1 is a diagram showing a configuration of an analysis system connected to a conventional sample introduction system. FIG. 13 is a diagram showing the lower limit value of the intermediate chamber. FIG. 13 is a diagram showing the upper limit value of the intermediate chamber. FIG. 13 is a diagram showing the change over time in the intake pressure of a rotary pump when an intermediate region at atmospheric pressure is connected to an intermediate chamber at a sufficiently reduced pressure. FIG. 13 is a diagram showing the change over time in the intake port pressure of a rotary pump when an intermediate chamber at atmospheric pressure is connected to the rotary pump.

The embodiments of the present disclosure will be described in detail with reference to the drawings. Note that the same or equivalent parts in the drawings will be given the same reference numerals and their description will not be repeated.

[Schematic configuration of analysis system]
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 ratio of the ions and their abundance.

The gas chromatograph mass spectrometer 101 includes a turbo molecular 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.

The turbomolecular pump 1 is connected to the analysis device 5, and exhausts the gas inside the analysis device 5 to maintain the inside of the analysis device 5 at a high vacuum. The turbomolecular pump is sometimes called the main pump. In this embodiment, the gas chromatograph mass spectrometer 101 is equipped with the turbomolecular pump 1 to reduce the pressure inside the analysis device 5, but the type of pump is not limited to a turbomolecular pump as long as it is possible to reduce the pressure inside the analysis device 5.

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. Note that in this embodiment, the gas chromatograph mass spectrometer 101 is equipped 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 value lower than a predetermined back pressure.

The specified back pressure is a back pressure that is low enough for the turbomolecular pump 1 to operate efficiently. The specified back pressure is sometimes referred to as the maximum exhaust port pressure. A turbomolecular pump has rotating turbine blades and fixed fixed blades. A turbomolecular pump exhausts gas by rotating the turbine blades at high speed, repelling gas molecules, and colliding the gas molecules with the fixed blades. If the gas molecules repelled by the turbine blades collide with other gas molecules before colliding with the fixed 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. The maximum exhaust port pressure differs depending on the type of turbomolecular pump, but is, for example, 600 Pa.

The analyzer 5 is, for example, a quadrupole mass spectrometer equipped with 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 to 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 the X-axis direction. The direction in which ions pass through the analyzer 5 is the Z-axis direction, and the direction perpendicular to the XZ plane is the Y-axis direction.

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 an 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.

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 about a predetermined axis parallel to the Y axis. The analysis device 5 is connected to the introduction device 7 of the sample introduction system 102 via the valve 6.

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 at a high vacuum. Note that the valve 6 is not limited to having the rotary valve 62 described above, and may be configured in any way that allows the probe P to pass through when open and prevents the passage of gas between the analysis device 5 and the introduction device 7 when closed.

The introduction device 7 is connected to the rotary pump 2 so that the gas inside the introduction device 7 is 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 the valve 6 so that the probe P can be introduced into the ionization chamber 51 of the analysis device 5.

The introduction device 7 includes an exhaust chamber 71, a seal member 73, and a valve 74. The sample S is directly introduced into the ionization chamber 51 via the introduction device 7, so that 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 intermediate region 72 is depressurized.

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

Figure 2 shows an example of the structure of the restriction section 3. The part surrounded by the dashed line corresponds to the restriction section 3. In (A), the restriction section 3 is a pipe that is thinner than the pipes before and after it, thereby increasing the flow path resistance. In (B), the length of the pipe of the restriction section 3 is increased, thereby increasing the flow path resistance, for example, a capillary tube is used. Note that in (B), it is possible to further increase the flow path resistance 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 Figure 2 is an example of the restriction section 3, and the structure of the restriction section 3 is not limited to that shown in Figure 2.

The intermediate chamber 4 is a housing having a space of a predetermined volume provided in the flow path that communicates between the restriction section 3 and the introduction device 7. The gas inside the intermediate chamber 4 is exhausted by the rotary pump 2 connected via the restriction section 3. The intermediate chamber 4 improves the efficiency of the pressure reduction 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 volume of the intermediate chamber 4 will be described later.

[Method of Probe Introduction and Sample Measurement]
Fig. 3 shows a state in which the 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 the 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.

