CN113903651B - Device for eliminating air flow in linear ion trap - Google Patents
Device for eliminating air flow in linear ion trap Download PDFInfo
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- CN113903651B CN113903651B CN202111153528.9A CN202111153528A CN113903651B CN 113903651 B CN113903651 B CN 113903651B CN 202111153528 A CN202111153528 A CN 202111153528A CN 113903651 B CN113903651 B CN 113903651B
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- linear ion
- air flow
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- 238000005040 ion trap Methods 0.000 title claims abstract description 50
- 238000011144 upstream manufacturing Methods 0.000 claims abstract description 5
- 150000002500 ions Chemical class 0.000 claims description 70
- 230000003287 optical effect Effects 0.000 claims description 17
- 230000033001 locomotion Effects 0.000 claims description 4
- 229910001220 stainless steel Inorganic materials 0.000 claims description 4
- 239000010935 stainless steel Substances 0.000 claims description 4
- 238000012876 topography Methods 0.000 claims 1
- 230000005540 biological transmission Effects 0.000 abstract description 7
- 230000005684 electric field Effects 0.000 description 5
- 239000011148 porous material Substances 0.000 description 4
- 239000012491 analyte Substances 0.000 description 3
- 238000004458 analytical method Methods 0.000 description 3
- 238000010586 diagram Methods 0.000 description 3
- 230000000694 effects Effects 0.000 description 3
- 238000000034 method Methods 0.000 description 3
- 230000035945 sensitivity Effects 0.000 description 3
- 230000002411 adverse Effects 0.000 description 2
- 238000013459 approach Methods 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 230000007935 neutral effect Effects 0.000 description 2
- 238000005086 pumping Methods 0.000 description 2
- 102000004310 Ion Channels Human genes 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000013461 design Methods 0.000 description 1
- 238000000688 desorption electrospray ionisation Methods 0.000 description 1
- 238000000132 electrospray ionisation Methods 0.000 description 1
- 238000004949 mass spectrometry Methods 0.000 description 1
- 238000001819 mass spectrum Methods 0.000 description 1
- 230000000116 mitigating effect Effects 0.000 description 1
- 238000011160 research Methods 0.000 description 1
- 238000000926 separation method Methods 0.000 description 1
Classifications
-
- 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
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
- H01J49/00—Particle spectrometers or separator tubes
- H01J49/02—Details
- H01J49/06—Electron- or ion-optical arrangements
- H01J49/067—Ion lenses, apertures, skimmers
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
- H01J49/00—Particle spectrometers or separator tubes
- H01J49/02—Details
- H01J49/24—Vacuum systems, e.g. maintaining desired pressures
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- Chemical & Material Sciences (AREA)
- Analytical Chemistry (AREA)
- Physics & Mathematics (AREA)
- Engineering & Computer Science (AREA)
- Plasma & Fusion (AREA)
- Other Investigation Or Analysis Of Materials By Electrical Means (AREA)
- Electron Tubes For Measurement (AREA)
Abstract
The invention provides a device for eliminating air flow in a linear ion trap, which comprises a device body, wherein the device body comprises four electrodes with the same internal morphology, the electrodes are rotationally symmetrical about a common symmetry axis, the symmetry axis is perpendicular to the symmetry axis of the linear ion trap, and the device body is arranged at the upstream of the linear ion trap. The invention solves the problem of the influence of the air flow on the ion trap without sacrificing the transmission efficiency and the resolution, and simultaneously does not change or complicate the time sequence of the mass spectrometer.
Description
Technical Field
The invention relates to the technical field of mass spectrometry instruments, in particular to a device for eliminating air flow in a linear ion trap.
Background
In a common design of ion trap mass spectrometers with an atmospheric pressure interface, the performance of the mass spectrometer is affected by the gas flow field, resulting in a decrease in resolution and mass accuracy. Eliminating or mitigating the effects of gas flow on ion trap mass analyzers is one of the important research aspects.
In patent document publication number CN101820979B, a method of interfacing an atmospheric pressure ion source including an electrospray ionization source and a desorption electrospray ionization source with a mass spectrometer, such as a small mass spectrometer, is disclosed, wherein an ionized sample is introduced into the mass spectrometer in a discontinuous manner. Ion introduction and trapping stage, since a large amount of gas is still introduced, the ion trap must be turned off to drive the rf power supply and the high voltage of the detector, which causes ion loss; and, because ions cannot be introduced continuously during the mass analysis stage, the efficiency (duty cycle) of the ion trap is reduced when a continuous ionization source (e.g., ESI) is used.
