JP3205635U - Sample plate moving mechanism and laser desorption ionization mass spectrometer equipped with the same - Google Patents

Abstract

A sample plate moving mechanism capable of moving on a wall surface of a vacuum chamber with extremely low frictional force. A sample plate moving mechanism includes a sample plate disposed in a vacuum chamber and a stage disposed outside the vacuum chamber and movable in XY directions. The sample plate includes a first permanent plate. Magnets 42 and 44 and a second permanent magnet 43 are arranged, and on the stage 31, third permanent magnets 31c and 31d attracted in the Z direction via the first permanent magnets 42 and 44 and the wall of the vacuum chamber. The electromagnet 50 is arranged, and at the time of analysis, the electromagnet 50 is controlled to repel the electromagnet 50 and the second permanent magnet 43 with a predetermined repulsive force in the −Z direction through the wall of the vacuum chamber. Like that. [Selection] Figure 2

Description

  The present invention relates to a sample plate moving mechanism for moving a sample plate in a vacuum chamber. In particular, the sample placed on the upper surface of the sample plate is irradiated with laser light, thereby vaporizing or ionizing the sample, and further moving the sample plate relative to the irradiation position of the laser light, so that the upper surface of the sample plate is sequentially The present invention relates to a matrix-assisted laser desorption ionization time-of-flight mass spectrometer (MALDI-TOFMS) that vaporizes or ionizes a large number of samples placed on the surface.

  In MALDI (Matrix Assisted Laser Desorption / Ionization), a sample mixed with a solution of sinapinic acid or the like called “matrix” and a small amount of analyte is irradiated with laser light, and the matrix that absorbs the laser light absorbs heat In this method, the substance to be analyzed is vaporized or ionized as part of it is heated and vaporized rapidly. When mass spectrometry is performed by MALDI-TOFMS, a sample is dropped in a spot shape on the upper surface of a sample plate, and the solvent is evaporated by drying and then placed in a vacuum chamber. Then, the analysis is started by starting the operation of the vacuum pump to evacuate the inside of the vacuum chamber. Usually, a plurality of samples are placed on the upper surface of the sample plate so as to be arranged in M rows and N columns, and by moving the sample plate and moving the placement location of each sample to the irradiation position of the laser beam, Samples are ionized one after another. In MALDI-TOFMS, the generated ions are extracted by an electric field having a predetermined strength and introduced into the flight space to perform mass spectrometry. The speed of each ion flying in the flight space depends on its mass-to-charge ratio, and the smaller the mass-to-charge ratio, the greater the speed.Therefore, depending on the flight time to reach the detector, various ions Separation / detection is performed every time (for example, see Patent Document 1).

  By the way, when an XY stage mechanism for driving the sample plate is provided in the vacuum chamber, there are contamination and heat generation due to electricity and mechanical structure, and there arises a problem that the cost cannot be increased and the size of the vacuum chamber cannot be reduced. In particular, the problem of the vacuum chamber size affects the evacuation speed and the ultimate vacuum, and becomes an obstacle to cost reduction and downsizing of vacuum pumps and the like.

  Therefore, as a sample plate moving mechanism suitable for these requirements, the sample plate is placed on the lower wall in the vacuum chamber and magnetically coupled to a stage arranged outside the vacuum chamber, so that the stage moves. In some cases, an arbitrary position on the sample plate is moved to the irradiation position of the laser beam.

FIG. 6 is a diagram illustrating an example of a configuration of a conventional MALDI-TOFMS. One direction horizontal to the ground is defined as an X direction, a direction horizontal to the ground and perpendicular to the X direction is defined as a Y direction, and a direction perpendicular to the X direction and the Y direction is defined as a Z direction.
The MALDI-TOFMS 101 includes a vacuum chamber 10, a detection chamber (detection means) 20 connected to the vacuum chamber 10, a vacuum pump (not shown) for evacuating the vacuum chamber 10, and a stage 131. A sample plate moving mechanism 130, a sample plate 140 placed in the vacuum chamber 10, irradiation means 60 for irradiating a sample with laser light, and a computer 170 for controlling the entire MALDI-TOFMS 101 are provided.

