CN110265282B - Matrix-assisted laser desorption ionization time-of-flight mass spectrometer and sample detection method - Google Patents
Matrix-assisted laser desorption ionization time-of-flight mass spectrometer and sample detection method Download PDFInfo
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- 238000001514 detection method Methods 0.000 title claims abstract description 23
- 238000001840 matrix-assisted laser desorption--ionisation time-of-flight mass spectrometry Methods 0.000 title claims abstract description 16
- 150000002500 ions Chemical class 0.000 claims abstract description 75
- 238000010884 ion-beam technique Methods 0.000 claims abstract description 56
- 230000005684 electric field Effects 0.000 claims abstract description 35
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- 238000001819 mass spectrum Methods 0.000 description 7
- 238000003384 imaging method Methods 0.000 description 5
- 239000011159 matrix material Substances 0.000 description 5
- 230000003287 optical effect Effects 0.000 description 5
- 230000003111 delayed effect Effects 0.000 description 3
- 238000003795 desorption Methods 0.000 description 3
- 230000035945 sensitivity Effects 0.000 description 3
- 230000001154 acute effect Effects 0.000 description 2
- 238000000668 atmospheric pressure chemical ionisation mass spectrometry Methods 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 238000002330 electrospray ionisation mass spectrometry Methods 0.000 description 2
- 238000004992 fast atom bombardment mass spectroscopy Methods 0.000 description 2
- 230000001678 irradiating effect Effects 0.000 description 2
- 238000005086 pumping Methods 0.000 description 2
- 239000010453 quartz Substances 0.000 description 2
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- 238000010586 diagram Methods 0.000 description 1
- 238000009434 installation Methods 0.000 description 1
- 230000002452 interceptive effect Effects 0.000 description 1
- 238000004949 mass spectrometry Methods 0.000 description 1
- 238000000691 measurement method Methods 0.000 description 1
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Abstract
The invention discloses a matrix-assisted laser desorption ionization time-of-flight mass spectrometer and a sample detection method. The mass spectrometer comprises: the laser comprises a sealed shell, a laser, a target plate, a modulating electrode group, a first deflection electrode group, a first reflecting mirror, a flight tube and a detector, wherein the sealed shell is used for forming a vacuum cavity, the laser is positioned outside the sealed shell, and the target plate, the modulating electrode group, the first deflection electrode group, the first reflecting mirror, the flight tube and the detector are contained in the sealed shell; the laser is used for emitting laser beams into the sealed shell; a first reflecting mirror for reflecting the laser beam so that the laser beam vertically irradiates the sample placed on the target plate; the modulating electrode group is used for modulating an ion beam emitted by the sample laser beam vertical irradiation and gasification ionization, and the ion beam contains effective ions, neutral particles and nonselective ions; and the first deflection electrode group is used for generating a first electric field to deflect the flight direction of the effective ions in the modulated ion beam, so that the effective ions deflected in the flight direction enter one end of the flight tube along the axial direction of the flight tube and are received by a detector arranged at the other end of the flight tube.
Description
Technical Field
The invention relates to the technical field of instruments and meters. More particularly, to a matrix-assisted laser desorption ionization time-of-flight mass spectrometer and sample detection method.
Background
A mass spectrometer is an instrument that measures mass-to-charge ratio (m/z) values of ions and their intensities using electronic measurement techniques. The sample to be detected is introduced into a mass spectrometer by a sample introduction system, the sample to be detected is ionized by an ion source, ions are separated according to the mass-to-charge ratio by a mass analyzer through applying an electric field, and a separated ion signal is recorded according to the mass-to-charge ratio and the intensity by a detector. In addition to fast atom bombardment mass spectrometry (FAB), atmospheric pressure chemical ionization mass spectrometry (APCI) and electrospray ionization mass spectrometry (ESI), matrix Assisted Laser Desorption (MALDI) is one of soft ionization techniques for ionization of a sample by mass spectrometry, wherein matrix assisted laser desorption is to mix an object to be measured with a matrix in a certain ratio and irradiate the mixture with laser, and the matrix transfers the energy of the laser to molecules of the object to be measured after absorbing the energy of the laser so as to gasify and ionize the molecules to form ions.
