Gas stable isotope magnetic mass spectrometer sample introduction system

Abstract

The application belongs to the technical field of mass spectrometers, and particularly relates to a gas stable isotope magnetic mass spectrometer sampling system. The technical scheme is as follows: a gas stable isotope magnetic mass spectrometer sampling system, comprising an ampoule container, a plurality of ampoule bottles loaded with sample gas and / or standard gas are contained in the ampoule container, a gas distribution unit is connected to an outlet pipeline of the ampoule container, the gas distribution unit is connected with a plurality of sampling system pipelines, a plurality of container units are connected to the sampling system pipelines, the sampling system further comprises a sampling device, the sampling device is connected with the other ends of the plurality of sampling system pipelines, and the sampling system further comprises a pre-vacuum unit and a high-vacuum unit, the pre-vacuum unit is connected with the plurality of sampling system pipelines respectively, and the high-vacuum unit is connected with the sampling device and the plurality of sampling system pipelines respectively. The gas stable isotope magnetic mass spectrometer sampling system provided by the application can first draw a vacuum chamber to a pre-vacuum state and then to a high-vacuum state to ensure the vacuum degree of the system.

Description

Technical Field

[0001] This invention belongs to the field of mass spectrometry technology, and specifically relates to a sample introduction system for a gas stable isotope magnetic mass spectrometer. Background Technology

[0002] Mass spectrometry is designed to determine the isotopic composition of chemical elements and their compounds in the gaseous state. The ion source converts gaseous molecules into positive ions and accelerates and focuses them into an ion beam, facilitating subsequent magnetic field analysis of charged ions. The ion receiver collects the ions after analysis by the electromagnet. The movement of charged ions generates an electric current, which is amplified by external equipment to measure the ratio of the collected ions, thereby measuring the isotopic ratios of different mass-to-charge ratios.

[0003] The working principle of a magnetic mass spectrometer is based on the spatial separation of analyte gas molecules. These gas molecules are ionized by mass to form an ion beam, and then the relative abundance and molecular weight of each component are determined. During operation, the gas to be analyzed is injected into the mass spectrometer's sample introduction system. After preliminary preparation, it enters the ion source located at the high vacuum position via a needle valve.

[0004] The sample introduction system, as part of a dedicated mass spectrometer, can be used in geology, geochronology, geochemistry, cosmochronology, mineralogy, paleontology, hydrology, petroleum exploration, soil science, biochemistry, and pharmacology. The vacuum assembly of the sample introduction system is placed on a plate with mounting holes for connection to the mass spectrometer. The sample introduction system is primarily used as a mixing device for gaseous stable isotope mass spectrometry analysis. It is used to prepare test samples in gaseous form, which are then introduced into the ion source of the mass spectrometer through two channels for precise measurement of minute variations in isotope ratios 13C / 12C, 15N / 14N, 18O / 16O, and 34S / 32S.

[0005] In the sample introduction system, all vacuum chambers must be evacuated to a high vacuum state to avoid the influence of air on the test sample. Summary of the Invention

[0006] In order to solve the above-mentioned problems in the prior art, the purpose of this invention is to provide a gas stable isotope magnetic mass spectrometer sample introduction system that first evacuates the vacuum chamber to a pre-vacuum state and then to a high vacuum state to ensure the vacuum degree of the system.

[0007] The technical solution adopted in this invention is as follows:

[0008] A sample introduction system for a gas stable isotope magnetic mass spectrometer includes an ampoule container containing a plurality of ampoules loaded with sample gas and / or standard gas. The outlet pipe of the ampoule container is connected to a gas distribution unit, which is connected to a plurality of sample introduction system pipes. A plurality of container units are connected to the sample introduction system pipes. The system also includes a sample introduction device connected to the other ends of the plurality of sample introduction system pipes. Furthermore, it includes a pre-vacuum unit and a high-vacuum unit. The pre-vacuum unit is connected to the plurality of sample introduction system pipes, and the high-vacuum unit is connected to the sample introduction device and the plurality of sample introduction system pipes.

