CN117936355A - Sectional sample injection device and on-line monitoring mass spectrometer - Google Patents
Sectional sample injection device and on-line monitoring mass spectrometer Download PDFInfo
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- CN117936355A CN117936355A CN202311679584.5A CN202311679584A CN117936355A CN 117936355 A CN117936355 A CN 117936355A CN 202311679584 A CN202311679584 A CN 202311679584A CN 117936355 A CN117936355 A CN 117936355A
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- 238000002347 injection Methods 0.000 title claims abstract description 24
- 239000007924 injection Substances 0.000 title claims abstract description 24
- 238000012544 monitoring process Methods 0.000 title claims description 14
- 239000012528 membrane Substances 0.000 claims abstract description 76
- 238000005070 sampling Methods 0.000 claims abstract description 10
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims description 21
- 229910002804 graphite Inorganic materials 0.000 claims description 21
- 239000010439 graphite Substances 0.000 claims description 21
- 238000007789 sealing Methods 0.000 claims description 13
- 230000006835 compression Effects 0.000 claims description 10
- 238000007906 compression Methods 0.000 claims description 10
- 238000010438 heat treatment Methods 0.000 claims description 10
- 239000002184 metal Substances 0.000 claims description 10
- 239000000956 alloy Substances 0.000 claims description 3
- 229910045601 alloy Inorganic materials 0.000 claims description 3
- 239000004205 dimethyl polysiloxane Substances 0.000 claims description 3
- 235000013870 dimethyl polysiloxane Nutrition 0.000 claims description 3
- CXQXSVUQTKDNFP-UHFFFAOYSA-N octamethyltrisiloxane Chemical compound C[Si](C)(C)O[Si](C)(C)O[Si](C)(C)C CXQXSVUQTKDNFP-UHFFFAOYSA-N 0.000 claims description 3
- 238000004987 plasma desorption mass spectroscopy Methods 0.000 claims description 3
- 229920000435 poly(dimethylsiloxane) Polymers 0.000 claims description 3
- 241000270295 Serpentes Species 0.000 claims description 2
- 238000001819 mass spectrum Methods 0.000 abstract description 2
- 239000007789 gas Substances 0.000 description 50
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 18
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 16
- 239000001301 oxygen Substances 0.000 description 16
- 229910052760 oxygen Inorganic materials 0.000 description 16
- 239000000243 solution Substances 0.000 description 9
- 239000012159 carrier gas Substances 0.000 description 7
- 238000004458 analytical method Methods 0.000 description 6
- 238000000034 method Methods 0.000 description 6
- 230000009286 beneficial effect Effects 0.000 description 5
- 239000000126 substance Substances 0.000 description 5
- 238000013461 design Methods 0.000 description 4
- 239000002245 particle Substances 0.000 description 4
- 230000008569 process Effects 0.000 description 4
- 230000000694 effects Effects 0.000 description 3
- 238000002955 isolation Methods 0.000 description 3
- 238000004949 mass spectrometry Methods 0.000 description 3
- YCKRFDGAMUMZLT-UHFFFAOYSA-N Fluorine atom Chemical compound [F] YCKRFDGAMUMZLT-UHFFFAOYSA-N 0.000 description 2
- 230000009471 action Effects 0.000 description 2
- 230000003749 cleanliness Effects 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 229910052731 fluorine Inorganic materials 0.000 description 2
- 239000011737 fluorine Substances 0.000 description 2
- 230000005484 gravity Effects 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 238000013375 chromatographic separation Methods 0.000 description 1
- 150000001875 compounds Chemical class 0.000 description 1
- 238000012864 cross contamination Methods 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 230000003111 delayed effect Effects 0.000 description 1
- 238000003795 desorption Methods 0.000 description 1
- 239000006185 dispersion Substances 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 230000006870 function Effects 0.000 description 1
- 238000002290 gas chromatography-mass spectrometry Methods 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 239000011261 inert gas Substances 0.000 description 1
- 229910001872 inorganic gas Inorganic materials 0.000 description 1
- 238000012423 maintenance Methods 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 230000013011 mating Effects 0.000 description 1
- 230000003446 memory effect Effects 0.000 description 1
- 238000005191 phase separation Methods 0.000 description 1
- 238000011155 quantitative monitoring Methods 0.000 description 1
- 238000001179 sorption measurement Methods 0.000 description 1
- 238000012360 testing method Methods 0.000 description 1
- 238000002834 transmittance Methods 0.000 description 1
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N27/00—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
