Ion trap mass spectrometry

• US 7,582,866 B2
• Filed: 10/03/2007
• Issued: 09/01/2009
• Est. Priority Date: 10/03/2007
• Status: Active Grant

• Current Assignee: Shimadzu Corporation
• Original Assignee: Shimadzu Corporation
• Inventors: Ogawa, Kiyoshi, Takeshita, Kengo, Furuhashi, Osamu
• Primary Examiner(s): Wells; Nikita
• Application Number:
  US11/866,794
• Publication Number:
  US 20090090860A1
• Time in Patent Office: 699 Days
• Field of Search: 250/292, 250/282, 250/281, 250/290
• US Class Current: 250/292
• CPC Class Codes: H01J 49/0059 by a photon beam, photo-dissociation
• CPC Class Codes: H01J 49/424 Three-dimensional ion traps, i.e. comprising end-cap and ring electrodes
• CPC Class Codes: H01J 49/427 Ejection and selection methods

Abstract

Disclosed is an ion trap mass spectrometer for MSⁿ analysis, which comprises a frequency-driven ion trap section operable to trap sample ions and isolate a precursor ion from the sample ions, while setting an ion-trapping RF voltage waveform at a first frequency providing a first low-mass cutoff (LMCO) value, and, then after setting the ion-trapping RF voltage waveform at a second frequency greater than the first frequency to provide a second LMCO value less than the first LMCO value, without changing an amplitude of the ion-trapping RF voltage waveform, to irradiate the precursor ion in a trapped state with light so as to photodissociate the precursor ion into fragment ions; and an analyzer section operable to subject the fragment ions ejected from the ion trap section, to mass spectrometry so as to obtain information about a molecular structure of the precursor ion. The ion trap mass spectrometer of the present invention can maximize a mass range coverable in one cycle of MSⁿ analysis.

Claims

1. An ion trap mass spectrometer for MSⁿ analysis, comprising:

a frequency-driven ion trap section operable to trap sample ions and isolate a precursor ion from said sample ions, while setting an ion-trapping RF voltage waveform at a first frequency providing a first low-mass cutoff (LMCO) value, and, then after setting the ion-trapping RF voltage waveform at a second frequency greater than said first frequency to provide a second LMCO value less than said first LMCO value, to irradiate said precursor ion in a tapped state with light so as to photodissociate said precursor ion into fragment ions; and

an analyzer section operable to subject said fragment ions ejected from said ion trap section, to mass spectrometry so as to obtain information about a molecular structure of said precursor ion.

2. The ion trap mass spectrometer as defined in claim 1, wherein said ion-trapping RF voltage waveform is formed as a rectangular voltage waveform.

3. An ion trap mass spectrometric method for MSⁿ analysis, comprising the steps of:

trapping sample ions and isolating a precursor ion from said sample ions, while setting an ion-trapping RF voltage waveform at a first frequency providing a first low-mass cutoff (LMCO) value;

after setting the ion-trapping RF voltage waveform at a second frequency greater than said first frequency to provide a second LMCO value less than said first LMCO value, irradiating said precursor ion in a trapped state with light so as to photodissociate said precursor ion into fragment ions; and

subjecting said fragment ions to mass spectrometry so as to obtain information about a molecular structure of said precursor ion.

4. The ion trap mass spectrometric method as defined in claim 3, wherein said ion-trapping RF voltage waveform is formed as a rectangular voltage waveform.