[0009] The pre-vacuum unit of this invention can evacuate the container unit, sample introduction device, gas distribution unit, etc. to a pre-vacuum state, while the high-vacuum unit can evacuate the container unit, sample introduction device, gas distribution unit, etc. to a high-vacuum state. When the sample gas and / or standard gas in the ampoule enter the system, no other gases will be mixed in with the sample gas and / or standard gas, ensuring the quality of the gas finally sent to the ion source and ensuring the accuracy of mass spectrometry analysis.

[0010] As a preferred embodiment of the present invention, a cold trap is connected to the gas distribution unit. The cold trap can prevent water vapor from entering and mixing into the sample gas and / or standard gas, thus ensuring the vacuum level of the system.

[0011] As a preferred embodiment of the present invention, the pre-vacuum unit includes a pre-vacuum pump, and the outlet pipeline of the pre-vacuum pump is connected to several sample injection system pipelines respectively.

[0012] As a preferred embodiment of the present invention, an oil and gas adsorption filter is connected to the outlet pipe of the pre-vacuum pump.

[0013] In a preferred embodiment of the present invention, a low vacuum pressure sensor is connected to the outlet pipe of the pre-vacuum pump. The turbomolecular pump is activated based on the reading of the low vacuum pressure sensor.

[0014] As a preferred embodiment of the present invention, the high vacuum unit includes a turbomolecular pump, one end of which is connected to a pre-vacuum chamber, and the other end of which is connected to the pre-vacuum unit and a plurality of sample injection system pipelines; the other end of the turbomolecular pump is connected to a high vacuum connection unit, which is connected to the sample injection device and a plurality of sample injection system pipelines.

[0015] In a preferred embodiment of the present invention, a high vacuum pressure sensor is connected to the high vacuum connection unit. The opening and closing of the sample injection valve is controlled based on the reading of the high vacuum pressure sensor.

[0016] As a preferred embodiment of the present invention, a first valve assembly and a second valve assembly are sequentially connected to the sample injection system pipeline. A first gas container is connected to the first valve assembly, and a second gas container is connected to the second valve assembly.

[0017] As a preferred embodiment of the present invention, the gas distribution unit, the first valve assembly, the second valve assembly, the sample introduction device, and the high-vacuum connection unit of the high-vacuum unit are all integrated into a single structure. This integrated valve design reduces interference from the piping on the mass spectrometer's analytical results and allows for selection of the number of sample introduction paths that can be modified according to the on-site process.

[0018] As a preferred embodiment of the present invention, the sample injection device is provided with a plurality of diaphragms, the diaphragms are provided with holes, the diaphragms are connected to the sample injection system pipeline, and the outlet pipelines of the plurality of diaphragms converge into one outlet.

[0019] The beneficial effects of this invention are as follows:

[0020] 1. The pre-vacuum unit of this invention can evacuate the container unit, sample introduction device, gas distribution unit, etc. to a pre-vacuum state, and the high-vacuum unit can evacuate the container unit, sample introduction device, gas distribution unit, etc. to a high-vacuum state. When the sample gas and / or standard gas in the ampoule enter the system, no other gases will be mixed in with the sample gas and / or standard gas, ensuring the quality of the gas finally sent to the ion source and ensuring the accuracy of mass spectrometry analysis.

[0021] 2. This invention adopts an integrated valve design, which can reduce the interference of pipelines on the analysis results of mass spectrometers and has the option to select the number of injection paths that can be modified according to the on-site process. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the structure of the present invention.

[0023] In the picture:

[0024] V1: Sample introduction device;

[0025] V4: Gas distribution unit;

[0026] V3, V6: First valve assembly;

[0027] V2, V5: Second valve assembly;

[0028] CV6: Pre-vacuum airbag;

[0029] CV3, CV7: Second gas containers;

[0030] CV4, CV8: First gas container;

[0031] CV5: Ampoule container;

[0032] BL4: Cold trap;

[0033] BS1: Oil and gas adsorption filter;

[0034] D1, D2: Diaphragm;

[0035] PT3: Low vacuum pressure sensor;

[0036] PM2: High vacuum pressure sensor;

[0037] VH4~VH26: Valves;

[0038] VE1, VE3: Injection valves;

[0039] VE2, VE4: Sample release valves;

[0040] VE5~VE8: Measuring tubes;

[0041] NL1: Pre-vacuum pump;

[0042] NR2: Turbomolecular pump. Detailed Implementation

[0043] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0044] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention. It should be noted that, unless otherwise specified, the embodiments and features described in the embodiments of the invention can be combined with each other.

