JP3505071B2 - Atmospheric pressure ionization mass spectrometer and method thereof - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an atmospheric pressure ionization mass spectrometer, and particularly to an ion source structure suitable for detecting and quantifying trace organic substances with high sensitivity. The present invention relates to an atmospheric pressure ionization mass spectrometer. 2. Description of the Related Art A conventional device is disclosed in, for example,
There is an atmospheric pressure ionization mass spectrometer described in US Pat. The conventional atmospheric pressure ionization mass spectrometer described in the above publication will be described with reference to FIG. FIG. 3 is a configuration diagram of a conventional atmospheric pressure ionization mass spectrometer. The atmospheric pressure ionization mass spectrometer includes an ion source 35 and a mass spectrometer 24 (referred to as an analyzer main body in this specification).
Are the ion generator 5, the first body 6, and the second body 7
A sample introduction unit including: a first insulator 8; a first electrode unit 9; a first electrode unit 9; a second insulator 11;
The mass analysis unit 24 includes a pore 19 and a mass analysis unit (not shown) in a vacuum region in the housing 36. The mixing unit 10 is formed in a region surrounded by the electrode unit 12. I have. In the ion generator 5, a first gas 1 for generating ions (referred to as a primary ion generating gas) introduced from a first gas inlet 15 is formed by discharging ions (e.g., primary ions) from the needle electrode section 14. (Hereinafter, referred to as primary ions) is mixed with the sample gas 2 from the sample gas inlet 15 in the mixing section 10, and the target substance contained in the sample gas 2 is ionized by an ion molecule reaction. The ions generated in the mixing section 10 are
It is introduced into the pores 19 by the action of the electric field formed by the electrode part 9 and the second electrode part 12. The ions that have passed through the pores 19 and introduced into the mass spectrometer 24 are separated by mass in the mass spectrometer 24 and detected. In this atmospheric pressure ionization mass spectrometer, as described above, the ion source and the sample gas introduction unit are separated, and the ions are efficiently transported to the pores. With respect to, trace impurities can be analyzed stably for a long time and with high sensitivity. According to the above conventional atmospheric pressure ionization mass spectrometer, the sample gas 2 is supplied to the gas inlet 1
8a through a gas introduction passage 18 provided inside each of the second body 7, the first insulator 8, and the first electrode portion 9 to pass through the mixing portion 10a.
It is a structure introduced to. Therefore, each part 7,
In order to prevent the sample gas 2 from leaking from the gas introduction path 18, two joint structures are required at the joints 8 and 9. On the other hand, since the inside and outside of the ion generator 5 also need to be separated, the seal between the sample gas 2 and the second body 7 and the first insulator 8 and between the first insulator 8 and the first electrode 9 are not formed. One location is required for sealing the ion generator 5. In order to simultaneously seal the three seal portions with a metal material at the same time, it is necessary to simultaneously and uniformly crush the so-called “crush margin” of the three metal material seal materials. However, it is difficult to achieve the above-mentioned simultaneous and uniform operation. Therefore, in the prior art, the seal of the sample gas 2 and the seal of the ion generating section 5 are made of a metal gasket 26 made of an inorganic material, and the other is used. Sample gas 2
An O-ring 25 made of an organic material was used in two places, that is, the seal for the ion generator 5 and the seal for the ion generator 5. In the case of analyzing a gas which easily contaminates an ion source such as a silane-based gas, a stable operation can be obtained with the atmospheric pressure analyzer having the above-mentioned structure. However, there is a problem that a trace amount of organic matter generated from the O-ring 25 made of the organic material increases a background value of an analyte, and as a result, it becomes difficult to detect a trace amount of organic substance as an analysis target substance. I was The present invention has been made in view of the above-mentioned problems of the related art, and in the gas contact portion in the analyzer main body including the ion source and the like,
Atmospheric pressure that uses inorganic materials such as metals and ceramics to completely eliminate materials that generate organic matter, thereby completely suppressing organic matter contamination from ion sources and the like and enabling trace organic matter analysis. It is an object of the present invention to provide an ionization mass spectrometer and a method thereof. [0008] To achieve the above object, an atmospheric pressure ionization mass spectrometer according to the present invention comprises:
In an atmospheric pressure ionization mass spectrometer including a mass spectrometer and an ion source, the mass spectrometer has a pore and a mass spectrometer in a region of the housing that is evacuated to a vacuum, and the ion source includes:
An electrode portion having an opening and attached to the ion source via an insulator is divided into two chambers, and the first chamber has an inlet for a first gas and an ionization means for generating ions of the first gas. The second chamber has an inlet for a second gas containing a substance to be analyzed, the gas contact portion in the analyzer main body is made of an inorganic material, and the second chamber is supplied from the opening by the second chamber. The ions of the first gas and the second gas from the inlet are mixed to perform secondary ionization, and the secondary ions are moved from the pores to the mass spectrometric unit by the electric field of the electrode unit. It is characterized in that ions are detected by analysis means. In the atmospheric pressure ionization mass spectrometer described in the preceding paragraph, the electrode portion is made of an inorganic material, the housing is provided with an inlet for the second gas, and the electrode portion is provided with a second inlet to the second chamber. A gas inlet is provided, and an inorganic insulating pipe and an inorganic pipe connected to the pipe are provided from the inlet of the housing to the inlet of the electrode portion. In the atmospheric pressure ionization mass spectrometer according to the preceding paragraph, the insulator to which the electrode unit is attached is made of an inorganic material, and instead of the inlet of the second gas to the second chamber of the electrode unit, the insulator is connected to the insulator. (2) An inlet for gas is provided, and the inorganic pipe is provided from an inlet of the housing to an inlet of the insulator. In the atmospheric pressure ionization mass spectrometer described in the preceding paragraph, a metal bellows-shaped flexible pipe is provided between the inlet of the casing and the inorganic insulating pipe. [0010] The constitution of the atmospheric pressure ionization mass spectrometry method according to the present invention is such that a first gas is introduced, ions are generated in a first chamber of an ion source, and then the generated ions are converted into the first chamber in a second chamber. While supplying from the chamber, a second gas containing a trace amount of the analyte is introduced, and then the first gas is supplied to the second chamber.
Gas ions and the second gas are mixed to perform secondary ionization, and then the generated secondary ions are moved to a mass spectrometer by an electric field generated by an electrode unit, and then the secondary ions are separated and detected. Atmospheric pressure ionization mass spectrometry method, wherein the first gas and the second gas containing the substance to be analyzed are introduced through a gas contact portion of an inorganic material in the main body of the analyzer,
It is characterized by analyzing a trace amount of organic matter. [0011] In the atmospheric pressure ionization mass spectrometry described in the preceding paragraph, the second gas is supplied from outside via an inorganic insulating pipe and an inorganic pipe connected thereto to an inlet provided in the electrode portion of the inorganic material. Is introduced. In the atmospheric pressure ionization mass spectrometer according to the preceding paragraph, instead of the inlet provided in the electrode portion of the inorganic material, the inorganic pipe is connected to the electrode portion of the inorganic material attached to the ion source through the inlet of the insulator of the inorganic material. Characterized in that the second gas is introduced from the outside via an external device. In the atmospheric pressure ionization mass spectrometry described in the preceding paragraph, a flexible pipe in the form of a metal bellows is connected to an external second gas inlet provided in the analyzer main body, and the second gas is introduced through the pipe. It is characterized by doing. The present invention having the above configuration will be functionally described. An atmospheric pressure ionization mass spectrometer according to the present invention includes an ion source and a mass spectrometer (referred to as a main body of the spectrometer). The ion source includes an ion generator, a sample introduction unit, a mixing unit, and a mass spectrometer. The generating section is an area that has an inlet for a primary ion generating gas and an ionizing means to generate primary ions, the sample introducing section is an area for introducing a sample gas, and the mixing section is an area for introducing a sample gas and an ion generating section. Is the area where the primary ions supplied from the sample are mixed with each other to produce ions of the target substance in the sample gas by an ion-molecule reaction. This is a part for mass-separating and detecting ions introduced into the high vacuum part through the pores. In the above structure, a sample introduction port and a sample discharge port are provided in an electrode section for partitioning the ion source into two chambers as a sample introduction section, so that the function of forming an electric field and introducing and discharging the sample can be shared. A structure in which a pipe for supplying a sample containing a trace amount of a substance to be analyzed is directly connected to the sample inlet of the electrode section through an inorganic insulating pipe made of ceramics, thereby contaminating organic matter from an ion source or the like. Except for
It enables analysis of trace amounts of organic matter. An embodiment of an atmospheric pressure ionization mass spectrometer according to the present invention will be described below with reference to FIGS. FIG. 1 is a configuration diagram of an atmospheric pressure ionization mass spectrometer according to one embodiment of the present invention, and FIG. 2 is a configuration diagram of an atmospheric pressure ionization mass spectrometer according to another embodiment of the present invention. 1 and 2, the same symbols as those in FIG.