The matrix assisted laser desorption ionization time of flight (Matrix Assisted Laser Desorption Ioniza tion-Time Of Flight Mass Spectrometer, MALDI-TOF) mass spectrometer is a novel soft ionization biological mass spectrum developed in recent years, is a commonly used instrument in biochemical analysis, has the characteristics of high sensitivity, high accuracy, high resolution and the like, and has been widely applied to genomics and proteomics.
At present, a laser introducing device of a matrix-assisted laser desorption ionization time-of-flight mass spectrometer comprises a laser, a reflector, a UV lens group and the like, wherein laser beams emitted by the laser enter a vacuum cavity formed by a sealed shell after passing through the reflector, are emitted into the vacuum cavity (vacuum ionization chamber) formed by the sealed shell at an angle of 0-90 degrees (namely an acute angle) with a bearing surface of a target plate, and then are irradiated on a sample after passing through the UV lens group arranged in the sealed shell.
On the one hand, in the incident mode of the laser beam, the laser beam irradiating the sample forms an acute angle with the bearing surface of the target plate, which can lead to low ionization degree of the sample and divergence of the initial angle of flight of most of formed ions, so that the utilization rate of the sample is low and the detection sensitivity of the mass spectrometer is low. On the other hand, bulk desorption of matrix molecules occurs during ionization by energy absorption from the laser beam, which results in the detector receiving a large amount of unwanted neutral particles and non-selective ions, shortening the lifetime of the detector, and interfering with the detection of the sample, reducing the signal-to-noise ratio of the detection signal of the mass spectrometer.
Therefore, it is desirable to provide a new matrix assisted laser desorption ionization time-of-flight mass spectrometer and sample detection method.
Disclosure of Invention
The invention aims to provide a matrix-assisted laser desorption ionization time-of-flight mass spectrometer and a sample detection method, which are used for solving at least one of the problems in the prior art.
In order to achieve the above purpose, the invention adopts the following technical scheme:
the invention provides a matrix-assisted laser desorption ionization time-of-flight mass spectrometer, which comprises a sealed shell, a laser, a target plate, a modulating electrode group, a first deflection electrode group, a first reflecting mirror, a flight tube and a detector, wherein the sealed shell is used for forming a vacuum cavity;
the laser is used for emitting laser beams into the sealed shell;
the first reflecting mirror is used for reflecting the laser beam so that the laser beam vertically irradiates the sample placed on the target plate;
the modulating electrode group is used for modulating an ion beam emitted by the sample through gasification ionization under the vertical irradiation of the laser beam, and the ion beam contains effective ions, neutral particles and nonselective ions;
the first deflection electrode group is used for generating a first electric field to deflect the flight direction of effective ions in the modulated ion beam, so that the effective ions deflected in the flight direction enter one end of the flight tube along the axial direction of the flight tube and are received by a detector arranged at the other end of the flight tube.
Optionally, the mass spectrometer further comprises: and the second deflection electrode group is positioned between the first deflection electrode group and the flight tube and is used for generating a second electric field with the same intensity as the first electric field and opposite in direction to deflect the flight direction of the effective ions deflected in the flight direction again, so that the effective ions deflected again in the flight direction enter one end of the flight tube along the axial direction of the flight tube and are received by a detector arranged at the other end of the flight tube.
Optionally, the mass spectrometer further comprises: the second reflecting mirror is positioned outside the sealing shell and used for reflecting the laser beam emitted by the laser into the sealing shell, and the adjusting mechanism is used for adjusting the reflecting angle of the second reflecting mirror.
Optionally, the mass spectrometer further comprises: and the displacement mechanism is used for driving the target plate to move in a plane perpendicular to the light path direction of the laser beam reflected by the first reflecting mirror.
