JP2007165335A - Charge adjustment method, its device and mass spectrometer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve a problem where, since a reaction of sample ions with reverse charge ions is stochastically controlled in a conventional example, charge can not be stopped at an arbitrary value in a charge reduction operation; that is to say, the ion/ion reaction progresses until the valence of the sample ions is set to 0, that is, neutral; in this case, the sample ions are lost from an ion trap, and as a result, analysis sensitivity is degraded. <P>SOLUTION: A charge reduction reaction is generated in one-side linear ion trap by using a tandem linear ion trap, and ions set at an arbitrary set charge value are selectively moved to the other-side linear ion trap. Thereby, by executing an MS/MS mass analysis, the structure of a biological polymer can be efficiently analyzed by a simple analysis. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

The present invention ionizes a sample solution with an atmospheric pressure ion source such as electro-spray ionization (ESI), and multivalent ions generated by the ion source are applied to a mass spectrometer. The present invention relates to a mass spectrometer that performs mass spectrometry by generating crushed ions by guidance, collision-induced dissociation (CID), and infrared multiphoton absorption dissociation (IRMPD).
In particular, a method for analyzing sample ions with a high sensitivity by simplifying the mass spectrum of fragmented ions, which is complicated by multivalent ions, by reducing the charge of the sample ions using ions having the opposite polarity to the ions. The present invention relates to a mass spectrometer that achieves the above.

  A mass spectrometer is a device that can directly measure a charge mass ratio (m / z, where m is mass and z is charge) of a substance with high sensitivity and high accuracy. Particularly recently, the scope of application has expanded to the analysis of peptides and proteins. Analysis of these biomolecules, which are major components of living bodies and function as enzymes, is expected to be widely applied from medical diagnosis to the development of new disease treatment drugs.

  There are many different types of mass spectrometers with different principles. Among them, the ion trap mass spectrometer is popular in many fields because it has many functions while being small.

In recent years, development of ionization methods for ion trap mass spectrometers has greatly contributed to the background of mass spectrometry of peptides, proteins, DNA and the like. Typical examples are matrix assisted laser desorption ionization (MALDI) and electrospray ionization (ESI). The MALDI method is an ionization method that mainly generates single-charged ions when proteins are ionized, and is compatible with time of flight (TOF) mass spectrometry. ESI is an ionization method that can extract biopolymers that are easily pyrolyzed as stable ions in a gas phase directly from a solution state. In ESI, biological macromolecules such as proteins and peptides become multivalent ions with many charges. Multivalent ions are ions in which one molecule (mass m) has a plurality of charges (n-valent). The mass spectrometer mass-analyzes ions according to the mass-to-charge ratio (m / z) (where z = me, e is an elementary charge). As analyzed.
Multi-stage mass spectrometry (MS / MS) is a method for determining the structure of biopolymer ions produced by the ionization method as described above by mass spectrometry. The mass-determined parent ion is dissociated using a method such as collision induced desociation (CID) or far-infrared multiphoton absorption (IRMPD). The fracture ion pattern is determined by mass spectrometry to determine the structure of the parent ion.

In the analysis of biological components, in many cases, since the analysis target is a picogram (pg = 10 ^-12 g) or less, there are overwhelming interference components compared to the analysis target component, which is a problem. This interference is called chemical noise. Among chemical noises, those that give m / z substantially equal to the ions to be analyzed become noises during actual analysis. These are assumed to be ions with a light mass and a small valence, or those with a large number of charges on heavy clusters.

As one of the solutions for discriminating chemical noise from analytes, the charge reduction method is known as Analytical Chemistry vol.68 (1996), page 4026 and Internal Journal of Mass Spectrometry and Ion Processes Vol. 162 (1997) 89. The ion trap constituting the mass spectrometer includes a negative ion source that generates negative ions of carbon fluoride by glow discharge. Positive ions generated by the ESI ion source are trapped in an ion trap mass spectrometer, and negative ions are introduced. Both are trapped by the ion trap and attracted by Coulomb force to cause an ion-ion reaction.
The m / z of multivalent ions whose charge is reduced by the ion-ion reaction is larger than the m / z before the ion-ion reaction. Since the change in m / z value due to the ion-ion reaction of ions to be analyzed can be clearly distinguished from that of chemical noise, chemical noise can be removed.

