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Accurate mass measurement by matrix‐assisted laser desorption/ionisation time‐of‐flight mass spectrometry. I. Measurement of positive radical ions using porphyrin standard reference materials
Author(s) -
Griffiths Nia W.,
Wyatt Mark F.,
Kean Suzanna D.,
Graham Andrew E.,
Stein Bridget K.,
Brenton A. Gareth
Publication year - 2010
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.4560
Subject(s) - monoisotopic mass , chemistry , mass spectrometry , analytical chemistry (journal) , time of flight mass spectrometry , porphyrin , calibration , ion , matrix (chemical analysis) , desorption , mass , ionization , mass spectrum , chromatography , photochemistry , organic chemistry , statistics , mathematics , adsorption
A method for the accurate mass measurement of positive radical ions by matrix‐assisted laser desorption/ionisation time‐of‐flight mass spectrometry (MALDI‐TOFMS) is described. Initial use of a conjugated oligomeric calibration material was rejected in favour of a series of meso ‐tetraalkyl/tetraalkylaryl‐functionalised porphyrins, from which the two calibrants required for a particular accurate mass measurement were chosen. While all measurements of monoisotopic species were within ±5 ppm, and the method was rigorously validated using chemometrics, mean values of five measurements were used for extra confidence in the generation of potential elemental formulae. Potential difficulties encountered when measuring compounds containing multi‐isotopic elements are discussed, where the monoisotopic peak is no longer the lowest mass peak, and a simple mass‐correction solution can be applied. The method requires no significant expertise to implement, but care and attention is required to obtain valid measurements. The method is operationally simple and will prove useful to the analytical chemistry community. Copyright © 2010 John Wiley & Sons, Ltd.