JP5032076B2 - Mass spectrometer - Google Patents

Description

  The present invention relates to a mass spectrometer, and more particularly to a mass spectrometer suitable for laser desorption ionization mass spectrometry.

  Conventionally, a reflection time-of-flight mass spectrometer equipped with a reflectron 24 formed by stacking a plurality of repetitive electrode plates (ion lenses) 25 as shown in FIG. 14 has been proposed (see, for example, Patent Document 1). .) In the time-of-flight mass spectrometer shown in FIG. 14, an upper end seal flange (top plate) 67p is connected to the upper end connection flange 68p at the upper end of the analysis tube 14p, and a lower end seal flange (to the lower end connection flange 66p at the lower end of the analysis tube 14p. (Bottom plate) 65p is connected to form a vacuum chamber. This vacuum chamber is connected to a vacuum pump (not shown) via an exhaust port flange 69 provided at an exhaust port branched from the analysis tube 14p into a T-shape. The lower end seal flange (bottom plate) 65p is provided with a through hole serving as a sample exchange port, and the sample exchange port is sealed by a sample exchange port blind plate 84. Inside the lower part of the analysis tube 14p in the vicinity of the lower end connection flange 66p are a first acceleration electrode (back plate) 85 having a central hole through which ions pass and a central hole through which ions above the first acceleration electrode 85 pass. The 2nd acceleration electrode (drawing grid) 21p provided is provided, and the accelerator (85, 21p) is comprised. A sample holder 83 fixed and loaded on the first acceleration electrode 85 is provided immediately below the central hole of the first acceleration electrode 85, and the sample 15 is stored on the upper portion of the sample holder 83.

  A laser beam introduction port 13 branched from the analysis tube 14p is provided below the analysis tube 14p. A laser introduction window 19 is provided in the laser beam introduction port 13, and the pulse laser beam 20 emitted from the laser 10 is introduced into the laser beam. The sample 15 is irradiated through the window 19 to leave the sample 15 and perform ionization. The ions 22 generated by the pulse laser beam 20 are given kinetic energy by a predetermined acceleration voltage in the accelerator (85, 21p), pass through the hole in the center of the MCP detector 23, and in the analysis tube (flight tube) 14p. After the flight in the field free section (no electric field drift space) 26, the aircraft enters the reflectron 24. A tilted electric field is formed inside the reflectron 24 by a plurality of repetitive electrode plates (ion lenses) 25, and the ions 22 are reflected in a direction slightly tilted from the incident direction by the tilted electric field, and the analysis tube (flight) Tube) 14p is returned and detected by the MCP detector 23.

  In the time-of-flight mass spectrometer shown in FIG. 14, the ions 22 generated by the pulse laser beam 20 are accelerated by a predetermined acceleration voltage in the accelerator (85, 21p), and the field-free section of the analysis tube (flight tube) 14p. Fly in the (electroless field drift space) 26.

The time for flying this predetermined distance varies depending on the initial speed of the ions 22, and this initial speed depends on the mass number (mass / charge number) of the ions 22. That is, the ions 22 having a smaller mass number have a larger initial velocity with the same acceleration voltage, and the ions 22 having a larger mass number have a smaller initial velocity with the same acceleration voltage. A normal reflectron 24 is essentially a decelerating electric field that decelerates the ions 22 to zero velocity, allowing the ions 22 to turn around and return along the same or nearly the same path. Ions 22 having high kinetic energy (velocity) penetrate deeper into the reflectron 24 than ions 22 having low kinetic energy and thus have a longer path to the MCP detector 23. When the ions 22 reach the MCP detector 23, they retain their initial kinetic energy distribution, but ions 22 of different masses arrive at different times. Therefore, the mass spectrum of the ions 22 is obtained by continuously measuring the detection amount of the ions 22 reflected by the voltage of the repetitive electrode plate (ion lens) 25 of the reflectron 24 and detected by the MCP detector 23. Can do.

In order to accelerate positive ions, generally, the second acceleration electrode (drawing grid) 21p is set to the ground potential, and a negative acceleration voltage (V) is applied to the first acceleration electrode (back plate) 85. The exit grid where the MCP detector 23 is arranged is usually at ground potential. The acceleration voltage (V) can be in the range of several hundred volts to 30 kV, and the flight time is about 5 to 100 microseconds, although it depends on the length of the field-free section (no electric field drift space) 26. . In general, the acceleration voltage is selected to be relatively high in order to minimize the effect of initial kinetic energy on mass resolution and to enable detection of large ions. For example, an acceleration voltage of 20 KV has been found to be sufficient to detect masses exceeding 300 kilodaltons (kDa).
JP 2003-151487 A

  Since moisture adhering to the inner wall of the vacuum chamber adversely affects the evacuation characteristics, the vacuum chamber should not be opened to the atmosphere. In the conventional time-of-flight mass spectrometer as shown in FIG. 14, in order to prepare the sample 15 serving as an ion source inside the analysis tube 14p, the inside of the vacuum chamber constituted by the analysis tube 14p is released to the atmosphere. There was a need. That is, the inside of the vacuum chamber is opened to the atmosphere, the sample exchange port blind plate 84 sealing the sample exchange port provided on the lower end seal flange (bottom plate) 65p is removed, the sample holder 83 is taken out from the sample exchange port, Thereafter, the sample 15 for mass spectrometry is placed on the sample holder 83, and again the sample holder 83 is inserted from the sample exchange port 84 and loaded on the first acceleration electrode 85, and the sample exchange port is sealed. After sealing with the blind plate 84, it was necessary to evacuate the inside of the vacuum chamber to a predetermined pressure again through a vacuum pump (not shown) through the exhaust port flange 69 over a predetermined time. Further, before performing the operation of taking out the sample holder 83 from the sample exchange port, it is required to cut off a high voltage of about several hundred volts to 30 kV applied to the first acceleration electrode 85.

