Simultaneous determination of fatty, dicarboxylic and amino acids based on derivatization with isobutyl chloroformate followed by gas chromatography - positive ion chemical ionization mass spectrometry

Gas chromatography-mass spectrometry (GC-MS) with positive ion chemical ionization (PICI) using isobutane as reagent gas was applied for analysis of isobutoxycarbonyl/isobutyl derivatives of 13 fatty, 6 dicarboxylic and 13 amino acids in a single run. For all investigated compounds (except several amino acids) the quasimolecular ions [MH](+) were registered. Asparagine underwent fragmentation via decarboxylation followed by elimination Of OC4H9 ([M - 117](+)), whereas serine and tyrosine produced the cluster ions [M + C4H9OCO](+). Estimated detection limits were 6-250 pg in the total ion current (TIC) mode and 3-10 times lower using the selected-ion monitoring (SIM) mode. (C) 2003 Elsevier B.V. All rights reserved.