  On the other hand, Analytical Chemistry, Vol. 72, (2000), 899 proposes to use charge reduction by ion-ion reaction to simplify the spectrum of multiply charged fragment ions generated after MS / MS analysis. ing. Due to the decrease in charge due to the ion-ion reaction, the number of candidates for m / z values based on the same mass m is reduced, so that the spectrum can be easily interpreted. Also, high-mass multivalent ions are clearly distinguished from low-mass chemical noise.

Analytical Chemistry vol.68 (1996), page 4026 Internal Journal of Mass Spectrometry and Ion Processes Vol. 162 (1997) 89

In the above prior art, chemical noise is removed and spectrum interpretation is facilitated by charge reduction, but the reaction between sample ions and reversely charged ions is probabilistic. The process proceeds until the valence of the sample ion is 0, that is, neutral.
In this case, sample ions are lost from the ion trap, and as a result, analysis sensitivity is lowered.

The present invention provides a mass spectrometer having a mechanism for stopping a charge reduction reaction for ions that have reached an arbitrary charge value by a charge reduction reaction. For this reason, it is characterized in that ions that have reached a charge for which the charge reduction reaction is to be stopped are selectively moved spatially to a position that is not affected by the reverse charge ions.
To achieve this, at least two ion traps are arranged in series, and an ion source that introduces ions that are oppositely charged to the sample ions into one of the ion traps and an ion that has undergone charge adjustment are selected. A power supply for applying an AC voltage to be moved to another ion trap is provided.
In particular, when a linear ion trap is used as at least two ion traps, the potential between them can be easily controlled, so that the ion transfer efficiency between the ion traps can be increased. Charge-adjusted ions are used as parent ions for multi-stage mass spectrometry (MS / MS). This MS / MS analysis may be performed in another ion trap into which charge-adjusted ions are introduced, or may be performed by returning from this other ion trap to the original ion trap. In particular, when returning to the original ion trap, the AC voltage source used for charge adjustment and the power source used for analysis can be shared. The second and subsequent mass spectrometric operations for identifying disrupted ions in MS / MS analysis may be performed using one of the ion traps, and the high mass resolution coupled to the charge reduction device. You may carry out using the mass spectrometer which has, for example, a pole trap type | mold ion trap mass spectrometer, a time-of-flight mass spectrometer, and a magnetic field type mass spectrometer.

  According to the present invention, multivalent ions of biopolymers can be converted into arbitrary charges set. By performing MS / MS mass spectrometry for the ions converted into arbitrary electrification, it is possible to analyze the structure of the biopolymer with high efficiency and simple analysis.

Examples of the present invention are shown below. For simplification of explanation, the polarity of the sample multiply-charged ion is positive, and the polarity of the reverse charge ion is negative. When the polarity of the sample multivalent ions is negative, the polarity of the reversely charged ions is positive, and the polarity of the applied electrostatic voltage, the method of the positive ion source, and the like may be changed. The value of the controlled charge can be arbitrarily set. In this embodiment, an ESI ion source is used, and the generated ions are adjusted so as to have a single charge (n = 1). It is possible to make relative to a MALDI ion source in which ions are easily generated.
First, the principle of operation of the linear ion trap employed in the following embodiments will be described. An infinitely long ideal linear quadrupole ion trap electric field is generated by applying a high-frequency voltage with a frequency Ω and amplitude Vrf and a static voltage Udc to an electrode whose cross section forms a hyperbola, as shown in FIGS. Can be made. The quadrupole electric field generated in this electrode is described by the following equation.

  Within this electric field, the equation of motion of ions with mass: m and charge: z = ne is described as follows:

  This equation of motion is equivalent to the Mathieu equation in the x and y directions as follows.

  Here, u = x, y, ξ = Ωt / 2, and the two parameters a and q are given as follows.