- G01N27/62—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating the ionisation of gases, e.g. aerosols; by investigating electric discharges, e.g. emission of cathode
- G01N27/64—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating the ionisation of gases, e.g. aerosols; by investigating electric discharges, e.g. emission of cathode using wave or particle radiation to ionise a gas, e.g. in an ionisation chamber
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
- H01J49/00—Particle spectrometers or separator tubes
- H01J49/02—Details
- H01J49/04—Arrangements for introducing or extracting samples to be analysed, e.g. vacuum locks; Arrangements for external adjustment of electron- or ion-optical components
- H01J49/0404—Capillaries used for transferring samples or ions
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
- H01J49/00—Particle spectrometers or separator tubes
- H01J49/02—Details
- H01J49/04—Arrangements for introducing or extracting samples to be analysed, e.g. vacuum locks; Arrangements for external adjustment of electron- or ion-optical components
- H01J49/0422—Arrangements for introducing or extracting samples to be analysed, e.g. vacuum locks; Arrangements for external adjustment of electron- or ion-optical components for gaseous samples
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
- H01J49/00—Particle spectrometers or separator tubes
- H01J49/26—Mass spectrometers or separator tubes
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- Other Investigation Or Analysis Of Materials By Electrical Means (AREA)
Abstract
The scheme belongs to the technical field of mass spectrum sample injection, and discloses a sectional sample injection device which comprises a membrane, a first channel, a second channel, a third channel and a fourth channel, wherein the first channel, the second channel and the third channel are arranged on one side of a membrane plane, and the fourth channel is arranged on the other side of the membrane plane; the first channel is provided with a first capillary, one end of the first capillary is communicated with one end of the third channel, and the other end of the first capillary is provided with a tee joint structure; the first interface of the three-way structure is communicated with the first capillary, the second interface is used for being communicated with a sample gas sampling point, and the third interface is communicated with a first pump for providing a first negative pressure P 1; one end of the second channel is communicated with the other end of the third channel, and the other end of the second channel is communicated with a second pump for providing a second negative pressure P 2; one side of the third channel is communicated with the surface of the membrane; the fourth channel is provided with a second capillary, one end of the second capillary is communicated with the surface of the membrane, the other end of the second capillary is used for being communicated with a mass spectrometer, and a third pump for providing a third negative pressure P 3 is arranged in the mass spectrometer; the first negative pressure P 1, the second negative pressure P 2, the third negative pressure P 3 and the atmospheric pressure P 0 satisfy the following conditions: p 0＞P1＞P2＞P3.
Description
Technical Field
The scheme belongs to the technical field of mass spectrum sampling, and particularly relates to a segmented sampling device and an on-line monitoring mass spectrometer.
Background
Electron bombardment ion sources are mostly applied to gas chromatography-mass spectrometry technology for ionizing substances subjected to gas phase separation. However, gas chromatographic separations can result in long analysis times and electron bombardment ion sources are not suitable for direct analysis of air samples, which can cause loss of filaments in the ion source due to the presence of water oxygen.
The structures such as the membrane, the capillary tube and the membrane-capillary tube can reduce the sample amount or the water oxygen of the isolation part to a certain extent, but when the air sample is directly analyzed by whichever structure, the water oxygen in the gas entering the ion source is still very high, the loss to the filament is still very high, the inert gas (carrier gas) is required to be additionally provided for loading the sample into the ion source, the device which needs continuous, stable and real-time monitoring is not suitable, and the carrier gas has high use cost.
Disclosure of Invention
The scheme aims at overcoming at least one defect in the prior art, and provides a sectional sample injection device which is used for solving the problem that the existing sample injection structure cannot effectively separate water and oxygen in an air sample.
