JPH03201355A - Spectrometry device for mass ionized under atmospheric pressure - Google Patents

Abstract

PURPOSE:To form an ion source by which sufficient measuring sensitivity can be obtained for any specimen by providing an ionization chamber in an ion passage in an intermediate exhaust chamber so that an ion can pass the inside of the ionization chamber. CONSTITUTION:A nonionized specimen molecule together with an specimen ion is introduced into an ionization chamber 14 from an API ion source via an incident port 12. The nonionized specimen molecule is ionized by an electron beam generated from a filament 15, pushed out from an ionization chamber 14 together with the specimen ion, and introduced into a mass spectrometry part 11 to be made mass spectrometry. Consequently the nonionized specimen molecule, introduced into the ionization chamber together with the specimen ion from the API ion source via the incident port 12, is ionized by an electron shock by providing the ionization chamber in a chamber (b) partitioned with a skimmer 8 in an intermediate exhaust chamber 6. This permits the formation of an ion source by which sufficient measuring sensitivity can be obtained for any specimen.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a mass spectrometer that introduces and analyzes ions generated by an atmospheric pressure ionization (API) ion source.

[Prior art] Atmospheric pressure ionization mass spectrometers use atmospheric pressure ionization methods,
For example, ions generated at atmospheric pressure or a pressure close to atmospheric pressure by a corona discharge ionization method, a Penning ionization method, an ion spray ionization method, or the like are introduced into a mass spectrometer in a vacuum atmosphere and subjected to mass spectrometry.

Conventionally, a mass spectrometer equipped with an API ion source using, for example, a needle electrode has a structure as shown in FIG.

In the figure, 1 is an API ion source with a glass cylinder 2,
Corona discharge chamber 3, needle electrode 4 provided in the corona discharge chamber 3
and a sample gas inlet 5. 6 is an intermediate exhaust chamber that communicates with the API ion source 1 through a cone 7 having a pinhole. This intermediate exhaust chamber 6 is provided with a skimmer 8 for reducing gases and unnecessary solvents flowing in from the atmosphere side, and a lens system 9 for converging and accelerating introduced sample ions, and is partitioned by the skimmer 8. The rooms a and b are kept at an appropriate degree of vacuum by vacuum pumps 10a and 10b. 11 is a mass spectrometry section maintained in high vacuum.

In such a configuration, the sample gas is introduced into the discharge chamber 3 from the sample gas inlet 5 together with a carrier gas such as argon gas. First, carrier gas atoms or ions are created by corona discharge generated between the needle electrode 4 provided in the discharge chamber 3 and a counter electrode (not shown). The excited carrier gas atoms or ions thus obtained ionize the sample.

A part of the sample ions thus generated are introduced into the intermediate exhaust chamber 6 maintained at an appropriate degree of vacuum through the pinhole of the cone 7, and other sample ions flow out to the outside. The sample ions pass through an opening in the skimmer 8 of the intermediate exhaust chamber 6 and a lens system 9 that converges and accelerates the sample ions introduced into the intermediate exhaust chamber 5, and are introduced into the mass spectrometer 11 where they are subjected to mass analysis. be done.

[Problems to be Solved by the Invention] In the prior art described above, the sample introduced into the discharge chamber from the sample gas inlet is not entirely ionized by the API ion source, and unionized sample molecules remain in the sample. It was introduced into the intermediate exhaust chamber 6 together with the ions. Therefore, depending on the sample, sufficient measurement sensitivity could not be obtained.

The present invention has been made in view of this point, and its main purpose is to provide an ion source with a simple configuration that can obtain sufficient 1lFI constant sensitivity for any sample.

[Means for Solving the Problems] In order to achieve the above object, the ion source for a mass spectrometer of the present invention converts ions generated by an atmospheric pressure ion source operating at or near atmospheric pressure to atmospheric pressure. In an atmospheric pressure ion source mass spectrometer in which ions are introduced into a mass spectrometer for mass analysis through an intermediate exhaust chamber that communicates with the ion source through a pinhole, ions enter the ion passage in the intermediate exhaust chamber. It is characterized by having an ionization chamber so that it can pass through the ionization chamber.

[Operation] An ionization chamber is provided in the ion passage in the intermediate exhaust chamber so that ions can pass therethrough, and sample molecules that were introduced into the intermediate exhaust chamber without being ionized are introduced into the added ionization chamber. The material was then ionized by electron impact, chemical ionization, etc.

[Example] Embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

FIG. 1 is a schematic diagram showing the main parts of an apparatus according to an embodiment of the present invention. In FIG. 1, the same components as in the conventional example shown in FIG. 4 are given the same numbers.

