CN112509908A - Pulse type ionization mass spectrometer and analysis method - Google Patents
Pulse type ionization mass spectrometer and analysis method Download PDFInfo
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- CN112509908A CN112509908A CN202011474838.6A CN202011474838A CN112509908A CN 112509908 A CN112509908 A CN 112509908A CN 202011474838 A CN202011474838 A CN 202011474838A CN 112509908 A CN112509908 A CN 112509908A
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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
- H01J49/10—Ion sources; Ion guns
- H01J49/16—Ion sources; Ion guns using surface ionisation, e.g. field-, thermionic- or photo-emission
- H01J49/161—Ion sources; Ion guns using surface ionisation, e.g. field-, thermionic- or photo-emission using photoionisation, e.g. by laser
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
- H01J49/00—Particle spectrometers or separator tubes
- H01J49/0027—Methods for using particle spectrometers
- H01J49/0031—Step by step routines describing the use of the apparatus
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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
Abstract
The invention discloses a pulse ionization mass spectrometer and an analysis method, comprising the following steps: the vacuum chamber body, install the ultraviolet lamp in the vacuum chamber body and have the ion analyzer module in ionization region, the ultraviolet lamp shines the direction orientation the ionization region of ion analyzer module, be equipped with the light source control module of switch between ultraviolet lamp and the ionization region, close light source control module can interrupt or weaken the light that the ultraviolet lamp shines to the ionization region. The invention can generate non-continuous pulse ionization by controlling the on and off of the light source control module, so that the ionization is only carried out in the ionization stage, the defect that ions are not sufficiently cooled or still generate ions in the scanning stage caused by continuous ionization is reduced, the noise generated by ultraviolet lamp photoelectrons in the scanning stage is reduced, and the measurement precision is improved.
Description
Technical Field
The invention relates to the field of detection of substance component analysis by using mass spectrometry, in particular to a pulse type photoionization ionization mass spectrometry instrument and an analysis method thereof.
Background
A mass spectrometer is an instrument for qualitative and quantitative analysis of a substance by ionizing the substance into ions and then separating the ions using an electromagnetic field. With the continuous development of mass spectrometry technology and the continuous increase of the demand of field in-situ detection, the research of small mass spectrometers capable of realizing field rapid detection is also more and more extensive. The mass spectrometer core component comprises an ionization source, an analyzer and a detection device. The ion trap analyzer is an ideal analyzer for mass spectrum miniaturization due to its small structure and high gas pressure tolerance, and can meet different application requirements by matching with different ion sources.
Among various ion sources, the ionization of a vacuum ultraviolet lamp is a soft ionization technology for realizing the ionization of gas molecules by utilizing the photoelectric effect, and can be used for the ionization of gas-phase molecules. In vacuum ultraviolet light ionization mass spectrometry, sample molecules absorb a single vacuum ultraviolet photon with certain energy and are ionized near the ionization energy threshold to generate gas ions. This type of ionization can avoid or reduce the generation of fragment ions and is the most stable ion source for mass spectrometers that could otherwise perform ion dissociation functions. Therefore, the high-sensitivity vacuum ultraviolet ionization mass spectrometer is widely applied to the field real-time detection and analysis fields of Volatile Organic Compound (VOC) detection in the atmosphere, explosive detection, industrial process detection and the like.
The existing ionization source of a vacuum ultraviolet lamp is used in a mass spectrometer, and the instrument structure mainly comprises two types:
one is that the ultraviolet light emitted by the vacuum ultraviolet lamp ionization source directly acts with the sample molecules in the analyzer, and the ions are directly generated in the analyzer and are then analyzed after being bound by the analyzer.
One is that the ultraviolet light emitted by the vacuum ultraviolet lamp ionization source reacts with the sample molecules in the ionization chamber, and the generated ions are led out from the ionization chamber, then pass through a series of focusing and transmitting lenses and pipelines to reach the analysis device, and are detected by the detector after being analyzed.
In the two schemes, because the on-off control of the ultraviolet lamp is slow and cannot match the working time sequence of the analyzer, most of the ultraviolet light is continuously irradiated in the whole detection period of the mass spectrometer, which means that ions are continuously generated in the whole detection period, including the subsequent analysis and detection stages. The continuously generated sample ions can cause interference to the subsequent analysis and detection stages, the macroscopic interference comprises the sharp rise of the bottom noise of the spectrogram, and the target peak is submerged. Therefore, the method has important significance for optimizing the ionization source of the vacuum ultraviolet lamp.
Disclosure of Invention
The invention provides a pulse ionization mass spectrometer and an analysis method, aiming at solving the technical problem of interference caused by continuous irradiation of an ultraviolet lamp in the prior art.
