JPS62140354A - Ms/ms device - Google Patents

Abstract

PURPOSE:To improve the permeability of daughter ions and obtain a high detecting sensitibity of them in the latter stage of the MS, by applying a high voltage to a collision chamber between MSs of a double focus mass spectro meter system of two-stage array to give high energy to the daughter ions. CONSTITUTION:Sample ions produced at an ion source S and accelerated by a voltage Va are led to the former stage MS, and only parent ions with a specific mass given by the intensity of an electric field E1 and a magnetic field B1 can pass through the former stage MS to flow to a collision chamber CC. A collision gas of an adequate pressure is fed to the collision chamber CC, and the parent ions collide with the gas molecles and split into daughter ions and neutral particles. Since a high voltage Vc is applied to the chamber CC, the daughter ions are given a high energy. By loading the daughter ions of such a high energy, the permeable efficiency of the daughter ions is improved, and the detecting sensitivity is also well improved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to an MS/MS device that performs analysis by arranging mass spectrometers (MS) in two stages.

[Prior art] MS/MS devices have been attracting attention in recent years, but magnetic field type MS
Figure 4 (a>
There are three types shown in , (b), and (C). In FIG. 4, S is an ion source, B is a magnetic field, E is an electric field, CC is a collision chamber, and D is an ion detector.

[Problems to be solved by the invention] Of these, (a) and (b) have a simple configuration and are advantageous in terms of cost, but the performance (resolution and sensitivity) is poor because the MS in the latter stage only uses a magnetic field or an electric field. It has the disadvantage of not being able to take enough
In (C), the resolution of the MS in the subsequent stage can be high, but the ion path becomes long, the ion passage rate decreases, and the sensitivity is insufficient.

An object of the present invention is to provide an MS/MS apparatus that can improve sensitivity while adopting the configuration shown in FIG. 4(C) or a configuration in which the electric field and magnetic field are exchanged in FIG. 4(C).

[Means for solving the problem] In order to achieve this object, the present invention includes an ion source and a first double focusing mass into which sample ions generated from the ion source and accelerated by an accelerating voltage Va are incident. an analysis system, a collision chamber into which the ions that have passed through the first double-focusing mass spectrometry system enter, a second double-focusing mass spectrometry system into which the ions that have passed through the collision chamber enter; MS/MS equipped with an ion detector that detects ions that have passed through a second dual focus mass spectrometry system
In the apparatus, means for applying a voltage Vc lower than the accelerating voltage Va to the collision chamber, means for sweeping the intensity B2 of the magnetic field constituting the second double convergence mass spectrometry system, and A second double convergence mass spectrometry system is constructed in response to the sweep, and a means is provided for sweeping the overlapping electric field strength F2 according to a function determined by the value of the ratio of Vc and Va and the value of 82. .

[Function] In the present invention, a high voltage is applied to the collision chamber disposed between the first MS and the second MS, and this allows large energy to be given to the daughter ions generated in the collision chamber. The ion transmittance of MS is improved and high sensitivity can be obtained.

Hereinafter, one embodiment of the present invention will be explained in detail using the drawings.

[Embodiment] FIG. 1 shows the configuration of an embodiment of the present invention, and in the figure, S
is an ion source, E+ and B+ are electric and magnetic fields forming the first MS, and E2 and B2 are electric and magnetic fields forming the second MS. CC is a collision chamber arranged between the first MS and the second MS, to which a collision gas such as helium is supplied from the outside, and a high voltage VC is applied from the power source 1. 2 is an electric field power source for the electric field E2, 3 is a magnetic field power source for the magnetic field B2, 4 is a scanning circuit, and 5 is a scanning signal generator.

In such a configuration, sample ions generated by the ion source S and accelerated by the accelerating voltage Va are introduced into the first MS, and are given a specific mass m1 determined by the strength of the electric field E+ and the magnetic field B1.
Only the parent ion m1+ having , passes through the first MS and heads toward the collision chamber CC. Collision gas is supplied to the collision chamber CC at an appropriate pressure, and the parent ions m1+ that have passed through the first MS collide with gas molecules in the collision chamber, forming daughter ions m2+ and mass (ml-second). It splits into neutral particles. The daughter ions m2+ generated in this way in the collision chamber CC
is introduced into the second MS and the electric field E2 and magnetic field B2 of the second MS are swept, a daughter ion spectrum indicating what mass of the daughter ion is derived from the parent ion m1+ can be obtained.