In order to solve the technical problems, the following technical scheme is adopted:
In a first aspect, a staging device is provided. The sectional sample injection device comprises a membrane, a first channel, a second channel and a third channel which are arranged on one side of a membrane plane, and a fourth channel which is arranged on the other side of the membrane plane; the first channel is provided with a first capillary, one end of the first capillary is communicated with the third channel, and the other end of the first capillary is provided with a tee joint structure; the first interface of the three-way structure is communicated with the first capillary, the second interface is used for being communicated with a sample gas sampling point, and the third interface is communicated with a first pump for providing a first negative pressure P 1; one end of the second channel is communicated with the third channel, and the other end of the second channel is communicated with a second pump for providing a second negative pressure P 2; one end of the third channel is communicated with the first channel, the other end of the third channel is communicated with the second channel, and one side of the third channel is communicated with the surface of the membrane; the fourth channel is provided with a second capillary, one end of the second capillary is communicated with the surface of the membrane, the other end of the second capillary is used for being communicated with a mass spectrometer, and a third pump for providing a third negative pressure P 3 is arranged in the mass spectrometer; the first negative pressure P 1, the second negative pressure P 2, the third negative pressure P 3 and the atmospheric pressure P 0 satisfy the following conditions: p 0＞P1＞P2＞P3.
According to the scheme, the multi-section pressure difference is formed in the combination of the capillary tube, the membrane and the capillary tube, compared with the single structural design of the membrane, the capillary tube, the membrane and the capillary tube in the prior art, the entry amount of water and oxygen in sample gas is greatly reduced, the method is particularly suitable for a mass spectrometer adopting an electron bombardment ion source, an air sample can be directly analyzed, the sample is loaded into the ion source without providing additional carrier gas, the service life of a filament cannot be influenced, and the vacuum degree in a mass spectrometry system can be fully ensured. In addition, the sample injection device has a small structure, and the installed capillary tube is short, so that the analysis speed is not influenced, and continuous, stable and real-time online monitoring is realized.
The first negative pressure P 1 is preferably between 1X 10 5 Pa and 1X 10 3 Pa, most preferably 4X 10 4 Pa, the second negative pressure P 2 is preferably between 1X 10 3 Pa and 1Pa, most preferably 200Pa, and the third negative pressure P 3 is preferably below 1X 10 -2 Pa, most preferably 1X 10 - 3 Pa, which is beneficial to further improving the water oxygen isolation capability of the device. The first pump may be a diaphragm pump, and the first negative pressure P 1 provided by the diaphragm pump is about 4×10 4 Pa; the second pump may be a mechanical pump, and the second negative pressure P 2 provided by the mechanical pump is about 200 Pa; the third pump may be a molecular pump, and the third negative pressure P 3 provided by the molecular pump is about 1×10 -3 Pa; in addition, other types of pumps may be used for the first, second and third pumps, provided that a stepped pressure (P 0＞P1＞P2＞P3) can be developed in the device and that the vacuum level of the mass spectrometer is ensured to meet operational requirements.
The membrane is clamped between the first fixing block and the second fixing block so as to be fixed. A sealing ring surrounding the membrane is arranged between the first fixing block and the second fixing block, so that sample gas is prevented from leaking out from between the first fixing block and the second fixing block. To further reduce the leakage probability, two coaxially arranged sealing rings are preferably arranged between the first and the second fixing blocks, which sealing rings can be fluorine-containing rubber rings. The first fixing block and the second fixing block can be fixedly connected with each other through fasteners such as screws, and therefore the sealing ring is compressed.
In order to fix the relative position between the membrane and the channels, the first channel and the second channel are arranged as pipelines arranged in the first fixed block, and the third channel is arranged as a groove arranged on the surface of the first fixed block. In order to improve the contact area between the third channel and the membrane, the third channel is in a snake shape, and the groove formed on the surface of the first fixed block is in a snake-shaped groove.
In order to enable sample gas to flow through the first channel and the fourth channel only from the capillary, one end of the first capillary communicated with the tee structure is fixed on a first interface of the tee structure through a first graphite compression ring, and one end of the surface of the second capillary communicated with the film is fixed on the fourth channel through a second graphite compression ring. In order to improve the sealing effect, the first graphite pressing ring is clamped between the tee structure and the first fixing block, and the second graphite pressing ring is clamped between the second fixing block and the third fixing block. In order to compress tightly the graphite clamping ring, the first interface of tee bend structure and first fixed block threaded connection, through fastener mutual fixed connection such as screw between second fixed block and the third fixed block. The second fixing block and the third fixing block are respectively provided with a pipeline forming a fourth channel, the second capillary tube is sleeved with a metal tube, and the metal tube is fixed in the pipeline of the third fixing block and plays a supporting and positioning role on the second capillary tube, so that the second capillary tube is not easy to deform.
