JPH05275054A - Tandem type mass spectrograph - Google Patents

Abstract

PURPOSE:To achieve high resolution and high mass spectrometric characteristic at low cost by improving an interface system lens of a tandem type mass spectrograph. CONSTITUTION:A mass spectrograph of fore stage (an ion source slit 2, electrostatic quadrupole lenses 3a, 3b, 3c, a sector magnetic field 4, a sector electric field 5, a collector slit 6) and a mass spectrograph of rear stage (an ion source slit 8, electrostatic quadrupole lenses 3a', 3b', 3c', a sector magnetic field 4', a sector electric field 5', a collector slit 6') are connected in series between an ion source 1 and a detector 9, and a pair of half plate lenses 7a, 7b is provided on the connection part. The lenses 7a, 7b have the converging characteristic in the horizontal direction of a trajectory plane and the deflectional function for adjusting axial deviation, and has no lens operation in the direction perpendicular to the trajectory plane.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mass spectrometer used for analyzing an organic structure of a polymer in the fields of medicine, pharmacy, organic chemistry, etc., and particularly to a tandem mass spectrometer having high resolution and high mass characteristics. Regarding the device.

[0002]

2. Description of the Related Art Conventionally, a tandem mass spectrometer is known in which a double-convergent mass spectrometer is connected in series.
This type of mass spectrometer uses a parent mass spectrometer to select a specific parent ion, and then analyzes the daughter ions generated by gas collisions in the latter mass spectrometer. Is evaluated as having.

As a typical conventional technique, FIG.
3 shows a tandem mass spectrometer disclosed in JP-A-3-136451. In the figure, 1 is an ion source, the mass spectrometer of the former stage is provided with an ion source slit 2, a sector electric field 5, a sector magnetic field 4, and a collector slit 6, and the mass spectrometer of the latter stage is an ion source slit 8 and a sector magnetic field 5. ’、 Fan magnetic field 4
′, And a collector slit 6 ′. Reference numeral 9 is an ion detector, and 13 is a collision chamber that dissociates parent ions selected by the mass spectrometer of the preceding stage to generate daughter ions.

In the invention described in this, an electrostatic quadrupole lens 3 having a converging action in the horizontal direction (x direction) of the orbit plane is arranged between the collector slit 6 in the front stage and the ion source slit 8 in the rear stage. ing. Further, a configuration in which a lens having a converging action is arranged in a direction (y direction) perpendicular to the orbit plane is claimed.

On the other hand, the recent progress of the ion optical system of the mass spectrometer is remarkable, and as in the mass spectrometer disclosed in Japanese Laid-Open Patent Publication No. 59-215650, two ion optics are provided between the ion source and the uniform magnetic field. An electrostatic quadrupole lens is arranged to narrow the beam between the narrow magnetic poles, and an electrostatic quadrupole lens is further arranged between the magnetic field and the electric field to make it converge in the direction perpendicular to the orbit plane. An ion optical system with a very high image reduction rate has been devised. This device has a high resolution because the image reduction rate is high even if the slit width of the ion source is wide, and the beam divergence is suppressed in the y direction by the converging action in the direction perpendicular to the orbital plane (y direction), resulting in a nearly parallel beam. Therefore, its analytical sensitivity is excellent.

[0006]

However, in order to apply the latter type of mass spectrometer (Japanese Patent Laid-Open No. 59-215650) to a tandem mass spectrometer, two units are connected in series and the When the electrostatic quadrupole lens 3 shown in FIG. 5 is installed as an interface lens between the front collector slit 6 and the rear ion source slit 8, the following problems occur.

That is, since the mass spectroscope in the previous stage has a high image reduction rate, the ion beam rapidly diverges in the x (lateral) direction after passing through the collector slit 6. In order to effectively pass this through the mass spectrometer of the latter stage, it is necessary to give a refocusing action in the x direction by the electrostatic quadrupole lens 3 to form a large magnified image on the ion source slit 8 of the latter stage. is there. Then, the electrostatic quadrupole lens 3 always has a strong diverging action in the y (longitudinal) direction.
FIG. 6 shows the state of the ion beam at this time, (a) of the figure shows the beam state in the x direction (convergence for giving an enlarged image), and (b) of the figure shows the beam state in the y direction. ..
As shown in FIG. 6B, the beam of the mass spectrometer of the previous stage flies almost parallel to the y direction, so if the electrostatic quadrupole lens 3 converges in the x direction [FIG. a)], the beam largely diverges in the y direction, and the transmittance to the mass spectrometer at the subsequent stage is significantly reduced.

Reference numeral 10 is a parent ion beam, 11 is a slit passing ion, and 12 is a daughter ion beam.