Using these two parameters, it is possible to give a condition that ions are stably held in the ion trap. The stable region is shown in FIG.
Ions trapped in the stable region have a harmonic oscillation mode called secular motion. The frequency, that is, the secular frequency ω (secular frequency) can be approximately given by the following equation.

Since the secular motion frequency is inversely proportional to the mass to charge ratio (m / z), mass spectrometry can be performed by measuring the secular motion frequency of the trapped ions. Disclosed is a mass spectrometric method based on the principle that the trapped ions are resonantly oscillated with an external AC electric field and discharged outside the ion trap and detected by an ion detector, etc. Has been. US Pat. No. 4,736,101 as a method using a pole trap and US Pat. No. 4,755,670 as a method using a linear ion trap. The same principle is also used to remove unwanted ions and background ions trapped in the ion trap. The principle of ion removal using a pole trap based on this principle is disclosed in US Pat. No. 5,134,286. Also in the present invention, these mass spectrometry methods and unnecessary ion removal methods can be adopted as necessary in the implementation.
In the linear ion trap, as a method of mass spectrometry and unnecessary ion removal, there is a method based on the principle of exciting the harmonic vibration caused by this potential by making the electrostatic potential applied in the direction in which no high frequency is applied, that is, the z-axis direction harmonic. U.S. Pat. No. 5,783,824. In the present invention, the same method can be adopted as necessary. In the description so far and FIGS. 2 and 3, the discussion was made using an electrode having an ideal quadrupole structure. However, it is difficult to produce an ideal quadrupole structure. Therefore, DR Dennison, Journal of Vacuum Science and Technology, 8 (1971) 266, relates to an electrode size such that a quadrupole electric field is generated approximately in the center of an ion trap by combining four cylindrical electrodes. The method is shown (FIGS. 4 and 5). According to this study, the radius R ₀ of the cylindrical electrode and the distance r ₀ from the center of the quadrupole to the electrode may be set as follows.

A feature of the linear ion trap is that a plurality of linear ion traps can be arranged in series because both ends thereof are physically open. By applying an arbitrary electrostatic voltage between the electrodes, the movement of ions can be manipulated. At that time, since the lateral direction (x, y direction) is constrained by a high frequency, the transport efficiency between the ion traps can be increased. US Pat. No. 6,075,244 discloses a series of inventions in which linear ion traps are arranged in series to realize a wide variety of ion operations and improve the accuracy and sensitivity of mass spectrometry. In the present invention, the same method can be appropriately employed as necessary.
(Embodiment 1) FIG. 9 shows a mass composed of a tandem linear trap, a sample ion source, a quadrupole deflector provided with a reverse charge ion source, a charge reducing device comprising an AC power source, and a TOF mass spectrometer connected thereto. It is an analysis device. The MS / MS operation using CID or IRMPD is performed in the charge reduction apparatus in which the negative ion source is stopped, using ions generated by charge reduction in the charge reduction apparatus as parent ions. The crushed ions are guided to a time-of-flight mass analyzer (TOF mass analyzer) and subjected to mass analysis with high mass resolution. Examples of research by combining a linear ion trap and a TOF mass spectrometer in this example are shown in BA Collings et al. Rapid Communications in Mass Spectrometry 2001; 25; 1777. The charge reducing apparatus of this embodiment uses a double tandem linear ion trap equipped with a quadrupole electrostatic deflector. Of the two linear ion traps constituting the double tandem linear ion trap, an AC power source for generating a dipole electric field used to resonate ions is connected to the ion trap on the quadrupole deflector side. A sample ion source and a negative ion source are connected to the quadrupole deflector. By using a quadrupole deflector, it is possible to guide ions having both polarities into the linear ion trap with high efficiency.

