Stable-isotope-labeling experiments have become a frequently used tool to investigate different metabolic systems. They have been recently applied to several comprehensive studies in plant metabolomics providing interesting insights into metabolic dynamics and regulation. However, the complexity of mass spectrometry data originating from such experiments is rarely fully explored. Data analysis often considers metabolites in their entirety which obscures important information at the atomic level. Recently, the use of mass spectrometry fragmentation for obtaining positional-labeling information was described for a few specific metabolites. Here, we describe a general methodology that can be applied for extracting positional-labeling information based on the characterization of fragments that are inherent in gas chromatography electron impact mass spectrometry (GC-EI-MS) chromatograms.
Keywords: Isotopomer; Mass spectrometry; Metabolic flux; Stable-isotope labeling.