The electrostatic quadrupole lens has a converging / diverging action for the beam along the axial symmetry, but since it does not have a action for deflecting the beam to the left and right, the ion beam is deflected by the electric field deflection of the mass spectrometer in the preceding stage. It becomes difficult to guide the beam, which is deviated from the central axis, to the ion source slit in the subsequent stage.

Further, the electrostatic quadrupole lens has a complicated structure, and the cost increases if the number of stages is increased.

The present invention has been made in view of the above points, and an object of the present invention is to provide a tandem mass spectrometer which is low in cost and further improves high resolution and high mass spectrometry characteristics.

[0012]

In order to achieve the above object, the present invention basically proposes the following means for solving the problems.

That is, in the tandem mass spectrometer, between the collector slit of the mass spectrometer of the previous stage and the ion source slit of the mass spectrometer of the latter stage, as a lens of the interface, a focusing characteristic and an axis deviation are provided in the horizontal direction of the orbit plane. A lens having a function of adjusting deflection and having no lens action in the direction perpendicular to the orbital plane is provided.

[0014]

With the above-mentioned constitution, especially Japanese Patent Laid-Open No. 59-21.
When an ion optical system disclosed in Japanese Patent No. 5650 is connected in series with a mass spectrometer of a type that has a small image reduction rate at a collector slit and allows a substantially parallel beam to pass in the y direction, the following action is performed. It

The ion beam (parent ion beam) converged at a high image reduction rate by the ion optical system of the mass spectrometer of the preceding stage (hereinafter simply referred to as "the preceding stage") passes through the collector slit of the preceding stage and is within the orbit plane. However, the lens of the interface given the above characteristics gently refocuses in the x direction and expands to the ion source slit of the latter mass spectrometer (hereinafter simply referred to as the latter). It can be focused as an image (this focusing is focused as a beam of daughter ions generated by the parent ion beam being dissociated in the gas collision chamber). In this case, not only the beam divergence in the x direction between the former stage and the latter stage can be prevented but also the beam can be formed as an enlarged image by the latter ion slit source, so that the divergence angle of the beam after passing through the latter ion source slit is increased. Is reduced to suppress divergence in the latter stage.

In the ion optical system in the front stage, the ion beam passes through the collector slit in the front stage almost in parallel.
Since the lens of the interface used in the present invention does not have a lens action in the y direction, the beam is sent to the ion optical system in the subsequent stage in the y direction as it is (in a substantially parallel state).

Even if the ion beam passing through the collector slit in the front stage is deviated from the central axis connecting the collector slit, the interface lens and the rear stage ion source slit by the deflection of the electric field in the front stage, the interface lens produces a beam. Since it has a function of arbitrarily deflecting the beam, it is possible to correct the axis deviation of the beam by this deflecting action. This deflection action is very effective for adjusting the axis deviation when deflecting a long orbital distance by a plurality of fan-shaped magnetic fields and electric fields as in an actual tandem mass spectrometer, and electrostatic 4
This is an effect that cannot be expected with a dipole lens.

[0018]

Embodiments of the present invention will be described with reference to the drawings.

First, the overall configuration of a tandem mass spectrometer according to an embodiment of the present invention will be described with reference to FIG.

In the present embodiment, a tandem mass spectrometer of a type in which a front-stage and a rear-stage double-focusing mass spectrometer are connected in series is 1 an ion source, and a front-stage mass analyzer is an ion source slit 2. A sector magnetic field 4, a sector electric field 5, a collector slit 6, electrostatic quadrupole lenses 3a and 3b arranged between the ion source slit 2 and the magnetic field 4, and an electrostatic quadrupole arranged between the magnetic field 4 and the electric field 5. It is composed of a polar lens 3c. The mass spectrometer in the latter stage comprises an ion source slit 8 with a gas collision chamber,
Between the sector magnetic field 4 ', the sector electric field 5', the collector 6 ', the electrostatic quadrupole lenses 3a' and 3b 'arranged between the ion source slit 8 and the magnetic field 4', and between the magnetic field 4'and the electric field 5 '. It is composed of an electrostatic quadrupole lens 3c 'arranged. Reference numeral 9 is an ion detector.

Half plate lenses 7a and 7b are arranged as a lens 7 of an interface between the collector slit 6 and the ion source slit 8 having a gas collision chamber, which serve as a connecting portion of the front and rear mass spectrometers. As shown in FIG. 2, a collision gas such as argon is introduced into the ion source slit 8 with the collision chamber through the inlet 13 to dissociate the parent ions.

Now, the half plate lenses 7a and 7b will be described with reference to FIG.

The half plate lenses 7a and 7b are composed of lens electrodes divided into left and right, are arranged in pairs in the horizontal direction of the orbit plane across the passage of the ion beam, and are surrounded by the ground electrode 14. .. Further, the voltages V and V'are independently applied to the half plate lenses 7a and 7b. Half plate lenses 7a, 7
With the above configuration, b has a converging characteristic in the horizontal direction (x direction) of the orbit plane, has a deflection function for adjusting the axis deviation, and is in the direction (y direction) perpendicular to the orbit plane. Is set to have no lens effect.