The technical scheme adopted by the invention is as follows:
the invention provides a pulse type ionization mass spectrometer, which comprises: the vacuum chamber body, install the ultraviolet lamp in the vacuum chamber body and have the ion analyzer module in ionization region, the ultraviolet lamp shines the direction orientation the ionization region of ion analyzer module, be equipped with the light source control module of switch between ultraviolet lamp and the ionization region, close light source control module can interrupt or weaken the light that the ultraviolet lamp shines to the ionization region.
Further, the light source control module is a switchable shutter, or a movable baffle, a valve, or an optical lens.
The ion analyzer module includes: the ion trap comprises two ion gates arranged in parallel at intervals, wherein the middle of each ion gate is provided with a light through hole, and a radio-frequency electrode which is arranged between the two ion gates and used for ion constraint and analysis, the radio-frequency electrode and the ion gates jointly enclose an ionization region and an analysis region, and the axis direction of the light through holes of the two ion gates is the same as the light irradiation direction of an ultraviolet lamp.
Preferably, the radio-frequency electrode is a radio-frequency electrode consisting of a ring-shaped polar plate, and the shape of the radio-frequency electrode is cylindrical or internally hyperbolic.
Preferably, the radio-frequency electrode is a radio-frequency electrode consisting of four separated electrode plates, and the shape of the radio-frequency electrode is cylindrical or hyperbolic.
The invention also includes an ion detector mounted within the vacuum chamber. Specifically, there are two embodiments:
the first embodiment: the ion detector is positioned outside the ion gate on one side far away from the ultraviolet lamp, and an opening on the ion gate is aligned with the ion detector.
The second embodiment: the ion detector is positioned beside the radio frequency electrode, and the radio frequency electrode is provided with a small hole or a slit for the ion to exit to the ion detector.
The invention also provides an analysis method of the pulse ionization mass spectrometer, which specifically comprises the following steps:
turning on the ultraviolet lamp to control the sample to enter an ionization region of the ion analyzer module;
turning on a light source control module to ionize the sample into ions by an ultraviolet lamp;
the light source control module is closed, and the ionized ions are bound by the ion analyzer module to be subjected to ion analysis;
and after the analysis is finished, emptying the ion analyzer module, and opening the light source control module for next sample introduction and analysis.
Compared with the prior art, the invention generates non-continuous pulse ionization by controlling the on and off of the light source control module, so that the ionization is only carried out in the ionization stage controlled by a time sequence, the defect that the ions are not sufficiently cooled or still generate ions in the scanning stage caused by continuous ionization is reduced, and the noise generated by the photoelectrons of the ultraviolet lamp in the scanning stage is reduced.
Drawings
In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings needed to be used in the embodiments or the prior art descriptions will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without inventive exercise.
FIG. 1 is a diagram illustrating a light source control module according to an embodiment of the present invention;
FIG. 2 is a schematic diagram illustrating turning off of a light source control module according to an embodiment of the present invention;
FIG. 3 is a schematic diagram illustrating the molecular state of a sample when a light source control module is turned off according to an embodiment of the present invention;
FIG. 4 is a diagram illustrating the molecular state of a sample when a light source control module is turned on according to an embodiment of the present disclosure;
FIG. 5 is a diagram illustrating the ion amount and shutter state at various stages according to an embodiment of the present invention.
Detailed Description
In order to make the technical problems, technical solutions and advantageous effects to be solved by the present invention more clearly apparent, the present invention is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.
In the description of the present invention, it is to be understood that the terms "center", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", and the like, indicate orientations and positional relationships based on those shown in the drawings, and are used only for convenience in describing the present invention and simplifying the description, but do not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and thus, should not be construed as limiting the present invention.
In the description of the present invention, it should be noted that, unless otherwise explicitly specified or limited, the terms "mounted," "connected," and "connected" are to be construed broadly, e.g., as meaning either a fixed connection, a removable connection, or an integral connection; can be mechanically or electrically connected; either directly or indirectly through intervening media, either internally or in any other relationship. The specific meanings of the above terms in the present invention can be understood by those skilled in the art according to specific situations.
The principles and construction of the present invention will be described in detail below with reference to the drawings and examples.
