COMPLEX SERIES OF PENTACYCLIC TRITERPANES IN A LACUSTRINE-SOURCED OIL FROM KOREA BAY BASIN

GC-MS analysis was undertaken of a waxy, paraffinic, low-sulphur oil from Korea Bay Basin, apparently deriving mainly from bacterially reworked terrestrial organic matter deposited in a lacustrine environment. In addition to the regular C27-C35 hopanes, a number of pentacyclic triterpanes was identified in the range C29-C32. These components appeared to be members of at least two homologous series, one of which has been previously postulated to be 18-alpha(H)-neohopanes. A further, previously unreported, series is characterized by a relatively intense molecular ion response during GC-MS analysis. A bacterial origin is suggested for these pentacyclic triterpane series, the presence of which may reflect a particular set of sedimentological conditions.