Extended diamondoid assessment in crude oil using comprehensive two-dimensional gas chromatography coupled to time-of-flight mass spectrometry

Comprehensive two-dimensional gas chromatography coupled to time-of-flight mass spectrometry (GC × GC-TOFMS) was explored as a powerful tool to assess diamondoids in petroleum fluids. This work demonstrates the possibility to calculate diamondoid indexes, perform relative quantitations, and complete saturated biomarker assessments in one chromatographic run. Tetramantanes and triamantanes identification resulted in new discovered compounds that can be used for assessment (e.g., for new maturity indexes) depending on the position of alkyl-substitution. Methyl-protodiamantanes and alkyl-substituted diamondoids with chains bigger than ethyl were detected (except for tetramantanes) as a consequence of the improved resolution achieved by GC × GC-TOFMS. Further studies using this method may lead to improved understanding of the formation mechanisms of diamondoids and highly mature petroleum fluid compositions.