That is, in mass spectrometry using a conventional time-of-flight mass spectrometer as shown in FIG.
For each mass analysis of different samples 15, it was necessary to open the atmosphere inside the vacuum chamber to the atmosphere and replace the sample 15 and to evacuate again. For this reason, much time was required for mass spectrometry, and the analysis work efficiency was remarkably reduced. Furthermore, moisture, organic matter, or their reactants attached to the inner wall of the vacuum chamber may be degassed to cause residual gas components, which may adversely affect the results of mass spectrometry and its reproducibility.

  In laser desorption ionization mass spectrometry, since the sample holder 83 on which the sample 15 is placed is fixed at the laser irradiation position, the laser irradiation position is fixed, and mass analysis of an arbitrary part of the sample 15 is impossible. The analysis range of the sample 15 was limited, resulting in a decrease in information collection of mass spectrometry spectrum and a decrease in analysis accuracy.

  In FIG. 14, the reflection type time-of-flight mass spectrometer equipped with the reflectron 24 is illustrated. However, in order to perform vacuum evacuation again by releasing the inside of the vacuum chamber to the atmosphere and exchanging the sample 15 each time. The problem of requiring a lot of time and remarkably reducing the analysis work efficiency is the same in the linear time-of-flight mass spectrometer without the reflectron 24, and other mass spectrometers such as a quadrupole mass spectrometer. Even so, as long as the vacuum chamber is used, there is a problem that the inside of the vacuum chamber is released to the atmosphere each time.

  Further, the problem of fixing the laser irradiation position in laser desorption / ionization mass spectrometry is not a problem inherent to the reflection type time-of-flight mass spectrometer having the reflectron 24 shown in FIG. Even in other mass spectrometers such as a linear time-of-flight mass spectrometer or a quadrupole mass spectrometer, when the pulse laser beam 20 irradiates the sample 15, leaves the sample 15, and performs ionization A similar problem occurs.

  An object of the present invention is to provide a mass spectrometer capable of mounting a sample from the atmosphere side to the inside of the vacuum chamber without opening the vacuum chamber to the atmosphere and maintaining electrical safety. .

  Another object of the present invention is to provide a mass spectrometer capable of laser desorption ionization mass spectrometry capable of obtaining a mass spectrometry spectrum from a wide range of a sample without limiting the analysis range of the sample.

The gist of the present invention for achieving the above object will be described below.
First, the “sample exchange / introduction mechanism” of the mass spectrometer targeted by the present invention is as follows.
There is a mass spectrometer tube with an extraction grid on one end side, an analysis sample chamber is connected to the one end side of the analysis tube, and it is adjacent to the sample chamber in a direction perpendicular to the longitudinal direction of the analysis tube. A sample preparation room is provided. In addition, there is a sample stage that functions as a back plate that constitutes an accelerator for ions to be measured at the time of mass analysis together with the extraction grid during mass analysis, and this sample stage uses a high voltage for acceleration applied to the device. It is fixed to an insulating support for insulating from the housing.
Furthermore, there is a first vacuum sealing means that separates the vacuum state of the analysis tube and the preparation chamber when the sample stage is located in the preparation chamber, and is opened when the sample stage is located in the sample chamber, In addition, when the sample stage is located in the sample chamber, the vacuum state between the analysis tube and the atmosphere is separated, and the sample stage is located in the preparation chamber. In some cases, there is a second vacuum sealing means for separating the vacuum state between the preparation chamber and the atmosphere. Further, only when the sample stage is moved to the sample chamber, a current introduction terminal for applying a high voltage for acceleration to the sample stage is provided. In addition, a “sample” for a mass spectrometer comprising: an X direction perpendicular to the longitudinal direction of the analysis tube; and a driving means for moving the sample stage in the Y direction perpendicular to the X direction in the plane of the sample stage Exchange It is the introduction mechanism ".
The solving means according to the present invention for the problems of the mass spectrometer equipped with the sample exchange / introduction mechanism is as follows.
(A) The above insulating support is constituted by a cylindrical insulating sleeve, and a sample stage is mounted on one end (sample chamber side) thereof.
(B) A first seal ring and a second seal ring are used as the first vacuum seal means and the second vacuum seal means, respectively. For example, the seal ring is an “O-ring” and is disposed on the outer peripheral portion of the insulating sleeve.
(C) The first seal ring is disposed at the tip of the insulating sleeve facing the sample chamber. The second seal ring is placed at a position where the analysis tube and the atmosphere side can be vacuum-separated when the sample stage is located in the sample chamber, and when the sample stage is located in the preparation chamber, the first and second seal rings are placed. It is arranged at a position where the vacuum seal of the preparation chamber is maintained by the seal ring.
(D) As a driving means for moving the sample stage between the sample chamber and the preparation chamber, an X / Y direction feed mechanism including a plurality of feed screws arranged coaxially is used. Further, with respect to the Y direction, there is provided a Y direction fine movement function for converting a fine movement displacement in the X direction into a fine movement displacement in the Y direction by an X direction fine movement pin in a guide groove having a predetermined angle with respect to the X direction.
(E) A sample holder detachable from the sample stage is provided.
The present invention has the characteristics shown in the above (A) to (E). Thereby, it is not necessary to open the analysis tube and the sample chamber to the atmosphere, and the influence of the adsorbed gas at the time of exchanging the sample can be suppressed. Furthermore, since the X / Y fine movement of the sample stage is possible, the mass analysis within the X / Y fine movement area of the sample is possible without limiting the analysis area of the sample to a narrow range. .

  According to the present invention, there is provided a mass spectrometer capable of mounting a sample from the atmosphere side to the inside of the vacuum chamber without releasing the vacuum chamber of the mass spectrometer to the atmosphere and maintaining electrical safety. can do.

  Furthermore, according to the present invention, it is possible to provide a mass spectrometer capable of laser desorption ionization mass spectrometry capable of obtaining a mass spectrometry spectrum from a wide range of the sample without limiting the analysis range of the sample.

  Next, first to third embodiments of the present invention will be described with reference to the drawings. In the following description of the drawings, the same or similar parts are denoted by the same or similar reference numerals. However, it should be noted that the drawings are schematic, and the relationship between the thickness and the planar dimensions, the ratio of the thickness of each layer, and the like are different from the actual ones. Therefore, specific thicknesses and dimensions should be determined in consideration of the following description. Moreover, it is a matter of course that portions having different dimensional relationships and ratios are included between the drawings.