A continuous sample introduction atmospheric pressure interface two-stage vacuum ion trap mass spectrometer is disclosed in the publication CN109256321a, which comprises a two-stage vacuum chamber. The first-stage vacuum chamber comprises a continuous sample introduction atmospheric pressure interface and a radio frequency ion guide device, the second-stage vacuum chamber comprises an electrostatic electrode, an ion trap and an ion detector, and the two-stage vacuum chambers are connected by adopting an open-pore electrode. The electrostatic electrode can keep the ion trap away from the open-pore electrode for a certain distance or deflect for a certain angle, so that the ion trap is prevented from being directly impacted by the air flow from the first-stage vacuum cavity, and the ion trap is ensured to have enough stability and resolution; meanwhile, the electrostatic electrode is adopted, so that the control circuit is simple in requirement. But this approach does not essentially eliminate the gas flow.
An atmospheric pressure interface ion source and mass spectrometer are disclosed in patent document publication No. CN102903595 a. The atmospheric pressure interface ion source comprises a capillary tube with one end extending into the mass spectrometer and the other end arranged in the atmosphere and a repulsive electrode, wherein the air pressure difference between the mass spectrometer and the atmosphere enables sample ions to form sample ion flow, the sample ions are sucked into the mass spectrometer through the capillary tube, an included angle alpha between the capillary tube and a mass analyzer of the mass spectrometer is 80-150 degrees, the repulsive electrode is arranged on the outer side of the included angle alpha, a direct current voltage of 110-380 volts is applied to the repulsive electrode, and the flying direction of the sample ions with small kinetic energy in the sample ion flow passing through the capillary tube is changed by 180-alpha degrees and then enters the mass analyzer. The method reduces the influence of air flow on the mass analyzer, and simultaneously loses ions with larger kinetic energy, thereby having adverse influence on the sensitivity of the instrument. In addition, ion deflection occurs at higher gas pressure conditions, which also causes problems of lower deflection efficiency.
An ion deflection apparatus for use in a mass spectrometer is disclosed in the patent publication CN104412356a and consists of two sets of lenses and a set of deflection electrodes. The ion optical axes of the two groups of lens groups are 90 degrees, and the deflection electrode is positioned at the intersection point of the ion optical axes of the two groups of lens groups. When the ion flow is used, the ion flow is incident from one group of lens groups, the ion flow is led into the deflection electrode after being focused, the deflection electrode consists of two electrodes, the internal appearance is plane, a direct current electric field is arranged between the two electrodes, and the ion flow is deflected for 90 degrees under the action of the direct current electric field and led out after being focused by the second group of lens groups, so that the separation of the ion flow and the air flow is realized. The ion flow is led into the deflection electrode after being focused in advance, so that the deflection efficiency of the ion flow is higher, but the direct current deflection mode still has the problem of discriminating the kinetic energy because the lens group can not realize the modulation of the axial kinetic energy of the ions.
In summary, the related art in the above description is generally divided into three types: one is to set ion transmission device (such as DC lens or RF ion guide) before ion trap mass analyzer to make ion trap far away from gas source to reduce the influence of gas on ion trap; or by reducing the pore size, thereby reducing the intensity of the air flow through the pores. This approach can lead to a decrease in sensitivity. The second is to set a valve in the upstream of the ion channel, such as the atmospheric pressure or the lens with holes in the middle of the two-stage vacuum cavity, and the working time sequence of the valve is controlled by the working stage of the ion trap: opening an ion passage in an ion capturing stage, and normally introducing ions into an ion trap; in the mass analysis stage, the ion passage is closed, and the influence of the air flow on the ion trap is stopped. This has the negative effect of being inefficient because the ion path is blocked, resulting in subsequent ion traps not being normally introduced. Thirdly, the ion is separated from the neutral gas by applying an electric field under the condition of higher air pressure on the ion transmission path, which has the defect that: one is inefficient in deflection and the other is having kinetic energy discrimination. Therefore, a technical solution is needed to improve the above technical problems.
