JPH10172504A - Mass spectrometry device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the adsorption of impurities and remove impurities adsorbed by installing a heater and a cooling means in a slender hole part, heating the slender hole part with the heater before measurement, lighting plasma, turning off the heater in starting the measurement, and cooling the slender hole part. SOLUTION: A first flange 22 containing a slender hole 9 for separating an atmospheric region from a vacuum region becomes very high temperature by heat of plasma when the plasma is lit in measurement. In order to cool the flange 22 containing the slender hole 9, cooling water is made flow in a flow path 12 on the inside of the flange 22. When the inside of a device containing a mass spectrometer is evacuated before starting measurement or during no measurement, in order to prevent the adsorption of impurities in the surrounding of the slender hole 9 cooled by adiabatic expansion, or in order to remove impurities already adsorbed in the surrounding of the slender hole 9, an electrode containing the slender hole 9 is heated with a heater 10 arranged so as to surround the slender hole 9. Electric power of the heater 10 is supplied from a heater power source 11.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a microwave plasma mass spectrometry (Microwave Induced Plasma / Mas) which is effective for simultaneous analysis of elemental ions as impurities contained in a trace amount of water.
s Spectrometry (hereinafter abbreviated as MIP / MS) or inductively coupled plasma / mass spectrometry (Induced Coupled Plasma / Mass)
Spectrometry (hereinafter abbreviated as ICP / MS) and a mass spectrometer including a plasma ion source.

[0002]

2. Description of the Related Art At present, in the field of elemental analysis, MIP / M
S and ICP / MS are becoming widespread. In an apparatus for performing these measurements, a sample in a liquid state is sprayed under atmospheric pressure, then ionized by plasma, and introduced into a mass spectrometer in a vacuum region. Here, the atmospheric pressure region and the vacuum region are separated by pores, which are located in the vicinity of high-temperature plasma, and therefore have a very high temperature when the plasma is turned on. For this reason,
The pore portion is constantly cooled for the purpose of preventing the material (mainly metal) in the portion forming the pore from melting. This is discussed in Analetical Chemistry, 1981, 1
Moon, No. 53, Vol. 1, etc.

[0003]

In the plasma ion source mass spectrometer of the prior art, when the plasma is turned on, the pores separating the atmospheric pressure region and the vacuum region are heated to a high temperature. In order to cool it, pores separating the atmospheric pressure region and the vacuum region are provided with cooling means such as water. However, there is no means for heating the pores separating the atmospheric pressure region and the vacuum region other than turning on the plasma near the pores.

[0004] When performing measurement using a plasma ion source mass spectrometer, it is necessary to maintain a vacuum inside the apparatus including the mass spectrometer before the measurement. When the inside of the apparatus is kept in a vacuum, adiabatic expansion occurs in the pores separating the atmospheric pressure region and the vacuum region, and the pores are cooled and adsorb impurities in the atmosphere to be contaminated. In order to remove the contamination of the pores, it is necessary to heat the pores.

[0005] In the prior art, the pores were heated by plasma turned on near the pores at the time of measurement to remove contamination. However, if the measurement is started before the contamination of the pores is sufficiently removed after the plasma is turned on, impurities that have not been completely removed may cause noise, which may deteriorate the measurement accuracy.

When the inside of the apparatus including the mass spectrometer is kept in a vacuum before the measurement, the pores are cooled by adiabatic expansion and remain contaminated. Therefore, in order to obtain low-noise and high-accuracy data, the plasma is turned on after maintaining the inside of the device in a vacuum, and the pores are sufficiently heated by the plasma to remove impurities adsorbed on the pores. Measurement must be performed before Then, before starting the measurement, it is necessary to continue to turn on the plasma until the impurities adsorbed in the pores can be sufficiently removed, and this time, a plasma gas of several tens of liters per minute and power of several kW are required before starting the measurement. And
Problems arise in terms of running costs.

[0007] The problem to be solved by the present invention is the time from when the plasma is turned on until the measurement can be started, that is, the removal of impurities adsorbed on the pores due to the heating of the pores separating the atmospheric pressure region and the vacuum region. Another object of the present invention is to provide a plasma ion source mass spectrometer having means for reducing the time required for performing the measurement sufficiently and reducing the running cost caused by plasma lighting before the start of measurement.

[0008]

In order to solve the above-mentioned problems, in the present invention, a heater or the like is separately attached to a pore portion separating an atmospheric pressure region and a vacuum region, and means for heating the pores is provided. As a result, without turning on the plasma,
It is possible to remove impurities adsorbed on the pores while keeping the inside of the apparatus including the mass spectrometer at a vacuum. Further, for example, when a ceramic heater is used as the heater, the power required to heat the pores and remove the adsorbed impurities is at most several tens of watts, and when the plasma is turned on before starting the measurement, Much less than the power required. In addition, the consumption of plasma gas required to keep the plasma on can be reduced.

