Utility of GCXGC-TOFMS in Analyzing Biomarkers from Crude Oil: A Case Study from Cambay Basin, Western India

Comprehensive two dimensional gas chromatography with time of flight mass spectrometer is a powerful instrument in the field of gas chromatography. It surprisingly overcomes the challenges faced by 1D GCMS where resolving a large number of compounds is hard to comprehend. This will give a precise assessment of mass spectra of compounds for their appropriate identification and/or quantification. The approach has been utilized to biomarkers analysis of Eocene oils from Cambay Basin, western India. keeping a focus on isomers of pentacyclic terpenoids and steroids. The oil fractions show the dominance of n-alkanes and acyclic isoprenoids. The biomarker distribution includes bicyclic sesquiterpanes, tricyclic terpanes, tetracyclic terpanes, pentacyclic terpanes and steroids including their isomers. Angiosperm-derived triterpenoids (bicadinane, oleanane) have also been recognized in the present study, which is difficult to distinguish in Cambay oils by conventional 1D GC. High Pristane/Phytane ratio and abundance of diagnostic biomarkers bicadianane and oleanane recognized in the oil fractions showing a significant contribution of terrestrial plants of angiosperm families to the source, which was deposited in a sub-oxic environment. The present study outlines efficiency of GCXGC, where it manages to improve the understanding on biotic contribution and palaeodepositional environment.