Below, the implementation method including the principle of charge reduction of this invention is demonstrated according to a time series. As shown in FIG. 7 and FIG. 8, the operation consists of (1) estimating the mass and charge of sample ions, (2) removing unnecessary ions, (3) reducing charge, and (4) controlling charge as required. Consisting of the movement of ions. In the mass analysis operation for confirming the state of ions for each final mass analysis operation or operation step, the ions are once moved to the linear ion trap immediately before the TOF mass spectrometer, and then the ions are fed into the TOF mass spectrometer. It is standardized to take the procedure.
(0) Generation of sample ions Sample ions having positive charges generated using an ESI ion source are introduced into an ion trap using a quadrupole deflector. In the quadrupole deflector, it is attracted by an electrode set at a negative potential and is incident on the end face of the linear ion trap in a fan-shaped orbit. At this time, the electrostatic potential of the tandem linear ion trap is set as shown in FIG. The reason why the potential wall on the TOF side is set high is to prevent incident ions from reaching the TOF and being lost. The tank in which the linear ion trap is installed is filled with helium gas of about 1 mTorr. The incident ions lose kinetic energy due to collision with helium gas and accumulate in the linear ion trap. At this time, as shown in FIG. 10 (1), the voltage wall between the two linear ion traps is lowered and the two linear ion traps are operated as if the ions to reach the voltage wall on the TOF side. This is to lengthen the trajectory of the ion and lose more kinetic energy of ions.

After a predetermined ion accumulation time, the electrostatic potential of the tandem linear ion trap is set as shown in FIG. 10 (3) via FIG. 10 (2). Thereby, trapped ions can be collected in the ion trap A.
(1) Estimation of mass and charge.
The charge reduction operation begins with estimation of the mass and charge of the sample ions. For this purpose, first, sample ions are subjected to mass spectrometry. In this embodiment, a TOF mass analyzer is used. A schematic diagram of the spectrum obtained at this time is shown in FIG.
For multiply charged ions, the m / z value obtained is given by m / n. Here, the elementary charge e is 1. From the peak position: _mn and the adjacent peak: _mn-1 , n and m can be estimated by calculation. That is, when m _n = m / n and m _n−1 = m / (n−1), n = m _n−1 / (m _n−1 −m _n ) and m = nm _n. Can do. This calculation can be performed on a plurality of peaks to improve the accuracy of the m and n.

  When sample ions having a plurality of types of mass are introduced, a plurality of distributions are superimposed. FIG. 8 (1) is a schematic diagram when ions having two kinds of masses are trapped. In this case, although the adjacent peak is not necessarily an ion having the same m as itself, it is generally estimated that the abundance distribution with respect to n is almost a Poisson distribution, so it is possible to separate and analyze different m. It is. This estimation is made at least once before performing the charge reduction of the present invention. Thereafter, the same condition is reused, or estimation is performed again as necessary.

(2) Removal of unnecessary ions:
When a plurality of m are included, unnecessary ions are removed as necessary. The removal is performed by referring to the spectrum measured in (1), adding a frequency that resonates with unwanted ions, and discharging the resonance (FIG. 8 (2)).

(3) Ion Movement Controlling Charges A method of moving ions having a specific secular motion frequency from one linear ion trap to another linear ion trap will be described. In particular, in this embodiment, n = 1
Select ions with.

Ions are moved to the ion trap A. Using the estimation result of m performed in (1), the secular motion frequency of the monovalent ion is calculated using Equation 6. An AC electric field having the frequency or an AC electric field having a frequency band including the frequency is applied to the ion trap A (FIG. 8 (3)). By making the depth of the B trap deeper than A, the negative ions are prevented from entering the B trap (FIG. 10 (3)). At the same time, the backflow of ions that have moved to B can be prevented. Here, the negative ion source is activated to reduce the charge. Using a quadrupole deflector and an ion source connected thereto, reversely charged ions are introduced into the ion trap with high efficiency. For negative ions, the electrostatic potential in the ion trap A is a potential peak (FIG. 10 (4)). Therefore, it is necessary to give the negative ions enough kinetic energy to climb this potential mountain. Since the kinetic energy of ions climbing the potential peak is reduced, the cross-sectional area and collision probability of the ion-ion reaction passing through the ion trap A are improved, and the reaction efficiency can be increased. For negative ions, the potential of the ion trap B is set higher than the potential of the ion trap A and the kinetic energy of the negative ions. According to this setting, negative ions can be prevented from reaching the ion trap B. That is, no ion-ion reaction occurs in the ion trap B.
The ion trap A is applied with an AC electric field having a frequency of the secular motion frequency of monovalent ions, or an AC electric field having a frequency band including the frequency, so that the valence n = 1 as a result of the ion-ion reaction. The ions that have reached the resonance vibration are started by the AC electric field. Resonantly oscillated ions have a large kinetic energy, so they reach the ion trap B over the potential barrier between the ion trap A and the ion trap B. Since there are no negative ions in the ion trap B, further charge reduction due to ion-ion reaction does not proceed.