  The first to third embodiments shown below exemplify apparatuses and methods for embodying the technical idea of the present invention, and the technical idea of the present invention is The material, shape, structure, arrangement, etc. are not specified below. The technical idea of the present invention can be variously modified within the technical scope described in the claims.

(First embodiment)
As shown in FIG. 1, the mass spectrometer according to the first embodiment of the present invention has a plurality of repetitive electrode plates (ion lenses) 25 on the upper portion of an analysis tube 14a made of a metal material such as stainless steel. This is a reflection time-of-flight mass spectrometer equipped with a stack of reflectrons 24. An upper end seal flange (top plate) 67a is connected to the upper end connection flange 68a at the upper end of the analysis tube 14a, and a sample chamber flange 72 constituting the sample chamber 27 is connected to the lower end connection flange 66a at the lower end of the analysis tube 14a. The sample chamber 27 constitutes a vacuum chamber. The sample chamber flange 72 is made of a metal material such as stainless steel, for example. This vacuum chamber is connected to a vacuum pump such as a turbo molecular pump (not shown) through an exhaust port flange 69 provided in an exhaust port branched from the analysis tube 14a into a T shape.

  At the time of laser desorption ionization mass spectrometry, a first acceleration electrode (back plate) is provided inside the sample chamber 27 surrounded by the sample chamber flange 72 as shown in enlarged views in FIGS. A sample stage 17 also serving as a position is located. A sample holder 16 in which a lower portion is inserted into a through hole (sample holder insertion hole) near the center of the sample stage 17 is fixed to the sample stage 17. A sample 15 is accommodated in the upper portion of the sample holder 16. The sample stage 17 and the sample holder 16 are made of a metal material such as stainless steel, for example.

  A plate-shaped or ring-shaped second acceleration electrode (drawing grid) 21 a having a central hole through which ions 22 pass is provided above the sample stage 17 in the lower part of the analysis tube 14 a in the vicinity of the lower end connection flange 66 a. In laser desorption ionization mass spectrometry, the sample stage (back plate) 17 and the second acceleration electrode (drawing grid) 21a can constitute an accelerator (17, 21a).

  As shown in FIG. 1, the reflectron 24 has a configuration in which a large number (a plurality of) ion lenses 25 are arranged via insulating spacers on a rod implanted in an upper end seal flange (top plate) 67 a. These many (plural) ion lenses 25 and spacers are tightened with nuts or the like through the back plate at the end. Each ion lens 25 is a thin metal plate having a center hole, and is cantilevered by an upper end seal flange (top plate) 67a.

  A laser beam introduction port 13 branching from the analysis tube 14a is provided below the analysis tube 14a, and a laser introduction window 19 is provided in the laser beam introduction port 13. The pulse laser beam 20 emitted from the laser 10 arranged outside the analysis tube 14a irradiates the sample 15 through the laser introduction window 19, leaves the sample 15, and performs ionization. In FIG. 2, the second accelerating electrode (drawing grid) 21 a has a plate shape in which a laser irradiation hole 211 and an ion passage hole 212 are opened, but the pulse laser beam 20 can be irradiated, Other electrode plate structures such as a mesh may be employed for the second acceleration electrode (drawing grid) 21a as long as the ions 22 can pass through at the same time. Although not particularly limited as the laser 10, an Nd-YAG laser or a nitrogen laser is suitable. As the pulse laser beam 20, an Nd-YAG fourth harmonic 266 nm, an Nd-YAG third harmonic 355 nm, a nitrogen laser 337 nm, or the like. A laser beam in the near-ultraviolet region is suitable. Therefore, a material transparent to the wavelength of the pulsed laser light 20 such as quartz glass or sapphire glass is selected as the material of the laser introduction window 19.

  Among the laser beams in the near ultraviolet region, the pulsed nitrogen laser 337 nm is used as the pulsed laser beam 20, and the laser 10 is small, stable, inexpensive, and easy to handle, and the wavelength 337 nm has a low absorbance in many compounds. Is preferred. Moreover, since the pulse nitrogen laser generates a half width (500 ps to 3 ns) and an output (one pulse: several tens to several hundreds μJ) sufficient for pulse ionization, the analysis object can be heated rapidly. By rapidly heating the analysis object, there is an advantage that ionization can be performed without decomposing the analysis object. For this reason, desorption ionization is possible without decomposing thermally unstable molecules such as proteins having a molecular weight exceeding 100 kDa.

  At the time of laser desorption ionization mass spectrometry, ions 22 generated by the pulsed laser beam 20 are given kinetic energy by a predetermined acceleration voltage in the accelerator (17, 21a), pass through the central hole of the MCP detector 23, and After flying in a field-free section (no electric field drift space) 26 in the analysis tube (flight tube) 14 a, it enters the reflectron 24. A tilted electric field is formed inside the reflectron 24 by a plurality of repetitive electrode plates (ion lenses) 25, and the ions 22 are reflected in a direction slightly tilted from the incident direction by the tilted electric field, and the analysis tube (flight) Tube) 14a is returned and detected by the MCP detector 23.

  In the time-of-flight mass spectrometer shown in FIG. 1, the ions 22 generated by the pulse laser beam 20 are accelerated by a predetermined acceleration voltage in the accelerator (17, 21a), and the field-free section of the analysis tube (flight tube) 14a. Fly in the (electroless field drift space) 26. The time for flying a predetermined distance varies depending on the initial velocity of the ions 22, and this initial velocity depends on the mass number (mass / charge number) of the ions 22. In a reflectron 24 that provides a decelerating electric field that essentially decelerates ions 22 to zero velocity, ions 22 with high kinetic energy (velocity) penetrate deeper into reflectron 24 than ions 22 with low kinetic energy, and thus It has a longer path to the MCP detector 23. When the ions 22 reach the MCP detector 23, they retain their initial kinetic energy distribution, but ions 22 of different masses arrive at different times. Therefore, the mass spectrum of the ions 22 can be obtained by continuously measuring the detection amount of the ions 22 reflected by the reflectron 24 and detected by the MCP detector 23.

