Identification of C2C4 alkylated benzenes in flash pyrolysates of kerogens, coals and asphaltenes

Abstract

Pseudo-Kovats indices were determined for all positional isomers of Ca-C, alkylated benzenes using a non-polar capillary column (CP Sil-5). These indices were applied in combination with mass spectral data to identify these compounds in complex mixtures of a relatively non-polar nature generated upon flash pyrolysis of macromolecular sedimentary organic matter (kerogens, asphaltenes and coals). Alkylbenzene distribution patterns were constructed by integration of appropriate mass chromatograms. Generally, toluene is the major pyrolysis product. Other specific alkylated benzenes (e.g. 1,2,3,4_tetramethylbenzeneand I-methyl-4-isopropylbenzene) were found to be enhanced in flash pyrolysates of different samples. Flash pyrolysates of asphaltene and kerogen fractions isolated from the same oil shale exhibit similar alkylbenzene distributions.1NTRODUCTlON

Changes in kerogen composition across an oxidation front in Madeira Abyssal Plain turbidites as revealed by pyrolysis GC-MS

“…Py-GC-mass spectrometry (Py-GC-MS) was performed using the same conditions as above. The column was inserted directly into the electron impact ion source of a VG Autospec Ultima mass spectrometer operated at 70 eV, with a mass range of m/z 40−800 and a cycle time of 1.8 s. Compounds were identified based on their mass spectra and retention times; identifications were also based partly on comparisons with published mass spectra and relative retention time data (Hartgers et al, 1992;Ioppolo et al, 1992;Sinninghe Damsté et al, 1988).…”

Aromatic units from the macromolecular material in meteorites: Molecular probes of cosmic environments

“…Table 1 Substituted benzenes listed in their elution order on a non-polar chromatography column alongside molecular weights and characteristic ions (with percentages in parenthesis). Compiled from Hartgers et al (1992) and Han, 1967; Table 3) indicates that the ratio between 1,3-dimethylbenzene and 1,4-dimethylbenzene with temperature remains constant (an approximately 2:1 ratio). The meta + para/ortho ratio for dimethylbenzenes generally approximates to 3:1.…”

“…The elution order of C 2 and C 3 substituted benzenes is known from studies on terrestrial materials. Hartgers et al (1992) used the elution times of n-alkane standards and pseudo-Kováts retention indices for data generated by the pyrolysis of macromolecular sedimentary organic matter followed by separation of products on a non-polar gas chromatography column, similar to that used in this study. The retention behaviour and characteristic mass spectra ions are given in Table 1.…”

Source(s) and cycling of the nonhydrolyzable organic fraction of oceanic particles

“…Data were acquired on the Opus software package. Major peaks were identified based on mass spectral comparison with the VG library and NIST library (using Xcalibur software), and comparison of relative retention times with literature values (van de Meent et al, 1980a,b;Hartgers et al, 1992;Ishiwatari et al, 1995;Nguyen et al, 2003).…”