Asphaltene analysis using size exclusion chromatography

A common technique used in coal liquefaction investigations is the asphaltene analysis, whereby products are separated into four major fractions (insolubles, preasphaltenes, asphaltenes and oils) by solvent extraction techniques. The fractions are defined by their solubility in organic solvents such as tetrahydrofuran, toluene and pentane. An instrumental method of analysis, using gel permeation liquid chromatography, was developed to reduce the problems with the conventional solvent separation. The technique relies upon the fact that the fractions differ in molecular size as well as solubility. The method uses one solvent (THF) and a single 100 Å microstyragel column to separate the three soluble fractions. The trends in the data obtained with the molecular size separation agree with the trends obtained by conventional solvent separations on the same samples.