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Ion fragmentation activated by matrix‐assisted laser desorption/ionization in an ion‐trap/reflectron time‐of‐flight device
Author(s) -
Fountain Scott T.,
Lee Heewon,
Lubman David M.,
Brodbelt Jennifer
Publication year - 1994
Publication title -
rapid communications in mass spectrometry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.528
H-Index - 136
eISSN - 1097-0231
pISSN - 0951-4198
DOI - 10.1002/rcm.1290080514
Subject(s) - reflectron , chemistry , fragmentation (computing) , ion , ion trap , mass spectrometry , analytical chemistry (journal) , ionization , atomic physics , argon , desorption , buffer gas , ion source , time of flight mass spectrometry , laser , chromatography , optics , physics , organic chemistry , adsorption , computer science , operating system
An ion‐trap storage/reflectron time‐of‐flight mass spectrometer has been used to study the decay of large ions following activation by matrix‐assisted laser desorption/ionization (MALDI). It is shown that large ions may undergo fragmentation over long periods of time, extending even to milliseconds in some cases. These fragments are stored in the trap and detected as stable ions in the reflectron device, rather than as metastable ions due to decay during the flight time to the detector. The ion decay is found to depend strongly on the laser intensity, while a smaller effect may be due to the matrix used in the MALDI process. The fragmentation observed was found to also depend strongly on the RF voltage applied to the ring electrode; higher RF voltage produced enhanced fragmentation. A gated RF experiment further demonstrated the importance of the level of the RF voltage, during the initial activation event, in producing fragmentation. A study of the effects of buffer gas composition and pressure showed that increased pressure may result in reduced fragmentation due to collisional cooling in the trap. However, the use of argon or nitrogen buffer gas at increased pressure in the trap may result in fragmentation upon extraction from the trap, producing metastable ions in the flight tube. The implications of the use of the time variable for obtaining fragmentation in the trap for rapid sequencing are discussed.