  In order to accelerate positive ions, generally, the second acceleration electrode (drawing grid) 21a is set to the ground potential, and a negative acceleration voltage (V) is applied to the sample stage 17 serving as the first acceleration electrode (back plate). The exit grid where the MCP detector 23 is arranged is usually at ground potential. The acceleration voltage (V) can be in the range of several hundred volts to 30 kV.

  As shown in detail in FIGS. 2 and 3, a feedthrough flange 71 made of a metal material such as stainless steel is connected to the sample chamber flange 72 via an O-ring at the left end of the sample chamber flange 72. A current introduction terminal 29 for introducing an acceleration voltage that penetrates the flange 71 is provided. As shown in FIGS. 2 and 3, at the time of laser desorption ionization mass spectrometry, the current introduction terminal 29 is electrically connected to a universal terminal 28 made of a conductive material such as copper or phosphor bronze. Note that the surface of the universal terminal 28 is preferably subjected to a surface treatment such as gold plating in terms of contact resistance, conductivity, oxidation resistance, and the like. A spring 48 is incorporated inside the universal terminal 28 to supply a predetermined mechanical pressure necessary for electrical connection between the distal end portion of the current introduction terminal 29 and the universal terminal 28.

  On the other hand, as shown in FIGS. 2 and 3, at the right end of the sample chamber flange 72, a preparation chamber flange 73 made of a metal material such as stainless steel is provided via an O-ring so as to constitute a preparation chamber 38 inside. The chamber flange 72 is connected. As can be seen from FIGS. 1 and 2, the preparation chamber flange 73 is provided with a detachable port 31. The sample holder 16 on which the sample 15 is placed is introduced into the preparation chamber 38 via the detachable port 31, and the sample holder 16 on which the sample 15 after measurement is placed is pulled out, and a new sample for measurement is scheduled. The sample holder 16 on which 15 is placed is introduced again.

  As shown in FIG. 2, the preparation chamber flange 73 has a sleeve-like portion extending rightward in FIG. 2, and an insulating sleeve 32 made of an insulating material such as plastic resin is provided inside the sleeve-like portion. Has been inserted.

  A first seal ring 36 is provided near the left end of the insulating sleeve 32, and a second seal ring 37 is provided on the left side of the center of the insulating sleeve 32. The first seal ring 36 and the second seal ring 37 are seal rings that can be vacuum-sealed, such as O-rings. When the sample 15 shown in FIGS. 4 and 5 is exchanged, the vacuum state between the analysis tube 14 a and the preparation chamber 38 is separated by the first seal ring 36 provided on the insulating sleeve 32. The second seal ring 37 functions as a seal ring that shuts off the preparation chamber 38 and the atmosphere when the sample 15 is replaced. On the other hand, at the time of mass analysis shown in FIGS. 1 to 3 and 7, the second seal ring 37 provided on the insulating sleeve 32 functions as a seal ring that shuts off the analysis tube 14 a and the atmosphere, and the first seal ring 36. Is open.

  As can be understood from FIGS. 1 to 3, a linear drive shaft 33 made of a metal material such as stainless steel is inserted into the insulation sleeve 32 in the left direction from the center of the insulation sleeve 32. On the right side of 32, the X fine movement knob 34 configured to swallow the preparation chamber flange 73 is moved in the X direction (horizontal direction in FIGS. 1 to 3). The feed screw provided on the X fine movement knob 34 and the insulating sleeve 32 has a structure of a summing screw in which both feed amounts are added, and the number of rotations of the X fine movement knob 34 can be reduced to move in the X direction. .

  As shown in FIG. 2, a sample stage fixing portion 49 is embedded in the insulating sleeve 32 near the left end of the insulating sleeve 32. The sample stage fixing part 49 is a member on which the sample stage 17 is mounted and fixed, and is made of a metal material such as stainless steel. A concave portion is provided at the left end of the sample stage fixing portion 49, and the universal terminal 28 set in a floating state by a spring 48 is accommodated in the concave portion. As can be understood from FIGS. 2 and 3, the sample stage fixing portion 49 has a pair of concave grooves facing each other (when viewed from the upper position in FIG. 2 in the vertical direction or viewed from the upper side in FIG. 3). And a sample stage 17 is accommodated inside the pair of recess grooves, and the sample stage 17 can be moved in the pair of recess grooves. On the other hand, the Y-direction drive actuator 30 is operated by a Y fine movement knob 35 provided adjacent to the X fine movement knob 34 as shown in FIG. As can be understood from FIGS. 2 and 3, the sample stage 17 is provided with a manipulate groove 40 which is a slit-like groove extending at an angle of 45 ° with respect to the horizontal direction on the paper surface of FIG. 3. A pin 41 attached to the Y-direction drive actuator 30 is housed inside the manipulate groove 40. As the Y-direction drive actuator 30 moves in the X direction, the sample stage 17 is moved in the Y direction by the manipulating groove 40 by the pin 41 and moves in the Y direction. The Y-direction drive actuator 30 is an actuator that relatively moves the sample stage 17 in the X direction. An electrostrictive element, a magnetostrictive element, an electromagnet, or the like can be used, but the whole is composed of an insulating material having high electrical insulation. Has been.

<Sample exchange procedure>
The replacement of the sample 15 is roughly performed by the following procedure:
(A) First, it is assumed that the first mass analysis is completed. Thereafter, if the X fine movement knob 34 is rotated, the sample stage 17 on which the sample 15 is mounted moves in the X direction (indicated by arrows in FIGS. 4 and 5) from the pulse laser beam irradiation position where the previous mass analysis is performed in the sample chamber 27. Move to the right). When the sample stage 17 moves in the direction of the arrow in FIGS. 4 and 5 (right direction) from the irradiation position of the pulse laser beam for performing mass analysis, the electrical connection between the current introduction terminal 29 and the universal terminal 28 is released. . 4 and 5 are views showing a state in which the sample stage 17 on which the sample 15 is mounted has moved from the sample chamber 27 in the X direction. In this state, the vacuum state between the analysis tube 14 a and the preparation chamber 38 is separated by the first seal ring 36 provided in the insulating sleeve 32, and the preparation chamber 38 and the atmosphere are blocked by the second seal ring 37.

