Moreover, the source of asphaltenes used in different studies can vary resulting in differences in the composition, heteroatoms and the surface-active fractions present in the samples. This could potentially lead to contrary observations. The nature of solvent also potentially impacts the results discussed in this paper. Some of the results are obtained with asphaltenes in poor solvents, while other experiment involves asphaltenes in good solvents. Thus, a systematic approach is needed, where the variability of solvent and surface activity of asphaltenes is minimized to ensure comparability of results.