The first channel and the second channel are perpendicular to the third channel, and a heating component positioned between the first channel and the second channel is arranged on the side of the third channel facing away from the membrane so as to heat the membrane and the first capillary tube to keep the membrane and the first capillary tube at a constant temperature. The heating assembly may be secured in a first fixed block provided with a fourth interface for connecting the second pump.
The membrane is preferably a PDMS semipermeable membrane supported by a metal mesh, which is preferably supported on the side of the membrane facing away from the third channel, to avoid deformation of the membrane over a large area.
The third interface of the tee structure is arranged downwards, so that large-particle water vapor and particles in the sample gas flow preferentially towards the outlet (the third interface) of the tee structure under the action of gravity, and the cleanliness of the first capillary tube is guaranteed.
In a second aspect, an on-line monitoring mass spectrometer is provided. The on-line monitoring mass spectrometer comprises a sample injection device, an ion source, a mass analyzer and an ion detector which are sequentially connected, wherein the sample injection device is the segmented sample injection device provided by the first aspect.
According to the sectional sample injection device, the sectional pressure difference is formed in the combination of the capillary tube, the membrane and the capillary tube, compared with the single structural design of the membrane, the capillary tube, the membrane and the capillary tube in the prior art, the entry amount of water oxygen in sample gas is greatly reduced, extra carrier gas is not required to be provided for loading the sample into an ion source, the air sample can be directly analyzed, and continuous, stable and real-time online monitoring is realized. The ion source can adopt electron bombardment ion source, and the filament in the electron bombardment ion source is preferably an alloy filament, which is beneficial to prolonging the service life of the filament.
Compared with the prior art, the scheme has the following beneficial effects: the multi-stage pressure difference is formed in the combination of the capillary tube, the film and the capillary tube, so that the entry amount of water and oxygen in the sample gas is greatly reduced, the method is particularly suitable for mass spectrometers adopting electron bombardment ion sources, air samples can be directly analyzed, extra carrier gas is not required to be provided for loading the samples into the ion sources, the service life of filaments is not influenced, and the vacuum degree in a mass spectrometry system can be fully ensured.
Drawings
The drawings are for illustrative purposes only and are not to be construed as limiting the present solution; for better illustration of the present solution, some parts of the figures may be omitted, enlarged or reduced, and do not represent the dimensions of the actual product; it will be appreciated by those skilled in the art that certain well-known structures in the drawings and descriptions thereof may be omitted.
Fig. 1 is a schematic structural diagram of a section sampling device.
Fig. 2 is a left side view of the first fixed block.
Fig. 3 is a schematic diagram of an on-line monitoring mass spectrometer.
Reference numerals illustrate: the membrane 100, the first channel 210, the first capillary 211, the first graphite press ring 212, the second channel 220, the fourth interface 221, the third channel 230, the fourth channel 240, the second capillary 241, the second graphite press ring 242, the metal tube 243, the three-way structure 300, the first interface 310, the second interface 320, the third interface 330, the heating assembly 400, the first fixing block 510, the second fixing block 520, the third fixing block 530, the sealing ring 501, the sample injection device 610, the ion source 620, the mass analyzer 630, the ion detector 640.
Detailed Description
In order to better understand the present solution, a further detailed description of the present solution will be provided below in conjunction with specific embodiments.
Fig. 1-2 illustrate one embodiment of a staging device. The device comprises a membrane 100, a first channel 210, a second channel 220, a third channel 230 and a fourth channel 240, wherein the first channel 210, the second channel 220 and the third channel 230 are arranged on one side of a plane of the membrane 100 (abbreviated as a plane of the membrane 100), and the fourth channel 240 is arranged on the other side of the plane of the membrane 100. The first channel 210 is provided with a first capillary tube 211, one end of the first capillary tube 211 is communicated with the third channel 230, and the other end of the first capillary tube 211 is connected with a three-way structure 300; the first port 310 of the three-way structure 300 is communicated with the first capillary tube 211, the second port 320 is used for communicating with a sample gas sampling point through a pipeline, and the third port 330 is communicated with a first pump for providing a first negative pressure P 1. The second passage 220 has one end connected to the third passage 230 and the other end connected to a second pump for supplying a second negative pressure P 2. One end of the third channel 230 is communicated with the first channel 210, the other end is communicated with the second channel 220, and a gas channel in which the first channel 210, the third channel 230 and the second channel 220 are sequentially communicated is formed; one side of the third channel 230 communicates with the surface of the membrane 100 so that the sample gas entering the gas channel can flow across the surface of the membrane 100 from one side of the membrane 100 to the other side of the membrane 100. The fourth channel 240 is provided with a second capillary 241, one end of the second capillary 241 is communicated with the surface of the membrane 100, and the other end is used for being communicated with a mass spectrometer, and a third pump for providing a third negative pressure P 3 is arranged in the mass spectrometer.