According to the above-mentioned structure, in the mass spectrometer of the preceding stage, the presence of the electrostatic quadrupole lenses 3a, 3b, 3c allows the specific parent ion beam 10 to be focused in the x direction at a high image reduction rate. With high resolution and high sensitivity, they are separated at the position of the collector slit 6.

The beam 11 that has passed through the slit 6 is subjected to a converging action in the x direction by the half plate lenses 7a and 7b (the action of this lens will be described later), and is then dissociated in the gas collision chamber to generate it. Daughter Ion Beam 12
To the ion detector 9 via the ion optical system of the double-focusing mass spectrometer in the latter stage.

The operation of the half plate lenses 7a and 7b of this embodiment will be described with reference to FIGS.

As shown in FIG. 3, the parent ion beam 10 focused at a high image reduction rate in the ion optical system in the preceding stage passes through the collector slit 6 and then, in the orbital plane, at an angle of α ₂ in the x (transverse) direction. , But the half-plate lens 7 has a phantom line (the broken line in FIG. 1 is an imaginary line of this divergence).
It is gently refocused by a and 7b, and becomes a daughter ion beam 12 in the ion source slit 8 with a collision chamber and is formed as an enlarged image. After that, since the divergence angle α ₁ ′ is smaller than α _2, it does not diverge in the subsequent mass spectrometer.
On the other hand, the ion beam 10 is y (vertical) perpendicular to the orbital plane.
In the direction, the beam passes through the collector slit 6 in a substantially parallel beam state by the action of the ion optical system in the front stage, but since the half plate lenses 7a and 7b do not have a lens action in the y direction, the beam 11 remains as it is in the rear stage. It is sent to the mass spectrometer.

As a result, even after the ion source slit 8 in the latter stage, the beam does not have a large divergence angle in the x direction and becomes a substantially parallel beam in the y direction.
Passes through the double-focusing mass spectrometer (8-6 ') with good transmittance,
It is detected by the ion detector 9. Since this tandem mass spectrometer is used for organic structure analysis, the specific parent beam 10 is dissociated in the gas collision chamber (also serving as the slit 8) to generate daughter ions 12 having different energies, as described above. However, since the daughter ions are mass-analyzed, B'of the magnetic field 4'and E'of the electric field 5'are scanned in a relation that B '/ E' = constant.

In the actual tandem mass spectrometer, the collector slit 6 and the half plate lens 7 are used.
The parent ion beam does not always pass along the mechanical central axis Z connecting the a and 7b and the ion source lens 8 with the collision chamber, and as shown in FIG. 4, the central axis Z ′ of the incident parent ion beam is It is possible that there is a lateral shift. However, according to the present embodiment, the central axis of the parent ion beam can be aligned with the mechanical central axis Z by adjusting the left and right applied voltages V and V'by using the half plate lenses 7a and 7b. it can.

This deflection action is very effective for adjusting the axis deviation when a long orbit distance is deflected by a plurality of fan-shaped magnetic fields and electric fields as in an actual tandem mass spectrometer.

The arrangement of the half plates 7a and 7b on the Z-axis is determined by how much the reduction ratio of the mass spectrometer of the preceding stage is enlarged, but an image with a magnification of 1 is formed on the ion source slit 8 of the mass spectrometer of the latter stage. If the distance from the collector slit 6 to the half plate lenses 7a and 7b is a, and the distance from the half plate lenses 7a and 7b to the ion source slit 8 with the collision chamber is b, the collector slit 6 The reduction ratio of M is set to M, and the relationship of a / b = M may be established.

When a conventional disk or square unipotential lens 15 or 15 'as shown in FIG. 8 is used in place of the half plate lens, the equipotentials changing in the y direction as shown in the right figure. A surface is generated, and the beam incident parallel to the y direction is subjected to a converging action, and as the distance in the Z direction becomes longer, the beam is focused once and then diverges, which is inconvenient. Moreover, since the deflection action in the x direction cannot be expected,
It is not suitable because the deviation of the central axis Z'of the beam cannot be corrected.

According to this embodiment, the following effects can be obtained.

A double-convergence mass spectrometer having a high image reduction ratio is used in the front and rear stages, and half plate lenses 7a and 7b having a simple structure are provided in the middle of the interface system lens 7.
By interposing as an ion beam, the divergence is sufficiently suppressed from the previous stage to the latter stage without giving extra convergence, and the ion beam is sent while correcting the axis deviation, so the cost is reduced and the high resolution of this type of mass spectrometer is achieved. The high mass spectrometry characteristics can be further improved.