Disclosure of Invention
In view of the shortcomings of the prior art, it is an object of the present invention to provide a device for eliminating gas flow in a linear ion trap.
The device for eliminating the airflow in the linear ion trap comprises a device body, wherein the device body comprises four electrodes with the same internal morphology, the electrodes are rotationally symmetrical about a common symmetry axis, the symmetry axis is perpendicular to the symmetry axis of the linear ion trap, and the device body is arranged at the upstream of the linear ion trap.
Preferably, the internal morphology of the four electrodes of the device body is circular, hyperbolic, parabolic.
Preferably, the device body is fitted with a shield case.
Preferably, voltages are applied to four electrodes of the device body, and the movement track of ions in the device body is deflected by 90 degrees under the pressure of 0.1pa to 0.001pa.
Preferably, the voltage is a direct current voltage or a voltage that is linearly scanned over time.
Preferably, the four electrodes of the device body are placed parallel to each other.
Preferably, the device body is provided as an ion optical lens group.
Preferably, the apparatus further comprises a mass spectrometer comprising a first stage vacuum chamber and a second stage vacuum chamber and an ionization source at atmospheric pressure, one end of a stainless steel capillary tube being at atmospheric pressure and the other end being within the first stage vacuum chamber.
Preferably, a molecular pump is arranged at the bottom of the second-stage vacuum cavity, one end of a forepump of the molecular pump is connected with the molecular pump, and the other end of the forepump of the molecular pump is connected with the first-stage vacuum cavity.
Preferably, an ion optical lens with holes is arranged between the first-stage vacuum cavity and the second-stage vacuum cavity.
Compared with the prior art, the invention has the following beneficial effects:
the invention solves the problem of the influence of the air flow on the ion trap without sacrificing the transmission efficiency and the resolution, and simultaneously does not change or complicate the time sequence of the mass spectrometer.
Drawings
Other features, objects and advantages of the present invention will become more apparent upon reading of the detailed description of non-limiting embodiments, given with reference to the accompanying drawings in which:
FIG. 1 is a schematic illustration of the apparatus of the present invention as applied to a particular mass spectrometer;
fig. 2 is a schematic diagram of a suitable voltage applied to the electrodes of the device of the present invention.
Detailed Description
The present invention will be described in detail with reference to specific examples. The following examples will assist those skilled in the art in further understanding the present invention, but are not intended to limit the invention in any way. It should be noted that variations and modifications could be made by those skilled in the art without departing from the inventive concept. These are all within the scope of the present invention.
The invention aims to provide a device formed by an ion optical lens group and a method for applying voltage, and the device for eliminating the adverse effect of air flow on a linear ion trap.
Fig. 1 is a schematic diagram of an apparatus for eliminating gas flow in a linear ion trap according to the present invention in a specific mass spectrometer. The mass spectrometer is structurally composed of a first-stage vacuum cavity 2, a second-stage vacuum cavity 3 and an ionization source 4 at atmospheric pressure. One end of a stainless steel capillary tube 1 is positioned at atmospheric pressure, the other end is positioned in a first-stage vacuum cavity 2, and the specific size is as follows: 0.18mm i.d.times.200 mm. One molecular pump with pumping speed of 67L/s is positioned at the bottom of the second-stage vacuum cavity 3, one end of a front-stage pump of the molecular pump is connected with the molecular pump, and the other end of the front-stage pump of the molecular pump is connected with the first-stage vacuum cavity 2. The pumping speed of the backing pump was 20L/min. Between the two vacuum cavities, there is an ion optical lens 5 with holes, the aperture is 0.2mm-0.5mm. Under such a vacuum system configuration, the air pressure in the first stage vacuum chamber is 120pa to 180pa, and the air pressure in the second stage vacuum chamber 3 is 0.1pa to 0.001pa.
In one embodiment, analyte ions generated by an ionization source 4 at atmospheric pressure are introduced into the first stage vacuum chamber 2 via capillary 1 along with neutral gas, and a portion of the gas is entrained with the analyte ions along an ion optical axis 7 into the one means for eliminating the flow of gas within the linear ion trap 8 by the split flow of the apertured ion optical lens 5. Since a suitable dc voltage has been applied to the electrodes of the device 8 in advance, the ion flow is deflected by 90 ° in its motion trajectory by the dc field, and is introduced into the interior of the linear ion trap 10 along the optical axis 6 of the linear ion trap 10, captured by the linear ion trap 10, and during the mass analysis phase, the captured ions are extracted from the linear ion trap 10 in a resonance expulsion manner and form a mass spectrum on the ion detector 11.
