JPH1055777A - Mass analyser and electrode heating method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve analysis precision of an ion trap mass analyzer by providing an inductance coil in the vicinity of a ring electrode and high-frequency heating the ring electrode by Joule's heat after generating eddy current on the ring electrode. SOLUTION: When a magnetic field is induced by an inductance coil 11, a ring electrode 5 generates an eddy current having an action for eliminating variation of that magnetic field. When an eddy current flows this electrode 5, Joule's heat is generated because of electric resistance of an electrode, and the ring electrode 5 is heated. The ring electrode can be heated efficiently by feeding an a.c. current to this coil 11 using an AC power source 12. In analysis of samples, after the samples are separated by a GC1, it is fed to an ion trap mass analyzer 3 by a pipe 2 together with carrier gas. The samples are ionized by an electron beam 9 to be discharged from an electron gun 8, stored in the mass analyzer for a constant time, and then mass-analyzed. The mass- analyzed ion is detected 10, and its output is processed by a data processor.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a mass spectrometer and a method for heating an electrode.

[0002]

2. Description of the Related Art At present, in the field of analysis, importance is attached to a method for separating and analyzing a mixture. For example, with increasing interest in environmental issues, regulations on chemical substances contained in tap water are being strengthened year by year, and substances subject to regulation and monitoring are increasing. Since such environment-related substances are present as a mixture in water or the atmosphere, there is a need for an apparatus that can simultaneously separate and detect the mixture. In such a flow, gas chromatography / mass spectrometry combining gas chromatography (hereinafter abbreviated as GC) with excellent separation of a mixture and a mass spectrometer (hereinafter abbreviated as MS) with an excellent ability to identify a substance. A total coupling device (hereinafter abbreviated as GC / MS) is very effective for analyzing environmentally relevant substances.

Referring to FIG. 3, a conventional GC / MS will be described. After being separated by the GC 1, the sample is sent to the ion trap mass spectrometer 3 via the pipe 2 together with a carrier gas called a carrier gas. The ion trap mass spectrometer 3 includes two end cap electrodes 4 a and 4 b and a ring electrode 5. The ion trap mass spectrometer 3 is disposed in a vacuum section 21 evacuated by an exhaust system 20. If the sample is deposited on the electrodes, the accuracy of the analysis will be reduced.
Is heated.

A sample is ionized by an electron beam 9 emitted from an electron gun 8. Ions relating to the sample are accumulated in the mass spectrometer for a certain period of time, and thereafter, mass analysis is performed by changing the amplitude of the high-frequency voltage applied to the ring electrode 5. This is because the m / z (a value obtained by dividing the molecular weight of the ion by the valence of the ion) of the ion stably confined in the ion trap mass spectrometer changes according to the amplitude of the high-frequency voltage. By repeating this operation, the samples separated by GC can be sequentially subjected to mass spectrometry. The mass-analyzed ions are detected by the detector 10, and the detected signal is processed by the data processing device.

[0005]

In the conventional mass spectrometer, a heater is provided in the vicinity of the ring electrode, and the ring electrode is heated by radiant heat from the heater to prevent the sample from adhering and depositing on the electrode surface. . By the way, since a high-frequency voltage of up to about 10 kilovolts is applied to the ring electrode at the time of mass analysis, it is difficult to attach a heater directly to the ring electrode. Therefore, this electrode heating method cannot heat the ring electrode to a sufficient temperature. As a result, substances are deposited on the surface of the ring electrode. Therefore, when used for a long time, there is a problem that the analysis accuracy is lowered.

In order to sufficiently heat the ring electrode, a method of increasing the amount of heat generated by a heater that emits radiant heat may be considered. However, this method requires a large-capacity power supply, and radiant heat causes heating other than the ring electrode, for example, a vacuum vessel, thereby causing an adverse effect such as a change in apparatus dimensions.

An object of the present invention is to improve the analysis accuracy of an ion trap mass spectrometer by providing a heating method capable of easily heating a ring electrode and a mass spectrometer using the same.

[0008]

According to the present invention, the above-mentioned object is attained by heating a ring electrode with high frequency. That is, an induction coil is provided near the ring electrode, and an eddy current is generated in the ring electrode to heat the ring electrode with Joule heat.