As shown in fig. 1 to 4, the present invention provides a pulsed ionization mass spectrometer, which is specifically ionized in vacuum, and can also be applied in non-vacuum. The method specifically comprises the following steps: the device comprises a vacuum cavity, an ultraviolet lamp 1, an ion analyzer module and a light source control module 2, wherein the ultraviolet lamp 1 and the ion analyzer module are installed in the vacuum cavity, and the irradiation direction of the ultraviolet lamp 1 faces to an ionization region of the ion analyzer module, so that ultraviolet light generated by the ultraviolet lamp 1 can enter the ionization region to ionize sample molecules. A light source control module 2 is arranged between an ultraviolet lamp 1 and an ionization region, the light source control module 2 can be opened and closed, ultraviolet light generated by the ultraviolet lamp can normally enter the ionization region when the ultraviolet lamp is opened, and light rays irradiated to the ionization region by the ultraviolet lamp can be interrupted or weakened when the ultraviolet lamp is closed, so that photons generated by the ultraviolet lamp 1 cannot continuously enter the ionization region, sample molecules in the ionization region stop an ionization process, and no new ions are generated. Therefore, the non-continuous pulse ionization is generated by controlling the on and off of the light source control module, the ionization is only carried out in the ionization stage, the defect that ions are not sufficiently cooled or still generate ions in the scanning stage due to continuous ionization is reduced, and the noise generated by ultraviolet lamp photoelectrons in the scanning stage can be reduced.
The ion analyzer module includes: two ion gates with light through holes in the middle and a radio frequency electrode arranged between the two ion gates are arranged in parallel at intervals. The ion gate is specifically: an upper ion gate 3 and a lower ion gate 6. The radio frequency electrode is used for ion confinement and analysis, and the radio frequency electrode and the ion gate jointly enclose an ionization region and an analysis region. And the axial direction of the light through holes of the two ion doors is the same as the light irradiation direction of the ultraviolet lamp, so that the irradiation light of the ultraviolet lamp can pass through the light through holes on the ion doors to enter an ionization region.
The radio-frequency electrode is cylindrical or internally hyperbolic, consists of four separated polar plates, specifically comprises a left polar plate 4, a right polar plate 7, a front polar plate and a rear polar plate 5, and is an ionization region which is a region enclosed by two ion gates and four polar plates and is also an analysis region.
The rf electrode may also be an rf electrode formed of a one-piece annular plate, and any arrangement that can be used for ion confinement and analysis is within the scope of the present invention.
The sample molecules are located in the ionization region into which ultraviolet light can enter from the upper ion gate 3. The light source control module 2 is disposed outside the upper ion gate 3 and between the upper ion gate 3 and the ultraviolet lamp 1. Therefore, the passing and blocking of the ultraviolet light can be controlled by switching the light source control module.
The light source control module 2 is specifically a switchable shutter, a valve, or the like, and can also be a movably adjustable baffle and an optical lens, wherein the ultraviolet light can be weakened when the optical lens is adopted for shielding, and the same effect can be achieved. In addition to these structures, any structure that can block or weaken ultraviolet light so that ions in the ionization region cannot be ionized is within the scope of the present invention.
In a specific embodiment, the ion analyzer module is an ion trap, such as a linear ion trap.
An ion detector is also arranged in the vacuum cavity, ultraviolet light and sample molecules directly act in the ion analyzer, and ions are directly generated in the ion analyzer and then detected by the ion detector after being analyzed. Meanwhile, the structure of the ion analyzer module is not limited to the linear ion trap, and can be any other kind of ion trap, and the invention is within the protection scope of the invention.
There are two different embodiments of the specific mounting location of the ion detector.
In the first embodiment, the ion detector is located outside the ion gate on the side away from the uv lamp, i.e. outside the lower ion gate 6, and the light-passing aperture on the ion gate is aligned with the ion detector, so that ions can enter the ion detector from the light-passing aperture.
In the second embodiment, the ion detector is mounted on a radio frequency electrode, which may be any one of the left electrode plate 4, the right electrode plate 7, the front electrode plate and the back electrode plate 5, and the radio frequency electrode is provided with a slit or a small hole corresponding to the ion detector, so that ions can exit to the ion detector through the slit or the small hole.
As shown in fig. 5, the whole detection cycle includes a sample injection phase, an ionization phase, a cooling phase, a scanning phase and an emptying phase, the light source control module can be controlled by the controller to be kept open in the ionization phase, and kept closed in the sample injection, cooling, scanning and emptying phases, and the sample molecules enter the ion analyzer in the sample injection phase, but because the shutter is in a closed state, no ions are generated in this phase. During the ionization phase, the shutter is opened, ions are continuously generated during this phase, and the generated ions are bound in the ion analyzer by the electric field. During the cooling phase, the shutter is closed and no new ions are generated at this stage. In the scanning stage, the shutter is in a closed state, and the previous ions are sequentially scanned out of the ion analyzer according to the mass-to-charge ratio, and the ions are reduced in a step shape. Thereby avoiding the generation of noise signals and signal interference during the scanning stage.
