The application of field-ionization and field-desorption mass spectrometry to the analysis of coal-derived oil.

概要

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Field-ionization (FI) and field-desorption (FD) mass-spectroscopic techniques have been applied to the analysis of ring-type fractions of coal-derived oil, obtained by liquid chromatography. These techniques produce only the molecular ion and its isotopic signals, free from fragment ions, of a molecule, consequently the exact molecularweight-distribution profiles of chromatographic fractions. The peak intensities are reproducible within a variation coefficient (σ/\barx) of about 5–8% on repeated runs. The number-average molecular weights (\barMn) of the ring-type fractions, as calculated from the peak intensities, are close to those obtained by means of a vapor-pressure osmometer (VPO). These techniques, on the whole, give reliable mass spectra of coal-derived oil, although the isotope-ion ratios are overestimated compared to the theoretical natural abundances. The group-type analysis of the ring-type fractions has been made on the basis of their mass spectra, and the skeletal structures corresponding to each mass z series have been proposed.