ELECTROSPRAY-IONIZATION AND MATRIX-ASSISTED-LASER-DESORPTION IONIZATION FOURIER-TRANSFORM ION-CYCLOTRON RESONANCE MASS-SPECTROMETRY OF PERMETHYLATED OLIGOSACCHARIDES/

Mass spectra of fragments of permethylated oligosaccharides are analyz ed by Fourier transform ion cyclotron resonance (FT-ICR) mass spectrom etry. Sustained off-resonance irradiation (SORT) collision-induced dis sociation (CID), quadrupolar axialization, multiple stages of isolatio n and dissociation (MSn), and ion remeasurement are exploited for carb ohydrate structural analyses. That SORT CID internal energies are adeq uate for linkage analysis of a permethylated glucose oligomer is demon strated by identifying ring-opened fragment ions from MALDI-generated mass-isolated and collisionally activated ions, Ion remeasurement and axialization techniques enhance the sensitivity of ion fragmentation a nalysis. Multiple stages of isolation and dissociation of ion fragment s (MSn) provide for structural analysis of an electrospray-ionized per methylated lacto-N-fucopentaose isomer (LNFP II). Compared to MS2 spec tra taken with a triple quadrupole, FT-ICR MSn (n > 2) provides more e xtensive characterization of the parent molecular structure than is av ailable from a single stage of ion isolation and dissociation (MS2).