Optionally, the mass spectrometer further comprises: a lens located between the first mirror and the first deflection electrode group.
Optionally, the lens is detachably mounted within the sealed housing.
Optionally, the position of the flight tube is set away from the target plate.
Optionally, the modulating electrode group includes a bias electrode group for filtering the ion beam, an extracting electrode group for extracting the filtered ion beam in a delayed manner, a focusing electrode group for focusing the ion beam in a spatial manner after extracting in a delayed manner, and an accelerating electrode group for accelerating the ion beam in a spatial manner after focusing.
Optionally, the mass spectrometer further comprises: and the UV lens group is positioned outside the sealing shell and is used for filtering and focusing the laser beam emitted by the laser.
A second aspect of the present invention provides a sample detection method using a mass spectrometer provided in the first aspect of the present invention, comprising:
driving the laser to emit laser beams to vertically irradiate the sample, so that the sample is gasified and ionized to emit ion beams; applying a modulating voltage to the modulating electrode set to modulate the ion beam; applying a first deflection voltage to the first deflection electrode group to deflect the flight direction of effective ions in the modulated ion beam through a generated first electric field, so that the effective ions deflected in the flight direction enter the flight tube along the axial direction of the flight tube;
a detector is utilized to receive the effective ions in the ion beam.
The beneficial effects of the invention are as follows:
the technical scheme of the invention can reduce the diameter of the light spot irradiated by the laser beam on the sample, improve the spatial resolution of mass spectrum imaging, enable the mass spectrum imaging to be clearer and can more easily identify the edge positions of the focus area and the healthy tissue. And neutral particles and non-selective ions in the ion beam can be screened out, and the signal to noise ratio of a detection signal of the mass spectrometer is improved.
Drawings
The following describes the embodiments of the present invention in further detail with reference to the drawings;
fig. 1 shows a schematic diagram of a matrix-assisted laser desorption ionization time-of-flight mass spectrometer provided by an embodiment of the present invention.
Detailed Description
In order to more clearly illustrate the present invention, the present invention will be further described with reference to preferred embodiments and the accompanying drawings. Like parts in the drawings are denoted by the same reference numerals. It is to be understood by persons skilled in the art that the following detailed description is illustrative and not restrictive, and that this invention is not limited to the details given herein.
As shown in fig. 1, one embodiment of the present invention provides a matrix-assisted laser desorption ionization time-of-flight mass spectrometer, which comprises a sealed housing 10 for forming a vacuum cavity, a laser 20 located outside the sealed housing 10, and a target plate 11, a modulating electrode group 12, a first deflecting electrode group 13, a first reflecting mirror 14, a flight tube 15 and a detector 16 contained in the sealed housing 10;
the laser 20 is used for emitting a laser beam into the sealed shell 10;
the first reflecting mirror 14 for reflecting the laser beam so that the laser beam vertically irradiates the sample 90 placed on the target plate 11;
the modulating electrode set 12 is configured to modulate an ion beam emitted by the sample 90 by being vertically irradiated by the laser beam and gasified and ionized, where the ion beam includes effective ions, neutral particles and non-selective ions;
the first deflection electrode group 13 is configured to generate a first electric field to deflect a flight direction of effective ions in the modulated ion beam, so that the effective ions deflected in the flight direction enter one end of the flight tube 15 along an axial direction of the flight tube 15 and are received by a detector 16 disposed at the other end of the flight tube 15.