  (B) In FIGS. 4 and 5, the preparation chamber 38 is subjected to a vacuum leak using a leak valve or the like (not shown) to bring it into an atmospheric pressure state. After the preparation chamber 38 is brought into an atmospheric pressure state, the sample holder 16 on which the sample 15 is placed is introduced into the preparation chamber 38 using the detachable port 31. As shown in FIG. 6 (a), the attachment / detachment jig is configured such that the attachment / detachment rod 56 is inserted into an attachment / detachment jig body (sleeve) 57 having a chuck 58 for gripping the sample holder 16 shown in FIG. 6 (b). Has a structure. As shown in FIG. 6A, the tip of the chuck 58 having elasticity is formed by pushing a detachable rod 56 having a tapered tip at the inside of the detachable jig body 57 into the operation hole in the upper part of the chuck 58. The part (sample holder mounting part) is opened, and the upper part of the sample holder 16 on which the measured sample 15 is placed is inserted into the tip of the attachment / detachment jig. In this state, when the pushing of the detachable rod 56 to the detachable jig body 57 is released, the tip end portion (sample holder attaching portion) of the chuck 58 is closed, and the upper portion of the sample holder 16 can be grasped by the tip end of the detachable jig.

  When the attachment / detachment jig with the sample holder 16 attached to the tip is pulled out from the attachment / detachment port 31, the sample holder is removed from the through hole (sample holder insertion hole) near the center of the sample stage 17 as shown in FIGS. The lower part of 16 is detached and separated.

(C) After the attachment / detachment jig is pulled out from the attachment / detachment port 31, when the attachment / detachment rod 56 is pushed again into the attachment / detachment jig body 57, the tip end portion (sample holder attachment portion) of the elastic chuck 58 is opened. Is released from the attachment / detachment jig. After the sample holder 16 is released from the attachment / detachment jig, the measured sample 15 is removed from the upper portion of the material holder 16, and a new sample (sample to be measured) 15 is filled in the upper portion of the sample holder 16. Alternatively, a plurality of sample holders 16 are prepared and replaced with another sample holder 16 filled with a new sample (sample to be measured) 15. That is,
When the detachable rod 56 is pushed into the detachable jig body 57, the tip end portion (sample holder mounting portion) of the elastic chuck 58 is opened, and the sample holder 16 filled with a new sample (sample to be measured next) 15 is chucked. 58 is inserted into the sample holder mounting portion 58, and then the pressing of the detachable rod 56 with respect to the detachable jig body 57 is released to close the sample holder mounting portion of the chuck 58, and the upper portion of the sample holder 16 is placed at the tip of the detachable jig. Grab it.

  (D) Thereafter, the sample holder 16 on which the sample (new sample) 15 to be measured next is placed is introduced again into the preparation chamber 38 using the detachable port 31. Specifically, the attaching / detaching jig is again introduced from the attaching / detaching port 31, and the sample holder 16 on which the sample 15 to be measured next is mounted is attached to the sample stage 17 using the attaching / detaching jig. That is, a detachable jig with the sample holder 16 attached to the tip is introduced from the detachable port 31 and the lower part of the sample holder 16 is inserted into a through hole (sample holder insertion hole) near the center of the sample stage 17. After fixing the sample holder 16 in the sample holder insertion hole of the sample stage 17, when the detachable rod 56 is pushed into the detachable jig body 57, the sample holder mounting portion of the chuck 58 is opened, and the sample holder 16 is released from the detachable jig. Is done. After the sample holder 16 is released from the attachment / detachment jig, the attachment / detachment jig is pulled out from the attachment / detachment port 31, the leak valve (not shown) is closed, and the attachment / detachment port 31 is also shut off to the atmosphere.

(E) After the detachable port 31 is cut off from the atmosphere, the preparation shown in FIGS. 3 and 5 is performed with the lower part of the sample holder 16 on which the sample 15 to be measured next is mounted (fixed) on the sample stage 17. Using the chamber exhaust port 39, the inside of the preparation chamber 38 is evacuated from the atmospheric pressure to a vacuum state of a predetermined ultimate pressure of about 10 ⁻² Pa, for example.

  (F) After evacuating the preparation chamber 38 to a predetermined ultimate pressure, the X fine movement knob 34 is rotated, and the sample stage 17 on which the sample 15 to be measured next is mounted is in a pulse laser beam irradiation position for performing mass analysis. It moves in the X direction (left direction opposite to the arrow in FIGS. 4 and 5) to the state.

FIG. 7 is a diagram illustrating a state in which the sample stage 17 has moved to a pulse laser beam irradiation position where mass analysis is performed. As shown in FIG. 7, when the sample stage 17 moves to the pulse laser beam irradiation position for performing mass analysis, the current introduction terminal 29 and the universal terminal 28 are caused by the pressure of the spring 48 incorporated in the universal terminal 28. Electrically connected. Thereafter, the inside of the analysis tube 14a is evacuated to a predetermined analysis pressure by a vacuum pump such as a turbo molecular pump, and a new mass analysis is performed on the sample 15 to be measured next.

<X-Y movement of sample in laser desorption ionization mass spectrometry>
As shown in the right ends of FIGS. 7 to 11, in this specification, a plane orthogonal to the longitudinal direction of the analysis tube is defined as an XY plane, and the movement of the sample stage 17 on the XY plane is performed. Will be described.

-Fine movement in the X direction-
8 and 9 show an operation for finely moving the sample 15 in the X direction (horizontal direction in FIGS. 8 and 9) relative to the irradiation position of the pulse laser beam 20 in laser desorption ionization mass spectrometry. It is a figure explaining.

