DISTINGUISHING AN ENANTIOMERS WITH THE AID OF BROADBAND FEMTOSECOND CIRCULAR-DICHROISM MASS SPECTROMETRY

摘要

The present invention provides an apparatus and a method for distinguishing enantiomers with the aid of broadband femtosecond circular-dichroism laser-ionization mass spectrometry. In this case, an fs laser system is used, the laser pulse duration (τ) of which is less than or equal to 200 fs, with respect to a bandwidth-limited pulse, and the central wavelength (λ) of which is in the range between 200 nm and 1.100 nm. The spectral bandwidth of the laser pulse is chosen from bandwidths of less than or equal to 40 nm and those of more than 40 nm. The laser pulses are circular-polarized, in which case it is possible to change between right-hand and left-hand circular-polarized light. The circular-polarized fs laser pulses are used directly for ionization, wherein the light material interaction is enantiomium-specific. There is therefore no need for separation of substance mixtures. The wavelength which is appropriate for ionization of a specific analyte need never be known in advance: for bandwidths of less than or equal to 40 nm, the wavelength is varied in order to determine the appropriate wavelength. For bandwidths of more than 40 mm, the wavelength which is appropriate for the respective molecule is intrinsically contained in the spectrum. The sample to be examined and an achiral reference substance are examined simultaneously in the flight-time mass spectrometer for both circular polarizations. For a given ionization wavelength and polarization of the laser pulse, each flight-time mass spectrum obtained in this way was not only substance-specific but also enantiomium-specific. The apparatus according to the invention and the associated method combine CD spectroscopy and mass spectrometry and are suitable for identification and examination of enantiomers even in previously unknown substance mixtures.