Program

Poster Presentations

Day 1, May 15（Tue.）　　Poster

1P-31　　PDF

Approaches towards Identification of Isomeric Small Molecules based on Energy-Resolved Tandem Mass Spectrometry

(¹RIKEN CSRS, ²Nihon Waters)
^oTakemichi Nakamura¹, Takenori Hama¹, Futoshi Sato²

Differentiation and/or identification of isomeric small organic molecules are a challenge for modern mass spectrometry including ambient in situ ionization setup. In principle, isomers may be differentiated based on differences in fragmentations since different molecular structures result in different decomposition chemistries. Hence, standardized 70 eV EI mass spectral databases have been utilized for molecular ID many years. However, we often need/wish to use soft ionization techniques such as ESI and rely on collision-induced dissociation (CID) tandem mass spectrometry (MS/MS) to observe fragmentations. Since CID spectra are highly platform and condition dependent, library searching strategy does not work well. In addition, isomers often give similar spectra, as available fragmentation channels for small molecules are limited. Energy-resolved (ER) MS/MS is a promising tool for solving this issue. Isomers can be differentiated by measuring crossing points in the breakdown diagrams. Another tool that can be used is ion mobility analysis. Both the isomeric precursor ion structures and isomeric fragment ion structures would have measurable differences in arrival time distributions that can be recorded in the ER-MS/MS experiments. We discuss current status and limitations of the ER-MS/MS based integrated approaches.