[0009]

FIG. 1 is a block diagram showing one embodiment of the present invention. An induction coil 11 is arranged near the ring electrode 5. When a magnetic field is induced by the induction coil 11, an eddy current is generated in the ring electrode 5 having a function of canceling the fluctuation of the magnetic field. When an eddy current flows through the ring electrode 5, Joule heat is generated due to the electric resistance of the electrode, and the ring electrode 5 is heated. Since the generation of the eddy current requires a change in the magnetic field, the ring electrode can be efficiently heated by supplying an AC current to the induction coil 11 using the AC power supply 12.

When the ring electrode is made of a material having poor heat conductivity, the ring electrode may not be heated evenly in the configuration having one induction coil shown in FIG. In such a case, a plurality of induction coils may be arranged along the outer periphery of the ring electrode.

Since the magnetic field generated by the induction coil becomes weaker as the distance from the coil increases, if the induction coil is provided near the ring electrode, portions other than the ring electrode,
For example, the heating of the vacuum vessel can be reduced, and the adverse effect such as a deviation of the apparatus size is small.

The method of analyzing a sample is the same as the conventional mass spectrometry described above. After being separated by the GC 1, the sample is sent to the ion trap mass spectrometer 3 through the pipe 2 together with a carrier gas called a carrier gas. The sample was an electron gun 8
It is ionized by the electron beam 9 emitted from the device and is stored in the mass spectrometer for a certain period of time and then subjected to mass analysis. The mass-analyzed ions are detected by the detector 10, and the detected signal is processed by the data processing device.

FIG. 2 is a timing chart when heating is performed. In an ion trap mass spectrometer, a high frequency voltage having a certain amplitude is applied to a ring electrode in order to create a potential for accumulating ions in the mass spectrometer. By injecting an electron beam in this state, the sample is ionized, and ions relating to the sample are confined in the ion trap mass spectrometer. Thereafter, scanning is performed by changing the amplitude of the voltage applied to the ring electrode. After the scan, the amplitude of the high-frequency voltage applied to the ring electrode is reduced to zero, and ions remaining in the ion trap mass spectrometer are discharged. If the magnetic field generated by the induction coil disturbs the ion trajectory in the ion trap mass spectrometer and affects ionization and scanning, as shown in FIG. An AC current may be applied to heat the ring electrode.

According to the present invention, the ring electrode of the ion trap mass spectrometer can be easily heated to 100 ° C. or higher, so that the sample can be prevented from depositing on the electrode surface, and the accuracy of the analysis can be improved even after long use. You can now keep.

The present invention is not limited to GC / MS, but is equally effective in a device in which another separation method such as a liquid chromatograph is coupled to an ion trap mass spectrometer when the ring electrode needs to be heated. It is.

[0016]

According to the present invention, the ring electrode can be sufficiently heated, and the deposition of the sample on the electrode can be prevented. Therefore, the analysis accuracy of the ion trap mass spectrometer can be improved.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a mass spectrometer according to an embodiment of the present invention for heating a ring electrode by high frequency.

FIG. 2 is a timing chart of electrode heating.

FIG. 3 is a block diagram showing a conventional mass spectrometer.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Gas chromatography, 2 ... Piping, 3 ... Ion trap mass spectrometer, 4a, 4b ... End cap electrode, 5
... Ring electrode, 6a, 6b ... End cap electrode heater, 8 ... Electron gun, 9 ... Electron beam, 10 ... Detector, 1
DESCRIPTION OF SYMBOLS 1 ... Induction coil, 12 ... AC power supply, 20 ... Exhaust system, 21
... vacuum section.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Minoru Sakairi, 1-280 Higashi Koikekubo, Kokubunji-shi, Tokyo Inside the Central Research Laboratory, Hitachi, Ltd. Central Research Laboratory

Claims (3)

[Claims] 1. A mass comprising: a sample supply means; an ionization means for ionizing a sample supplied by the sample supply means; and an ion trap mass analysis means for performing mass analysis on ions relating to the sample ionized by the ionization means. A mass spectrometer characterized in that the spectrometer has an induction coil for inducing an induction current in an electrode constituting the ion trap mass spectrometry means. 2. The mass spectrometer according to claim 1, wherein an alternating current flowing through said induction coil is controlled in accordance with an operation of said ion trap mass spectrometer. 3. A mass comprising sample supply means, ionization means for ionizing a sample supplied by the sample supply means, and ion trap mass analysis means for mass analysis of ions relating to the sample ionized by the ionization means. An electrode heating method in an analyzer, wherein an electrode constituting the ion trap mass spectrometer is Joule-heated by an induced current induced by electromagnetic induction.