  When the X fine movement knob 34 is rotated and the sample 15 is moved to the irradiation position of the pulse laser beam 20 for performing mass analysis, the universal terminal 28 comes into contact with the current introduction terminal (feedthrough) 29 and ions are applied from the acceleration voltage introduction terminal. An acceleration voltage is applied to the sample stage 17 that also serves as the first acceleration electrode (back plate). The position of the sample 15 shown in FIG. 9 moves in the right direction (+ X direction) with respect to the position of the sample 15 shown in FIG. A state of fine movement in the X direction in the −Y plane is shown. The moving position of the sample 15 in the X direction is indicated by a scale or the like provided on the surface of the X fine movement knob 34.

  Since the universal terminal 28 is in a floating state by the spring 48, the electrical connection between the current introduction terminal 29 and the universal terminal 28 is sufficiently reliably maintained in the range of fine movement in the X direction, and is within the XY plane with respect to the irradiation position. The ion acceleration voltage can be stably supplied in the movement range at.

-Fine movement in the Y direction-
10 and 11 show operations in which fine movement of the sample 15 in the Y direction (vertical direction in FIGS. 10 and 11) is performed relative to the irradiation position of the pulsed laser light 20 in laser desorption ionization mass spectrometry. It is a figure explaining.

  Compared to the position in the XY plane of the sample 15 shown in FIG. 10, the position in the XY plane of the sample 15 shown in FIG. 11 shows a state of being finely moved downward (−Y direction). 10 and 11, when the Y fine movement knob 35 is finely rotated and the linear drive shaft 33 is finely moved in the X-axis direction, the Y-direction drive actuator 30 moves in the X-axis direction. A pin 41 attached to the Y-direction drive actuator 30 is fitted into a manipulating groove 40 provided in the sample stage 17. The manipulate groove 40 is a groove provided at an angle of 45 ° with respect to the horizontal direction on the paper surface of FIGS. 10 and 11. Since the pin 41 attached to the Y-direction drive actuator 30 is accommodated in the manipulating groove 40, the manipulator is moved by the pin 41 when the Y-direction drive actuator 30 moves in the X direction (left-right direction). The rate groove 40 causes movement in the Y direction (vertical direction), and the sample stage 17 moves in the Y direction. That is, FIG. 10 shows a state in which the pin 41 moves relatively to the lower left end of the manipulate groove 40, and as a result, the sample stage 17 slightly moves upward (+ Y direction). Moves relative to the upper right end of the manipulating groove 40, and as a result, the sample stage 17 is finely moved downward (−Y direction).

  The moving position of the sample 15 is indicated by a scale or the like provided on the surface of the Y fine movement knob 35. Similar to the fine movement in the X direction, the electrical connection between the current introduction terminal 29 and the free terminal 28 is sufficiently reliably maintained in the fine movement range in the X direction, and in the movement range in the XY plane with respect to the irradiation position. The ion acceleration voltage can be supplied stably.

  As described above, according to the reflective time-of-flight analyzer according to the first embodiment, the sample 15 can be mounted from the atmosphere side without releasing the vacuum chamber inside the analysis tube 14a. Since this is possible, the mass spectrometric performance and operability are improved.

  Furthermore, according to the reflective time-of-flight mass spectrometer according to the first embodiment, it is possible to control the movement of the sample 15 relative to the laser irradiation position in the XY plane. When the sample stage 17 is moved from the laser irradiation position to the outside-vacuum extraction position, the ion acceleration voltage is automatically cut off, so that the mass analysis performance, operability, and safety are improved.

(Second Embodiment)
In the first embodiment of the present invention, the case of the reflection type time-of-flight mass spectrometer provided with the reflectron 24 has been described as an example. However, the technical idea of the present invention includes the reflectron 24. The same applies to a linear type time-of-flight mass spectrometer.

  FIG. 12 is a diagram showing a schematic configuration of a linear time-of-flight analyzer according to the second embodiment of the present invention, and an MCP detector 23 is provided above the analysis tube 14b. As shown in FIG. 12, an upper end seal flange (top plate) 67b is connected to the upper end connection flange 68b at the upper end of the analysis tube 14b, and the MCP detector 23 is a metal implanted in the upper end seal flange (top plate) 67b. Located on the exit grid connected to the rod made of steel. Accordingly, the MCP detector 23 and the exit grid where the MCP detector 23 is arranged are set to the ground potential. The sample chamber flange 72 constituting the sample chamber 27 is connected to the lower end connection flange 66b at the lower end of the analysis tube 14b, and the vacuum chamber is constructed from the analysis tube 14b. The point of being evacuated by a vacuum pump such as a turbo molecular pump through an exhaust port flange 69 provided in an exhaust port that branches into a T-shape is the reflective time-of-flight mass according to the first embodiment. It is the same as the analyzer.

  As shown in FIG. 12, in the linear time-of-flight analyzer according to the second embodiment, a plate-shaped or ring-shaped second accelerating electrode (withdrawal) provided in the lower part of the analytical tube 14b. (Grid) 21b is provided, and the accelerator stage (17, 21a) is constituted by the sample stage 17 also serving as the first acceleration electrode (back plate) and the second acceleration electrode (drawing grid) 21a.

  The structure of the sample chamber flange 72 and the preparation chamber flange 73 connected to the right end of the sample chamber flange 72, and the vacuum seal and the drive mechanism of the sample stage 17 by them are the same as those in the first embodiment, and redundant explanations are given. Is omitted. The electrical connection relationship between the current introduction terminal 29 and the universal terminal 28 is also the same as in the first embodiment, and a duplicate description is omitted.

  Similar to the first embodiment, the sample 15 is irradiated with the pulsed laser light 20 from the laser introduction window 19 to leave the sample 15 and ionize 22. The ions 22 are accelerated by the accelerator (17, 21a), pass through the linear flight field free section 26b, and detected by the MCP detector 23. Since the flight trajectory and flight time of the ions 22 differ depending on the mass of the ions 22, a mass spectrometry spectrum can also be obtained by the linear time-of-flight analyzer shown in FIG.