The method for transporting ions between ion traps employed in the present invention is the one mentioned in PCT: WO01 / 15201 A2.
MS / MS analysis is performed using biomolecular ions whose valence is adjusted by charge reduction. Thereby, a simple spectrum of structure interpretation according to the MALDI ionization method can be obtained. ESI has a higher throughput than MALDI because samples can be continuously introduced.

  Below, the example of MS / MS operation using a linear ion trap is shown. Ions are introduced into the linear ion trap A. At this time, the q value of the parent ion whose valence is adjusted is set to about 0.1. This makes it possible to hold both the valence-adjusted parent ion and ions produced by crushing the parent ion in the ion trap. An AC voltage is applied here to cause the ions to resonate. The ions are collided (CID) due to collision with helium gas filled in the ion trap and are crushed. The crushed ions are guided to the ion trap B (FIG. 10 (5)), and further introduced into TOF mass analysis from here to perform high mass resolution mass spectrometry (FIG. 10 (6)).

  (Embodiment 2) FIG. 11 shows a charge reducing device in which a negative ion source by glow discharge is provided on the side of a linear ion trap. The ions generated here are guided to a pole trap type ion trap mass spectrometer having high mass resolution, and MS / MS mass spectrometry is performed inside the mass spectrometer. The pole trap mass spectrometer has the advantage that the apparatus can be made smaller than the TOF mass spectrometer, and that an inexpensive apparatus can be constructed after all.

  The basic configuration of the linear ion trap is configured based on the concept equivalent to the first embodiment. In this embodiment, the end of the electrode is shaped according to the shape of the end cap so that the linear ion trap can be close to the hole of the pole trap end cap.

  Negative ions are introduced from the gap of the linear ion trap. Thereby, since a quadrupole deflector can be omitted, an inexpensive apparatus can be configured. However, since negative ions are decelerated and trapped by the viscosity of the gas filled inside the ion trap, the trapping efficiency is slightly lower than in the case of a quadrupole deflector.

The negative ion source by glow discharge is configured as follows. The carbon fluoride gas supplied from the gas cylinder is sent to the glow discharge ion source. The ion source is exhausted by a vacuum pump. A negative high voltage power supply is connected to the electrode, and a current for maintaining glow discharge is supplied. A negative voltage is normally applied to the ion valve electrode, and ions cannot pass through the hole of this electrode. When introducing ions, drop to ground potential. As a result, negative ions can pass through the hole and enter the gap of the linear ion trap A through the hole of the ion valve. Incident ions are decelerated by the helium gas filled inside the ion trap. The decelerated negative ions and the sample positive ions attract each other by Coulomb force, and both cause an ion-ion reaction, thereby reducing the charge of the sample ions. The charge reduction operation is the same as in the first embodiment.
The method of performing MS / MS analysis with a pole trap mass spectrometer is generally well known. It should be noted that when applying to the present invention, chemical noise such as droplets generated in a sample ion source arranged in series directly hits the ion detector of the pole trap mass spectrometer and becomes a background. . In order to avoid this, the ion detector is arranged avoiding the straight line connecting the two holes of the pole trap end cap. In this embodiment, one charge conversion electrode (conversion dynode) is shifted from the straight line, and a negative high voltage is applied individually. Secondary electrons are generated from the positively charged ions incident on the mass spectrum. The electrons are incident on the scintillator, and the generated fluorescence is detected by a photomultiplier tube. From the above description, it is apparent that the following method and apparatus are included in the present invention.
A charge reduction method for stopping a charge reduction reaction by spatially moving a target ion reaching an arbitrary charge to a position not affected by a reverse charge ion when a positive ion and a negative ion are reacted to reduce the charge.
At least two ion traps arranged in series, a power supply system that applies a hyperbolic AC electric field to at least one of the ion traps, a sample ion source, and an ion source that generates ions having opposite charges to the sample ions A device that performs charge reduction.