In the conventional method in which the collision chamber is given a ground potential at this time,
The energy possessed by the parent ion is 2:m depending on the mass of the daughter ion and the neutral particle.

-m2, and the daughter ions with the distributed energy leave the collision chamber and head toward the second MS. Therefore, if the question of the daughter ion is small, the energy of the daughter ion is also small, and even if such a low-energy daughter ion is introduced into the second MS, the passage efficiency of the daughter ion will be low and the detection sensitivity will not be sufficient. It was inevitable that there wouldn't be one.

In this regard, in the present invention in which a high voltage Vc is applied to the collision chamber, it is possible to impart high energy to the daughter ions. For example, considering the case where VC=Va, the energy of the parent ion becomes zero in the collision chamber, and the resulting daughter ion m2+ receives energy from the parent ion, but the voltage Vc is applied to the collision chamber. Therefore, the daughter ions exiting from the collision chamber to the free space toward the second MS have high energy corresponding to the high voltage Vc (=Va). Therefore, if these high-energy daughter ions are introduced into the second MS, the passage efficiency of the daughter ions is high and the detection sensitivity is also sufficiently high.

In reality, when Vc = Va, the energy of the parent ion becomes zero in the collision chamber and the generation of daughter ions does not go well, so Vc is set lower than Va, and the parent ion has a certain amount of energy (Va - Vc It is necessary to have

Thus, in the present invention, since the voltage Vc is applied to the collision chamber as described above, the second MS must be swept as follows.

The velocity v1 of the parent ion m1+ in the collision chamber CC is expressed by the equation 1ζ.

V I = J"-2-'e'-te1./-a
-Vc ) /m+ (1) Letting the intensity of the electric field (B2) through which the ions accelerated by the accelerating voltage Va pass as B20, Va/E2o=K (2), then the intensity of the electric field E2 through which the daughter ion m2+ passes. [ is expressed by the following formula.

E = m 2 V + 2/ 28 K 10 V C/
K= ((mz /m+ (Va - Vc) +
VC) Similarly, if B is the strength of the magnetic field B2 through which the daughter ion m2+ passes, a is the radius of the center orbit of the ion which is applied to the 11-field B2, and v2 is the velocity of the daughter ion m2+, the following equation is obtained.

V2=aeB/mz (4) Also,
According to the law of conservation of energy, the following equation holds: mzVz2/2− m2V+ 2/2+eVc (5) By substituting equation (5) into equation (3), the following equation is obtained.

mz V22/2=KeE (6) Then, by eliminating V2 from equations (4) and (6), the following equation is obtained.

Em2/B2=a2e/2K (7) Furthermore,
By eliminating mz from equations (3) and (7), the following equation is obtained.

2m+ (8
) If E and B are changed so that Equation (8) always holds, that is, by sweeping the electric field F2 and magnetic field B2, the daughter ion spectrum can be obtained by (q).

In order to further organize equation (8), −VC/Va
(9) ε-KE/Va
(10) B2 = a2 eB2 / 2
Put m+ (11) and (9)~(
By substituting equation (11) into equation (8), the following equation is obtained.

If ε is calculated from the equation (12), the following equation is obtained.

ε = (to +41-) B2) /2 (13) Furthermore,
In the above equations (10) and (11), K/Va and a2e
Since the value of B2/2m+ is constant during measurement, ε, B2 and β
and B2 can be considered equivalent. Therefore, by sweeping the electric field E2 and the magnetic field B2 so that equation (13) always holds true, a daughter ion scan can be performed to detect all daughter ions derived from a specific parent ion.

Figure 2 shows the electric field E2 and magnetic field B2 based on this equation (13).
FIG. 2 is a block diagram showing an example of a scanning circuit 4 for performing a sweep. In Figure 2, 6 is a divider circuit, 7.8 is a squaring circuit, 9 is an amplifier with a gain of 4 times, 10 is a subtraction circuit, 11 is a multiplication circuit, 12 is an addition circuit, 13 is a square root circuit, and VR is variable. It is resistance.

