Organic Geochemistry Characteristic of Aliphatic Hydrocarbon Fraction of Sawahlunto Coal, Ombilin Basin, West Sumatra

Sawahlunto coal from West Sumatra has been analyzed to determine the characteristics of organic geochemistry. Coal was extracted by Soxhlet method with a mixture of aceton : methanol : chloroform (47:23:30) as solvent. The extracts were fractioned using column chromatography. Aliphatic hydrocarbon fraction was analyzed using Gas Chromatography - Mass Spectrometry (GC-MS). The analysis of aliphatic hydrocarbon fraction shows the presence of n-alkanes and isoprenoids. The n-alkanes compounds are distributed from n-C-16 to n-C-31 with predominance of carbon long chains (>20). These compound were expected formed by higher plants terrestrial. The presence of pristane and phytane compounds with maximum abundance in pristane compounds exhibits a deposition environment of coal under oxic conditions. Two samples of Sawahlunto coal were classified as sub-bituminous coal based on the value of caloric analysis.