FRAGMENTATION OF COMPLEX CARBOHYDRATES FOLLOWING IONIZATION BY MATRIX-ASSISTED LASER-DESORPTION WITH AN INSTRUMENT FITTED WITH TIME-LAG FOCUSING

Matrix-assisted laser desorption/ionization time-of-flight spectra of carbohydrates recorded with an instrument using time-lag focusing (del ayed extraction) were found to exhibit fragment ions, whereas, in the non time-lag focusing mode, fragment ions were not observed, Fragment ions consisted both of glycosidic and cross-ring cleavage products who se absolute, but not relative abundance increased with the delay time and indicated that they were formed within the ion source. Only the gl ycosidic cleavage ions were present in post-source decay spectra and t heir abundance was inversely correlated with the delay time, The resul ts indicated that the cross ring cleavages were predominately the prod ucts of fast reactions whereas the glycosidic cleavages occurred over a longer time frame, (C) 1997 by John Wiley & Sons, Ltd.