Mass chromatograph

• US 20060054806A1
• Filed: 03/04/2005
• Published: 03/16/2006
• Est. Priority Date: 09/16/2004
• Status: Active Grant

• Current Assignee: Hitachi, Ltd.
• Original Assignee: Hitachi, Ltd.
• Inventors: Waki, Izumi, Yamada, Masuyoshi, Kasima, Hideo
• Granted Patent: US 7,064,320 B2
• Time in Patent Office: Days
• US Class Current: 250/288
• CPC Class Codes: G01N 30/7213 splitting of the gaseous effluent
• CPC Class Codes: H01J 49/0422 for gaseous samples interfaces to gas chromatographs G01N30/7206
• CPC Class Codes: H01J 49/145 using chemical ionisation
• CPC Class Codes: H01J 49/168 field ionisation, e.g. corona discharge atmospheric pressure corona discharge per se H01T19/00

Abstract

A mass spectrometer has an atmospheric pressure chemical ionization source that includes a first ionization portion including a needle electrode, for generating a primary ion by discharge of the needle electrode a primary ion introduction aperture, and a second ionization portion including an introduction aperture, for generating a sample ion by the reaction between the primary ion and the sample gas introduced from an end of a column of gas chromatography, a sample ion movement aperture; and a mass analysis portion; wherein the end is arranged at a position satisfying the relation r≦2R where R is a radius of an inner diameter of the aperture and r is a distance between an axis connecting the center of the aperture and the center of the aperture, and the end.

Claims

1. A mass spectrometer comprising:

an atmospheric pressure chemical ionization (APCI) source including;

(a1) a first ionization portion including a needle electrode to which a voltage for corona discharge is applied, and an exhaust aperture for said primary ion generation gas, for generating a primary ion from said primary ion generation gas by discharge of said needle electrode;

(a2) a primary ion introduction aperture through which said primary ion flows; and

(a3) a second ionization portion including an introduction aperture of said primary ion generation gas, for generating a sample ion of a sample gas by the reaction between said primary ion introduced from said primary ion introduction aperture and said sample gas introduced from an end of a column of gas chromatography, said second ionization portion having the end of said column arranged therein;

(b) a sample ion movement aperture through which said sample ion moves; and

(c) a mass analysis portion for conducting mass analysis of said sample ion;

wherein;

said exhaust aperture is arranged at a portion on the opposite side to the tip end of said needle electrode, said primary ion generation gas introduced into said second ionization portion is caused to flow to said exhaust aperture from the distal end of said needle electrode through said primary ion introduction aperture, and the end of said column is arranged at a position satisfying the relation r≦

2R where R is a radius of an inner diameter of said primary ion introduction aperture and r is a distance between an axis connecting the center of said primary ion introduction aperture and the center of said sample ion movement aperture, and end of said column.

2. A mass spectrometer as defined in claim 1, which satisfies the relation 0.02Q≦

Q′

≦

0.95Q where Q is the flow rate of said sample gas at the end of said column and Q′

is the flow rate of said sample gas introduced into said second ionization portion and exhausted from said sample ion movement aperture.

3. A mass spectrometer as defined in claim 1, which satisfies the relation 0.4Q≧

Q′

≧

0.6Q where Q is the flow rate of said sample gas at the end of said column and Q′

is the flow rate of said sample gas introduced into said second ionization portion and exhausted from said sample ion movement aperture.

4. A mass spectrometer as defined in claim 1, wherein said sample ion moving in said sample ion movement aperture is introduced into said mass analysis portion through a differential exhaust portion.

5. A mass spectrometer as defined in claim 1, which includes a sample gas piping connected to the end of said column, and wherein the end of said sample gas piping is arranged inside said second ionization portion in place of the end of said column disposed inside said second ionization portion.

6. A mass spectrometer comprising:

(a) an atmospheric pressure chemical ionization (APCI) source including a needle electrode to which a voltage for corona discharge is applied, and an ionization portion having a primary ion generation gas introduction aperture, for generating a primary ion from said primary ion generation gas by discharge of said needle electrode, having an end of a column of gas chromatography disposed therein, and generating a sample ion of a sample gas by the reaction between said sample gas introduced from the end of said column and said primary ion;

(b) a sample ion movement aperture through which said sample ion moves; and

(c) a mass analysis portion for conducting mass analysis of said sample ion;

wherein the end of said column is arranged at a portion between the tip end of said needle electrode and said sample ion movement aperture.

7. A mass spectrometer as defined in claim 6, wherein the end of said column is arranged at a position satisfying the relation x≧

a where a is a distance between the center of a tip end of said needle electrode and the center of an ion inlet of said sample ion movement aperture and x is a distance between the center of the tip end of said needle electrode and an aperture at the end of said column.

8. A mass spectrometer as defined in claim 6, which includes a sample gas piping connected to the end of said column, and wherein the end of said sample gas piping is arranged inside said atmospheric pressure chemical ionization (APCI) source in place of the end of said column.

9. A mass spectrometer as defined in claim 6, wherein said sample ion moving in said sample ion movement aperture is introduced into said mass analysis portion through a differential exhaust portion.

10. A mass spectrograph comprising:

an atmospheric pressure chemical ionization (APCI) source including;

(a1) an ionization portion including a needle electrode to which a voltage for corona discharge is applied, and a primary gas generation gas introduction aperture, generating a primary ion from said primary ion generation gas by discharge of said needle electrode, having a column of gas chromatography disposed therein and generating the sample ion of said sample gas by the reaction between said sample gas introduced from an end of said column and said primary ion;

(a2) an ion passage aperture through which said sample ion, said primary ion, said primary ion generation gas and said sample gas flow; and

(a3) an area into which said sample ion, said primary ion, said primary ion generation gas and said sample gas are introduced through said ion passage aperture;

(b) a sample ion movement aperture through which said sample ion moves; and

(c) a mass analysis portion for conducting mass analysis of said sample ion;

wherein the end of said column is arranged between the tip end of said needle electrode and said ion passage aperture.

11. A mass spectrometer as defined in claim 10, wherein the end of said column is arranged at a position satisfying the relation x≧

a where a is a distance between the center of a tip end of said needle electrode and the center of an ion inlet of said sample ion movement aperture and x is a distance between the center of the tip end of said needle electrode and an aperture at the end of said column.

12. A mass spectrometer as defined in claim 10, wherein said sample ion moving through said sample ion movement aperture is introduced into said mass analysis portion through a differential exhaust portion.

13. A mass spectrometer as defined in claim 10, which includes a sample gas piping connected to the end of said column, and wherein the end of said sample gas piping is arranged inside said atmospheric pressure chemical ionization (APCI) source in place of the end of said column.