According to the matrix-assisted laser desorption ionization time-of-flight mass spectrometer, on one hand, the laser beam is vertically irradiated to the sample 90, the diameter of a light spot irradiated on the sample 90 by the laser beam can be reduced, the spatial resolution of mass spectrum imaging is improved, the mass spectrum imaging is clearer, and the edge positions of a focus area and healthy tissues can be identified more easily. On the other hand, the first electric field generated by the first deflection electrode group 13 can only deflect the flight direction of the effective ions in the ion beam more obviously, the effective ions in the ion beam deflected in the flight direction can bypass the first reflecting mirror 14 and enter the flight tube 15 along the axial direction of the flight tube 15 after continuing to fly, but neutral particles which are not influenced by the deflection of the first electric field and non-selective ions which are weaker by the deflection of the first electric field can strike the lens 18, so that the neutral particles and the non-selective ions in the ion beam can be screened out, and the signal to noise ratio of a detection signal of the mass spectrometer can be improved. It will be appreciated that although not shown in the figures, support elements such as frames or struts may be provided to fix the position of the laser 20, the hermetic shell 10, the target plate 11, the modulating electrode set 12, the first deflecting electrode set 13, the first mirror 14, the flight tube 15 and the detector 16.
In one particular example, as shown in fig. 1, the modulating electrode set 12 includes a set of modulating electrode plates, each of which has a middle region that is a flight region of the ion beam; the first deflection electrode group 13 includes two deflection electrode plates which are oppositely arranged, the middle area of the two deflection electrode plates is a flight area of the ion beam, and a first electric field can be generated in the middle area of the two deflection electrode plates by respectively applying different voltages to the two deflection electrode plates; the first reflecting mirror 14 is a rectangular prism, specifically may be a quartz rectangular prism; a valve (not shown) may be provided on the sealing case 10, and the vacuum environment in the sealing case 10 may be released by opening the valve, so that the inner cavity of the sealing case 10 may be in a vacuum chamber by a vacuum pumping device (not shown) communicating with the sealing case 10 in an atmospheric pressure state.
In some alternative implementations of the present embodiment, the mass spectrometer further comprises: a second deflection electrode group 17 located between the first deflection electrode group 13 and the flight tube 15, for generating a second electric field having the same intensity as the first electric field and opposite in direction to deflect the flight direction of the effective ions deflected in the flight direction again, so that the effective ions deflected again in the flight direction enter one end of the flight tube 15 in the axial direction of the flight tube 15 and are received by a detector 16 provided at the other end of the flight tube 15. It is understood that the positioning of the second deflection electrode group 17 between the first deflection electrode group 13 and the flight tube 15 means that the position of the second deflection electrode group 17 in the flight direction of the effective ions is positioned between the first deflection electrode group 13 and the flight tube 15, and further that the position of the second deflection electrode group 17 is positioned between the first mirror 14 and the flight tube 15 in fig. 1. The second deflection electrode group 17 being located between the first deflection electrode group 13 and the flight tube 15 means that the second deflection electrode group is housed in the seal case 10. With this implementation, the correspondence between the first electric field strength and the axial angle of the flight tube 15 may not be considered, so that the first electric field strength and the axial angle of the flight tube 15 are strictly matched, or the correspondence between the amount of deflection of the effective ion in the flight direction under the action of the first electric field and the axial angle of the flight tube 15 may not be strictly required, and the axial direction of the flight tube 15 may be directly set to be perpendicular to the bearing surface of the target plate 11, so that the position and the axial angle of the flight tube 15 are conveniently set. In addition, the structure of the mass spectrometer is simplified, and the volume of the mass spectrometer is reduced.
In some alternative implementations of the present embodiment, the mass spectrometer further comprises: a second reflecting mirror 30 located outside the sealed housing 10, and an adjusting mechanism (not shown in the figure), wherein the second reflecting mirror 30 is used for reflecting the laser beam emitted from the laser 20 into the sealed housing 10, and the adjusting mechanism is used for adjusting the reflecting angle of the second reflecting mirror 30 so as to adjust the incident angle of the laser beam incident into the sealed housing 10, so that the laser beam incident into the sealed housing 10 can vertically irradiate the sample 90 placed on the target plate 11 after being reflected by the first reflecting mirror 14. Since the reflection angle of the first reflecting mirror 14 located inside the hermetic case 10 is inconvenient to adjust, the optical path of the laser beam can be precisely and conveniently adjusted by the second reflecting mirror 30 located outside the hermetic case 10 and the adjusting mechanism to ensure that the laser beam can vertically irradiate the sample 90 placed on the target plate 11.