As can be seen from this Figure 2, the acceleration voltage Va at the ion source
, voltage applied to the collision chamber VC, scanning signal I, fixed value I
If o is input externally, the electric field power supply 2 has
IO-) is supplied with a signal corresponding to 12.

In the measurement, first, set the value of ■ to the maximum (corresponding to I-Io). At this time, the reference input signal to power supply 2 is
+Io-)IO2, but the power source 2 is adjusted so that the strength of the electric field E2 becomes E. As a result, equation (13) comes to hold true.

Further, the strength of the magnetic field B2 is adjusted by adjusting the variable resistance vR*wJ so that the strength of the magnetic field B2 becomes the magnetic field strength Bo at which parent ions are detected.

After completing such adjustment, if the scanning signal I is swept in the direction of decreasing from 10, the strength of the magnetic field B2 will be swept linearly, and the strength of the electric field E2 will be swept according to equation (13), so that the detector A daughter ion spectrum can be obtained from the sample.

FIG. 3 shows the B2-F2 sweep curve depending on the value of .

−0, that is, Vc=O, corresponds to the conventional sweep in which no voltage is applied to the collision chamber, and −=1 corresponds to the sweep in the case of VC−Va. As mentioned earlier, the value of is set to O〈〈1.

Furthermore, once you obtain the daughter Ion vector, the daughter Io that exists
Since the mass of the daughter ion is known, the amount of that particular daughter ion can be monitored over time by supplying a constant level signal specifying the daughter ion as the scanning signal (2). When monitoring multiple daughter ions, it is sufficient to supply a signal that switches stepwise at multiple levels specifying the multiple daughter ions as a scanning signal. By time-divisionally capturing specific daughter ions of
It is possible to monitor changes in each intensity over time.

The MS in the latter stage has an electrostatic lens (
For example, if the lens includes a quadrupole lens, a hexapole lens, an octupole lens, it goes without saying that it is necessary to apply a voltage corresponding to the voltage supplied to the electric field E2 to these lenses as well.

[Effect] As detailed above, according to the present invention, the first MS and the second M
A high voltage is applied to the collision chamber placed between J and S, which can give high energy to the daughter ions, so the passage rate of the daughter ions in the second MS increases and the detection Sensitivity can also be sufficiently increased.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the configuration of an embodiment of the present invention, FIG. 2 is a block diagram showing an example of a scanning circuit for sweeping the electric field E2 and magnetic field B2 based on equation <13), and FIG. The figure shows a B2-E2 sweep curve depending on the value of , and FIG. 4 shows a basic type of MS/MS apparatus using a magnetic field type MS. S: Ion source E+, [2: Electric field B+, B
2: Magnetic field CC:! Actual character 1: Power supply 2
: Electric field power supply 3: Magnetic field power supply 4: Scanning circuit 5: Scanning signal generator 6: Divide circuit 7.8: Square circuit 9: Amplifier 10: Subtraction circuit 11: Multiplication circuit 12: Addition circuit 13: Square root circuit VR : Variable resistance

Claims (2)

[Claims] (1) An ion source and an accelerating voltage Va generated from the ion source
a first double-focusing mass spectrometry system into which sample ions accelerated by the ion beam are incident; a collision chamber into which ions that have passed through the first double-focusing mass spectrometry system are incident; and a collision chamber into which ions that have passed through the collision chamber are incident. In the MS/MS apparatus, the MS/MS apparatus includes a second double-focus mass spectrometry system that detects ions, and an ion detector that detects ions that have passed through the second double-focus mass spectrometry system. means for applying a magnetic field strength B_2 to the collision chamber, means for sweeping a magnetic field strength B_2 constituting the second double-focus mass spectrometry system, and a second double-focus mass spectrometer corresponding to the sweeping of the magnetic field strength B_2. An MS/MS apparatus characterized in that it is provided with means for sweeping the intensity E_2 of an electric field constituting an analysis system according to a function determined by the value of the ratio of Vc to Va and the value of B_2. (2) The above function uses B_0 as a constant and √(Va/Vc)^2+4{1-(Va/Vc)}(
The MS/MS device according to claim 1, characterized in that it is proportional to B_2/B_0)^2.