Comprehensive characterization of chemical structures in heavy crude oil asphaltenes by using liquid chromatography and ultrahigh resolution mass-spectrometry

Crude oil is known as the main global energy source, however the reserves are limited. As the remaining valuable light oils are diminishing, alternative solutions such as upgrading of high boiling conventional and unconventional oil sources such as tar sands and oil shales have to be exploited for replacement to overcome the worlds emerging energy needs. These alternative sources contain a high amount of heteroatoms (e.g. N, O, S) and are of high viscosity causing difficulties to the environment and on industrial sites during oil transportation and production. Most of the problems are associated with asphaltenes which are the heaviest fraction of crude oil. Asphaltenes are considered to be responsible for clogging pipelines and wellbores, creating deposits. A thorough understanding of the chemical and physical attributes of asphaltenes is essential to contribute to optimization, improvements and new technological developments in up to date refining processes. The extreme complexity of crude oil consisting of probably more than one million different chemical compounds leads to a broad range of properties in terms of polarity, molecular weights and molecular architecture. In order to receive a more clear and comprehensive picture of structural details, different approaches, meaning combinations of advanced analytical techniques,need to be involved. Mass spectrometry with ultrahigh resolution and mass accuracy provides information on a molecular level. One of the main objectives of this study is the structural elucidation of individual compounds in very complex oil mixtures using MS/MS measurements as the method of choice. Unfortunately, isolation of small mass windows leads to a large number of different compounds that would participate in the fragmentation process leading to MS/MS spectra that are extremely difficult to interpret. Therefore, prior simplification is required to reduce the different types of species within the selected mass window subjected to fragmentation. Application of two different ...