  The vacuum chamber 10 is formed in a rectangular parallelepiped shape (for example, 20 cm × 40 cm × 20 cm) by a vessel wall made of aluminum and having a thickness of 1 cm. An irradiation window 11 that transmits laser light is formed on the right side wall.

In the detection chamber 20, an ion transport optical system 21, a mass analyzer 22, and a detector 23 are arranged in this order in the -Z direction. As the ion transport optical system 21, for example, an electrostatic electromagnetic lens, a multipole type high frequency ion guide, or the like is used. As the mass analyzer 22, a quadrupole analyzer, an ion trap, a time-of-flight analyzer, a magnetic sector type analyzer, or the like is used.
According to such a detection chamber 20, ions emitted from the sample by laser irradiation from the irradiation means 60 are introduced into the detection chamber 20, sent to the mass analyzer 22 through the ion transport optical system 21, and mass analysis. Various ions are separated by the vessel 22 in accordance with the mass to charge ratio. When the separated ions reach the detector 23, the detector 23 outputs a detection signal corresponding to the amount of ions reached, and this detection signal is transmitted to the analysis control unit 71b of the computer 170 described later.

  The irradiation means 60 is disposed so as to be positioned on the outer right side of the vacuum chamber 10, and includes a laser focusing optical system 61 and a laser irradiation unit 62. According to such irradiation means 60, the ionizing laser light emitted from the laser irradiation unit 62 is narrowed by the laser focusing optical system 61 and directed toward the sample on the sample plate 140 through the irradiation window 11 of the vacuum chamber 10. Is irradiated. At this time, the irradiation diameter of the laser light irradiated on the sample is, for example, a minute diameter of 1 μm to several tens of μm.

  The computer 170 includes a CPU 171 and an operation unit 72 serving as an input device. Further, the function processed by the CPU 171 will be described as a block. The analysis control unit 71b controls the stage control unit 171a and the laser irradiation unit 62, and digitizes the detection signal from the detector 23 to execute appropriate data processing. And have. The analysis control unit 71b creates a mass spectrum of the sample, for example, and performs qualitative analysis and quantitative analysis based on the mass spectrum. The analysis control unit 71b performs qualitative analysis and quantitative analysis of a large number of samples by creating a mass spectrum each time the laser irradiation position is scanned by the stage control unit 171a.

Here, FIG. 7 is a perspective view showing an example of a conventional sample plate and a sample plate moving mechanism.
The sample plate 140 shown in FIG. 7A is made of a plastic plate-like body (for example, 8 cm × 3 cm × 0.2 cm) 141 having a metal surface of 20 g, for example, on the upper surface of the plate-like body 141, for example, A sample having a diameter of about 3 to 5 mm is placed side by side in M rows and N columns. In addition, a columnar (for example, 1 cm in diameter) first permanent magnet 142 is disposed at a central portion inside the plate-like body 141. The first permanent magnet 142 is arranged so that the upper side is the S pole and the lower side is the N pole.

The sample plate moving mechanism 130 shown in FIG. 7B is disposed on the lower outside of the vacuum chamber 10 and includes a stage 131, an X-axis linear actuator 32, and a Y-axis linear actuator 33.
The stage 131 includes a plate-like body (for example, 1 cm × 3 cm × 4 cm) 131a and a stage attachment portion 131b formed on the lower surface of the plate-like body 131a. In addition, a third permanent magnet 131c having a columnar shape (for example, a diameter of 1 cm) is disposed at the center of the upper surface of the plate-like body 131a. The third permanent magnet 131c is arranged so that the upper side is the S pole and the lower side is the N pole.