In some alternative implementations of the present embodiment, the mass spectrometer further comprises: a displacement mechanism (not shown) for moving the target plate 11 in a plane perpendicular to the optical path direction of the laser beam reflected by the first reflecting mirror 14. With this implementation manner, a plurality of samples (for example, samples respectively placed on the left and right sides of the sample 90 in fig. 1) can be simultaneously placed on the target plate 11, and in one detection process, the plurality of samples can be sequentially detected, so as to improve the detection efficiency. The displacement mechanism is a two-dimensional displacement mechanism, as shown in fig. 1, the displacement mechanism may drive the target plate 11 to move in two directions perpendicular to each other in a horizontal plane (may set an X-axis direction and a Y-axis direction), in a specific example, the target plate 11 is provided with a plurality of targets arranged in an equidistant array, a plurality of samples are respectively dotted on the plurality of targets, after detecting the sample on one target, the displacement mechanism is controlled to drive the target plate 11 to move in the horizontal plane so that the sample on the next target is located at a position where the laser beam is vertically irradiated (for example, in fig. 1, after detecting the sample 90 in fig. 1, the displacement mechanism is controlled to drive the target plate 11 to move rightward so that the sample on the left side is located at a position where the laser beam is vertically irradiated).
In some alternative implementations of the present embodiment, the mass spectrometer further comprises: a lens 18 located between the first mirror 14 and the first deflection electrode group 13. The laser beam may be transmitted through the lens 18 without neutral particles being deflected by the first electric field and non-selective ions being deflected less by the first electric field striking the lens 18 to screen out neutral particles and non-selective ions. In one particular example, the lens 18 is a quartz lens.
In some alternative implementations of this embodiment, the lens 18 is removably mounted within the sealed housing. With this implementation, cleaning of neutral and non-selective ions on the lens 18 is facilitated. In addition, if the lens 18 is not provided, that is, the first reflecting mirror 14 is impacted by the neutral particles not subjected to the deflection of the first electric field and the non-selective ions weak to the deflection of the first electric field to screen out the effects of the neutral particles and the non-selective ions, the first reflecting mirror 14 may be provided to be detachably mounted in the hermetic case 10 so as to clean the neutral particles and the non-selective ions on the first reflecting mirror 14.
In some alternative implementations of the present embodiment, the position of the flight tube 15 is set away from the target plate 11. With this implementation, the effect of screening neutral particles and non-selective ions in the ion beam can be ensured.
In some alternative implementations of this embodiment, the modulating electrode set 12 includes a bias electrode set for filtering the ion beam, an extraction electrode set for time-lapse extracting the filtered ion beam, a focusing electrode set for spatially focusing the time-lapse extracted ion beam, and an accelerating electrode set for ion accelerating the spatially focused ion beam. In one specific example, the bias electrode set, the extraction electrode set, the focus electrode set, and the acceleration electrode set may each include a respective electrode plate, and a corresponding voltage may be applied to the respective electrode plates, respectively, so that each electrode set performs its function.
In some alternative implementations of the present embodiment, the mass spectrometer further comprises: a UV lens group 40 located outside the sealed housing 10 for filtering and focusing the laser beam emitted from the laser 20.
