title: Separation of 18α(H)-, 18β(H)-oleanane and lupane by comprehensive two-dimensional gas chromatography.
abstract: 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 addition, 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 compounds has been impeded by inadequate chromatographic separation by traditional one-dimensional gas chromatography. In this study, we present the separation of 18α(H)-, 18β(H)-oleanane and lupane with comprehensive two-dimensional gas chromatography (GC×GC). Furthermore, it was observed 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 separation of the triterpenoids of interest in complex mixtures such as sediment extracts and crude oils.
authors: Curtin University, WA Organic and Isotope Geochemistry Centre, Department of Chemistry, GPO Box U1987, Perth, WA 6845, Australia. c.eiserbeck@curtin.edu.au
authors: Christiane
authors: C
authors: Eiserbeck
authors: Robert K
authors: RK
authors: Nelson
authors: Kliti
authors: K
authors: Grice
authors: Joseph
authors: J
authors: Curiale
authors: Christopher M
authors: CM
authors: Reddy
authors: Paolo
authors: P
authors: Raiteri
mesh_terms: D002849:Chromatography, Gas / Q000379:methods*; D007536:Isomerism; D019684:Magnoliopsida / Q000737:chemistry*; D015394:Molecular Structure; D009828:Oleanolic Acid / Q000031:analogs & derivatives* / Q000737:chemistry / Q000302:isolation & purification; D010578:Petroleum / Q000032:analysis; D014315:Triterpenes / Q000737:chemistry*; D053978:Pentacyclic Triterpenes
chemical_list: D009828:Oleanolic Acid; D010578:Petroleum; D014315:Triterpenes; C413246:oleanane; C480546:lupane; D053978:Pentacyclic Triterpenes