As shown in FIG. 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 analysis device 5 and the introduction device 7 is blocked, the valve 6 is closed. When the valve 6 is closed, the analysis device 5 and the introduction device 7 are blocked, and the user cannot introduce the probe P into the analysis device 5.

On the other hand, as shown in FIG. 3, when the rotation angle of the rotary valve 62 causes the direction of the through hole 63 to coincide 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.

The sample S injected or applied to the tip of the probe P is introduced into the ionization chamber 51. The ions generated in the ionization chamber 51 are guided by the ion guide 53, pass through the partition electrode 54, and are introduced into the 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 the ion detector 56.

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

When analyzing a sample without using a gas chromatograph, a device for directly introducing the sample into the ion source of the gas chromatograph mass spectrometer is connected. Figure 4 is a diagram showing the schematic configuration of an analysis system 100B in which a conventional sample introduction system 102B is connected to a gas chromatograph mass spectrometer 101. 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 that are difficult to analyze using a gas chromatograph, and compounds that are thermally unstable.

The sample introduction system 102 B includes an introduction device 7 and a rotary pump 8 .
The rotary pump 8 is connected to the introduction device 7 so that the inside of the introduction device 7 can be depressurized. When the introduction device 7 is used, if the sample S that exists under atmospheric pressure is introduced directly into the ionization chamber 51, the pressure inside the analysis device 5 may increase, and the analysis accuracy may decrease. Therefore, the sample S is depressurized inside the introduction device 7 before being introduced into the ionization chamber 51. The rotary pump 8 is a necessary component for depressurizing the sample S.

In other words, when connecting the introduction device 7 to the gas chromatograph mass spectrometer 101, the user must prepare a separate rotary pump 8. For the user, the cost of introducing a sample introduction system may increase.

On the other hand, it is also possible to use the rotary pump 2 of the analytical device 5 as a pump used to reduce the pressure inside the introduction device 7. However, if the inside of the introduction device 7 becomes atmospheric pressure 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.

For example, matrix-assisted laser desorption/ionization mass spectrometry and X-ray fluorescence spectrometry also have a process of introducing a sample that is at atmospheric pressure into a high vacuum. Some of these instruments can share the auxiliary pump and the decompression pump at the sample introduction section. The above-mentioned sharing of the pump is achieved by temporarily closing the valve on the exhaust side of the turbomolecular pump to prevent the back pressure from increasing. On the other hand, in gas chromatography mass spectrometry, carrier gas is constantly flowing into the high vacuum region. Therefore, the turbomolecular pump is constantly exhausting carrier gas, and if a valve is attached to the exhaust side of the turbomolecular pump and closed, the back pressure of the turbomolecular pump will increase. Therefore, in gas chromatography mass spectrometry, it is difficult to share the pump using the method realized in instruments such as matrix-assisted laser desorption/ionization mass spectrometry and X-ray fluorescence spectrometry.

[Features of the sample introduction system according to the embodiment]
Therefore, the sample introduction system 102 according to the present embodiment includes a restriction section 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 section 3 having a predetermined flow resistance. The predetermined flow resistance makes it possible to restrict the inflow amount of gas from the intermediate region 72 to the rotary pump 2 per unit time, and even if the intermediate region 72 becomes atmospheric pressure, the back pressure of the turbo molecular pump 1 can be prevented from exceeding the maximum exhaust port pressure. With this configuration, the rotary pump 2 and the rotary pump 8 in FIG. 4 can be shared, and when the sample introduction system 102 is connected to the gas chromatograph mass spectrometer 101, it is not necessary to prepare a separate rotary pump for depressurizing the introduction device 7.

Furthermore, the sample introduction system 102 is provided with 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, it may take time to depressurize the intermediate region 72 due to the flow path resistance of the restriction section 3, and the measurement time may be longer 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 keeping the back pressure of the turbo molecular pump 1 below the maximum exhaust port pressure. By providing the intermediate chamber 4, it is possible to improve the efficiency of depressurizing the intermediate region 72 and shorten the measurement time.