In one specific example, referring to the laser beam path and ion beam flight direction shown in fig. 1, the workflow of a mass spectrometer employing all the above implementations is as follows:
first, each device is mounted at a corresponding position as shown in fig. 1, and the laser beam is perpendicularly irradiated on the sample 90 by adjusting the reflection angle of the second mirror 30 of the mechanism. Wherein the first mirror 14 and the lens 18 are fixedly mounted within the hermetic housing 10. The UV lens assembly 40 includes a plurality of lens elements that are fixedly arranged in combination according to an optical principle. The laser beam with the wavelength of 349nm emitted by the laser 20 is filtered and focused by the UV lens group 40 and then irradiates on the second reflecting mirror 30, irradiates on the first reflecting mirror 14 after primary reflection, and then passes through the lens 18 to vertically irradiate the center of the central hole (namely the position of the sample 90 in the middle) of the tool after secondary reflection. In the initial installation, the angle of the adjusting mechanism (optical adjusting frame) is not fixed, the laser beam is required to vertically irradiate the center of the central hole of the tool by roughly adjusting and finely adjusting the reflection angle of the second reflecting mirror 30 under the non-vacuum condition, specifically, the valve of the sealing shell 10 is opened, the inner cavity of the sealing shell is in the atmospheric pressure state, the laser 20 is driven to emit the laser beam, the adjusting mechanism comprises a roughly adjusting nut and a finely adjusting bolt, the roughly adjusting nut in the vertical direction is firstly adjusted, the laser beam is enabled to be positioned at the vertical center of the central hole of the tool, the roughly adjusting nut in the horizontal direction is adjusted, and the laser beam is enabled to be positioned at the horizontal center of the central hole of the tool. The laser beam is fine-tuned by fine-tuning the bolt. And adjusting the fine adjustment bolt to enable the laser beam to sweep through the central hole of the tool, rotating clockwise, changing the rotating direction to be anticlockwise after the light spot disappears until the light spot disappears in the opposite direction, and fixing the fine adjustment bolt at a position of half of the total circle number, namely that the laser beam is perpendicular to the sample. The diameter of the laser beam vertically irradiated on the sample 90 is 10um at the minimum, which can improve the sensitivity of mass spectrum detection and the spatial resolution of mass spectrum imaging.
After that, a sample is placed on the target plate 11 by using a sample introduction system (not shown), and after the sealed housing 10 is formed into a vacuum chamber by using a vacuum pumping device, detection is started:
driving the laser 20 to emit laser beams, and vertically irradiating the sample 90 after passing through the UV lens group 40, the second reflecting mirror 30, the first reflecting mirror 14 and the lens 18 in sequence, so that the sample 90 is gasified and ionized to emit ion beams;
the ion beam emitted by the sample 90 through gasification ionization is sequentially filtered, extracted in a delayed manner, spatially focused and accelerated modulated by the modulating electrode group 12, and then enters a region where different voltages are respectively applied to the two deflecting electrode plates of the first deflecting electrode group 13 to generate a first electric field, the flying direction of effective ions in the ion beam bypasses the lens 18 after once deflection of the first electric field and enters a region where different voltages are respectively applied to the two deflecting electrode plates of the second deflecting electrode group 17 to generate a second electric field, and neutral particles and nonselective ions in the ion beam impact the lens 18; the effective ions in the ion beam are deflected by the second electric field vertically upwards into the flight tube 15 and finally received by the detector 16. The distances between the two deflection electrode plates included in the first deflection electrode group 13 and the second deflection electrode group 17 are the same, the applied voltage values are the same and the directions are opposite, as shown in fig. 1, before the detection, the polarity (positive or negative) of the ionized ions of the sample is determined, and the polarity of the ionized ions can be determined according to the chemical characteristics of the detected sample and the substrate, for example: based on the characteristic of strong electronegativity of the sample being measured (the concept of electronegativity is used to indicate the relative strength of the ability of two atoms to attract bound electrons when forming a chemical bond, the larger the electronegativity value of an element, the more strongly the atoms are able to attract bound electrons in the compound), it can be determined that most of the ionization generated is negative ions, only a small part is positive ions, and the positive ions are screened off under the action of the first electric field and cannot reach the detector 16. If the ions are positively charged, i.e., positive ions, the voltage applied to the right deflection