  The X-axis linear actuator 32 includes an X-axis linear guide 32a, an X-axis screw 32b, one end of the X-axis linear guide 32a and one end of the X-axis screw 32b, and an X-axis linear actuator mounting portion 32d. And an X-axis motor 32c attached to one end of the linear guide 32a and the X-axis linear actuator attachment portion 32d. A stage mounting portion 131b is fixed to the other end portion of the X-axis linear guide 32a and the other end portion of the X-axis screw 32b. Accordingly, the stage mounting portion 131b can move in the X direction with respect to the X-axis linear actuator mounting portion 32d by the rotation of the X-axis motor 32c.

  The Y-axis linear actuator 33 supports a Y-axis linear guide 33a, a Y-axis screw 33b, one end of the Y-axis linear guide 33a and one end of the Y-axis screw 33b, and is fixed to a housing or the like. An actuator mounting portion 33d and one end portion of a Y-axis linear guide 33a and a Y-axis motor 33c mounted on the Y-axis linear actuator mounting portion 33d are provided. An X-axis linear actuator mounting portion 32d is fixed to the other end of the Y-axis linear guide 33a and the other end of the Y-axis screw 33b. Thereby, the X-axis linear actuator mounting portion 32d is movable in the Y direction with respect to the Y-axis linear actuator mounting portion 33d (a housing or the like) by the rotation of the Y-axis motor 33c.

  When performing mass spectrometry using such a MALDI-TOFMS 101, first, the operator places the sample plate 140 on the lower wall in the vacuum chamber 10. At this time, the first permanent magnet 142 of the sample plate 140 and the third permanent magnet 131c of the stage 131 attract each other, so that the sample plate 140 is pressed against the lower wall of the vacuum chamber 10 and passes through the lower wall of the vacuum chamber 10. Thus, the sample plate 140 and the stage 131 are integrated.

  Next, after starting the operation of the vacuum pump, the operator inputs an analysis start signal using the operation unit 72. As a result, the stage controller 171a outputs necessary drive signals to the X-axis motor 32c and the Y-axis motor 33c, and moves the stage 131 in the desired X and Y directions, simultaneously with the sample plate. 140 can be moved in the desired X and Y directions.

International Publication WO2008 / 068847

  By the way, when performing mass spectrometry, it is necessary to accurately move the position of the sample plate so that each sample is accurately irradiated with laser light, and to shorten the time required for analyzing many samples. It is necessary to move the sample plate so that the movement between the samples is performed as fast as possible.

However, in the MALDI-TOFMS 101, there is not much problem in moving the sample plate 140 when the moving speed is low. However, if the moving speed is high, the sample plate 140 is displaced due to friction between the sample plate 140 and the bottom wall of the vacuum chamber 10. A problem occurred.
Accordingly, an object of the present invention is to provide a sample plate moving mechanism capable of moving on a wall surface of a vacuum chamber with an extremely low frictional force, and a laser desorption ionization mass spectrometer equipped with the same.

  A sample plate moving mechanism according to the present invention made to solve the above-described problems includes a sample plate disposed in a vacuum chamber, and a sample disposed outside the vacuum chamber and movable in the X direction and the Y direction. A plate moving mechanism, wherein the sample plate includes a first permanent magnet and a second permanent magnet, and the stage includes the first permanent magnet and the vacuum chamber wall. A third permanent magnet attracting in the Z direction and an electromagnet are arranged. When analyzing, the electromagnet and the second permanent magnet are controlled via the wall of the vacuum chamber by controlling the electromagnet. Repulsion is performed in the Z direction with a predetermined repulsive force.

  Here, the “predetermined repulsive force” is an arbitrary numerical value predetermined by a designer or the like, and reduces the frictional force acting between the sample plate and the wall surface of the vacuum chamber.

  As described above, according to the sample plate moving mechanism of the present invention, the electrical and mechanical burden in the vacuum chamber is reduced by installing the stage outside the vacuum chamber. Since the sample plate is magnetically levitated when the sample plate is moved, the sample plate is moved on the wall surface of the vacuum chamber with an extremely low frictional force, so that high-speed and high-precision operation can be realized.