Wherein the inner diameter of the first capillary tube 211 is smaller than the inner diameter of the outlet of the first pump and the difference is larger, the amount of the sample gas entering the first capillary tube 211 can be reduced, and the total amount of the water oxygen in the sample gas contacting the membrane 100 when the sample gas passes through the third channel 230 can be reduced. The membrane 100 has an enrichment function, can increase the concentration of substances to be detected in the sample gas, has selectivity to the sample gas, is difficult for inorganic gas to pass through, and can reduce the transmittance of water and oxygen, thereby further reducing the consumption of the filament by the water and oxygen in the sample gas. More importantly, the first negative pressure P 1, the second negative pressure P 2, the third negative pressure P 3 and the atmospheric pressure P 0 satisfy: p 0＞P1＞P2＞P3, at least three sections of different pressure differences are formed in the sample injection process of the sample gas, so that the entry amount of water and oxygen in the sample gas is reduced to a greater extent.
The first stage pressure difference is formed between the sample gas sampling point (atmospheric pressure P 0) and the first pump (first negative pressure P 1). The negative pressure caused by the operation of the first pump causes the sample gas to be continuously conveyed from the sample gas sampling point to the three-way structure 300 near the first pump through the pipeline, i.e. to flow from high pressure to low pressure, and to be discharged by the first pump.
The second stage pressure difference is formed between the first pump (first negative pressure P 1) and the second pump (second negative pressure P 2). The negative pressure caused by the operation of the second pump sucks the sample gas entering the three-way structure 300 from the inlet end of the first capillary tube 211, and makes the sample gas pass through the first capillary tube 211, the third channel 230 and the second channel 220, finally reach the second pump and be discharged by the second pump.
The third stage pressure difference is formed between the second pump (second negative pressure P 2) and the third pump (third negative pressure P 3). The mass spectrometer ensures the vacuum degree of the vacuum cavity by the third pump, and the sample gas flows through the surface of the membrane 100 when passing through the third channel 230, wherein the components which can pass through the membrane 100 are directly led into the mass spectrometer through the second capillary 241 by the negative pressure of the third pump through the membrane 100, and the components which cannot pass through the membrane 100 are taken away by the second pump.
A pressure P 2' is also present between the second pump and the third pump, influenced by the second capillary 241. Because the second capillary 241 has a smaller inner diameter, there is a larger difference between the pressures at both ends, and the pressure P 2' near one end of the membrane 100 is between P 2 and P 3, which is specifically related to the inner diameter of the second section capillary, so that the sample gas actually forms a further pressure difference in the sample injection process.
The device forms a multistage pressure difference in the combination of the capillary tube, the membrane and the capillary tube, compared with the single structural design of the membrane, the capillary tube, the membrane and the capillary tube in the prior art, the entry amount of water and oxygen in the sample gas is greatly reduced, and the device is particularly suitable for a mass spectrometer adopting an electron bombardment ion source, can directly analyze an air sample, does not need to provide additional carrier gas to load the sample into the ion source, and does not influence the service life of a filament. The pressure difference of multistage formula reduces the pressure of sample gas step by step under the atmospheric pressure environment to the ion source simultaneously, can fully guarantee the vacuum in the mass spectrometry system. In addition, the device has a small structure, the installed capillary (comprising the first capillary 211 and the second capillary 241) is short, the analysis speed is not influenced, and the sample gas can be updated in time by using a plurality of pumps, so that the analysis time of the sample is not delayed, and continuous, stable and real-time online monitoring is realized.