[Flow resistance of restriction section]
The restricting unit 3 restricts the amount of gas per unit time flowing from the intermediate region 72 of the introduction device 7 into the rotary pump 2. The greater the value of the flow path resistance of the restricting unit 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 unit 3 is that it is greater than a predetermined value. The predetermined value is the value of the flow path resistance of the restricting unit 3 that satisfies that when the intermediate region 72 becomes atmospheric pressure, the back pressure of the turbo molecular pump 1 does not exceed the maximum exhaust port pressure.

On the other hand, if the flow resistance of the restriction section 3 is large, it will take time to reduce the pressure in the intermediate region 72, and it will take 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 will be long, which may be inconvenient for the user. For example, if it is necessary to measure a certain number of samples in a certain period of time, it is preferable that the measurement time is short.

Therefore, it is preferable that the flow path resistance value of the restriction section 3 be the smallest value that satisfies the above-mentioned conditions.

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.

Here, if the back pressure of the turbo molecular pump 1 is N (Pa), the atmospheric pressure is W (Pa), and the conductance of the flow path resistance of the restriction section 3 is C ( ^m3 /s), then the following equation (1) holds for the gas flow rate Q (Pa· ^m3 /s) per unit time of the restriction section 3.

Q=C×(W-N) (1)
Furthermore, if the pumping speed of the rotary pump 2 is S (m ³ /s), the following formula (2) is established for the back pressure N of the turbo molecular pump 1 .

N = Q / S (2)
By substituting equation (1) into equation (2) and solving for the back pressure N of the turbo molecular pump 1, the following equation (3) is obtained.

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

P>N (4)
By substituting equation (3) into equation (4) and solving for the conductance C of the flow path resistance of the restriction portion 3, the following equation (5) is obtained.

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).

[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.

After the intermediate region 72 has been sufficiently depressurized to a pressure below a predetermined level, the sample S placed in the intermediate region 72 can be introduced into the ionization chamber 51. Therefore, the time required to depressurize 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.

The volume of the intermediate chamber 4 is preferably such that when the valve 74 is opened in a sufficiently decompressed state, the intermediate region 72, which is at atmospheric pressure, falls below a predetermined pressure, allowing the sample S to be quickly introduced into the ionization chamber 51.

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 analysis system 100. The conditions constituting the analysis system 100 are, for example, the performance of the turbomolecular pump 1, the performance of the rotary pump 2, the type of analysis device 5, and the diameter of the pipe through which the gas flows and the material constituting it.

Next, the volume of the intermediate chamber 4 and the time it takes for the intermediate region 72 to reach a predetermined pressure will be described. In Figure 5, line L1 shows the relationship between the time it takes 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 is connected to the intermediate region 72 at atmospheric pressure.

As shown in Figure 5, if the volume of the intermediate chamber 4 is small, it takes time for the intermediate region 72 to be depressurized to the specified pressure. This is because the intermediate region 72 is not depressurized to the specified pressure when the valve 74 is opened, so it is depressurized by the rotary pump 2. If the intermediate chamber 4 has a volume equal to or larger than volume D, the intermediate region 72 quickly becomes equal to or lower than the specified 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.

If the time required for the pressure in the intermediate region 72 to be reduced to a predetermined pressure that is acceptable to the user is t1, then it is preferable that the volume of the intermediate chamber 4 is E or greater. Furthermore, if the volume of the intermediate chamber 4 is D or greater, the intermediate region 72 will quickly reach a predetermined pressure or less 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 reach a predetermined pressure or less 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, 1 minute.

Note that volumes D and E can vary depending on the conditions for configuring the analysis system 100. The conditions for configuring the analysis 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 introduction device 7 and the intermediate chamber 4.

Next, the volume of the intermediate chamber 4 and the time it takes for the intermediate chamber 4 to be depressurized will be explained. 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.

In Figure 6, the relationship between the time (required time) required for the internal pressure of the intermediate chamber 4 to be reduced to a level where the valve 74 can be opened and the volume of the intermediate chamber 4 is shown by line L2. The required time is set to 0 when the valve 74 is closed.

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

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 volume F. Here, t2 is, for example, 10 minutes.