(Means and effects for solving other problems)
In the above device, the first permanent magnet arranged on the sample plate is composed of two permanent magnets, arranged in the X direction and the −X direction of the second permanent magnet, The arranged third permanent magnet may be composed of two permanent magnets and arranged in the X direction and the −X direction of the electromagnet.

  In the above device, the polarity of the second permanent magnet may be opposite to the polarity of the first permanent magnet.

In the above device, a holding member having a predetermined friction force or less may be disposed on the lower surface of the sample plate.
Here, the “predetermined frictional force” is an arbitrary numerical value predetermined by a designer or the like, and reduces the frictional force acting between the sample plate and the wall surface of the vacuum chamber.

  In the above device, a plurality of samples may be placed on the upper surface of the sample plate.

  Further, in the laser desorption / ionization mass spectrometer of the present invention, the sample plate moving mechanism as described above, the vacuum chamber, irradiation means for irradiating the sample with laser light, and emission from the sample irradiated with the laser light. Detecting means for detecting the vaporized sample or ions, and detecting the vaporized sample or ions discharged from each sample on the sample plate while moving the stage in the X direction and / or the Y direction, respectively. And a control unit that performs the processing.

The block diagram which shows MALDI-TOFMS concerning this invention. The perspective view which shows an example of the sample plate which concerns on this invention, and a sample plate moving mechanism. The perspective view which shows an example of the electromagnet used by this invention. The figure which shows the magnetism by the electromagnet of FIG. Explanatory drawing which shows the state which the sample plate magnetically levitated. The block diagram which shows the prior art example of MALDI-TOFMS. The perspective view which shows the prior art example of a sample plate and a sample plate moving mechanism.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that the present invention is not limited to the embodiments described below, and includes various modes without departing from the spirit of the present invention.

FIG. 1 is a diagram showing a configuration of a MALDI-TOFMS according to the present invention. In addition, about the thing similar to MALDI-TOFMS101 mentioned above, description is abbreviate | omitted by attaching | subjecting the same code | symbol.
The MALDI-TOFMS 1 includes a vacuum chamber 10, a detection chamber (detection means) 20 connected to the vacuum chamber 10, a vacuum pump (not shown) for evacuating the vacuum chamber 10, and a stage 31. A sample plate moving mechanism 30, a sample plate 40 placed in the vacuum chamber 10, irradiation means 60 for irradiating a sample with laser light, and a computer 70 for controlling the entire MALDI-TOFMS 1 are provided. The partition wall of the vacuum chamber 10 sandwiched between the sample plate 40 and the stage 31 has a thickness of, for example, 3 mm so as not to damage the coupling by a magnet described later.

  The computer 70 includes a CPU 71 and an operation unit 72 serving as an input device. Further, the function processed by the CPU 71 will be described as a block. The analysis control unit 71b controls the stage control unit 71a and the laser irradiation unit 62 and digitizes the detection signal from the detector 23 to execute appropriate data processing. And have.

FIG. 2 is a perspective view showing an example of a sample plate and a sample plate moving mechanism according to the present invention.
A sample plate 40 shown in FIG. 2A is made of a plastic plate-like body (for example, 8 cm × 3 cm × 0.2 cm) 41 having a metal surface of 20 g, for example. A holding member 45 made of Teflon (registered trademark) or graphite and having a cylindrical shape (for example, a diameter of 5 mm) having a predetermined frictional force or less is disposed. On the upper surface of the plate-like body 41, for example, a sample having a diameter of about 3 to 5 mm is placed side by side in M rows and N columns.

  Further, inside the plate-like body 41, a first permanent magnet 42 having a columnar shape (for example, 5 mm in diameter), a second permanent magnet 43 having a rectangular parallelepiped shape (for example, 7 mm × 15 mm × 3 mm), and a columnar shape (for example, 5 mm in diameter) ) First permanent magnets 44 in this order along the X direction. The second permanent magnet 43 has a rectangular parallelepiped shape that is longer in the Y-axis direction than the X-axis, and the magnetic flux spreads with respect to the Y-axis. The first permanent magnets 42 and 44 are arranged so that the upper side is the S pole and the lower side is the N pole, and the second permanent magnet 43 is arranged so that the upper side is the N pole and the lower side is the S pole. Has been.