Since they are equivalent products having the same configuration, repeated description is omitted because it is complicated. [Embodiment 1] As shown in FIG. 1, an atmospheric pressure ionization mass spectrometer of the present embodiment has an ion
, A sample introduction unit 40, an ion source unit 35 including the mixing unit 10, and the mass analysis unit 24. The ion generator 5 includes a first body 6, a second body 7, and a first body 6.
In a region surrounded by the insulator 8 and the first electrode portion 9, the needle electrode portion 14 and the cylindrical glass tube 21 are disposed therein, and the primary ion generating gas 1 introduced through the gas inlet 15 is provided. To generate primary ions. The first body 6 is provided with a needle electrode section 14 to which a power supply 13 is connected and a gas inlet 15. The mixing section 10 is formed in a region surrounded by the first electrode section 9, the second electrode section 12, and a second insulator 11 sandwiched between the two members. The second body 7 is provided with an outlet 17 for a gas for generating primary ions, and the first insulator 8 holds the first electrode portion 9 therebetween.
The second body 7 is insulated from the first electrode portion 9. A power supply 22 is connected to the first electrode unit 9 to generate an electric field, and through holes 9c and 9d are provided in the first electrode unit 9 to introduce a sample of the sample gas 2 and unnecessary It also plays the role of exhaust gas emission. The sample introduction section 40 is provided with a gas introduction port 18 provided in the housing 36 and an insulating pipe A2 made of ceramic.
The pipe B27 made of an inorganic material is connected to the gas inlet 9a of the sample gas 2 of the first electrode section 9 through the pipe 8. Also, the gas outlet 20 provided in the housing 36 and the insulating pipe B29
Through the gas outlet 9 of the first electrode portion 9
b. In this manner, the sample gas 2 is directly introduced from the gas inlet 18 and the exhaust gas 4 is directly introduced or discharged from the gas outlet 20. The needle electrode section 14 is connected to a power supply 13, and when a high voltage is applied, the primary ion generating gas 1 is ionized by corona discharge. The glass tube 21 is arranged in a cylindrical shape around the needle electrode portion 14 so that the gas 1 for preventing abnormal discharge and generating primary ions flows through the opening 16. The mixing section 10 is a region surrounded by the first electrode section 9, the second insulator 11, and the second electrode section 12,
Primary ions generated by the ion generator 5 and the sample introduction unit 4
The sample gas 2 introduced from 0 is mixed, and the substance to be analyzed in the sample gas 2 is ionized by an ion-molecule reaction. The second insulator 11 insulates the first electrode unit 9 and the second electrode unit 12 from each other. The second electrode portion 12 has a pore 1 at its center.
