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The initial ion velocity and its dependence on matrix, analyte and preparation method in ultraviolet matrix‐assisted laser desorption/ionization
Author(s) -
Glückmann Matthias,
Karas Michael
Publication year - 1999
Publication title -
journal of mass spectrometry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.475
H-Index - 121
eISSN - 1096-9888
pISSN - 1076-5174
DOI - 10.1002/(sici)1096-9888(199905)34:5<467::aid-jms809>3.0.co;2-8
Subject(s) - chemistry , analyte , ionization , desorption , ion , matrix (chemical analysis) , fragmentation (computing) , ultraviolet , analytical chemistry (journal) , extraction (chemistry) , chromatography , optics , organic chemistry , physics , adsorption , computer science , operating system
Since the early days of matrix‐assisted laserdesorption/ionization (MALDI), measurements showingthat MALDI ions and neutrals have high initial velocities have led towide acceptance of the idea that a jet of released material entrainsanalyte ions. The initial velocity, which could previously bedetermined only with large uncertainty, can be measured today withhigh reliability in a delayed‐extractionMALDI/time‐of‐flight system by following the lineardependence of ion flight time vs the applied extraction delay. Thedetection of different initial velocities for different matrices,with and without additives, for various preparation protocols and fordifferent classes of analytes proves that the magnitude of theinitial velocity can indeed be regarded as a valuable and meaningfulcharacteristic of the MALDI process. Based on the results reportedhere, it is postulated that a high initial velocity results fromincorporation of the analyte into the matrix crystals and thatcooling upon expansion is effective at high initial velocities andresponsible for reduced fragmentation observed in such cases comparedwith ‘slow’ matrices. Copyright © 1999 John Wiley& Sons, Ltd.