  According to the linear time-of-flight analyzer according to the second embodiment, the vacuum chamber inside the analysis tube 14b is released to the atmosphere as in the case of the reflective time-of-flight mass spectrometer according to the first embodiment. Therefore, the sample 15 can be mounted from the atmosphere side, and the mass spectrometric performance and operability are improved.

  Furthermore, similarly to the reflective time-of-flight mass spectrometer according to the first embodiment, according to the linear time-of-flight analyzer according to the second embodiment, the sample 15 is placed on the laser irradiation position. The relative movement in the XY plane can be controlled, and in addition, when the sample stage 17 is moved from the laser irradiation position to the outside-vacuum extraction position, the ion acceleration voltage is automatically cut off. Analytical performance, operability and safety are improved.

(Third embodiment)
In the first and second embodiments of the present invention, the case of the time-of-flight mass spectrometer has been exemplarily described, but the technical idea of the present invention is limited to the time-of-flight mass spectrometer. It is not a thing.

  FIG. 13 is a diagram showing a schematic configuration of a quadrupole mass spectrometer according to the third embodiment of the present invention. Similarly to the linear time-of-flight analyzer according to the second embodiment, the analysis tube An MCP detector 23 is provided on the upper part of 14c. As shown in FIG. 13, an upper end seal flange (top plate) 67c is connected to the upper end connection flange 68c at the upper end of the analysis tube 14c, and the MCP detector 23 is a metal implanted in the upper end seal flange (top plate) 67c. Located on the exit grid connected to the rod made of steel. Accordingly, the MCP detector 23 and the exit grid where the MCP detector 23 is arranged are set to the ground potential. An exhaust port flange 69 is provided at an exhaust port that branches into a T-shape from the analysis tube 14c, and is structured such that it can be evacuated by a vacuum pump such as a turbo molecular pump. Four rods (columns) having a circular cross section are arranged inside the quadrupole lens 54 so as to constitute the quadrupole lens 54.

  The sample chamber flange 72 constituting the sample chamber 27 is connected to the lower end connection flange 66c at the lower end of the analysis tube 14c, and the sample chamber 27 and the sample chamber 27 constitute a vacuum chamber. This is the same as the mass spectrometer according to the embodiment.

  As shown in FIG. 13, in the quadrupole mass spectrometer according to the third embodiment, a second acceleration electrode (drawing grid) 21c is provided inside the lower portion of the analysis tube 14c, and the first acceleration electrode is provided. The sample stage 17 also serving as a (back plate) and the second acceleration electrode (drawing grid) 21a constitute an accelerator (17, 21a).

  The structure of the sample chamber flange 72 and the preparation chamber flange 73 connected to the right end of the sample chamber flange 72, and the vacuum seal and the drive mechanism of the sample stage 17 by them are the same as in the first and second embodiments. A duplicate description is omitted. The electrical connection relationship between the current introduction terminal 29 and the universal terminal 28 is also the same as in the first and second embodiments, and redundant description is omitted.

  Similar to the first and second embodiments, the sample 15 is irradiated with the pulse laser beam 20 from the laser introduction window 19 to leave the sample 15 and ionize 22. The ions 22 are accelerated by the accelerator (17, 21 a), pass through the quadrupole lens 54, and are detected by the MCP detector 23. The path of the ions 22 through the space in the quadrupole lens 54 is determined by the DC voltage U and the high frequency voltage Vcosωt applied to the rod of the quadrupole lens 54 and by the mass to charge ratio of each ion 22, thereby , Ions 22 in the beam having different mass to charge ratios can pass continuously to the MCP detector 23. Therefore, the MCP detector 23 detects ions 22 having a specific mass-to-charge ratio determined with respect to the specific DC voltage U and the high-frequency voltage V applied to the rod of the quadrupole lens 54. A mass analysis spectrum is obtained by sweeping the DC voltage U and the high-frequency voltage applied to the rod of the quadrupole lens 54.

  According to the quadrupole mass spectrometer according to the third embodiment, as in the mass spectrometers according to the first and second embodiments, the vacuum chamber inside the analysis tube 14c is not released to the atmosphere. Since the sample 15 can be mounted from the atmosphere side, mass spectrometric performance and operability are improved. Further, similarly to the mass spectrometers according to the first and second embodiments, according to the quadrupole mass spectrometer according to the third embodiment, the sample 15 is placed on the laser irradiation position by XY. It is possible to control the relative movement in the plane. In addition, when the sample stage 17 is moved from the laser irradiation position to the outside vacuum position, the ion acceleration voltage is automatically cut off. Operability and safety are improved.

(Other embodiments)
As described above, the present invention has been described according to the first to third embodiments. However, it should not be understood that the description and drawings constituting a part of this disclosure limit the present invention. From this disclosure, various alternative embodiments, examples and operational techniques will be apparent to those skilled in the art.

  In the first and second embodiments of the present invention described above, the case of the time-of-flight mass spectrometer is described, and in the third embodiment, the quadrupole mass spectrometer is described. The technical idea of the present invention is not limited to a time-of-flight mass spectrometer and a quadrupole mass spectrometer, but also an ion trap type, a sector type, a Fourier transform type, or a combination thereof, or Further, a time-of-flight mass spectrometer, a quadrupole mass spectrometer, and a composite mass spectrometer of these may be used.

  As described above, the present invention naturally includes various embodiments not described herein. Therefore, the technical scope of the present invention is defined only by the invention specifying matters according to the scope of claims reasonable from the above description.

