A gas chromatographic separation for the H and C stable isotope ratio determination of coal compounds

A new, completely automated gas chromatography technique has been developed to separate the different gaseous compounds produced during underground coal gasification for their C-13/C-12 and D/H isotope ratio measurements, ?he technique was designed for separation and collection of Hz, CO, CO2, H2O, H2S, CH4, and heavier hydrocarbons. These gaseous compounds are perfectly separated by the gas-phase chromatograph and quantitatively sent to seven combustion and collection lines. H-2, CO, CH4, and heavier hydrocarbons are quantitatively oxidized to CO2 and/or H2O. The isotopic analyses are performed by the sealed-tube method, The zinc method is used for reduction of both water and H2S to hydrogen for D/H analysis, Including all preparation steps, the reproducibility of isotope abundance values, for a quantity higher than or equal to 0.1 mt of individual components in a mixture (5 mt of gases being initially injected in the gas chromatograph), is +/-0.1 parts per thousand for delta(13)C(PDB) and +/-6 parts per thousand for delta(13)C(PDB) and +/-6 parts per thousand for delta(SMOW).