The first pump may be a diaphragm 100 pump (limit negative pressure is about 4×10 4 Pa), and the second pump may be a mechanical pump (limit negative pressure is about 200 Pa); the third pump is a pump body of the mass spectrometer, is used for guaranteeing the vacuum degree of a vacuum cavity, and can adopt a molecular pump (the pressure is about 1 multiplied by 10 -3 Pa). In addition, other types of pumps may be used for the first, second and third pumps, provided that a stepped pressure (P 0＞P1＞P2＞P3) can be developed in the device and that the vacuum level of the mass spectrometer is ensured to meet operational requirements. The first negative pressure P 1 is preferably between 1X 10 5 Pa and 1X 10 3 Pa, most preferably 4X 10 4 Pa, the second negative pressure P 2 is preferably between 1X 10 3 Pa and 1Pa, most preferably 200Pa, and the third negative pressure P 3 is preferably below 1X 10 -2 Pa, most preferably 1X 10 -3 Pa, which is beneficial to further improving the water oxygen isolation capability of the device.
The second port 320 of the three-way structure 300, which is connected to the sample gas sampling point, is not only the inlet of the second port itself but also the sample inlet of the whole device, and under the negative pressure of the first pump connected to the third port 330, the sample gas can be rapidly pumped to the device, so that the sample injection time is shortened, and the gas in the pipeline is rapidly updated, so as to avoid cross contamination. The third port 330 of the three-way structure 300, which is connected to the first pump, is an outlet of the third port, the outlet is vertically downward, and during on-line monitoring, some large-particle water vapor and particles in the sample gas will preferentially flow towards the outlet of the three-way structure 300 under the action of gravity, so that the cleanliness of the first capillary tube 211 is ensured.
The first capillary 211 is connected with one end of the three-way structure 300 to form an inlet end, the second capillary 241 is connected with one end of the surface of the membrane 100 to form an inlet end, the inlet ends of the two capillaries are all fixed through graphite compression rings, wherein the inlet end of the first capillary 211 is fixed on the first interface 310 of the three-way structure 300 through the first graphite compression ring 212, the inlet end of the second capillary 241 is fixed on the fourth channel 240 through the second graphite compression ring 242, and the graphite compression rings ensure tightness, so that sample gas can only flow through the capillaries.
The sample gas flowing through the first capillary 211 flows through the surface of the membrane 100 via the third channel 230, and the third channel 230 may be configured in a serpentine shape so as to extend the distance the sample gas flows through, increase the contact area of the sample gas with the membrane 100, where the space design is compact, and reduce the memory effect due to dead volume.
The organic gas in the sample gas undergoes the process of adsorption and re-desorption on the membrane 100, and the substances in the sample gas possess a motive force to move toward the other side of the membrane 100 due to the pressure difference across the membrane 100. The side of the membrane 100 facing away from the third channel 230 may be supported by a metal mesh, avoiding deformation of the membrane 100 over a large area. In particular, the membrane 100 may be configured as a PDMS semi-permeable membrane 100.
When the components in the sample gas which can penetrate through the membrane 100 pass through the second capillary 241, the components are focused by the second capillary 241 and are conducted into an ion source of the mass spectrometer, so that the dispersion of the sample is reduced, and the substances to be detected in the sample can be ionized better.
The first channel 210 and the second channel 220 are perpendicular to the third channel 230, and a heating assembly 400 is provided at a side of the third channel 230 facing away from the membrane 100, between the first channel 210 and the second channel 220, and the heating assembly 400 includes a heating rod and a temperature sensor so as to heat the membrane 100 and the first capillary 211 and keep them at a constant temperature.
The film 100 may be fixed by the first fixing block 510 and the second fixing block 520. Specifically, the membrane 100 may be sandwiched between the first fixing block 510 and the second fixing block 520, and a sealing ring 501 surrounding the membrane 100 is disposed between the first fixing block 510 and the second fixing block 520, so as to prevent the sample gas from leaking out from between the first fixing block 510 and the second fixing block 520. To further reduce the leakage probability, two coaxially arranged sealing rings 501 are preferably arranged between the first fixing block 510 and the second fixing block 520, and the sealing rings 501 can be fluorine-containing rubber rings. The first fixing block 510 and the second fixing block 520 may be fixedly connected to each other by a fastener such as a screw, thereby compressing the sealing ring 501.
