An investigation of the use of size exclusion chromatography for the determination of molar mass distributions and fractionation of coal tars

The use of size exclusion chromatography (SEC) for the determination of molar mass distribution and fractionation of coal tars has been investigated. The construction of a calibration graph based on typical components of the tars for use in the determination of molar mass distributions has revealed anomalously low retention volumes for phenols and amines when THF is used as the mobile phase. Consequently the molar mass distribution for a tar with a high phenolic content was not reliable when determined in THF but chloroform was shown to be a suitable solvent for this purpose. However the effect was used to fractionate the tar into two components, one of which contained a mixture of mainly phenols and long chain paraffins while the other was composed predominantly of polynuclear aromatics. A coke oven tar of low phenolic content was also fractionated into two components according to molecular weight and the fractions characterised in detail.