A sample plate moving mechanism 30 shown in FIG. 2B is arranged outside and below the vacuum chamber 10 and includes a stage 31, an X-axis linear actuator 32, and a Y-axis linear actuator 33.
The stage 31 includes a plate-like body (for example, 1.5 cm × 3 cm × 4 cm) 31a and a stage attachment portion 31b formed on the lower surface of the plate-like body 31a. On the upper surface of the plate-like body 31a, a third permanent magnet 31c having a cylindrical shape (for example, 5 mm in diameter), an electromagnet 50 having a rectangular parallelepiped shape (for example, 7 mm × 15 mm × 7 mm), and a third having a cylindrical shape (for example, 5 mm in diameter). The permanent magnet 31d is arranged in this order along the X direction. The third permanent magnets 31c and 31d are arranged so that the upper side is the S pole and the lower side is the N pole.

FIG. 3 is a perspective view showing an example of an electromagnet used in the present invention, and FIG. 4 is a diagram showing magnetism by the electromagnet of FIG. 4A is a YZ sectional view, and FIG. 4B is an XZ sectional view.
The electromagnet 50 includes a rectangular parallelepiped magnetic pipe 51 that is longer in the Y-axis direction than the X-axis, and three columnar electromagnetic coils 52. The three electromagnetic coils 52 are arranged in the Y direction inside the magnetic pipe 51. When a current is passed by the computer 70, the upper side becomes the S pole, the lower side becomes the N pole, and the Y axis is the same. As a result, the magnetic flux spreads. As a result, the electromagnet 50 and the second permanent magnet 43 are repelled with a predetermined repulsive force in the −Z direction via the lower wall of the vacuum chamber 10.

  The predetermined repulsive force is based on the weight of the sample plate 40, the attractive force of the first permanent magnet 42 and the third permanent magnet 31c, and the attractive force of the first permanent magnet 44 and the third permanent magnet 31d. The repulsive forces of the three electromagnetic coils 52 and the second permanent magnet 43 are adjusted so as to balance (slightly toward the suction side).

Here, an analysis method for analyzing a large number of samples using the MALDI-TOFMS 1 according to the present invention will be described. FIG. 5 is a diagram for explaining a state in which the sample plate is levitated by magnetism.
First, the operator places the sample plate 40 on the lower wall in the vacuum chamber 10. At this time, the first permanent magnet 42 of the sample plate 40 and the third permanent magnet 31c of the stage 31 attract each other, and the first permanent magnet 44 of the sample plate 40 and the third permanent magnet 31d of the stage 31 attract each other. The plate 40 is pressed against the lower wall of the vacuum chamber 10, and the sample plate 40 and the stage 31 are integrated via the lower wall of the vacuum chamber 10.

  Next, after starting the operation of the vacuum pump, the operator inputs an analysis start signal using the operation unit 72. Thereby, the stage control unit 71 a causes the electromagnet 50 and the second permanent magnet 43 to repel each other with a predetermined repulsive force in the −Z direction through the lower wall of the vacuum chamber 10 by passing a current through the electromagnet 50. At this time, the first permanent magnet 42 of the sample plate 40 and the third permanent magnet 31c of the stage 31 are attracted, the first permanent magnet 44 of the sample plate 40 and the third permanent magnet 31d of the stage 31 are attracted, and the sample plate The second permanent magnet 43 of 40 and the electromagnet 50 of the stage 31 repel each other so that the sample plate 40 is magnetically levitated with respect to the lower wall of the vacuum chamber 10 and the sample is passed through the lower wall of the vacuum chamber 10. The plate 40 and the stage 31 are integrated. Thereby, vibration and shaking can be prevented and the sample plate 40 can be moved stably.