[0045] like Figure 1 As shown, the gas stable isotope magnetic mass spectrometer sample introduction system of this embodiment includes an ampoule container CV5, which contains several ampoules loaded with sample gas and / or standard gas. The outlet pipe of the ampoule container CV5 is connected to a gas distribution unit V4, which is connected to two sample introduction system pipes. Two container units are connected to the sample introduction system pipes. The system also includes a sample introduction device V1, which is connected to the other end of several sample introduction system pipes. Furthermore, it includes a pre-vacuum unit and a high-vacuum unit. The pre-vacuum unit is connected to the two sample introduction system pipes respectively, and the high-vacuum unit is connected to the sample introduction device V1 and the two sample introduction system pipes respectively.

[0046] The pre-vacuum unit of this invention can evacuate the container unit, sample introduction device V1, gas distribution unit V4, etc., to a pre-vacuum state, while the high-vacuum unit can evacuate the container unit, sample introduction device V1, gas distribution unit V4, etc., to a high-vacuum state. When the sample gas and / or standard gas in the ampoule enter the system, no other gases will be mixed in with the sample gas and / or standard gas, ensuring the quality of the gas finally sent to the ion source and ensuring the accuracy of mass spectrometry analysis.

[0047] The CV5 ampoule container is used to hold several ampoules containing gas samples and / or standard gas mixtures. The CV5 container holds up to six ampoules, which are opened one by one after evacuation and degassing. The outer diameter of the ampoule is 5–6 mm or 8 mm, the total length is 70–110 mm, and the length of the cylindrical portion is 40–70 mm. The CV5 ampoule container is equipped with a heating device for vacuum degassing. The CV5 ampoule container has design elements to prevent glass dust from entering the vacuum system, and glass residue can be easily removed from the internal volume of the CV5 after opening.

[0048] The gas distribution unit V4 includes a valve VH11 connected to the outlet pipe of the ampoule container CV5. The outlet pipe of valve VH11 is connected to two sample injection system pipes. Samples and / or standards enter one of the channels of the two sample injection system pipes via manual valve VH10 or valve VH12. A cold trap BL4 is connected to the outlet pipe of valve VH11. The cold trap BL4 prevents water vapor from entering and mixing with the sample gas and / or standard gas, ensuring the vacuum level of the system.

[0049] The sample introduction system pipeline is sequentially connected to first valve assemblies V3 and V6 and second valve assemblies V2 and V5. First gas containers CV4 and CV8 are connected to the first valve assemblies V3 and V6, and second gas containers CV3 and CV7 are connected to the second valve assemblies V2 and V5. The first valve assembly V3 includes valves VH9, VH8, and VH7 arranged sequentially. Valve VH9 is connected to a pre-vacuum unit and a high-vacuum unit via pipeline, and valve VH7 is connected to the first gas container CV4. The first valve assembly V6 includes valves VH24, VH25, and VH26 arranged sequentially. Valve VH24 is connected to the pre-vacuum unit and the high-vacuum unit via pipeline, and valve VH26 is connected to the first gas container CV8. The second valve assembly V2 includes valve VH6, metering tube VE6, metering tube VE5, and valve VH5 connected in sequence to form a closed loop. The pipeline between valve VH5 and valve VH6 is connected to the high vacuum unit, and the pipeline between valve VH5 and metering tube VE5 is connected to the second gas container CV3. The second valve assembly V5 includes valve VH23, metering tube VE8, metering tube VE7, and valve VH22 connected in sequence to form a closed loop. The pipeline between valve VH22 and valve VH23 is connected to the high vacuum unit, and the pipeline between valve VH22 and metering tube VE7 is connected to the second gas container CV7.

