Chapter 4 New mass spectral approaches to ganglioside structure determinations

Abstract

Over the years, mass spectrometry has been employed quite effectively in the structural determinations of many complex natural products, including gangliosides. The thermal instability and frequent heterogeneity of gangliosides make their analysis a challenging task that tries the limits of any new mass spectral methodology. There is now an exciting array of developments in mass spectrometry—new techniques and instruments offer opportunities for more sensitive and more detailed mass spectral analyses, as well as increased mass range. Liquid secondary ionization produces abundant molecular weight related peaks and fragments that provide structural details. Its effectiveness can be enhanced by utilization of collision-induced decomposition and a tandem mass spectrometer, and by the preparation of' derivatives designed to improve sensitivity and direct fragmentation along structurally informative pathways. Other ionization methods also show great promise for ganglioside analysis: supercritical fluid chromatographykhemical ionization (SFCKI) and electrospray ionization (ESI), each coupled successfully with both quadrupole and sector mass spectrometers, and matrix-assisted laser desorption ionization (MALDI), usually coupled to a time-of-flight mass spectrometer (TOFMS), but not limited to that analyzer.