electrode plate of the first deflection electrode group 13 in fig. 1 is V1, and the voltage applied to the left deflection electrode plate of the first deflection electrode group 13 is V2, wherein V1> V2 (otherwise, if the ions are negatively charged, i.e., negative ions, V1< V2). When the ion beam passes through the first deflection electrode group 13, the ion beam is subjected to a first electric field E1 (where e1= (V1-V2)/d, d is the distance between the left and right deflection electrode plates of the first deflection electrode group 13), the flight direction of the effective ions is deflected by a certain angle relative to the vertical direction, and after freely flying through the field-free region between the first deflection electrode group 13 and the second deflection electrode group 17, the ion beam bypasses the lens 18 and the first reflecting mirror 14 and enters the second deflection electrode group 17, but the neutral particles and the non-selective ions continue to fly and strike the lens 18. When the ions are positively charged, i.e., positive ions, the voltage applied to the left deflection electrode plate in the second deflection electrode group 17 in fig. 1 is V1, and the voltage applied to the right deflection electrode plate in the second deflection electrode group 17 is V2, where V1> V2 (otherwise, if the ions are negatively charged, i.e., negative ions, V1< V2). The second electric field E2 generated by the second deflection electrode group 17 and the first electric field E1 generated by the first deflection electrode group 13 are equal in magnitude and opposite in direction. The effective ions in the ion beam are subjected to a second electric field E2 (where e2= (V2-V1)/d, d is the distance between the left and right deflection electrode plates of the second deflection electrode group 17) while passing through the second deflection electrode group 17, and the flight direction of the effective ions is deflected by a certain angle from the vertical direction to return to the vertical direction, and then enters the flight tube 15 of the non-electric field region, and reaches the detector 16 to be detected. The voltages V1 and V2 applied to the deflection electrode plates of the second deflection electrode group 13 and the second deflection electrode group 17 can be obtained by resistive voltage division or can be generated by a high voltage module via a control unit.
In fig. 1, the optical path of the laser beam and the flight path of the effective ions in the ion beam have a space crossing, but since the laser beam diameter is um-order and the ion beam diameter is mm-order, the influence between them is small. The laser 20 may be driven to emit a pulsed laser beam so that the laser beam and the ion beam are time-shifted, that is, the same space is used in a time-sharing manner.
After the detection of the sample 90 is completed, the displacement mechanism is controlled to drive the target plate 11 to move rightward so that the sample on the left side is positioned at the position where the laser beam on the center is vertically irradiated, and the above detection process is repeated until the detection of all the samples placed on the target plate 11 is completed.
Another embodiment of the present invention provides a sample detection method using the above-described mass spectrometer, including:
driving the laser to emit laser beams to vertically irradiate the sample, so that the sample is gasified and ionized to emit ion beams; applying a modulating voltage to the modulating electrode set to modulate the ion beam; applying a first deflection voltage to the first deflection electrode group to deflect the flight direction of effective ions in the modulated ion beam through a generated first electric field, so that the effective ions deflected in the flight direction enter the flight tube along the axial direction of the flight tube;
a detector is utilized to receive the effective ions in the ion beam.
It should be noted that, the sample detection method provided in this embodiment is similar to the principle and the workflow of the matrix-assisted laser desorption ionization time-of-flight mass spectrometer, and the relevant parts can be referred to the above description and will not be repeated here.
In the description of the present invention, it should be noted that the azimuth or positional relationship indicated by the terms "upper", "lower", etc. are based on the azimuth or positional relationship shown in the drawings, and are merely for convenience of describing the present invention and simplifying the description, and are not indicative or implying that the apparatus or element in question must have a specific azimuth, be constructed and operated in a specific azimuth, and thus should not be construed as limiting the present invention. Unless specifically stated or limited otherwise, the terms "mounted," "connected," and "coupled" are to be construed broadly, and may be, for example, fixedly connected, detachably connected, or integrally connected; can be mechanically or electrically connected; can be directly connected or indirectly connected through an intermediate medium, and can be communication between two elements. The specific meaning of the above terms in the present invention can be understood by those of ordinary skill in the art according to the specific circumstances.
