JP2545528B2 - Atmospheric pressure ionization mass spectrometry method and mass spectrometer - Google Patents

Description

TECHNICAL FIELD The present invention relates to a mass spectrometer, and particularly to an atmospheric pressure ionization mass suitable for estimating a molecular structure using an atmospheric pressure ion source that ionizes at atmospheric pressure. Regarding the analyzer.

[Conventional technology]

In the conventional atmospheric pressure ionization mass spectrometer, it is known that the dissociation of cluster ions can be controlled by changing the drift voltage of the atmospheric pressure ion source (In
ternational J. of Mass Spe. and Ion Phys. 25 (197
7), Bunseki 1979).

Similarly, in Japanese Patent Laid-Open No. 53-81289, cluster ions generated in an ionization chamber at atmospheric pressure, that is, ions generated by binding water molecule ions around sample molecules and the like have an intermediate pressure. It is proposed that the cluster ions are guided to the collision chamber and the electric field is applied to the collision chamber to break the cluster ions, thereby eliminating the inconvenience in mass spectrometry due to the cluster ions. Further, it is described that cluster ions are cleaved to molecular ions or quasi-molecular ions (for example, molecular ions to which hydrogen atom ions are bonded) by changing the drift voltage that forms the electric field in the collision chamber.

As described above, according to the conventional technique, it is possible to perform mass spectrometry of sample molecules (sample single molecules) without the influence of cluster ions.

[Problems to be Solved by the Invention]

However, when examining the mass spectrometry data of the chromatogram and mass spectrum obtained for the sample molecule, in order to improve the accuracy of analysis, etc., information on the molecular structure obtained by further cleaving the single molecule of the sample is obtained. Is often desired.

However, the above conventional techniques do not consider obtaining information about the molecular structure of the sample molecule.

An object of the present invention is to provide an atmospheric pressure ionization mass spectrometry method and a mass spectrometer capable of obtaining information on the molecular structure of a sample molecule.

[Means for solving the problem]

In order to achieve the above object, an atmospheric pressure ionization mass spectrometry method and a mass spectrometer of the present invention introduce a sample molecule and ionize the sample molecule at about atmospheric pressure to generate an ion of the sample molecule, and generate the generated ion in a large amount. In the atmospheric pressure ionization mass spectrometry, in which a sample molecule is mass-analyzed in the high-vacuum section that is maintained below the intermediate pressure section through an intermediate-pressure section that is maintained below the atmospheric pressure, the single molecule of the sample is solved. It is characterized in that an electric field of a magnitude necessary for breaking is applied to the intermediate pressure portion.

In this case, it is desirable to make the magnitude of the electric field applied to the intermediate pressure portion variable.

Further, it is desirable to change the magnitude of the electric field of the intermediate pressure portion and obtain a chromatogram related to mass spectrometry by making it correspond to a plurality of different magnitude electric fields. In this case, the magnitude of the electric field in the intermediate pressure part can be variably set within a range from the size at which the sample monomolecules do not cleave to the size at which the sample monomolecules cleave, or the sample monomolecules cleave. It is preferable to variably set the size that does not cleave and the size that the single molecule of the sample cleaves. Further, the electric field applying means can change the magnitude of the electric field in synchronization with the mass scanning of the mass spectrometer. [Operation] According to the present invention, the sample molecular ions are cleaved by the electric field applied to the intermediate pressure portion, so that information on the molecular structure can be obtained. As a result, based on the analysis result of the sample molecule ions obtained by cleaving the cluster ions, in conducting the examination such as identifying the sample molecule, the information on the molecular structure of the sample molecule, that is, the molecules constituting the sample molecule By comparing the analysis data, the analysis result of the sample molecule can be properly examined.

By the way, in order to obtain a chromatogram which is an analysis result of the sample molecule and a chromatogram which is information about the molecular structure of the sample molecule, the electric field (drift voltage) of the intermediate pressure portion is measured while changing it in two steps, for example. In this case, if a new sample is injected for each electric field of different magnitude and each chromatogram is measured, there is a problem that the work becomes complicated and the analysis time becomes long.