9 is provided, and a power supply 23 is connected. Then, the second electrode unit 12 allows the ions to pass through the pores 19 due to a potential difference from the first electrode unit 9 and introduces the ions into the high vacuum mass analysis unit 24 surrounded by the housing 36. Next, the operation of the atmospheric pressure ionization mass spectrometer according to the present embodiment will be described. The primary ion generating gas 1 passes through the gas inlet 15 and is introduced into the ion generating unit 5, and is ionized by corona discharge generated at the tip of the needle electrode unit 14 to generate primary ions. A part of the primary ion generating gas 1 introduced into the ion generating section 5 flows into the mixing section 10 through an opening 16 provided in the first electrode section 9.
The primary ions generated in the ion generating section 5 are introduced into the mixing section 10 together with a partial flow of the gas 1. The remainder of the primary ion generating gas 1 is exhausted from the gas outlet 17 as the exhaust gas 3. The sample gas 2 introduced from the gas inlet 18 passes through a pipe A27 that insulates the second body 7 from the first electrode section 9 through an insulating pipe A28, and is mixed with primary ions in a mixing section 10. Then, the substance to be analyzed in the sample gas 2 is ionized. The generated ions are caused by the potential difference between the first electrode portion 9 and the second electrode portion
Is introduced into the mass spectrometer 24 and detected. As described above, according to this embodiment, the first electrode section 9 is insulated from the first electrode section 9 through the insulating pipes 28 and 29 made of ceramic, and directly supplies the sample containing a trace amount of the substance to be analyzed. By connecting the exhaust pipe 27 to the exhaust pipe 27, organic matter contamination from an ion source or the like is completely suppressed, and a trace amount of organic matter can be analyzed. [Embodiment 2] Next. Another embodiment of the atmospheric pressure ionization mass spectrometer according to the present invention will be described. As shown in FIG. 2, the atmospheric pressure ionization mass spectrometer according to the present embodiment includes an ion generator 5, a sample introduction unit 40, a sample discharge unit 50, a mixing unit 10, and a mass analysis unit 24. I have. The sample introduction part 40 includes a first electrode part 9, a pipe A27 connected to the first electrode part 9, and a pipe A2.
7 and the insulating pipe A28.
The flexible pipe 31 is connected to the gas inlet 18 provided in the second body 7, and the sample gas 2 is introduced from the gas inlet 18. The sample discharging section 50 includes a first electrode section 9,
A pipe B30 connected to the first electrode portion 9, an insulating pipe B29 connected to the pipe B30, and an insulating pipe B
The flexible pipe 32 is connected to a gas outlet 20 provided in the second body 7, and the sample gas 2 is discharged from the gas outlet 20. The flexible pipe 3
1 and 32 are the gas inlet 18 of the sample gas 2 and the insulating pipe A
28, the space between the gas discharge port 20 and the insulating pipe B29 is inserted between the gas discharge port 20 and the insulating pipe B29. Next, the operation of the atmospheric pressure ionization mass spectrometer of this embodiment will be described. The sample gas 2 introduced from the gas inlet 18 passes through the flexible pipe 31 from the gas inlet 18, passes through the inorganic pipe A 27 insulated from the first electrode section 9 by the insulating pipe A 28, and passes through the first electrode section. The mixture 9 is guided to a mixing unit 10, mixed with primary ions in the mixing unit 10, and ionizes a target substance in the sample gas 2. The generated ions are caused by the potential difference between the first electrode portion 9 and the second electrode portion
Is introduced into the mass spectrometer 24 and detected. In the atmospheric pressure ionization mass spectrometer thus configured, first, a gas (1) for generating primary ions is introduced into the ion generating section (5). Next, the gas (1)
Are ionized by ionization means such as corona discharge from the needle electrode section (14), which is ionization means, to generate primary ions. Further, the primary ions are introduced into the mixing section (10), mixed with the sample gas (2) introduced from the sample introduction section, and the target substance in the sample gas (2) is ionized by an ion-molecule reaction. Is done. Next, the generated ions pass through the pores (19) and enter the mass spectrometer (2).
Introduced in 4), mass-separated and detected. The gas contact part of the sample introduction part does not use a material that generates organic substances, so that a trace amount of organic substances can be analyzed. As described above, in both [Embodiment 1] and [Embodiment 2], the material which generates an organic substance is excluded from the gas contact part, and the organic O-ring (see 25 in FIG. 3) is not used. Has become. Here, specifically, the organic O-ring is a general rubber such as nitrile rubber, viton, or the like.
