Matrix-assisted ultraviolet laser-desorption ionization time-of-flight mass spectrometry of sulfated mannans from the red seaweed Nothogenia fastigiata

Matrix-assisted ultraviolet laser-desorption ionization time-of-flight mass spectrometry (UV-MALDI-TOF-MS) was applied to sulfated xylo-mannan fractio ns from Nothogenia fastigiata in order to determine their molecular weights and distribution profiles. The number-average molecular weight calculated from the spectra was similar to that determined by chemical end-group analy sis for the lower molecular weight fractions. For the other fractions, the number-average molecular weight was lower than that chemically determined; the increased difference may be attributed to higher desorption difficultie s and, consequently, mass-dependent discrimination. A reconstructed spectru m, using the peaks obtained from all the fractions, suggested an unimodal d istribution. The best results were obtained by using 2,5-dihydroxybenzoic a cid as matrix doped with 1-hydroxyisoquinoline and with harmane and nor-har mane. (C) 2000 Elsevier Science Ltd. All rights reserved.