Mass spectrometer

A mass analyzing method, comprising:

• generating ions of sample,
• isolating a precursor ion from said ions of sample,
• accumulating said precursor ion in a ion trap composed of a multipole rod set and wall electrodes at the each end of said multipole rod set,
• irradiating an electron beams to said precursor ion for ECD reaction,
• ejecting fragment ions by said ECD reaction from said ion trap, and
• analyzing said ejected ions by analyzer,
• wherein said ion trap is applied a radio frequency ion trap electric field and a magnetic field for said ECD reaction, and said magnetic field is not less than 0.02 T.

A mass analyzing method, comprising:

• generating ions of sample,
• isolating a precursor ion from said ions of sample,
• introducing said precursor ion in a ion trap composed of a multipole rod set and wall electrodes at the each end of said multipole rod set,
• carrying out CID or IRMPD reaction to said introduced precursor ion in said ion trap and determining modified molecular species of said precursor ion, introducing said precursor ion in said ion trap and carrying out CID or IRMPD reaction to said precursor ion to remove modified sites,
• carrying out CID or IRMPD or ECD reaction to said modified sites removed precursor ion and determining the sequence structure of backbone,
• introducing said precursor ion in said ion trap and carrying out ECD reaction to said precursor ion to cut said backbone,
• determining posttranslational modified site by information of determined said modified molecular species and said backbone.

A mass spectrometer comprising:

• an ion source for generating sample ions,
• an ion trap composed of a multipole rod set and wall electrodes at the each end of said multipole rod set and radio frequency electric field in the r direction of said multipole rod set and a static electric field and a magnetic field,
• a vacuum vessel for setting said ion trap in vacuum pressure,
• an electron source for generating an electron beam,
• a reaction cell for irradiating the ions stored in the said trap with the electron beam, and effecting an electron capture dissociation reaction, and
• a mass analysis part for performing mass analysis of the dissociated ions generated in the reaction cell,
• wherein said vacuum pressure is no less than 10−3 Pa and no more than 10−1 Pa.