In addition, in FIG. 6, the graph shown in FIG. 5 is indicated by line L1. From FIG. 6, it is preferable that the volume of the intermediate chamber 4 is equal to or greater than E and equal to or less than F, which satisfies the condition indicated by region R. It is more preferable that the volume of the intermediate chamber 4 is equal to or greater than D and equal to or less than F, so that the user can introduce the sample S into the intermediate region 72 and quickly introduce the sample S into the ionization chamber 51. Note that if the volume of the intermediate chamber 4 is equal to or greater than E and less than D, after the sample S is introduced into the intermediate region 72, time is required to reduce the pressure in the intermediate region 72 depending on the volume of the intermediate chamber 4.

[Example]
The following is an example in which the volume of the intermediate chamber 4 is considered when a certain analytical system 100 is used. In the analytical system 100, the volume of the intermediate region 72 is 3.1 ^cm3 . Also, it is assumed that t1 in the example of FIG. 5 is 0 seconds.

Figure 7 shows the time change in the intake pressure of the rotary pump 2 when the intermediate region 72, which is at atmospheric pressure, is connected to an intermediate chamber 4 that is sufficiently decompressed. Figure 7 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, 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" larger than the intermediate region 72, respectively. This pressure change indirectly indicates the change in the internal pressure of the intermediate region 72.

For any of the volumes of the intermediate chamber 4 shown in FIG. 7, when the valve 74 is opened (time 0 seconds), the pressure in the intermediate region 72 falls below 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 "1x", "5x", or "7x" the volume of the intermediate region 72, the stopper of the valve 6 is not released immediately even when the valve 74 is opened.

Therefore, in a given analysis system 100, it is preferable that the volume of the intermediate chamber 4 is at least 9 times the volume of the intermediate region 72.

FIG. 8 shows the time change in the inlet 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 specified analysis system 100 similar to that in FIG. 7. The inlet pressure of the rotary pump 2 when the volume of the intermediate chamber 4 relative to the intermediate region 72 is changed is shown, with "5 times", "9 times", "13 times", and "34 times" indicating that the volume of the intermediate chamber 4 is "5 times", "9 times", "13 times", and "34 times" larger than the intermediate region 72, respectively. This pressure change indirectly indicates the change in the internal pressure of the intermediate chamber 4. The dashed line indicates a specified pressure of 30 Pa. When the inlet pressure of the rotary pump 2 falls below the specified pressure, the internal pressure of the intermediate chamber 4 is reduced to a level that allows the valve 74 to be opened. In addition, a case where t2 in FIG. 6 is 600 seconds is assumed.

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

Therefore, in a given analytical system 100, it is preferable that the volume of the intermediate chamber 4 is no more than 34 times the volume of the intermediate region 72.

In view of 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 than the volume of the intermediate region 72.

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 resistance of the piping between the intermediate chamber 4 and the rotary pump 2, which determines the amount of gas flowing out of the intermediate chamber 4 per unit time, is greater than the flow resistance of the piping between the intermediate chamber 4 and the intermediate region 72, which determines the amount of gas flowing in to the intermediate chamber 4 per unit time.

　It will be understood by those skilled in the art that the exemplary embodiments described above are specific examples of the following aspects:

(1) In one embodiment, the sample introduction system is connected to a gas chromatograph mass spectrometer having a mass spectrometry section, a first pump that exhausts gas inside the mass spectrometry section, and a second pump that exhausts gas exhausted from the first pump, and includes an introduction device connected to the mass spectrometry section and directly introducing a sample into the mass spectrometry section, and a restriction section disposed in a connection path between the second pump and the introduction device and restricting the flow rate of gas flowing from the introduction device to the second pump, and the gas inside the introduction device is exhausted by the second pump, and the flow path resistance of the restriction section may be set so that the flow rate of gas does not exceed a predetermined back pressure when the pressure inside the introduction device becomes equal to atmospheric pressure.

The sample introduction system described in paragraph 1 provides a technology for reducing the cost of introducing a sample introduction system by having an auxiliary pump provided to maintain the back pressure of the main pump of a gas chromatograph mass spectrometer evacuate the intermediate region while maintaining the back pressure of the main pump.

