Enantiomer-specific analysis of multi-component mixtures by correlated electron imaging–ion mass spectrometry

• Published in: Nature communications Vol. 6; no. 1; p. 7511
• Main Authors: Fanood, Mohammad M Rafiee, Ram, N. Bhargava, Lehmann, C. Stefan, Powis, Ivan, Janssen, Maurice H. M.
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 24.06.2015; Nature Publishing Group; Nature Pub. Group
• Subjects: 140/125; 639/638/11/296; 639/638/440; 639/766/36; Humanities and Social Sciences; multidisciplinary; Science; Science (multidisciplinary)
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/ncomms8511

Simultaneous, enantiomer-specific identification of chiral molecules in multi-component mixtures is extremely challenging. Many established techniques for single-component analysis fail to provide selectivity in multi-component mixtures and lack sensitivity for dilute samples. Here we show how enantiomers may be differentiated by mass-selected photoelectron circular dichroism using an electron–ion coincidence imaging spectrometer. As proof of concept, vapours containing ∼1% of two chiral monoterpene molecules, limonene and camphor, are irradiated by a circularly polarized femtosecond laser, resulting in multiphoton near-threshold ionization with little molecular fragmentation. Large chiral asymmetries (2–4%) are observed in the mass-tagged photoelectron angular distributions. These asymmetries switch sign according to the handedness ( R - or S -) of the enantiomer in the mixture and scale with enantiomeric excess of a component. The results demonstrate that mass spectrometric identification of mixtures of chiral molecules and quantitative determination of enantiomeric excess can be achieved in a table-top instrument. Detecting enantiomers in dilute mixtures of volatile organic compounds is a challenge. Here, the authors demonstrate a method to identify enantiomers and enantiomeric excess in a multi-component mixture containing two chiral species using laser mass spectrometry and photoelectron circular dichroism.