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Ionization analysis method and apparatus

外国特許コード F120006900
整理番号 P08-019US
掲載日 2012年10月4日
出願国 アメリカ合衆国
出願番号 200913001330
公報番号 20110108726
公報番号 8253098
出願日 平成21年6月4日(2009.6.4)
公報発行日 平成23年5月12日(2011.5.12)
公報発行日 平成24年8月28日(2012.8.28)
国際出願番号 JP2009060653
国際公開番号 WO2009157312
国際出願日 平成21年6月4日(2009.6.4)
国際公開日 平成21年12月30日(2009.12.30)
優先権データ
  • 特願2008-169679 (2008.6.27) JP
  • 2009JP060653 (2009.6.4) WO
発明の名称 (英語) Ionization analysis method and apparatus
発明の概要(英語) An ionization apparatus comprises a first electrode provided on the outer periphery of a dielectric cylindrical body and a second cylindrical electrode placed inside at a center of the cylindrical body.
When an AC high voltage is impressed across the first electrode and the second cylindrical electrode, a barrier discharge occurs within the cylindrical body.
A distal end portion of the second cylindrical electrode projects outwardly from the distal end of the cylindrical body, a thermal equilibrium plasma P having a low electron temperature is generated outwardly from the distal end of the cylindrical body without a plasma jet ascribable to the barrier discharge emerging outwardly from the distal end of the cylindrical body.
By exposing a sample S to the thermal equilibrium plasma P, particles (atoms, molecules) desorbed from the sample S undergo soft ionization without being decomposed or polymerized.
従来技術、競合技術の概要(英語) BACKGROUND ART
Examples of an ionization analysis method and apparatus utilizing barrier discharge are described in the following literature:
1. Na Na, Chao Zhang, Mengxia Zhao, Sichun Zhang, Chengdui Yang, Xiang Fang and Xinrong Zhang, "Direct detection of explosives on solid surfaces by mass spectrometry with an ambient ion source based on dielectric barrier discharge", J. Mass Spectrom. 2007; 42:1079-1085
2. Na Na, Mengxia Zhao, Sichun Zhang, Chengdui Yang and Xinrong Zhang, "Development of a Dielectric Barrier Discharge Ion Source for Ambient Mass Spectrometry", J Am Soc Mass Spectrom. 2007, 18, 1859-1862
The ion analysis method and apparatus described in these references have a plate-shaped electrode, a glass plate placed on the surface of the plate-shaped electrode and a needle-shaped electrode disposed substantially perpendicular to the surface of the glass plate (the plate-shaped electrode) and spaced away from the glass plate, and impress an alternating high-voltage across the plate-shaped electrode and needle-shaped electrode and induce a barrier discharge.
A sample serving as an object to undergo analysis is placed on the glass plate and is exposed to a plasma torch produced by the barrier discharge.
As a result, atoms and molecules are desorbed from the sample and ionized.
The ions are introduced to a mass analyzer and analyzed.
Since a sample is exposed directly to a plasma torch (non-equilibrium plasma) produced by barrier discharge in the ion analysis method and apparatus described in the references cited above, decomposition of the sample itself by high-energy electrons in the plasma, decomposition of molecules desorbed from the sample and ionized, and polymerization of fragment ions produced by decomposition and the like occur.
A problem, therefore, is that there are cases where accurate analysis cannot always be achieved.

特許請求の範囲(英語) [claim1]
1. An ionization apparatus comprising: a first cylindrical body comprising a dielectric;
a first electrode provided on the outer side of said first cylindrical body in the vicinity of a distal end portion thereof; and
a second electrode disposed inside said first cylindrical body in the vicinity of the center thereof defining a clearance between itself and an inner surface of said first cylindrical body, extending along the longitudinal direction of said first cylindrical body, projecting outwardly from the distal end of said first cylindrical body and passing a position at which said first electrode is provided;
wherein said second electrode is a second cylindrical body for supplying a sample gas or for introducing generated ions and has a distal end that is open.
[claim2]
2. An ionization apparatus according to claim 1, wherein said second electrode is a slender tube made of metal.
[claim3]
3. An ionization apparatus according to claim 1, wherein said second electrode is a capillary for supplying a sample gas, the sample gas being supplied from a rear end thereof.
[claim4]
4. An ionization apparatus according to claim 1, wherein said second electrode is a capillary for introducing ions, the capillary communicating with the interior of a mass analyzer.
[claim5]
5. An ionization apparatus according to claim 1, wherein said second electrode is formed as a metal portion on the surface of an inner cylindrical body, which exhibits an insulating property, at least from the position of said first electrode to the distal end.
[claim6]
6. An ionization apparatus according to claim 1, further comprising a mesh electrode disposed outwardly of a distal end of said second electrode in close proximity to this distal end.
[claim7]
7. An ionization analysis apparatus comprising the ionization apparatus, which is set forth in claim 1, and a mass analyzer.
[claim8]
8. An ionization method using the ionization apparatus set forth in claim 1 comprising: impressing an AC voltage across said first and second electrodes; and
exposing a sample to a charged gas stream generated from the distal end of said first cylindrical body.
[claim9]
9. An ionization method according to claim 8, further comprising impressing a DC voltage across said first and second electrodes and generating a positive-ion rich or negative-ion rich charge gas current in accordance with polarity of this DC voltage.
[claim10]
10. An ionization method according to claim 9, further comprising applying a voltage having a polarity the same as that of said DC voltage and an absolute value larger than that of said DC voltage to a conductor placed rearwardly of the sample.
[claim11]
11. An ionization method according to claim 8, further comprising applying a positive or negative DC voltage to a mesh electrode disposed outwardly of the distal end of said second electrode in close proximity to this distal end.
[claim12]
12. An ionization method according to claim 8, further comprising supplying a discharge gas or carrier gas to a gap in said first cylindrical body between said first cylindrical body and said second electrode.
[claim13]
13. An ionization method according to claim 12, further comprising promoting desorption of the sample by heating said discharge gas or carrier gas.
[claim14]
14. An ionization method according to claim 8, further comprising spraying fine droplets of a solvent onto the sample and promoting desorption of the sample.
[claim15]
15. An ionization method according to claim 8, further comprising promoting desorption of the sample by heating the sample.
[claim16]
16. An ionization method according to claim 8, further comprising promoting desorption of the sample by subjecting the sample to ultrasonic vibration.
[claim17]
17. An ionization method according to claim 8, further comprising promoting desorption of the sample by irradiating the sample with laser light.
[claim18]
18. An ionization method according to claim 8, further comprising promoting desorption of the sample by forming a photon field in the vicinity of the sample surface.
[claim19]
19. An ionization analysis method comprising introducing sample ions, which have been produced by the ionization method set forth in claim 8, to an analyzing apparatus.
  • 発明者/出願人(英語)
  • HIRAOKA KENZO
  • CHEN LEE CHUIN
  • UNIVERSITY OF YAMANASHI
国際特許分類(IPC)
米国特許分類/主・副
  • 250/288
  • 250/423.000R
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