(2) In the sample introduction system described in 1, the predetermined back pressure may be the maximum exhaust port pressure of the first pump.

The sample introduction system described in paragraph 2 provides a technology for reducing the cost of introducing a sample introduction system by having an auxiliary pump provided to maintain the back pressure of the main pump of a gas chromatograph mass spectrometer evacuate the intermediate region while maintaining the back pressure of the main pump so as not to exceed the maximum exhaust port pressure of the main pump.

(Clause 3) In the sample introduction system described in clause 1 or 2, when the conductance in the restriction section is C, the exhaust 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). . . (1).

The sample introduction system described in paragraph 3 provides a technology for reducing the cost of introducing a sample introduction system by having an auxiliary pump provided to maintain the back pressure of the main pump of a gas chromatograph mass spectrometer evacuate the intermediate region while maintaining the back pressure of the main pump.

(4) The sample introduction system described in 1 or 2 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.

The sample introduction system described in paragraph 4 provides technology for improving the efficiency of pressure reduction in the intermediate region and shortening the time required for measurement.

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

The sample introduction system described in paragraph 5 provides technology to improve the efficiency of pressure reduction in the intermediate region and shorten the time required for measurement.

(6) In one embodiment, the sample introduction system is connected to a gas chromatograph mass spectrometer that includes a mass spectrometry section, a first pump that exhausts gas from inside the mass spectrometry section, and a second pump that exhausts gas exhausted from the first pump, and includes an introduction device that is connected to the mass spectrometry section and directly introduces a sample into the mass spectrometry section, and an intermediate chamber that is 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.

The sample introduction system described in paragraph 6 provides a technology for reducing the cost of introducing a sample introduction system by having an auxiliary pump provided to maintain the back pressure of the main pump of a gas chromatograph mass spectrometer evacuate the intermediate region while maintaining the back pressure of the main pump.

It is anticipated that the embodiments disclosed herein may be combined as appropriate to the extent that no technical contradiction occurs. The embodiments disclosed herein should be considered in all respects as illustrative and not restrictive. The scope of the present invention is indicated by the claims, not by the description of the embodiments above, and is intended to include all modifications within the meaning and scope of the claims.

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 sealing member, 100, 100B analysis system, 101 gas chromatograph mass spectrometer, 102, 102B sample introduction system.

Claims (6)

A sample introduction system connected to a gas chromatograph mass spectrometer, the sample introduction system comprising: a mass spectrometry section; a first pump that exhausts gas inside the mass spectrometry section; and a second pump that exhausts gas exhausted from the first pump,
an introduction device connected to the mass spectrometry unit and configured to directly introduce a sample into the mass spectrometry unit;
A restricting unit is provided in a connection path between the second pump and the introduction device, and restricts a flow rate of gas flowing from the introduction device to the second pump;
The gas inside the introduction device is discharged by the second pump,
A sample introduction system, wherein 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. The sample introduction system of claim 1, wherein the predetermined back pressure is a maximum exhaust port pressure of the first pump. The conductance at the restriction is C,
The pumping speed of the second pump is S,
Atmospheric pressure is P,
When the predetermined back pressure of the first pump is W,
Satisfying the following formula (1):
C<S×W/(P-W). ．． ．． (1)
The sample introduction system according to claim 1 or 2. The sample introduction system according to claim 1 or 2, further comprising an intermediate chamber between the restriction section and the second pump, the intermediate chamber having a volume larger than a predetermined volume. The sample introduction system of claim 4, wherein the predetermined volume is 9 times or more and 34 times or less than the internal volume of the introduction device. A sample introduction system connected to a gas chromatograph mass spectrometer, the sample introduction system comprising: a mass spectrometry section; a first pump that exhausts gas inside the mass spectrometry section; and a second pump that exhausts gas exhausted from the first pump,
an introduction device connected to the mass spectrometry unit and configured to directly introduce a sample into the mass spectrometry unit;
An intermediate chamber is disposed in a connection path between the second pump and the introduction device,
A sample introduction system, wherein the resistance of a flow path between the second pump and the intermediate chamber is greater than the resistance of a flow path between the introduction device and the intermediate chamber.

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