The half plate lenses 7a and 7b do not necessarily need the ground electrode 14, and the half plates 7a and 7b alone can produce a sufficient effect. Also,
In the above-described embodiment, the half plate lens has only one stage on the left and right in the Z direction, but a multi-stage half plate lens in which two or three stages of multi-stage half plates are arranged in the Z direction can also exert the effect. A two-stage embodiment is shown in FIG. The aligned electrodes in the Z direction is optimum potentials V _1, V ₂ differ is applied, slightly different V ₁ relative to V _1, V ₂ in the x direction of the trace deflection ', V _2' optimal potential of Adjusted to the value.

Although not shown, appropriate positions (for example, the electrostatic quadrupole lens 3b 'and the magnetic field 4'in the mass spectroscope in the subsequent stage are also shown.
TIM (total between
By adjusting the voltage values V and V'of the half plate lenses 7a and 7b while observing the ion beam amount by this TIM, the optimum focusing action and beam axis adjustment of the half plate lens can be performed. , The maximum beam amount can be obtained.

[0037]

As described above, according to the present invention, a converging action and a deflecting action are given in the horizontal direction of the orbit plane between the front stage and the rear stage of the tandem mass spectrometer, and the lens is provided in the direction perpendicular to the orbit plane. By interposing a lens having no action as an interface, this lens is structurally simple and cost-effective, but a half lens can be used. It is possible to provide a tandem mass spectrometer that further improves mass spectrometry characteristics.

[Brief description of drawings]

FIG. 1 is a plan view showing the overall configuration of a tandem mass spectrometer according to an embodiment of the present invention.

FIG. 2 is a front collector slit used in the above embodiment,
Partially cutaway perspective view showing arrangement of half plate lens and post-stage ion source slit

FIG. 3 is an explanatory view showing a beam orbit under the action of the half plate.

FIG. 4 is an explanatory view showing a beam axis deviation correction state by the half plate.

FIG. 5 is a plan view showing an example of a conventional tandem mass spectrometer.

FIG. 6 is an explanatory diagram that points out problems with the conventional tandem mass spectrometer.

FIG. 7 is an explanatory view showing a usage mode of a half plate used in another embodiment of the present invention.

FIG. 8 is an explanatory view showing the vertical directional convergence and divergence action of a conventional unipotential lens.

[Explanation of symbols]

1 ... Ion source, 2 ... Ion source slit, 3a, 3b, 3
c, 3a ', 3b', 3c '... Electrostatic quadrupole lens, 4 ...
Fan-shaped magnetic field, 5 ... fan-shaped electric field, 6 ... collector slit, 7
a, 7b ... Half plate lens (interface lens), 8 ... Ion source slit with collision chamber, 9 ... Ion detector, 10 ... Parent ion beam, 11 ... Slit passing ion, 12 ... Daughter ion beam.

Claims (6)

[Claims] 1. Connecting two mass spectrometers in series,
In the tandem mass spectrometer, in which a specific parent ion is selected by the former mass spectrometer and then the daughter ions generated by dissociation in gas collision are analyzed by the latter mass spectrometer, the collector slit of the former mass spectrometer and the latter A lens having an interface lens between the ion source slits of the mass spectrometer, which has a converging characteristic in the horizontal direction of the orbit plane and a deflection function for adjusting the axis deviation, and has no lens action in the direction perpendicular to the orbit plane. A tandem mass spectrometer, characterized by being provided with. 2. The lens according to claim 1, wherein the lens of the interface is composed of a pair of half plate lenses arranged to face each other in a horizontal direction of an orbit plane across an ion beam passage path, and each half plate lens is independently provided with a voltage. The tandem mass spectrometer is characterized in that it is set so that 3. The lens according to claim 1 or 2, wherein the lens of the interface is arranged near a collector slit of the mass spectrometer of the former stage and an enlarged image is taken on an ion source slit of the mass spectrometer of the latter stage. And a tandem mass spectrometer. 4. The mass spectrometer of any one of claims 1 to 3, wherein a plurality of electrostatic quadrupole lenses are arranged between the ion source slit and the magnetic field in order to reduce the image reduction ratio. A tandem mass spectrometer as a high ion optical system. 5. The mass spectroscope according to claim 4, wherein an electrostatic quadrupole lens is installed between the magnetic field and the electric field,
A tandem mass spectrometer as an ion optical system in which an ion beam travels almost parallel in a direction perpendicular to an orbital plane at a collector slit at a double focusing point. 6. The TIM (total ion monitor) according to claim 1, further comprising: a TIM (total ion monitor) for monitoring an amount of an ion beam passing through a mass spectrometer at a subsequent stage,
The tandem mass spectrometer is characterized in that the voltage applied to the electrode of the lens of the interface is adjusted while observing the ion beam amount by the TIM.