It is typical sectional drawing for demonstrating the outline of the whole structure of the mass spectrometer (reflective time-of-flight mass spectrometer) which concerns on the 1st Embodiment of this invention. FIG. 4 is a schematic partial cross-sectional view for enlarging and explaining in detail a part of the sample chamber flange and the preparation chamber flange of the mass spectrometer according to the first embodiment of the present invention (B in FIG. 3). It is sectional drawing seen from -B direction.). It is a typical fragmentary sectional view for enlarging and explaining the outline of a part of sample chamber flange and preparation chamber flange of a mass spectrometer concerning a 1st embodiment of the present invention in detail (A of Drawing 2) It is sectional drawing seen from the -A direction.). In the mass spectrometer according to the first embodiment of the present invention, a schematic cross section corresponding to FIG. 1 for explaining the outline of the entire configuration in a state where the sample stage is moved to the preparation chamber for sample replacement FIG. In the mass spectrometer which concerns on the 1st Embodiment of this invention, it is typical sectional drawing for demonstrating the outline of the whole structure of the state which moved the sample stage to the preparation chamber for sample replacement (FIG. It is sectional drawing equivalent to sectional drawing seen from the AA direction of 2.). In the mass spectrometer which concerns on the 1st Embodiment of this invention, it is typical sectional drawing for demonstrating the outline of the attachment / detachment jig | tool used when exchanging a sample in a preparation chamber. In the mass spectrometer according to the first embodiment of the present invention, in order to explain an outline of the entire configuration in which the sample stage loaded with the sample to be measured next is moved from the preparation chamber to the sample chamber after sample replacement. FIG. 6 is a schematic cross-sectional view (a cross-sectional view corresponding to a cross-sectional view seen from the direction AA of FIG. 2). FIG. 8 is a schematic cross-sectional view illustrating a state in which the sample stage is further moved (finely moved) in the −X direction (leftward in FIG. 8) from the position in the X direction shown in FIG. 7. FIG. 8 is a schematic cross-sectional view illustrating a state in which the sample stage is further moved (finely moved) in the + X direction (rightward in FIG. 9) from the position in the X direction shown in FIG. 7. FIG. 8 is a schematic cross-sectional view illustrating a state where the sample stage is further moved (finely moved) in the + Y direction (upward in FIG. 10) from the position in the Y direction shown in FIG. 7. FIG. 8 is a schematic cross-sectional view illustrating a state where the sample stage is further moved (finely moved) in the −Y direction (downward in FIG. 11) from the position in the Y direction shown in FIG. 7. It is typical sectional drawing for demonstrating the outline of the whole structure of the mass spectrometer (linear time-of-flight mass spectrometer) which concerns on the 2nd Embodiment of this invention. It is typical sectional drawing for demonstrating the outline of the whole structure of the mass spectrometer (quadrupole mass spectrometer) which concerns on the 3rd Embodiment of this invention. It is typical sectional drawing for demonstrating the outline of the whole structure of the conventional reflection type time-of-flight mass spectrometer.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Laser 13 ... Laser beam introduction port 14a, 14b, 14c, 14p ... Analytical tube 15 ... Sample 16 ... Feed holder 16 ... Sample holder 17 ... Sample stage (back plate)
DESCRIPTION OF SYMBOLS 19 ... Laser introduction window 20 ... Pulse laser beam 21a, 21b, 21c, 21p ... Second acceleration electrode (drawing grid)
DESCRIPTION OF SYMBOLS 22 ... Ion 23 ... MCP detector 24 ... Reflectron 25 ... Ion lens 26, 26b ... Linear flight field free section 27 ... Sample chamber 28 ... Free terminal 29 ... Current introduction terminal 30 ... Y direction drive actuator 31 ... Detachable port 32 ... Insulating sleeve 33 ... Linear drive shaft 34 ... X fine adjustment knob 35 ... Y fine adjustment knob 36 ... first seal ring 37 ... second seal ring 38 ... preparation chamber 39 ... preparation chamber exhaust port 40 ... manipulate groove 41 ... pin 48 ... Spring 49 ... Sample stage fixing part 54 ... Quadrupole lens 56 ... Removable rod 57 ... Removable jig body 58 ... Chuck 66a, 66b, 66c, 66p ... Lower end connection flange 68a, 68b, 68c, 68p ... Upper end connection flange 69 ... Exhaust port flange 71 ... Feed-through flange 72 ... Sample chamber Lunge 73 ... preparation chamber flange 83 ... sample holder 84 ... sample exchange port 84 ... sample exchange port blind plate 85 ... first accelerating electrode

Claims (1)

An analysis tube for carrying out mass spectrometry with a drawing grid on one end side,
A sample chamber flange connected to the one end of the analysis tube and defining a sample chamber therein;
A preparation chamber flange connected to the sample chamber flange in a direction perpendicular to the longitudinal direction of the analysis tube and defining a preparation chamber therein;
A sample stage that functions as a back plate that constitutes an accelerator of ions to be measured at the time of mass analysis together with the extraction grid, at the time of mass analysis,
An insulating support for insulating the acceleration high voltage applied to the sample stage from the apparatus housing;
When the sample stage is located in the preparation chamber, the vacuum state of the analysis tube and the preparation chamber is separated, and when the sample stage is located in the sample chamber, the first vacuum sealing means is opened. When,
When the sample stage is located in the sample chamber, the vacuum state between the analysis tube and the atmosphere is separated when the sample stage is located in the sample chamber. A second vacuum sealing means for separating a vacuum state between the preparation chamber and the atmosphere when located in a chamber;
Only when the sample stage moves to the sample chamber, a current introduction terminal to which a high voltage for acceleration is applied to the sample stage;
In a mass spectrometer comprising: an X direction orthogonal to the longitudinal direction of the analysis tube; and a driving means for moving the sample stage in a Y direction orthogonal to the X direction in the plane of the sample stage.
The insulating support is composed of a cylindrical insulating sleeve, the sample stage is mounted on one end thereof, and can move linearly between the sample chamber and the preparation chamber,
Further, the first vacuum sealing means and the second vacuum sealing means are each constituted by a first seal ring and a second seal ring, which are disposed on an outer peripheral portion of the insulating sleeve,
Furthermore, the driving means for moving the sample stage is a X / Y-direction feed mechanism comprising a plurality of feed screw arranged coaxially with respect to the Y direction, the guide having a predetermined angle with respect to the X-direction Provided with a fine movement function in the Y direction by converting a fine movement displacement in the X direction into a fine movement displacement in the Y direction by means of a groove and an X direction fine movement pin in the guide groove,
Furthermore, a mass spectrometer comprising: a sample holder that can be attached to and detached from the sample stage.

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