In FIG. 1, an ionization chamber 14 having an entrance port 12 and an exit port 13 through which ions pass is provided in the ion passageway of the room partitioned by the skimmer 8 of the intermediate exhaust chamber 6. . The ionization chamber 14 is provided with an opening 16 through which the electron beam generated from the filament 15 is introduced, and a voltage is applied thereto to provide energy necessary for analysis.

In such a configuration, from the API ion source to the entrance aperture 12
Unionized sample molecules are introduced into the ionization chamber 14 together with the sample ions through the ionization chamber 14 . These non-ionized sample molecules are ionized by the electron beam generated from the filament 15, and are pushed out of the ionization chamber 14 together with the sample ions described above, introduced into the mass spectrometer 11, and subjected to mass spectrometry.

Therefore, an ionization chamber is provided in the room partitioned by the skimmer 8 in the intermediate exhaust chamber, and an ionization chamber is provided from the API ion source to the entrance port 1.
Unionized sample molecules introduced into the ionization chamber together with the sample ions through the ionization chamber are ionized by electron impact, so the number of sample ions increases compared to the conventional device.
1 constant sensitivity is improved.

FIG. 2 is a schematic diagram showing the main parts of an apparatus according to another embodiment of the present invention. In FIG. 2, the same components as in the conventional example shown in FIG. 4 are given the same numbers. In FIG. 2, the ionization chamber 14 is provided with an opening 16 through which an electron beam generated from a filament 15 is introduced, and an opening 18 through which a reaction gas is introduced through an introduction tube 17.

Then, an electron beam generated from the filament 15 is introduced into the ionization chamber 14 through the opening 16.

Next, the reaction gas introduced from the opening 18 through the introduction tube 17 is ionized by an electron beam. Then, as described in FIG. 1, unionized sample molecules are introduced from the API ion source into the ionization chamber 14 through the entrance port 12 along with the sample ions. These non-ionized sample molecules are ionized by a chemical reaction with the reaction gas ions ionized by the electron beam, and are pushed out of the ionization chamber 14 together with the sample ions, introduced into the mass spectrometer 11, and subjected to mass spectrometry. Ru.

In the device of this embodiment, chemical ionization is performed using an electron beam generated by a filament, but instead of the filament, a glow discharge generating device may be provided to perform chemical ionization by glow discharge.

FIG. 3 is a schematic diagram showing the main parts of an apparatus according to another embodiment of the present invention. In FIG. 3, the ionization chamber 19 is constructed using the opening of the skimmer 8 as the entrance port 12. The ionization chamber 19 is provided with an opening 16 through which the electron beam generated from the filament 15 is introduced.

Note that the apparatus of this embodiment may also be provided with an opening for introducing the reaction gas into the interior, and ionized by chemical ionization in the same manner as the apparatus of the embodiment shown in FIG. Alternatively, a glow discharge generating device may be provided to cause chemical ionization by glow discharge. [Effects] As detailed above, according to the present invention, the ion passage in the intermediate exhaust chamber is provided with a structure that allows ions to pass through the interior thereof. An ionization chamber was installed in the chamber, and sample molecules that had been introduced into the intermediate exhaust chamber without being ionized were introduced into the additional ionization chamber and ionized by electron impact, chemical ionization, etc. It is possible to provide an ion source that can obtain a sufficient aPj constant sensitivity even for samples of various types.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram showing the main parts of an embodiment of the present invention, and FIG.
The figure is a schematic diagram showing the main parts of another embodiment of the device of the present invention.
FIG. 4 is a schematic diagram showing the main parts of an apparatus according to another embodiment of the present invention. FIG. 4 is a schematic view of a conventional apparatus. 1: API ion source 3: Corona discharge chamber 5: Sample gas inlet A: Cone 9: Lens system 11: Mass spectrometer 13: Output port 14.19: Ionization chamber 15: Filament 16.18: Opening 2: Cylindrical body 4: Needle electrode 6: Intermediate exhaust chamber 8: Skimmer 10: Vacuum pump 12: Inlet port 17: Inlet pipe

Claims (1)

[Claims] Ions generated by an atmospheric pressure ion source that operates at atmospheric pressure or a pressure close to it are introduced into the mass spectrometer through an intermediate exhaust chamber that communicates with the atmospheric pressure ion source through a pinhole for mass spectrometry. An atmospheric pressure ionization mass spectrometer characterized in that an ionization chamber is provided in the ion passage in the intermediate exhaust chamber so that ions can pass therethrough.