Figure 41.

Comparison of the performance of several MS-based techniques in distinguishing between the diastereoisomeric glycolipids Glc- and Gal-sphingosine (So). (A) Classical CID induces cleavage of the glycosidic bond and concomitant loss of the stereochemical information. (B/C) RDD and charge inversion induce alternative fragmentation mechanisms and yield different relative intensities of fragments. (D) SLIM IM-MS can partially separate sodiated Glc and Gal sphingosine after four passes (ca. 60 m). (E) Gas-phase IR spectroscopy is sensitive toward stereochemical changes and yields diagnostic spectroscopic fingerprints for Glc and Gal epimers.