Contains rubber represented by trade name such as Kalreiz
It goes without saying that V, U, etc. are also included. The present invention is not limited to the above-mentioned [Embodiment 1] and [Embodiment 2], and many modifications are conceivable. For example, the pipe 27 of FIG. 2 is connected to a small hole provided in the insulator 11, and the sample gas 2 is ejected from the small hole. The processing of the small holes in the insulator 11 is easy, and unlike the case where the ejection port for the sample gas 2 is provided in the electrode 9, no voltage is applied to the pipe 27.
8B becomes unnecessary. With the configuration as in the present invention, the background of organic substances can be reduced by three orders of magnitude, and trace organic substances can be analyzed with high accuracy. As described above in detail, according to the structure of the present invention, all the gas contact portions in the main body of the analyzer are made of a structure using an inorganic material. Atmospheric pressure ionization mass spectrometer and method thereof capable of completely suppressing organic matter contamination from water, lowering the background of organic matter, and analyzing trace amounts of organic matter can be provided.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a configuration diagram of an atmospheric pressure ionization mass spectrometer according to an embodiment of the present invention. FIG. 2 is a configuration diagram of an atmospheric pressure ionization mass spectrometer according to another embodiment of the present invention. FIG. 3 is a configuration diagram of a conventional atmospheric pressure ionization mass spectrometer. [Explanation of Signs] 1 ... Primary ion generating gas, 2 ... Sample gas, 3 ... Exhaust gas, 5 ... Ion generator, 6 ... First body, 7 ... Second
Body, 8: first insulator, 9: first electrode section, 10: mixing section, 11: second insulator, 12: second electrode section, 13: power supply, 14: needle electrode section, 15: gas inlet , 16 ... opening, 17 ... gas outlet, 18 ... gas inlet, 19 ... pore, 20 ... gas outlet, 21 ... glass tube, 22, 23 ...
Power supply, 24: mass analyzer, 25: O-ring, 26: metal gasket, 27: pipe A, 28: insulating pipe A, 29
... Insulated piping B, 30 ... Piping B, 31, 32 ... Flexible piping

────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Keiji Hasumi 3-3-2 Fujihashi, Ome-shi, Tokyo Hitachi Tokyo Electronics Co., Ltd. (56) References JP-A-8-273586 (JP, A) JP-A-8 -1006878 (JP, A) JP-A-5-275052 (JP, A) JP-A-59-35348 (JP, A) JP-A-6-310091 (JP, A) JP-A-6-52825 (JP, A) JP-A-1-194241 (JP, A) JP-A-53-60883 (JP, U) JP-A-5-1222993 (JP, U) JP-A-61-194949 (JP, U) Field (Int.Cl. ⁷ , DB name) H01J 49/00-49/42

Claims (1)

(57) [Claim 1] In an atmospheric pressure ionization mass spectrometer comprising a mass spectrometer and an ion source, the mass spectrometer is located in a region of the housing evacuated to a vacuum. ,
An ion generator for generating primary ions by ionizing a gas for generating primary ions by corona discharge of a needle electrode unit; A mixing section for mixing with a measurement sample gas to ionize an analysis target substance in the sample gas, a sample introduction section for introducing the sample gas into the mixing section, and for discharging a remaining portion of the sample gas. The mixing unit is configured by a region surrounded by a first electrode unit, an insulator, and a second electrode unit, and the mixing unit is configured by a potential difference between the first electrode unit and the second electrode unit. The sample introduction section has a function of passing ions of the analysis target substance through the pores and introducing the ions into the mass analysis means, and the sample introduction section is provided with a metal bellows-shaped flexible pipe and an inorganic pipe through a sample introduction port provided in the housing. material Atmospheric pressure ionization mass spectrometer, characterized in that it is constituted by connecting to the holes made in the first electrode portion through the pipe.