  Then, the stage control unit 71a outputs necessary drive signals to the X-axis motor 32c and the Y-axis motor 33c, and moves the stage 31 in the desired X and Y directions, simultaneously with the sample plate 40. Can be moved in the desired X and Y directions. At this time, the sample plate 40 moves through the four holding members 45 so as to slide on the lower wall of the vacuum chamber 10 with a sufficiently small frictional force.

  Finally, the operator inputs an analysis end signal using the operation unit 72. Thereby, the stage controller 71 a releases the repulsive force between the electromagnet 50 and the second permanent magnet 43 by stopping the current supply to the electromagnet 50.

  As described above, according to the MALDI-TOFMS 1 of the present invention, the electrical and mechanical burden in the vacuum chamber 10 is reduced by installing the stage 31 outside the vacuum chamber 10. Then, when the sample plate 40 is moved, it is magnetically levitated and moved on the lower wall of the vacuum chamber 10 with an extremely low frictional force, whereby a high-speed and high-precision operation can be realized.

<Other embodiments>
(1) In the above-described embodiment, the mass spectrometer using the ion source based on the laser desorption ionization method (LDI) and the matrix-assisted laser desorption ionization method (MALDI) has been described as an example. Can be applied. Specifically, energy dispersive X-ray fluorescence analyzer (EDX), X-ray diffractometer (XRD), electron beam microanalyzer (EPMA), scanning probe microscope (SPM), scanning electron microscope (SEM), X-ray photoelectron It can also be applied to a spectroscopic analyzer (XPS) or the like.

(2) In the MALDI-TOFMS 1 described above, the configuration in which the four holding members 45 are arranged on the lower surface of the plate-like body 41 is shown, but instead of this, a rotatable holding member (wheel) is arranged. It is good also as such a structure.

  The present invention can be suitably used for a sample plate moving mechanism for moving a sample plate in a vacuum chamber.

1 MALDI-TOFMS (Laser Desorption / Ionization Mass Spectrometer)
10 Vacuum chamber (vacuum chamber)
30 Sample plate moving mechanism 31 Stages 31c and 31d Third permanent magnet 40 Sample plates 42 and 44 First permanent magnet 43 Second permanent magnet 50 Electromagnet

Claims (6)

A sample plate placed in a vacuum chamber;
A sample plate moving mechanism provided outside the vacuum chamber and provided with a stage movable in the X direction and the Y direction,
In the sample plate, a first permanent magnet and a second permanent magnet are arranged,
On the stage, a third permanent magnet attracted in the Z direction via the first permanent magnet and the wall of the vacuum chamber, and an electromagnet are arranged,
When analyzing, a sample plate moving mechanism characterized in that the electromagnet and the second permanent magnet are repelled with a predetermined repulsive force in the -Z direction through the wall of the vacuum chamber by controlling the electromagnet. . The first permanent magnet disposed on the sample plate is composed of two permanent magnets, and is disposed in the X direction and the -X direction of the second permanent magnet,
2. The sample plate movement according to claim 1, wherein the third permanent magnet disposed on the stage includes two permanent magnets and is disposed in an X direction and a −X direction of the electromagnet. 3. mechanism.   3. The sample plate moving mechanism according to claim 1, wherein the polarity of the second permanent magnet is opposite to the polarity of the first permanent magnet. 4.   The sample plate moving mechanism according to any one of claims 1 to 3, wherein a holding member having a predetermined friction force or less is disposed on a lower surface of the sample plate.   The sample plate moving mechanism according to any one of claims 1 to 4, wherein a plurality of samples are placed on an upper surface of the sample plate. A sample plate moving mechanism according to claim 5;
The vacuum chamber;
Irradiating means for irradiating the sample with laser light;
Detection means for detecting a vaporized sample or ions emitted from the sample irradiated with the laser beam;
And a controller that detects the vaporized sample or ions emitted from each sample on the sample plate by the detection means while moving the stage in the X direction and / or the Y direction. Laser desorption ionization mass spectrometer.

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