Advances in Comprehensive Two-Dimensional Gas Chromatography (GC X GC)

Thirty years ago Giddings (1984) proposed a vision of 2D separation techniques that has only now been realised with comprehensive 2D gas chromatography (GC×GC). This technique has revolutionised the separation power of complex organic mixtures using chromatographic techniques. The additional dimension of separation compared to traditional 1D GC is particularly valuable for analyses of geological samples such as petroleum and rock extracts. Many applications have been explored in the past decade including monitoring of oil spills, tracking of contaminants, fingerprinting of crude oils, and detailed biomarker identification. Recent developments and applications across the geosciences are discussed and the potential of GC×GC unveiled

Separation of 18α(H)-, 18β(H)-oleanane and lupane by comprehensive two-dimensional gas chromatography

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 x 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