Unimolecular Decomposition of N-Ethoxycarbonyl Heptafluorobutyl Ester Derivatives of Amino Acids upon Electron Ionization

Abstract

The fragmentation pathways of N-(ethoxycarbonyl)glycine-2,2,3,3,4,4,4-heptafluorobutyl ester (glycine derivative) (1) and N-(ethoxycarbonyl)alanine-2,2,3,3,4,4,4-heptafluorobutyl ester (alanine derivative) (2) upon electron ionization were investigated using a gas chromatograph/double-focusing mass spectrometer and time-of-flight mass spectrometer. To estimate the fragmentation pathways, the B/E-linked scan mass spectra of ¹³C-labeled derivatives (1-¹³C₂ and 2-¹³C₃) were compared with those of non-labeled derivatives. An elemental composition of each of the precursor ions was estimated by accurate mass measurements.