Chemical characterization of Hungarian brown coals by Curie-point pyrolysis-low-energy electron impact mass spectrometry and multivariate analysis and by Curie-point pyrolysis-gas chromatography-photoionization mass spectrometry

A series of Hungarian Miocene brown coals were analysed by pyrolysis-low-energy electron impact mass spectrometry and discriminant analysis. Correlation patterns in the mass peaks of these brown coals coincided with the geothermal history determined from the reflectivity of the macerals. Coal rank and the first discriminant function had a correlation coefficient of 0.96. Discriminant analysis also classified the coals according to their depositional environment.

The mass peaks were deconvoluted using pyrolysis-gas chromatography-mass spectrometry data obtained under low-energy photoionization conditions. Several apparently homologous series of mass peaks in the pyrolysis-low-energy electron impact mass spectra were found to represent entirely different types of pyrolysis products. The low-energy fragmentation patterns of isoprenoid and alicyclic hydrocarbons are substantially different from the usual 70 eV electron impact spectra and may cause erroneous interpretation of non-deconvoluted pyrolysis-low-energy electron impact mass spectrometric data. The deconvoluted pyrolysis-low-energy electron impact mass spectrometric data resulted in a more detailed reconstruction of the original environments of deposition. Marine influences were deduced from several types of organic sulphur compounds. Markers for lignified wood, leaf and root remains and resins were present in the pyrolysates.