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.

With heavy crude oil refining on the rise, upgrading strategies are fundamental to yield high-value products. Hydroconversion and thermal cracking are well-established and widely used upgrading processes for heavy oils' distillation cuts and residues. Recognizing molecular changes in these fractions after upgrading, particularly of asphaltenic compounds, is fundamental to understand and optimize the processes. In this work, we follow compositional changes in the asphaltene fraction of a Colombian heavy crude, after hydroconversion and thermal cracking, using high-resolution mass spectrometry. The liquid products from the upgrading processes were fractionated into maltenes and residual asphaltenes, with yields between 33% and 38% in maltenes from the original asphaltene feedstock. Contoured plots of double bond equivalents versus carbon number and van Krevelen diagrams show maltenic fractions exhibiting lower aromaticity, smaller molecular size, fewer heteroatomic species, and higher content of alkyl side chains than the starting asphaltenic material. Residual asphaltenes, on the other hand, consist of compounds with lower H/C ratios and reduced content of alkyl groups than the feedstock. In addition, structural information about the feedstock, such as archipelago or island structures, can be derived from the plots. This information is useful to establish trends between compound class reactivity and the suitability to produce valuable maltenic compounds through upgrading technologies.

Asphaltene adsorption properties on mineral surfaces are fundamental to understanding wettability changes in rocks and fluid behavior in reservoirs. In this contribution we report an analytical approach to investigate the molecular features responsible for asphaltene−silica interactions. We used high performance thin layer chromatography silica plates and an elutropic series of solvents to fractionate asphaltenes according to their particular affinity with the mobile and stationary phases. We observed three characteristic asphaltene fractions (with R f ́s of 0, 0.69, and 0.90), which were in turn desorbed and analyzed by atmospheric pressure photoionization FT-ICR mass spectrometry (APPI-FT-ICR-MS). In general, polar noneluted compounds highly retained by the silica surface with R f = 0 exhibit molecular compositions with N 1 , N n O o and O o (o = 1, 2, 3 and n = 1, 2) classes and the lowest H/C ratios compared to the other subfractions. Polar CH 2 Cl 2 :MeOH-eluted compounds, with R f = 0.69, have predominantly HC, N

Amphiphilic dendrimers, which contain both hydrophobic and hydrophilic groups in every repeat unit, exhibit environment-dependent assemblies both in hydrophilic solvent, water, and in lipophilic solvent, toluene. Upon investigating the status of these assemblies in a mixture of immiscible solvents, these dendrimers were found to be kinetically trapped in the solvent in which they are initially assembled. This property has been exploited to selectively extract peptides from aqueous solution into an organic phase, where the peptides bind to the interior functionalities of the dendritic inverse micelles. While the corresponding small molecule surfactant does not exhibit any selective binding toward peptides, all dendrons (G1-G3) are capable of this selective binding. We show that the inverse micelle-type assembly itself is crucial for the binding event and that the assembly formed by the G1 dendron has a greater capability for binding compared to the G2 or G3 dendrons. We have also shown that the average apparent pKa of the carboxylic acid functionalities varies with generation, and this could be the reason for the observed differences in binding capacity.

Crude oils differ from one another in numerous chemical and physical properties, many of which play an important role in defining their quality and price. Generally, statistical analysis of price differentials has focused on two main properties: density and sulfur content. However, the growing significance of high total acid number (TAN) crude oils, especially from developing countries, has aroused the necessity for extending these models. Consequently, refineries must obtain real and exact information regarding crude oil quality to achieve optimal crude oil selection and processing decisions. This could be attained when a detailed molecular-level characterization is performed. The present work presents the combination of negative electrospray ionization [(−)­ESI] and positive atmospheric pressure photoionization [(+)­APPI] Fourier transform ion cyclotron resonance (FT-ICR) mass spectrometry, as a prominent approach to semi-quantify the acid species comprised in crude oils. A novel polarity index is proposed that corrects the relative abundances of (−)­ESI classes, where mainly acid species are detected. By consideration of different indexes, it was possible to enhance the correlation coefficients (R 2) from 0.579 to 0.986 between the percentage of acid compounds and TAN of crude oils, where most of the samples stand close to a linear tendency. These results avoid the deviations observed in previous works on the correlations between relative abundances of the O2 class through (−)­ESI and TAN and could support achieving optimal crude oil selection and defining their quality and price.