A device that performs the above-described charge reduction consisting of two linear ion traps.
An apparatus for performing charge reduction as described above, comprising a quadrupole deflector comprising a sample ion source and its oppositely charged ion source.
An apparatus for performing charge reduction as described above, comprising a sample ion source for generating positively charged ions and a reversely charged ion source by fluorocarbon glow discharge.
An apparatus for performing charge reduction as described above, wherein a spectrum of pre-reaction ions is measured before an operation for generating a charge reduction reaction.
An apparatus for performing charge reduction as described above, comprising estimating the mass and charge values of sample ions based on the measured spectrum.
An apparatus for performing charge reduction as described above, wherein an unnecessary ion is detected based on a measured spectrum and then removed to generate a charge reduction reaction.
An apparatus for performing charge reduction as described above, wherein unnecessary ions are removed by resonance ejection.
An apparatus that performs the above-described charge reduction when introducing sample ions into a linear ion trap, with the potential barrier between them being the same value.
An apparatus for performing charge reduction as described above, wherein a hyperbolic AC electric field having a secular motion frequency to stop the charge reduction reaction is applied.
A device for performing charge reduction as described above, wherein a hyperbolic alternating electric field having a frequency band including a secular motion frequency to stop the charge reduction reaction is applied.
A device for performing the above charge reduction, characterized in that the beam energy of reversely charged ions incident on a quadrupole deflector is greater than the potential of a linear ion trap in which sample ions are trapped.
The apparatus for charge reduction as described above, wherein the beam energy of the reversely charged ions incident on the quadrupole deflector is smaller than the potential of the linear ion trap in which the charge-adjusted sample ions are trapped.
An apparatus for performing charge reduction as described above, wherein reversely charged ions are incident from a gap of a linear ion trap in which sample ions are trapped.
A mass spectrometer provided with a device for performing charge reduction as described above.
A mass spectrometer having the above-described charge reduction device equipped with a time-of-flight mass spectrometer.
A mass spectrometer having an apparatus for charge reduction as described above, equipped with an ion trap mass analyzer.
A mass spectrometer having the above-described device for charge reduction, equipped with a high-resolution magnetic field type mass analyzer.
The mass spectrometer which has the apparatus which performs the above-mentioned charge reduction provided with the Fourier-transform type | mold ion cyclotron resonance mass spectrometer.

The figure which shows the component of this invention. One method of applying a hyperbolic voltage in a linear ion trap consisting of hyperbolic electrodes. Another method of applying a hyperbolic voltage in a linear ion trap consisting of hyperbolic electrodes. One method of applying a hyperbolic voltage in a linear ion trap using a cylindrical electrode. Another method of applying a hyperbolic voltage in a linear ion trap consisting of cylindrical electrodes. The figure which shows the stable area | region of a linear ion trap. The figure explaining the typical operation procedure of this invention. The figure explaining the history of the mass spectrum obtained by the typical operation procedure of this invention. The figure explaining the linear ion trap-time-of-flight mass spectrometer provided with the electric charge reduction apparatus of this invention. The figure explaining the history of the positive voltage applied to the linear ion trap in the typical operation procedure of this invention. The figure explaining the linear ion trap-pole trap type | mold analyzer provided with the electric charge reduction apparatus of this invention.

