Eiserbeck, Christiane; Nelson, Robert, K.; Grice, Kliti; Curiale, Joseph; Reddy, Christopher M.; Raiteri, Paolo, Separation of 18α(H)-, 18β(H)-oleanane and lupane by comprehensive two-dimensional gas chromatography, Journal of Chromatography, A (2011), 1218(32), 5549-5553.
18α(H)-, 18β(H)-oleanane and lupane are angiosperm-derived biomarkers that are used as age indicators for the Late Cretaceous onwards when the first proliferation of angiosperms occurred. In addn., the 18α(H)-/18β(H)-oleanane ratio is employed as a thermal maturity parameter of crude oil. However, evidence has shown that accurate quantification of these compds. has been impeded by inadequate chromatog. sepn. by traditional one-dimensional gas chromatog. In this study, we present the sepn. of 18α(H)-, 18β(H)-oleanane and lupane with comprehensive two-dimensional gas chromatog. (GC × GC). Furthermore, it was obsd. that 18β(H)-oleanane elutes earlier than 18α(H)-oleanane in second dimension (polarity) which we attribute to steric hindrance effects. Two GC conditions have been developed in order to achieve baseline sepn. of the triterpenoids of interest in complex mixts. such as sediment exts. and crude oils.