It is further noted that in the description of the present invention, relational terms such as first and second, and the like are used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Moreover, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising one … …" does not exclude the presence of other like elements in a process, method, article, or apparatus that comprises the element.
It should be understood that the foregoing examples of the present invention are provided merely for clearly illustrating the present invention and are not intended to limit the embodiments of the present invention, and that various other changes and modifications may be made therein by one skilled in the art without departing from the spirit and scope of the present invention as defined by the appended claims.
Claims (10)
1. The matrix-assisted laser desorption ionization time-of-flight mass spectrometer comprises a sealed shell, a laser, a target plate, a modulating electrode group, a first deflection electrode group, a first reflecting mirror, a flight tube and a detector, wherein the sealed shell is used for forming a vacuum cavity, the laser is positioned outside the sealed shell, the target plate is accommodated in the sealed shell;
the laser is used for emitting laser beams into the sealed shell;
the first reflecting mirror is used for reflecting the laser beam so that the laser beam vertically irradiates the sample placed on the target plate;
the modulating electrode group is used for modulating an ion beam emitted by the sample through gasification ionization under the vertical irradiation of the laser beam, and the ion beam contains effective ions, neutral particles and nonselective ions;
the first deflection electrode group is used for generating a first electric field to deflect the flight direction of effective ions in the modulated ion beam, so that the effective ions deflected in the flight direction enter one end of the flight tube along the axial direction of the flight tube and are received by a detector arranged at the other end of the flight tube.
2. The mass spectrometer of claim 1, further comprising: and the second deflection electrode group is positioned between the first deflection electrode group and the flight tube and is used for generating a second electric field with the same intensity as the first electric field and opposite in direction so as to deflect the flight direction of the effective ions deflected in the flight direction again, so that the effective ions deflected again in the flight direction enter one end of the flight tube along the axial direction of the flight tube and are received by a detector arranged at the other end of the flight tube.
3. The mass spectrometer of claim 1, further comprising: the second reflecting mirror is positioned outside the sealing shell and used for reflecting the laser beam emitted by the laser into the sealing shell, and the adjusting mechanism is used for adjusting the reflecting angle of the second reflecting mirror.
4. The mass spectrometer of claim 1, further comprising: and the displacement mechanism is used for driving the target plate to move in a plane perpendicular to the light path direction of the laser beam reflected by the first reflecting mirror.
5. The mass spectrometer of claim 1, further comprising: a lens located between the first mirror and the first deflection electrode group.
6. The mass spectrometer of claim 5, in which the lens is removably mounted within the sealed housing.
7. The mass spectrometer of claim 1, in which the flight tube is positioned away from the target plate.
8. The mass spectrometer of claim 1, in which the modulation electrode set comprises a bias electrode set for filtering the ion beam, an extraction electrode set for time-lapse extraction of the filtered ion beam, a focusing electrode set for spatial focusing of the time-lapse extracted ion beam, and an acceleration electrode set for ion acceleration of the spatially focused ion beam.
9. The mass spectrometer of claim 1, further comprising: and the UV lens group is positioned outside the sealing shell and is used for filtering and focusing the laser beam emitted by the laser.
10. A method of sample detection using a mass spectrometer as claimed in any one of claims 1 to 9, comprising:
driving the laser to emit laser beams to vertically irradiate the sample, so that the sample is gasified and ionized to emit ion beams; applying a modulating voltage to the modulating electrode set to modulate the ion beam; applying a first deflection voltage to the first deflection electrode group to deflect the flight direction of effective ions in the modulated ion beam through a generated first electric field, so that the effective ions deflected in the flight direction enter the flight tube along the axial direction of the flight tube;
a detector is utilized to receive the effective ions in the ion beam.
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| CN114334600A (en) * | 2021-12-25 | 2022-04-12 | 广州禾信仪器股份有限公司 | Mass spectrometer, ion source and ion transmission structure thereof |
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