Stepped combustion was examined for its applicability to the resolution of isotopically distinct carbon components of complex organic matter such as kerogen. A kerogen (isolated from Green River shale), a standard oil (NBS-22), and two single-component, pure, organic compounds (sucrose and pentadecane) were subjected to a modified procedure of stepped combustion. The modified procedure was designed to test for completeness of reaction at an arbitrarily selected relatively low combustion temperature (225 °C) in repeated periods of heating. In sequential periods at 225 °C, the rate of carbon release as CO2 and CO generally diminished from several percent C per hour to near-zero percent C per hour, over a combined combustion time of up to 38 h. Nearly half of the carbon in all four materials remained as charred, oxidation-resistant residues that were readily combusted at 500°C. The carbon fractions released at 225 and 500°C, respectively, were Isotopically relatable to the chemical alteration of the organic substances that occurred during the analytical process, rather than to isotopically distinct components in the original materials.
|Original language||English (US)|
|Number of pages||6|
|State||Published - Dec 1 1991|
ASJC Scopus subject areas
- Analytical Chemistry