The invention also provides an analysis method of the pulse ionization mass spectrometer, which specifically comprises the following steps: firstly, turning on an ultraviolet lamp, and controlling a sample to enter an ionization region of an ion analyzer module; opening a valve of the light source control module to enable the sample to be ionized into ions by the ultraviolet lamp; turning off the light source control module, and restraining the ionized ions by the ion analyzer module; the ion analyzer module performs mass analysis, and the ultraviolet lamp is blocked at the moment, so that the mass analysis of the ion analyzer module is not influenced; and after the analysis is finished, emptying the ion analyzer module, and opening a valve of the light source control module to perform next sample introduction and analysis.
The invention can generate ions only in a pulse mode at a designated time sequence stage, thereby overcoming the inherent defects that the ions are continuously generated and noise signals are continuously generated during mass analysis in the prior art; the defects that the existing ultraviolet lamp ionization scheme can continuously generate interference signals of photoelectrons in the mass analysis stage of the ion trap mass spectrum and the like are overcome.
The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents and improvements made within the spirit and principle of the present invention are intended to be included within the scope of the present invention.
Claims (8)
1. A pulsed ionization mass spectrometer comprising: the utility model provides a vacuum chamber, install the ultraviolet lamp in vacuum chamber and have the ion analyzer module in ionization region, the ultraviolet lamp shines the direction orientation the ionization region of ion analyzer module, its characterized in that, be equipped with the light source control module of switch between ultraviolet lamp and the ionization region, close light source control module can break off or weaken the light that the ultraviolet lamp shines to the ionization region.
2. The pulsed ionization mass spectrometer of claim 1, wherein the ion analyzer module comprises: the ion trap comprises two ion gates arranged in parallel at intervals, wherein the middle of each ion gate is provided with a light through hole, and a radio-frequency electrode which is arranged between the ion gates and used for ion constraint and analysis, the radio-frequency electrode and the ion gates jointly enclose an ionization region and an analysis region, and the axial direction of the light through holes of the two ion gates is the same as the light irradiation direction of an ultraviolet lamp.
3. The pulsed ionization mass spectrometer of claim 1 wherein the light source control module is a switchable shutter, or a movable shutter, valve, optical lens.
4. The pulsed ionization mass spectrometer of claim 2 wherein the rf electrode is an rf electrode comprising a ring-shaped plate, the electrode being cylindrical or internally hyperbolic.
5. The pulsed ionization mass spectrometer of claim 2 wherein the rf electrode is an rf electrode comprising four separate plates, the electrode being cylindrical or hyperbolic in shape.
6. The pulsed ionization mass spectrometer of claim 2 further comprising an ion detector mounted in the vacuum chamber, said ion detector being located outside an ion gate on a side remote from the ultraviolet lamp, the ion gate having an opening aligned with the ion detector.
7. The pulsed ionization mass spectrometer of claim 2 further comprising an ion detector mounted in the vacuum chamber, said ion detector being located adjacent to the rf electrode, said rf electrode having an aperture or slit for exit of ions to the ion detector.
8. An analysis method using a pulsed ionization mass spectrometer according to any one of claims 1 to 7, comprising the steps of:
turning on the ultraviolet lamp to control the sample to enter an ionization region of the ion analyzer module;
turning on a light source control module to ionize the sample into ions by an ultraviolet lamp;
the light source control module is closed, and the ionized ions are bound by the ion analyzer module to be subjected to ion analysis;
and after the analysis is finished, emptying the ion analyzer module, and opening the light source control module for next sample introduction and analysis.
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Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104143495A (en) * | 2013-05-07 | 2014-11-12 | 许洋 | Automatic control system of mass spectrometer core component |
| US20170243728A1 (en) * | 2014-10-17 | 2017-08-24 | Thermo Fisher Scientific (Bremen) Gmbh | Method and Apparatus for the Analysis of Molecules Using Mass Spectrometry and Optical Spectroscopy |
| CN108198743A (en) * | 2018-01-11 | 2018-06-22 | 清华大学深圳研究生院 | A kind of vacuum ionization noncontinuity sampling device and method for gas detection |
| CN112259440A (en) * | 2020-10-29 | 2021-01-22 | 上海裕达实业有限公司 | Vacuum ultraviolet internal ionization mass spectrometry device and mass spectrometry method |
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Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104143495A (en) * | 2013-05-07 | 2014-11-12 | 许洋 | Automatic control system of mass spectrometer core component |
| US20170243728A1 (en) * | 2014-10-17 | 2017-08-24 | Thermo Fisher Scientific (Bremen) Gmbh | Method and Apparatus for the Analysis of Molecules Using Mass Spectrometry and Optical Spectroscopy |
| CN108198743A (en) * | 2018-01-11 | 2018-06-22 | 清华大学深圳研究生院 | A kind of vacuum ionization noncontinuity sampling device and method for gas detection |
| CN112259440A (en) * | 2020-10-29 | 2021-01-22 | 上海裕达实业有限公司 | Vacuum ultraviolet internal ionization mass spectrometry device and mass spectrometry method |
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