[0050] The first valve assemblies V3 and V6 can be used to evacuate the corresponding first gas containers CV4 and CV8 to a pre-vacuum state, and to feed samples and / or standards into the corresponding first gas containers CV4 and CV8. First gas container CV4 is evacuated to a pre-vacuum state via manual valves VH7-VH9, and first gas container CV8 is evacuated to a pre-vacuum state via manual valves VH24-VH26. Each container is equipped with a heating device for vacuum degassing. The container material is 304 stainless steel. Using the metering chamber between valves VH7-VH8 and VH25-VH26, approximately 14.5 sm³ of sample or standard can be extracted from the entire volume of the sample or standard. The second valve assemblies V2 and V5 are used to evacuate the second gas containers CV3 and CV7 to pre-vacuum (LV) and high vacuum (HV) states, and to feed samples and / or standards into the second gas containers CV3 and CV7. Using the metering chamber between metering tubes VE5-VE6 and VE7-VE8, approximately 1 sm³ of sample or standard can be extracted from the entire volume of the sample or standard. The metering tube for injecting gas into the second gas container has a rubber sealing element that can withstand heating up to 150°C. Manual valves VH5 and VH22 are used to vent the vacuum chambers of the second gas containers CV3 and CV7, as well as the corresponding pipeline valves, to achieve a high vacuum. Manually driven valves VH6 and VH23 are used to vent the vacuum chambers of the first gas containers CV4 and CV8, as well as the corresponding pipeline valves, to achieve a high vacuum.

[0051] The pre-vacuum unit includes a pre-vacuum pump NL1, whose outlet pipe is connected to several sample injection system pipes. An oil-gas adsorption filter BS1 is connected to the outlet pipe of the pre-vacuum pump NL1. A low-vacuum pressure sensor PT3 is also connected to the outlet pipe of the pre-vacuum pump NL1. The turbomolecular pump NR2 is activated based on the reading of the low-vacuum pressure sensor PT3.

[0052] The high vacuum unit includes a turbomolecular pump NR2, one end of which is connected to a pre-vacuum chamber CV6, and the other end of CV6 is connected to a valve VH20. Valve VH20 is connected to the pre-vacuum unit and several sample injection system pipelines. The other end of the turbomolecular pump NR2 is connected to a high vacuum connection unit, which is connected to a valve VH19. The high vacuum connection unit is connected to a sample injection device V1 and several sample injection system pipelines. A high vacuum pressure sensor PM2 is connected to the high vacuum connection unit. The opening of sample injection valves VE1 and VE3 is determined based on the reading of the high vacuum pressure sensor PM2.

[0053] A diaphragm D1 is installed on one side of the sample introduction device V1. A valve VH4 is connected to one end of the sample introduction system pipeline connecting to the diaphragm D1, and the other end of the diaphragm D1 is connected to the sample introduction valve VE1. The pipeline between the sample introduction valve VE1 and the diaphragm D1 is connected to the high vacuum connection unit via a pipeline, and a vent valve VE2 is installed therein. A diaphragm D2 is installed on the other side of the sample introduction device. A valve VH21 is connected to one end of the sample introduction system pipeline connecting to the diaphragm D2, and the other end of the diaphragm D2 is connected to the sample introduction valve VE3. The pipeline between the sample introduction valve VE3 and the diaphragm D2 is connected to the high vacuum connection unit via a pipeline, and a vent valve VE4 is installed therein. The outlet pipelines of the sample introduction valves VE1 and VE3 merge into one outlet, which sends the gas to the ion source.

