Recent FAB-MS Work on Carbohydrates

The work described herein deals mainly with recent experiments aimed at evaluating FAB as a stereochemical probe. As it is shown in Section II, no definitive methods or rules are available in mass spectrometry for such analysis, although several reports indicate that it should be possible to make such use of this physical method. This is due to the relatively small amount of data available on FAB. Consequently, we will present several original data that we obtained in our laboratories and that are unpublished as yet. 

In order to follow a systematic approach for these investigations, it is necessary to concentrate our efforts on one family of molecules. Our choice is 

Analysis of the FAB spectra of a series of oligosaccharides to determine whether or not some stereochemically dependent characteristics are exhibited. 

Interpretative discussion will focus exclusively on positive ion data recorded in a glycerol support matrix. Some compounds will also be analyzed in other support matrices (with or without doping) to allow for a preliminary insight into the solvent, matrix, and charge effects. 

Variations in the data will be discussed in terms of the stereochemistry of the glycosides used and correlated to existing stereoelectronic concepts. This leads to a discussion on the effects glycerol has on the type of compounds studied (and on those being used as a dispersive/dissolution medium). 

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