The first, second and third channels 210, 220 and 230 may be configured on the first fixing block 510. Specifically, both the first channel 210 and the second channel 220 may be configured as pipes opened in the first fixed block 510, the third channel 230 may be configured as grooves opened in the surface of the first fixed block 510, and the serpentine-shaped third channel 230 may be configured as a serpentine-shaped groove opened in the surface of the first fixed block 510. Thus, the relative positions of the first channel 210, the second channel 220, the third channel 230 and the membrane 100 can be determined, thereby facilitating assembly, disassembly and maintenance of the device.
The first capillary 211 and the second capillary 241 are consumable materials, and need to be replaced in time so as not to influence the analysis result. The resistance of the first capillary tube 211 can be changed by changing the inner diameter of the first capillary tube 211, so that the total amount of gas flowing through the first capillary tube 211 is changed, and the first capillary tube 211 with the proper inner diameter can be adapted to the test of samples under different environmental concentrations according to application scenes.
The first graphite clamping ring 212 can be clamped between the tee structure 300 and the first fixing block 510, so that the first graphite clamping ring 212 can be tightly pressed, a better sealing effect is achieved, and the first capillary tube 211 can be conveniently detached and replaced. The tee structure 300 can be fixed on the first fixing block 510 through threaded connection, so that the tee structure 300 is convenient to be connected with the first fixing block 510, and the first graphite compression ring 212 can be compressed. Specifically, an external thread located at the inlet end of the first channel 210 may be configured on the first fixing block 510, while an internal thread that mates with the external thread is configured at the first interface 310 of the three-way structure 300; internal threads on the first block 510 at the inlet end of the first channel 210 may also be provided, while external threads mating with the internal threads are provided on the first interface 310 of the three-way structure 300.
The second graphite pressing ring 242 can be clamped between the second fixing block 520 and the third fixing block 530, so that the second graphite pressing ring 242 can be pressed tightly, a better sealing effect is achieved, and the second capillary 241 can be detached and replaced conveniently. The second fixing block 520 and the third fixing block 530 may be fixedly connected to each other by a fastening member such as a screw, so as to compress the second graphite compression ring 242. The second fixing block 520 and the third fixing block 530 are both provided with a pipeline forming the fourth channel 240, the second capillary tube 241 is sleeved with a metal tube 243, and the metal tube 243 is fixed in the pipeline of the third fixing block 530 to support and position the second capillary tube 241, so that the second capillary tube 241 is not easy to deform.
The second pump may be connected to the first fixed block 510 and thus communicate with the second passage 220; accordingly, the first fixed block 510 is provided with a fourth port 221 at the outlet end of the second channel 220 for connection to the second pump. The heating assembly 400 may be fixed in the first fixing block 510, and accordingly, the first fixing block 510 is provided with a mounting groove facing away from the third passage 230 for mounting the heating assembly 400.
Fig. 3 illustrates one embodiment of an on-line monitoring mass spectrometer. The mass spectrometer comprises a sample injection device 610, an ion source 620, a mass analyzer 630 and an ion detector 640, which are connected in sequence. The sample injection device 610 adopts the above-mentioned segmented sample injection device 610, most of water and oxygen in the sample gas can be isolated in the sample injection process, and the air sample can be directly analyzed without additionally providing carrier gas to load the substance to be tested into the ion source 620, so that the air sample can be timely delivered to the ion source 620, and the components in the gas can be monitored in real time. The ion source 620 employs electrons to bombard the ion source 620, which can realize continuous and rapid on-line quantitative monitoring of the mixed compounds in the sample site gas. Since the segmented sample injector 610 isolates a substantial portion of the water and oxygen in the sample gas, which is beneficial to extending the life of the filament in the electron bombardment ion source 620, the filament may employ an alloy filament to further increase the life of the filament, thereby making the instrument more stable.
It is apparent that the above examples of the present solution are merely examples for clearly illustrating the present solution and are not limiting of the embodiments of the present solution. Other variations or modifications of the above teachings will be apparent to those of ordinary skill in the art. It is not necessary here nor is it exhaustive of all embodiments. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present solution should be included in the protection scope of the present solution claims.
