Unexpected behavior of diastereomeric ions in the GasPhase: A stimulus for pondering on ee measurements by ESI-MS

Caterina Fraschetti, Antonello Filippi, Maria Elisa Crestoni, Tadashi Ema, Maurizio Speranza

Research output: Contribution to journalArticlepeer-review

7 Citations (Scopus)


The most common protocols for the quantitative determination of the enantiomeric excess (ee) of raw mixtures by ESI-MS reveal inadequate in cases where the distribution of diastereomeric derivatives diverges from the ee of original solutions. This phenomenon is attributable to a matrix effect, i.e.; to the stereospecific formation of high order noncovalent adducts in the ESI droplets, which alters the actual availability of the diastereomeric species under MS analysis. In this frame, the assumption of classic protocols that the ionization correction factor q is independent on the composition of the mixture submitted to analysis is questionable. An alternative methodology is presented in this paper, which is aimed at circumventing the problem by excluding any chemical derivatization of the original raw mixture. It is based on the measurement of the actual distribution of ESI-formed proton-bound diastereomeric complexes from the enantiomeric mixture through a careful analysis of their reaction kinetics with a suitable reactant. [Figure not available: see fulltext.]

Original languageEnglish
Pages (from-to)573-578
Number of pages6
JournalJournal of the American Society for Mass Spectrometry
Issue number4
Publication statusPublished - Apr 1 2013


  • ESI-FT-ICR mass spectrometry
  • Enantiomeric excess
  • Gas-phase kinetics
  • High-throughput parallel screening
  • Noncovalent complexes

ASJC Scopus subject areas

  • Structural Biology
  • Spectroscopy


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