Fig. 2 is a schematic diagram of a means for eliminating gas flow in a linear ion trap according to the present invention by applying a suitable voltage to electrodes 9, 13, 14, 15 placed parallel to each other and rotationally symmetrical about an axis of symmetry 16. The electrodes 13, 9, 14 apply positive polarity voltages, and the electrode 15 applies negative polarity voltages. Ions are introduced along the trajectory 12 from the gap between the negative polarity voltage applying electrode 15 and the positive polarity voltage applying electrode 13, and are extracted along the gap between the negative polarity voltage applying electrode 15 and the positive polarity voltage applying electrode 14 under the action of the electric field force.
In the above embodiment, the analyte ions trapped by the air flow are strongly affected by the air flow, so that the distribution of the kinetic energy of the ions is wider. If the voltages applied to the electrodes 9, 13, 14, 15 are dc voltages, kinetic energy discrimination is caused, i.e. only ions of suitable kinetic energy can be deflected effectively, ions of too small kinetic energy are directly lost to the electrode 15 of negative polarity, for example positive ions; ions with excessive kinetic energy are drawn directly from the gap between the positive polarity voltage applying electrode 9 and the positive polarity voltage applying electrode 14 with the gas flow as they are not effectively deflected.
To solve this problem, the positive polarity voltages on the electrodes 13, 9, 14 are scanned linearly. The voltage polarity is kept unchanged and the amplitude of the voltage increases linearly with time. Therefore, the low-kinetic-energy ions and the high-kinetic-energy ions can be considered to the greatest extent, the deflection of ions in a wider kinetic energy range is realized, and the sensitivity of the instrument is improved.
The symmetry axis is vertical to the symmetry axis of the linear ion trap, the device is arranged at the upstream of the linear ion trap, proper voltage is applied to four electrodes of the device, 90-degree deflection of ions in the motion track of the device is realized under the pressure of 0.1pa-0.001pa, the four electrodes of the device are circular, hyperbolic and parabolic in internal appearance, the device is provided with a shielding box, and the proper voltage is direct-current voltage or voltage for linear scanning along with time.
The ion transmission path is changed by arranging an ion optical lens group at the front end of the ion trap mass analyzer and applying a proper voltage signal to the ion optical lens group, so that ions are extracted from the air flow and introduced into the linear ion trap mass analyzer. The ion optical lens group consists of four electrodes with the same internal morphology and is provided with a rotation symmetry structure, and the rotation symmetry axis of the ion optical lens group is perpendicular to the ion optical symmetry axis of the linear ion trap mass analyzer. The voltage signal can be a direct current signal or a voltage signal which is synchronously and linearly scanned along with time so as to realize the transmission of ions in a wider mass range and eliminate the discrimination of kinetic energy. The ion optical lens group electrode has circular and hyperbolic internal shape, and a shielding box is arranged outside for shielding an electric field.
The invention solves the problem of the influence of the air flow on the ion trap without sacrificing the transmission efficiency and the resolution, and simultaneously does not change or complicate the time sequence of the mass spectrometer.
In the description of the present application, it should be understood that the terms "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," and the like indicate orientations or positional relationships based on the orientations or positional relationships illustrated in the drawings, merely to facilitate description of the present application and simplify the description, and do not indicate or imply that the devices or elements being referred to must have a specific orientation, be configured and operated in a specific orientation, and are not to be construed as limiting the present application.
The foregoing describes specific embodiments of the present invention. It is to be understood that the invention is not limited to the particular embodiments described above, and that various changes or modifications may be made by those skilled in the art within the scope of the appended claims without affecting the spirit of the invention. The embodiments of the present application and features in the embodiments may be combined with each other arbitrarily without conflict.