A cooling means is provided in the pore portion at the same time as the heater. When the plasma is turned on and the measurement is started, the heater is turned off so that the pore portion can be cooled.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION

(Embodiment 1) FIG. 1 shows a MIP /
FIG. 2 is a diagram illustrating a configuration of an entire MS device. A solution 1 containing a sample is supplied from a gas cylinder 2 and introduced into a nebulizer 4 together with a carrier gas whose flow rate is adjusted by a flow meter 3. The solution containing the sample atomized inside the nebulizer 4 is supplied from the gas cylinder 2 and introduced into the plasma torch 6 together with the plasma gas whose flow rate is adjusted by the flow meter 5.

The plasma gas introduced into the plasma torch 6 receives microwave power supplied from a high frequency power supply 8 through a cavity 7 to generate plasma. The solution containing the atomized sample is likewise introduced into the plasma torch 6 and ionized by the plasma. The generated ions are introduced into a device including a mass spectrometer through a pore 9 separating an atmospheric pressure region and a vacuum region.

The inside of the apparatus including the mass spectrometer includes a rotary pump (hereinafter abbreviated as RP) 13 and a turbo molecular pump (hereinafter abbreviated as TMP).
RP for exhaust after 14, 15 and TMP
The vacuum is maintained by 16.

The sample introduced into the apparatus is an in-lens 1
7 and introduced into a quadrupole mass spectrometer 18 for mass analysis. It goes without saying that a magnetic field type mass spectrometer, an ion trap type mass spectrometer, a time-of-flight type mass spectrometer and the like can be used as the mass spectrometer. The mass-analyzed ions are deflected by the deflection electrode 19 and detected by the ion detector 20. A voltage for controlling ions is applied from a power supply 21 to the ion lens 17, the quadrupole mass spectrometer 18, the deflection electrode 19, and the like.

When the plasma is turned on at the time of measurement, the first flange 22 including the pores 9 separating the atmospheric pressure region and the vacuum region becomes extremely high due to the heat. Then, in order to cool the first flange 22 including the pores 9, cooling water is caused to flow through the flow channel 12 inside the first flange 22. In addition, when the inside of the apparatus including the mass spectrometer is evacuated before the start of the measurement or other than during the measurement, the pores 9 cooled by adiabatic expansion may be used.
In order to prevent impurities from adsorbing around the pores, or to remove impurities already adsorbing around the pores 9,
An electrode including the pores 9 is heated by a heater 10 installed so as to surround the pores 9. The power of the heater 10 is supplied from a power supply 11 for the heater. Further, it is more preferable to provide a heating means also for the skimmer electrode subsequent to the first flange 22 because the pores of the skimmer electrode can be heated by means other than plasma lighting and impurities can be removed.

(Embodiment 2) FIG. 2 shows an example of a specific configuration of the flange 22 of FIG. 1, which is a second embodiment of the present invention.

Cooling water for cooling the flange 22 flows from an inlet 24 to an outlet 25. The positions of the water inlet and water outlet are arbitrary. The heater 10 is fixed in contact with the first flange 22 by a screw in a screw hole 23, and is installed so as to surround the periphery of the pore 9. The heater 10 can be easily attached and detached, and the measurement can be performed with the heater removed during plasma lighting. The heater 22 can heat the flange 22 to prevent impurities from being adsorbed around the pores 9 and remove impurities already adsorbed.

[0017]

According to the present invention, the pores separating the atmospheric pressure region and the vacuum region can be heated without turning on the plasma until the start of the measurement, and the pores are cooled by adiabatic expansion to the atmosphere. Prevents impurities from adsorbing inside,
It is possible to remove impurities that have already been adsorbed. As a result, the time from turning on the plasma to the start of measurement can be reduced, and the running cost can be reduced.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an apparatus configuration according to an embodiment of the present invention.

FIG. 2 is a perspective view of a flange having pores according to one embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Solution containing sample, 2 ... Gas cylinder, 3, 5 ... Flow meter, 4 ... Nebulizer, 6 ... Plasma torch, 7 ... Cavity, 8 ... High frequency power supply, 9 ... Porous, 10 ... Heater, 1
DESCRIPTION OF SYMBOLS 1 ... Power supply for heaters, 12 ... Cooling water flow path, 13, 16 ... Rotary pump, 14, 15 ... Turbo molecular pump, 17
... In-lens, 18 quadrupole mass spectrometer, 19 deflection electrode, 20 ion detector, 21 power supply, 22 first flange, 23 screw hole, 24 water inlet, 25 water outlet.

Claims (3)

[Claims] An ionizing means for ionizing a solution containing a sample in an atmospheric pressure region, and introducing the ionized sample into a vacuum region separated from the atmospheric pressure region by a flange having fine holes through the fine holes. A mass spectrometer, comprising: means for mass spectrometric analysis, wherein the mass spectrometer further comprises means for heating the flange and means for cooling the flange. 2. The mass spectrometer according to claim 1, wherein the heating means for the flange having pores separating the atmospheric pressure region and the vacuum region is an electric heater. 3. The mass spectrometer according to claim 1, wherein the cooling means of the flange having pores separating the atmospheric pressure region and the vacuum region is water-cooled.