| 摘要 |
Metal ions are attached to a sample gas in an ionization chamber to produce ions of the sample gas. The ions of the sample gas pass through a mass spectrometer formed by an electromagnetic field for separation by mass. The mass separated ions of the sample gas are detected and measured by a detector as an ion current. Further, a metal ion emitter for emitting metal ions is arranged at the upstream side of a region controlled to a reduced pressure atmosphere where the flow of gas becomes viscous, a sample gas inflow part for introducing the sample gas to the downstream side where the metal ions are transported, and the sample gas ionized by attachment of the metal ions passes through the opening of the aperture plate and transported to the mass spectrometer. A second gas inflow part is arranged at the upstream side of the metal ion producing region. A second gas supplied by the second inflow part flows through the metal ion producing region and sample gas ionization region. Due to this configuration, it is possible to suppress contact of the sample gas with the metal ion emitter, prevent contamination of the metal ion emitter, and perform mass spectrometry stably over a long term.
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