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Matrix‐assisted ultraviolet laser desorption/ionization time‐of‐flight mass spectrometry of β‐(1 → 3), β‐(1 → 4)‐xylans from Nothogenia fastigiata using nor ‐harmane as matrix
Author(s) -
Fukuyama Yuko,
Kolender Adriana A.,
Nishioka Masae,
ami Hiroshi,
Matulewicz María C.,
ErraBalsells Rosa,
Cerezo Alberto S.
Publication year - 2005
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.1783
Subject(s) - chemistry , mass spectrometry , reflectron , analytical chemistry (journal) , matrix (chemical analysis) , desorption , chloride , matrix assisted laser desorption/ionization , analyte , ionization , dispersity , molar concentration , chromatography , ion , time of flight mass spectrometry , organic chemistry , adsorption
Three xylan fractions isolated from the red seaweed Nothogenia fastigiata (Nemaliales) were analyzed by ultraviolet matrix‐assisted laser desorption/ionization time‐of‐flight mass spectrometry (UV‐MALDI‐TOFMS). UV‐MALDI‐TOFMS was carried out in the linear and reflectron modes, and as routine in the positive and negative ion modes. Of the several matrices tested, nor ‐harmane was the only effective one giving good spectra in the positive ion mode. The number‐average molar masses of two of the fractions, calculated from the distribution profiles, were lower than those determined previously by 1 H NMR analysis, suggesting a decrease in the ionization efficiency with increasing molecular weight; weight‐average molar mass and polydispersity index were also determined. As the xylans retained small but significant quantities of calcium salts, the influence of added Ca 2+ as CaCl 2 on UV‐MALDI‐MS was investigated. The simultaneous addition of sodium chloride and calcium chloride was also analyzed. Addition of sodium chloride did not change the distribution profile of the native sample showing that the inhibitory effect is due to Ca 2+ and not to Cl − . Addition of calcium chloride with 1:1 analyte/salt molar ratio gave spectra with less efficient desorption/ionization of oligomers; the signals of these oligomers were completely suppressed when the addition of the salt became massive (1:100 analyte/salt molar ratio). Copyright © 2005 John Wiley & Sons, Ltd.