Occurrence of extended tetracyclic polyprenoid series in crude oils

摘要

A homologous series of tetracyclic polyprenanes from C-24 to C-41 was identified in crude oils from Espirito Santo Basin (Brazil) by comprehensive two-dimensional gas chromatography-time-of-flight mass spectrometry (GCxGC-TOFMS) and gas chromatography-tandem mass spectrometry (GC-MS-MS) analyses. These products were separately characterized by elution order in first- and second-dimension retention times ((1)t(R) and (2)t(R), respectively), time-of-flight mass spectra (TOFMS), MRM chromatograms, product ion spectra including diagnostic ions at m/z 191, m/z 259 and m/z 149 + 14n (n = 0-17), the latter a key mass fragment for the evaluation of side chain extension at the C-18 position in tetracyclic polyprenoids. The tetracyclic compounds were thus identified as scalarane-like structures related to abundant C-30 tetracyclic polyprenoids, an important indicator of input from fresh to brackish water paleoenvironments. (C) 2018 Elsevier Ltd. All rights reserved.