Explanation of symbols

101 Ion trap A
102 Ion trap B
103 AC power supply
104 Sample ion source
105 Reverse-charged ion source
901 Ion trap vacuum chamber
902 vacuum pump
903 TOF mass spectrometer vacuum chamber
904 vacuum pump
905 Ion source vacuum pump
906 Reverse charge ion source
907 Reverse-charge ionic solution tank and pump
908 Sample ion source
909 liquid chromatograph
910 Quadrupole deflector
911 Ion Trap A
912 Ion trap B
913 RF, DC power supply
914 AC power supply
915 Helium cylinder
916 Kicker
917 Kicker power supply
918 Reflectron
919 Reflectron power supply
920 MCP
921 MCP power supply
922 Controller
1101 ion trap vacuum chamber
1102 Vacuum pump
1103 Vacuum pump
1104 Sample ion source
1105 Reverse charge ion source
1106 High voltage power supply
1107 Gas source for reverse charge
1108 Ion trap A
1109 Ion trap B
1110 AC power supply
1111 RF and DC power supplies
1112 Helium gas cylinder
1113 Pole-type ion trap mass spectrometer
1114 RF, AC power supply
1115 Conversion dynode
1116 High voltage power supply
1117 Scintillator
1118 Optical window
1119 Photomultiplier tube
1120 Control unit.

Claims (7)

A sample ion source;
First and second linear ion traps arranged in series for introducing ions generated by the sample ion source;
A first power supply system that provides a potential to the first and second linear ion traps;
A second power supply system for applying a hyperbolic alternating electric field to the first linear ion trap;
The reverse charge generated in the first linear ion trap that generates ions having a reverse charge to the sample ions and is given a shallower potential than the second linear ion trap by the first power supply system. And a reverse charge ion source for introducing ions of
The second power supply system converts a hyperbolic AC electric field having a secular motion frequency of a sample ion reaching an arbitrary charge or a hyperbolic AC electric field having a frequency band including the secular motion frequency to the first linear ion. A charge adjusting apparatus, wherein sample ions that have been applied to a trap and have reached an arbitrary charge are selectively moved to the second linear ion trap.   2. The charge adjusting device according to claim 1, wherein a beam energy of the ion of the reverse charge is larger than a potential of the first linear ion trap.   2. The charge adjusting device according to claim 1, wherein a beam energy of the ion of the reverse charge is smaller than a potential of the second linear ion trap. Ionizing the sample;
Introducing ionized sample ions into a first linear ion trap;
Measuring a spectrum of the sample ion and estimating a value of the mass and charge of the sample ion based on the spectrum;
Applying a potential of the first linear ion trap shallower than a potential of a second linear ion trap arranged in series with the first linear ion trap;
Generating ions having opposite charges to the sample ions, and reacting the oppositely charged ions and the sample ions in a first linear ion trap;
A predetermined alternating electric field determined from the estimated mass and charge value of the sample ions is applied to the first ion trap, and the sample ions that have reached an arbitrary charge are selectively transmitted from the first linear ion trap to the first ion trap. Moving to a second ion trap,
The predetermined AC electric field is a hyperbolic AC electric field having a secular motion frequency of a sample ion reaching an arbitrary charge or a hyperbolic AC electric field having a frequency band including the secular motion frequency. Adjustment method.   5. The charge adjusting method according to claim 4, further comprising: detecting unnecessary ions based on the measured spectrum, removing the unnecessary ions, and reacting the oppositely charged ions with the sample ions. A sample ion source;
First and second linear ion traps arranged in series for introducing ions generated by the sample ion source;
A first power supply system that provides a potential to the first and second linear ion traps;
A second power supply system for applying a hyperbolic alternating electric field to the first linear ion trap;
The reverse charge generated in the first linear ion trap that generates ions having a reverse charge to the sample ions and is given a shallower potential than the second linear ion trap by the first power supply system. A reversely charged ion source that introduces ions of
A mass spectrometer for mass-analyzing the sample ions;
The second power supply system converts a hyperbolic AC electric field having a secular motion frequency of a sample ion reaching an arbitrary charge or a hyperbolic AC electric field having a frequency band including the secular motion frequency to the first linear ion. A sample ion that has been applied to the trap and has reached an arbitrary charge is selectively moved to a second linear ion trap, and the sample ion that has reached the arbitrary charge is subjected to mass analysis by the mass spectrometer. Mass spectrometer.   The mass spectrometer according to claim 6, wherein the mass spectrometer is a time-of-flight mass spectrometer.

Images