In this respect, if the magnitude of the electric field in the intermediate pressure part is changed in synchronization with the mass scanning of the mass spectrometer, the information on the analysis result of the sample molecule and the molecular structure of the sample molecule can be obtained by one sample injection. Since both of the above can be obtained, the work is simple and the increase in analysis time can be suppressed.

Further, since those data are obtained by one-time sample injection, analytical conditions other than the electric field condition related to molecular cleavage hardly change. As a result, the analysis data of the sample molecule and the data relating to the molecular structure can be obtained under the same conditions, so that the analysis results (quantitative comparison, etc.) of the analysis results of the sample molecule can be appropriately performed by comparing the data. That is, when the measurement is performed in two steps, the state of the pores provided on the ionization section side of the intermediate pressure section such as dirt or clogging may change, and the pressure of the intermediate pressure section may change for each measurement. If the pressure in the intermediate pressure part changes, it will affect the cleavage of cluster ions and molecular ions, and there is a problem that quantitative comparison cannot be performed appropriately.

〔Example〕

An embodiment of the atmospheric pressure ionization mass spectrometer according to the present invention will be described below.

First, in FIG. 1, there are LC and LC / MS interfaces 1, and dew-like components flow out from the interfaces 1. The dew-shaped component flows out to the tip of the needle electrode 2. This needle electrode 2
Corona discharge is generated at the tip of the electrode by the voltage applied to the electrode, and an ionized portion is formed by this. Due to the primary ions generated by this corona discharge and the subsequent ion molecule reaction under atmospheric pressure, the sample composed of the dew-like component is ionized and passes through the first pores 3. It has become. This first
The second pore 4 opposes the pore 3, and the pressure between the first pore 3 and the second pore 4 is about 0.2 to 1 Torr.
Is held in. That is, the intermediate pressure portion is formed in the space between the first fine hole 3 and the second fine hole 4. Further, a voltage, that is, a drift voltage is applied between the first fine hole 3 and the second fine hole 4 by the drift power supply 11. By changing the applied voltage,
The degree of ion collision dissociation in the ionized sample can be changed. In this case, if the drift voltage is low, cluster ions are not cleaved and accurate molecular weight information cannot be obtained. When the drift voltage is increased, the thruster is disassembled and information on each molecular ion is obtained. Then, when the drift voltage is further increased, the molecular ion is cleaved to obtain information on the molecular structure. In this embodiment, the drift voltage is about 10V.
About 200V is set.

The ions thus cleaved pass through the second pore 4 and are separated by the magnetic field 7 according to the mass-to-charge ratio, detected by the detectors 8 and 9, and taken into the data processing device 13. ing. The pressure from the second pore 4 to the detector 8 is maintained at a high vacuum pressure as in the conventional case.

In FIG. 1, 5 is an extraction electrode, 10 is an exciting power source, 6 is an exciting coil, and 12 is a recorder.

In this case, the drift voltage is constant during one magnetic field scan. Here, one magnetic field scan is a scan in which the magnetic field strength is gradually changed in order to separate the molecular ions in the magnetic field 7 according to the mass-to-charge ratio, and is also called mass scan. By presetting a program, the data is collected and organized for each same drift voltage and then output, whereby a plurality of data having different drift voltages can be obtained. For example, as shown in FIG. 2, the magnetic field is repeatedly operated up to m / z 50 to 300 at intervals of about 1 second, and at the same time, the drift voltage is alternately switched to 50V and 200V.

In this case, for example, a mixture of inosine and adenosine
The results of injection into the LC column and output are shown in FIG.

FIG. 7A shows data obtained when the drift voltage is 200 V. The upper part shows the total ion chromatogram, and the lower part shows the mass spectrum of the adenosine at the 179th scanning.

Further, FIG. 6B shows data obtained when the drift voltage is 50 V. Again, the upper part shows the total ion chromatogram and the lower part shows the mass spectrum at the 179th scanning.

As is clear from the figures (a) and (b), the proton-added molecular ion m / z 268 of adenosine is the main ion in the figure (b) where the drift voltage is low, whereas in the figure (a), In addition to m / z 268, m / z 136, which is the dissociation of the purine salt computing part, is observed.

