GC-MS analysis of crocetane, phytane and some of their stereoisomers using cyclodextrin-based stationary phases

The detection and complete separation of crocetane (2,6,11,15-tetramethylhexadecane) and phytane (2,6,10,14-tetramethylhexadecane), two widely investigated hydrocarbon biomarkers for archaea in geological environments, are reported. The essential components of the analysis are a series of derivatized cyclodextrin capillary GC stationary phases. In addition, the further separation of stereoisomers of both compounds was observed on the highly selective permethyl-2-hydroxypropyl-β-cyclodextrin stationary phase. In Nature, as in the laboratory, the synthesis (diagenesis) of these biomarkers determines their structures and stereochemistry. Hence, methods that allow their characterization and quantitation provide useful geochemical information.