Claims (6)
1. A device for eliminating the air flow in a linear ion trap, characterized by comprising a device body (8), wherein the device body (8) comprises four electrodes (15) with the same internal morphology, the electrodes (15) are rotationally symmetrical about a common symmetry axis (16), the symmetry axis (16) is perpendicular to the symmetry axis of the linear ion trap (10), and the device body (8) is arranged at the upstream of the linear ion trap (10);
applying voltages to four electrodes (15) of the device body (8), wherein ions deflect by 90 degrees in a motion track (12) in the device body (8) under the pressure of 0.1pa-0.001 pa;
the voltage is linearly scanned along with time;
the device also comprises a mass spectrometer, wherein the mass spectrometer comprises a first-stage vacuum cavity (2), a second-stage vacuum cavity (3) and an ionization source (4) which is positioned under the atmospheric pressure, one end of a stainless steel capillary tube (1) is positioned under the atmospheric pressure, and the other end of the stainless steel capillary tube is positioned in the first-stage vacuum cavity (2);
an ion optical lens (5) with a hole is arranged between the first-stage vacuum cavity (2) and the second-stage vacuum cavity (3).
2. The device for eliminating the air flow in a linear ion trap according to claim 1, characterized in that the internal topography of the four electrodes (15) of the device body (8) is circular, hyperbolic, parabolic.
3. The device for eliminating the air flow in the linear ion trap according to claim 1, characterized in that the device body (8) is equipped with a shielding box.
4. A device for eliminating air flow in a linear ion trap according to claim 1, characterized in that the four electrodes (15) of the device body (8) are placed parallel to each other.
5. The apparatus for eliminating air flow in a linear ion trap according to claim 1, wherein the apparatus body (8) is arranged as a set of ion optical lenses (5).
6. The device for eliminating the air flow in the linear ion trap according to claim 1, wherein a molecular pump is arranged at the bottom of the second-stage vacuum cavity (3), one end of a forepump of the molecular pump is connected with the molecular pump, and the other end of the forepump of the molecular pump is connected with the first-stage vacuum cavity (2).
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202111153528.9A CN113903651B (en) | 2021-09-29 | 2021-09-29 | Device for eliminating air flow in linear ion trap |
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| Application Number | Priority Date | Filing Date | Title |
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| CN202111153528.9A CN113903651B (en) | 2021-09-29 | 2021-09-29 | Device for eliminating air flow in linear ion trap |
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| Publication Number | Publication Date |
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| CN113903651A CN113903651A (en) | 2022-01-07 |
| CN113903651B true CN113903651B (en) | 2024-03-29 |
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| CN202111153528.9A Active CN113903651B (en) | 2021-09-29 | 2021-09-29 | Device for eliminating air flow in linear ion trap |
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Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH1173911A (en) * | 1997-09-01 | 1999-03-16 | Hitachi Ltd | Ion-trap mass spectrometer |
| US6124592A (en) * | 1998-03-18 | 2000-09-26 | Technispan Llc | Ion mobility storage trap and method |
| US6423965B1 (en) * | 1998-08-24 | 2002-07-23 | Hitachi, Ltd. | Mass spectrometer |
| WO2005001878A2 (en) * | 2003-06-21 | 2005-01-06 | Leco Corporation | Multi reflecting time-of-flight mass spectrometer and a method of use |
| CN109256321A (en) * | 2018-09-19 | 2019-01-22 | 清华大学 | It is a kind of to continue sample introduction atmospheric pressure interface secondary vacuum ion trap mass spectrometer |
-
2021
- 2021-09-29 CN CN202111153528.9A patent/CN113903651B/en active Active
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH1173911A (en) * | 1997-09-01 | 1999-03-16 | Hitachi Ltd | Ion-trap mass spectrometer |
| US6124592A (en) * | 1998-03-18 | 2000-09-26 | Technispan Llc | Ion mobility storage trap and method |
| US6423965B1 (en) * | 1998-08-24 | 2002-07-23 | Hitachi, Ltd. | Mass spectrometer |
| WO2005001878A2 (en) * | 2003-06-21 | 2005-01-06 | Leco Corporation | Multi reflecting time-of-flight mass spectrometer and a method of use |
| CN109256321A (en) * | 2018-09-19 | 2019-01-22 | 清华大学 | It is a kind of to continue sample introduction atmospheric pressure interface secondary vacuum ion trap mass spectrometer |
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| Publication number | Publication date |
|---|---|
| CN113903651A (en) | 2022-01-07 |
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