Tracking Changes in Asphaltene Nanoaggregate Size Distributions as a Function of Silver Complexation via Gel Permeation Chromatography Inductively Coupled Plasma Mass Spectrometry

Asphaltene elution behavior in gel permeation chromatography (GPC) was studied with and without the presence of silver triflate (AgOTf) via inductively coupled plasma mass spectrometry. The experiments highlighted the influence of AgOTf on the molecular weight profiles for atmospheric residues (ARs), asphaltenes, and their extrography subfractions. Specifically, the molecular weight distribution of the sulfur-, vanadium-, and nickel-containing compounds changed markedly with the addition of AgOTf, which suggests that AgOTf disrupts/alters the interaction between Ni and vanadyl porphyrins and select S-containing compounds within asphaltene nanoaggregates. However, similar effects were not observed with AgOTf addition to the high-molecular-weight GPC fractions of AR and the acetone extrography asphaltene fraction, which is comprised of abundant, highly aromatic/single-core compounds.