Derivatization of Lipid Amines: Fluorenylmethyloxycarbonyl (FMOC)

Abstract

Analysis of lipid remodeling can be achieved by monitoring the lyso metabolites of ethanolamine glycerophospholipids. However, mass spectrometric analyses cannot distinguish between alkenyl and alkyl lysoglycerophosphoethanolamines without chromatography. In this chapter, we describe the use of fluorenylmethyloxycarbonyl chloride (FMOC) to distinguish these isobars by direct infusion and MS². FMOC is a useful reagent for derivatizing the free amine group of lipid ethanolamines (Han et al., J Lipid Res 46:1548–1560, 2005):

$$ \mathrm{R}\hbox{--} N{H}_2+ Cl\hbox{--} C O\hbox{--} \mathrm{O}\hbox{--} C{H}_2\hbox{--} \mathrm{Fluren}\to \mathrm{R}\hbox{--} N H\hbox{--} C O\hbox{--} \mathrm{O}\hbox{--} C{H}_2\hbox{--} \mathrm{Fluren} $$

The amine-containing lipids are augmented in mass by 222.06808 after derivatization with FMOC and the [M-H]⁻ ions of these derivatives are monitored in ESI. In this chapter, we describe the use of FMOC for quantitating ethanolamine plasmalogens, lysophosphatidylethanolamines (LPE), alkenyl-LPEs, and alkyl-LPEs.