Claims (10)
1. The sectional sample injection device is characterized by comprising a membrane, a first channel, a third channel, a second channel and a fourth channel, wherein the first channel, the third channel and the second channel are arranged on one side of a membrane plane, and the fourth channel is arranged on the other side of the membrane plane; the first channel is provided with a first capillary, one end of the first capillary is communicated with the third channel, and the other end of the first capillary is provided with a tee joint structure; the first interface of the tee joint structure is communicated with a first capillary, the second interface is used for being communicated with a sample gas sampling point, and the third interface is communicated with a first pump for providing a first negative pressure P 1; one end of the second channel is communicated with the third channel, and the other end of the second channel is communicated with a second pump for providing a second negative pressure P 2; one end of the third channel is communicated with the first channel, the other end of the third channel is communicated with the second channel, and one side of the third channel is communicated with the surface of the membrane; the fourth channel is provided with a second capillary, one end of the second capillary is communicated with the surface of the membrane, the other end of the second capillary is used for being communicated with a mass spectrometer, and a third pump for providing a third negative pressure P 3 is arranged in the mass spectrometer; the first negative pressure P 1, the second negative pressure P 2, the third negative pressure P 3 and the atmospheric pressure P 0 satisfy: p 0＞P1＞P2＞P3.
2. The sectioning point of claim 1, wherein the section of the sample feeding device,
The first negative pressure P 1 is between 1×10 5 Pa and 1×10 3 Pa, the second negative pressure P 2 is between 1×10 3 Pa and 1Pa, and the third negative pressure P 3 is below 1×10 -2 Pa; and/or the first pump is a diaphragm pump, the second pump is a mechanical pump, and the third pump is a molecular pump.
3. The sectioning point of claim 1, wherein the section of the sample feeding device,
One end of the first capillary tube communicated with the tee joint structure is fixed on a first interface of the tee joint structure through a first graphite compression ring; and/or
One end of the surface of the second capillary tube communication membrane is fixed on the fourth channel through a second graphite compression ring; and/or
The third channel is arranged in a snake shape; and/or
The first channel and the second channel are perpendicular to the third channel, and a heating component positioned between the first channel and the second channel is arranged on one side of the third channel, which is away from the membrane.
4. The sectioning point of claim 3, wherein the section of the sample feeding device,
The membrane is clamped between the first fixed block and the second fixed block, and a sealing ring surrounding the membrane is arranged between the first fixed block and the second fixed block; the first channel and the second channel are arranged as pipelines which are arranged in the first fixed block, and the third channel is arranged as a groove which is arranged on the surface of the first fixed block.
5. The sectioning point of claim 4, wherein,
The first graphite pressing ring is clamped between the tee joint structure and the first fixed block; and/or
The second graphite pressing ring is clamped between the second fixed block and the third fixed block; and/or
The heating component is fixed in the first fixed block; and/or
The first interface of the tee joint structure is in threaded connection with the first fixed block; and/or
The first fixed block is provided with a fourth interface for connecting a second pump.
6. The sectioning point of claim 5, wherein,
The second fixing block and the third fixing block are respectively provided with a pipeline forming a fourth channel, the second capillary tube is sleeved with a metal tube, and the metal tube is fixed in the pipeline of the third fixing block.
7. The sectioning point of claim 1 to 6,
The membrane is a PDMS semipermeable membrane; and/or
The membrane is supported by a metal mesh.
8. The sectioning point of claim 1 to 6,
The third interface of the tee joint structure is arranged downwards.
9. An on-line monitoring mass spectrometer comprising a sample injection device, an ion source, a mass analyzer and an ion detector connected in sequence, wherein the sample injection device is a segmented sample injection device according to any one of claims 1 to 8.
10. The on-line monitoring mass spectrometer of claim 9, wherein,
The ion source is an electron bombardment ion source, and filaments in the electron bombardment ion source are alloy filaments.
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| Application Number | Priority Date | Filing Date | Title |
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| CN202311679584.5A CN117936355A (en) | 2023-12-07 | 2023-12-07 | Sectional sample injection device and on-line monitoring mass spectrometer |
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| Application Number | Priority Date | Filing Date | Title |
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| CN202311679584.5A CN117936355A (en) | 2023-12-07 | 2023-12-07 | Sectional sample injection device and on-line monitoring mass spectrometer |
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| CN117936355A true CN117936355A (en) | 2024-04-26 |
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| CN202311679584.5A Pending CN117936355A (en) | 2023-12-07 | 2023-12-07 | Sectional sample injection device and on-line monitoring mass spectrometer |
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| Country | Link |
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