[0054] Sample introduction device V1 is used to introduce gas into the mass spectrometer through two independent sample channels. Sample introduction device V1 includes diaphragms D1 and D2, and corresponding sample introduction valves VE1 and VE3, and vent valves VE2 and VE4. Sample introduction valves VE1 and VE3 ensure that gas passes through diaphragms D1 and D2 into the ion source of the mass spectrometer. When sample introduction valve VE1 or VE3 is closed, vent valves VE2 and VE4 allow vacuum evacuation between diaphragm D1 and sample introduction valve VE1, or between diaphragm D2 and sample introduction valve VE3, using a turbomolecular pump NR2. Sample introduction valves VE1 and VE3, and vent valves VE2 and VE4, have sealing elements made of polytetrafluoroethylene (PTFE). Sample introduction device V1 must be connected to the ion source body of the mass spectrometer via an inlet pipe through appropriate connectors. Valves VH4 and VH21 are used to close the corresponding sample introduction containers when changing diaphragms D1 and D2. The diaphragms D1 and D2, which allow gas to enter the ion source, have pore sizes of 10–15 μm, are located in easily accessible positions, and are easy to replace. The materials of diaphragms D1 and D2 are copper, nickel, and aluminum.

[0055] The vacuum system of the sample introduction system is made of stainless steel and has a detachable connection with metal seals, allowing all components to be cleaned during pretreatment cleaning and maintenance. The inner surfaces of all vacuum components must be treated to meet vacuum cleanliness requirements. The sample introduction system is designed to ensure that all components for introducing the preparative gases can be heated to 150°C.

[0056] The sample introduction system employs vacuum valve assemblies to reduce vacuum line length and parasitic (excess) volume. The valve assemblies with manual valves VH4–VH26 feature a metal-sealed flow section, a high-vacuum (HV) design, a "CF" type seal for the valve mechanism relative to the housing, and a stainless steel bellows seal for the vacuum actuator. The valves are heatable up to 150°C in the closed state and up to 250°C in the open state. Solenoid valves VE1–VE4 also feature a high-vacuum (HV) design with a seal made of fluoroplastic for the transition section. The valve mechanism's seal relative to the housing is fluoroplastic, and the vacuum actuator seal is a stainless steel bellows seal. Solenoid valves VE5–VE8 also feature a high-vacuum (HV) design with a seal at the transition section. The cover seal is made of heat- and chemically resistant fluororubber ("viton"), the valve mechanism's seal relative to the housing is fluoroplastic, and the vacuum actuator seal is a stainless steel bellows seal. All solenoid valves are designed to heat the working parts to 150°C. The electromagnet coil is structurally removed from the working parts and is designed to heat to 90°C. Specifically, valves VH4–VH18 are DN-10 valves; valve VH19 is a DN-32 valve; valves VH20–VH26 are DN-10 valves; injection valves VE1 and VE3 are DN-3 solenoid valves; and discharge valves VE2 and VE4 are DN-3 solenoid valves.

[0057] The gas distribution unit V4, the first valve assembly V3 / V6, the second valve assembly V2 / V5, the sample introduction device V1, and the high-vacuum connection unit of the high-vacuum unit are all integrated structures. This invention employs an integrated valve design, which reduces interference from piping on the mass spectrometer's analytical results and allows for selection of the number of sample introduction paths that can be modified according to on-site processes.

[0058] In this invention, the pre-vacuum pump NL1 evacuates all vacuum chambers of the sample introduction system to a pre-vacuum state via the oil-gas adsorption filter BS1, valves VH9, VH20, and VH24. The high vacuum of the sample introduction system vacuum chamber is provided by the turbomolecular pump NR2 via valve VH19 with a DN32 flange interface. The pumping speed of the turbomolecular pump NR2 is at least 50 l / s. The inlet pressure of the turbomolecular pump NR2 is measured by a high vacuum pressure sensor PM2, which is a cold cathode magnetic ionization vacuum gauge. The turbomolecular pump NR2 is equipped with a pre-vacuum bladder CV6 to ensure long-term operation of the turbomolecular pump NR2 without requiring continuous evacuation by the pre-vacuum pump NL1 via valve VH20 during operation.

[0059] The order of using the injection system:

[0060] 1) In the initial position, all valves (manual and solenoid valves) must be closed;

[0061] 2) Turn on the control and indication unit of the low vacuum pressure sensor PT3;

[0062] 3) Turn on the pre-vacuum pump NL1;

[0063] 4) Open valve VH20 to evacuate the pump casings of pre-vacuum air bag CV6 and turbomolecular pump NR2 to a pressure not exceeding 100Pa, and control the process based on the reading of low vacuum pressure sensor PT3.