〔The invention's effect〕

As described above, according to the present invention, since the sample molecular ions are cleaved by the electric field applied to the intermediate pressure portion, it is possible to obtain information on the molecular structure. As a result, based on the analysis result of the sample molecule ions obtained by cleaving the cluster ions, the information on the molecular structure of the sample molecule, when performing the examination such as identifying the sample molecule,
That is, by comparing the analysis data of the molecules constituting the sample molecule, the analysis result of the sample molecule can be properly examined.

Further, according to the present invention, there are advantages that a chromatogram corresponding to a plurality of drift voltages can be obtained, and more spectrum information can be obtained.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing an embodiment of an atmospheric pressure ionization mass spectrometer according to the present invention, FIG. 2 is a diagram showing a relationship between a drift voltage and a magnetic field control voltage, and FIG. 3 is an atmospheric pressure ionization mass spectrometry according to the present invention. It is a graph which shows the measurement data of a meter. 1 ... Liquid chromatograph, 2 ... Needle electrode, 3 ... First
Micropore electrode, 4 ... Second micropore electrode, 6 ... Excitation coil, 10
...... Excitation power supply, 11 ...... Drift power supply, 13 ...... Control data processing device.

Claims (8)

(57) [Claims] 1. An ionization section for introducing sample molecules and ionizing them at about atmospheric pressure to generate ions of the sample molecules, an intermediate pressure section kept below atmospheric pressure, and an intermediate pressure section kept below the intermediate pressure section. In an atmospheric pressure ionization mass spectrometer, which has a high vacuum portion and takes in ions of the sample molecule into the high vacuum portion through the intermediate pressure portion to perform mass analysis, it is necessary to dissociate a single molecule of the sample. An atmospheric pressure ionization mass spectrometer characterized by comprising an electrolytic application means for applying an electric field of various magnitudes to the intermediate pressure part. 2. The atmospheric pressure ionization mass spectrometer according to claim 1, wherein the electric field applying means is variable in magnitude of an electric field applied to the intermediate pressure section. Atmospheric pressure ionization mass spectrometer. 3. The atmospheric pressure ionization mass spectrometer according to claim 2, wherein the magnitude of the electric field of the intermediate pressure portion is changed so as to correspond to a plurality of electric fields of different magnitudes. An atmospheric pressure ionization mass spectrometer characterized by comprising means for obtaining such a chromatogram. 4. The atmospheric pressure ionization mass spectrometer according to claim 3, wherein the magnitude of the electric field at the intermediate pressure portion is set such that the single molecule of the sample does not dissociate from the magnitude of the single molecule of the sample. An atmospheric pressure ionization mass spectrometer characterized by being variably set within a size range of fragmentation. 5. The atmospheric pressure ionization mass spectrometer according to claim 3, wherein the magnitude of the electric field at the intermediate pressure portion is such that a single molecule of the sample is not cleaved and a single molecule of the sample is An atmospheric pressure ionization mass spectrometer characterized in that the size of fragmentation is variably set. 6. The atmospheric pressure ionization mass spectrometer according to any one of claims 3 to 5, wherein the electric field applying means synchronizes with a mass scan of the mass spectrometer to increase the magnitude of the electric field. Atmospheric pressure ionization mass spectrometer characterized by varying the height. 7. The atmospheric pressure ionization mass spectrometer according to claim 1, wherein the intermediate pressure section communicates with the ionization section through a first fine hole section. And a high-vacuum portion that communicates with the second fine hole portion, and the electric field applying means is means for applying a voltage between the first fine hole portion and the second fine hole portion. Atmospheric pressure ionization mass spectrometer. 8. A sample molecule is introduced and ionized at about atmospheric pressure to generate an ion of the sample molecule, and the generated ion is kept lower than the intermediate pressure portion through an intermediate pressure portion kept lower than atmospheric pressure. In an atmospheric pressure ionization mass spectrometric method in which the sample molecules are subjected to mass analysis in the high vacuum portion, an electric field having a magnitude necessary for decomposing a single molecule of the sample is applied to the intermediate pressure portion. An atmospheric pressure ionization mass spectrometric method, characterized by applying.