Field desorption glycolipids

Conventional electron impact or chemical ionization mass spectrometry requires that volatilization precede ionization and this is clearly a limiting factor in the analysis of many biochemically significant compounds. A newer ionization technique, field desorption (FD) (1, 2 ) removes this requirement and makes it possible to obtain mass spectrometric information on thermally unstable or non-volatile organic compounds such as glycoconjugates and salts. This development is particularly significant for those concerned with the analysis of glycolipids and we have therefore explored the suitability of field desorption mass spectrometry (FDMS) for this class of compounds. We have evaluated experimental procedures in order to enhance the efficiency of the ionization process and to maximize the information content of spectra obtained by this technique. 

The simplicity of FD spectra obtained at low emitter currents made possible the analysis of complex mixtures of glycolipids to obtain information about molecular weight distributions. Figure 8 shows the field desorptive mass spectrum obtained for a mixture... 

The opportunity to obtain molecular weight and structural information from very polar involatile materials by field desorption as described in this preliminary survey offers many advantages for the study of glycolipid structures. 

Of the many analytical techniques now available to the lipid chemist, mass spectrometry (MS), is probably the one that has experienced the fastest growth in the last two decades. This is due both to the development of new techniques (gas and liquid chromatography combined with MS, soft-ionization MS, field desorption MS, atmospheric pressure MS etc.) and to the refinement of more traditional methods and their successful application to very complex problems, e.g. the elucidation of glycolipid structure, or the study of structures in lipid mixtures. Much progress has been made since the pioneering work of Ryhage and Stenhagen (1963) on fatty acid methyl esters. 

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