[0064] 5) Turn on turbomolecular pump NR2. After turbomolecular pump NR2 enters the operating mode, turn on the high vacuum pressure sensor PM2 on the control display unit and use it to control the pump to further pump to a high vacuum (HV).

[0065] 6) Insert the ampoule containing the sample and / or standard into the corresponding ampoule container CV5 interchangeable box, and fix the installation position of the ampoule;

[0066] 7) With the help of the vacuum valve, all gas containers, pipes and valves, including the outer shell of the ampoule container CV5, are first pumped to pre-vacuum by the pre-vacuum pump NL1, and then pumped to high vacuum by the turbomolecular pump NR2.

[0067] 8) Close all valves (manual and solenoid valves) except for valves VH19 and VH20;

[0068] 9) Place the standard and / or sample into ampoule container CV5 and open the required ampoule;

[0069] 10) Using appropriate vacuum valves and vacuum circuit diagrams, samples and / or standards are delivered into the corresponding sample containers.

[0070] 11) Open valves VH4 and VH21;

[0071] 12) Inject the sample and / or standard into the mass spectrometer through the appropriate inlet valve VE1 or VE3;

[0072] 13) After several consecutive cycles of sample-standard, the corresponding isotope ratios are calculated using the mass spectrometer software and computer complex.

[0073] This invention is not limited to the above-described optional embodiments. Anyone can derive other various forms of products under the guidance of this invention. However, regardless of any changes made in their shape or structure, any technical solution that falls within the scope of the claims of this invention shall be protected by this invention.

Claims

1. A sample introduction system for a gas stable isotope magnetic mass spectrometer, characterized in that: The device includes an ampoule container containing several ampoules filled with sample gas and / or standard gas. The ampoule container's outlet line is connected to a gas distribution unit, which is connected to several sample injection system lines. Several container units are connected to the sample injection system lines. The device also includes a sample injection device connected to the other end of the sample injection system lines. Furthermore, it includes a pre-vacuum unit and a high-vacuum unit. The pre-vacuum unit is connected to several sample injection system lines, and the high-vacuum unit is connected to the sample injection device and several sample injection system lines. The pre-vacuum unit includes a pre-vacuum pump, and the outlet pipeline of the pre-vacuum pump is connected to several sample injection system pipelines respectively. A low vacuum pressure sensor is connected to the outlet pipe of the pre-vacuum pump; The high vacuum unit includes a turbomolecular pump, one end of which is connected to a pre-vacuum chamber, and the other end of which is connected to the pre-vacuum unit and several sample injection system pipelines; the other end of the turbomolecular pump is connected to a high vacuum connection unit, which is connected to the sample injection device and several sample injection system pipelines. A high vacuum pressure sensor is connected to the high vacuum connection unit; The sample injection system pipeline is connected in sequence to a first valve assembly and a second valve assembly. A first gas container is connected to the first valve assembly, and a second gas container is connected to the second valve assembly. The injection device is provided with several diaphragms, each with a hole. The diaphragms are connected to the injection system pipeline, and the outlet pipelines of the several diaphragms converge into one outlet. The turbomolecular pump is activated based on the reading of the low vacuum pressure sensor; the sample introduction device includes an injection valve and a vent valve, and the decision to open the injection valve is determined based on the reading of the high vacuum pressure sensor.

2. The sample introduction system for a gas stable isotope magnetic mass spectrometer according to claim 1, characterized in that: A cold trap is connected to the gas distribution unit.

3. The sample introduction system for a gas stable isotope magnetic mass spectrometer according to claim 1, characterized in that: An oil and gas adsorption filter is connected to the outlet pipe of the pre-vacuum pump.

4. The sample introduction system for a gas stable isotope magnetic mass spectrometer according to claim 1, characterized in that: The gas distribution unit, the first valve assembly, the second valve assembly, the sample injection device, and the high vacuum connection unit of the high vacuum unit are all integrated structures.

Images