Boscan vacuum residuum (VR), and Maya atmospheric residuum (AR), were separated into operationally defined components by an isooctane asphaltene precipitation followed by a modified D 2007-80 separation of the isooctane soluble material. These collected fractions were examined by size exclusion chromatography (SEC) with element specific detection employing inductively coupled plasma emission spectroscopy (ICP) to investigate the effect the separation has on the the V and Ni compounds. The V and Ni SEC-ICP profiles of the asphaltene fractions indicated some of the metal-containing molecules are substantially larger in size than those observed in the residua. The asphaltene precipitation appears to cause an increase in molecular size through agglomeration of smaller constituents, and accomplishes only limited size separation of the metal-containing compounds.