In
this contribution, we use high-resolution mass spectrometry
to unveil the molecular composition of occluded compounds inside Colombian
asphaltenes macrostructures. We use Soxhlet extraction, with n-heptane, coupled with asphaltene maceration to obtain
four fractions enriched with chemical compounds occluded inside asphaltene
networks. We focused our efforts on the fraction enriched with compounds
interacting with asphaltenes via strong intermolecular forces, and
used normal phase column chromatography to fractionate it and atmospheric
pressure photoionization coupled to Fourier transform ion cyclotron
resonance mass spectrometry to obtain a detailed molecular description.
Our results indicate that the occluded compounds obtained in the last
stage of the washing process are by themselves a complex mixture,
consisting mostly of saturated compounds including molecular formulas
corresponding to biomarkers, alkyl aromatics with high heteroatom
content (up to four heteroatoms), vanadyl porphyrins, and highly aromatic
species, which we believe are low-molecular weight asphaltenes transferred
to the n-heptane during the extraction process. We
consider this information valuable because analysis of occluded compounds
gives us a more thorough molecular description of asphaltenes; besides,
knowledge of compounds closely related to asphaltenes could not only
improve deasphalting processes in pilot plants, but also will help
to find new geochemical biomarkers occluded within asphaltenes.