Direct Mass Spectrometry of Chiral Molecules: MS-PECD
Here you will find information about a novel technology for the enantiomer-selective detection of chiral molecules called Mass Selective - Photo Electron Circular Dichroism (MS-PECD). MS-PECD is a laser-based table-top technology that provides direct Mass Spectrometry of chiral molecules and enantiomeric excess measurement in complex chiral mixtures.
Listen and watch:
Introductory 10 minute lecture on MS-PECD at this link.
MS-PECD is developed, commercialized and marketed by MassSpecpecD BV, Enschede, the Netherlands.
What is MS-PECD ?
MS-PECD is a novel table-top technology enabling the enantiomer-specific analysis of multi-component mixtures of chiral molecules by direct Mass Spectrometry using correlated electron-ion imaging. A circular polarized pulsed laser ionizes the gaseous chiral molecules. The three-dimensional angular distribution of photoelectrons is measured on a time- and position sensitive particle detector. The forward-backward asymmetry of the electron angular distribution along the laser beam (Photo Electron Circular Dichroism, PECD) is measured on the electron imaging detector. The molecular ion is also detected in coincidence with the electron on a time-sensitive particle detector, providing the mass of the chiral molecule from the ion Time-of-Flight. Every electron is tagged by the mass of the ion that it originated from. The (electron,ion) correlation and the measured PECD provide a direct Mass Spectrometric indentification of the enantiomers present in the chiral mixture. The magnitude of the MS-PECD asymmetry of every molecule in the multi-component mixture scales directly to the enantiomeric excess of the compound.
Advantages, capabilities and potential of MS-PECD
- PECD has large enantiomeric sensitivity, typically between 1-10%, a factor of 100-1000 larger than CD, VCD or ROA.
- Mass-Selected PECD gives direct enantiomeric selectivity of every chiral molecule observed in the mass spectrum.
- Direct quantitative measurement of the enantiomeric excess of chiral molecules in multi-component mixtures.
- No prior enantiomeric separation of the sample with chiral GC, HPLC, SFC or IMS is needed before MS-detection.
- No prior enantiomeric selective clustering of the sample with chiral ligands is needed before MS-detection.
- Laser ionization via intermediate vibronically excited states provides additional spectral selectivity and identification.
- The electron kinetic energy spectrum provides additional spectroscopic information on the correlated ion.
- MS-PECD is performed with a table-top laser-based spectrometer.
- Ionization with an ultrafast intense laser is a universal ionization technique for molecules providing soft-ionization.
- MS-PECD in combination with spatially selective (laser) desorption techniques provides spatial chiral sensitivity.
Detailed information on the science, the technology and analytical applications is provided in the following publications:
Enantiomer-specific analysis of multi-component mixtures by correlated electron imaging–ion mass spectrometry
Mohammad M Rafiee Fanood, N. Bhargava Ram, C. Stefan Lehmann, Ivan Powis and Maurice H.M. Janssen
Nature Communications 6, 7511 (2015) pdf link
Imaging photoelectron circular dichroism of chiral molecules by femtosecond multiphoton coincidence detection
C. Stefan Lehmann, N. Bhargava Ram, Ivan Powis, and Maurice H. M. Janssen
The Journal of Chemical Physics 139, 234307 (2013) pdf link
Awarded the 2013 JCP Editors` choice for groundbreaking research in Chemical Physics.
Detecting chirality in molecules by imaging photoelectron circular dichroism
Maurice H.M. Janssen and Ivan Powis
Phys. Chem. Chem. Phys. 16, 856 (2014) pdf link
For a historic review of the development of laser-based MS-PECD see the special technology archive at this link.
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