Title of article :
Thin-layer chromatography of pitch and a petroleum vacuum residue: Relation between mobility and molecular size shown by size-exclusion chromatography
Author/Authors :
Li، نويسنده , , W. and Morgan، نويسنده , , T.J and Herod، نويسنده , , A.A and Kandiyoti، نويسنده , , R.، نويسنده ,
Issue Information :
روزنامه با شماره پیاپی سال 2004
Abstract :
A coal tar pitch and a petroleum vacuum residue have been separated by TLC using pyridine, acetonitrile, toluene and pentane to develop the chromatograms. The bands of material detected were recovered in 1-methyl-2-pyrrolidinone (NMP) solvent and examined by size-exclusion chromatography (SEC) in NMP eluent. The relation between elution time in SEC and mobility on the TLC plate indicated that molecular size increased steadily with increasing immobility on the plate. This relation was reinforced by UV fluorescence spectroscopy in that the fluorescence moved to longer wavelengths with increasing immobility. The molecular size of the material excluded from the porosity of the SEC column remains undefined; some excluded material was found in all of the fractions from both samples. The valley of zero intensity separating the retained material from the excluded material may suggest a change of structure from near-planar in the retained region to three-dimensional in the excluded region.
Keywords :
Coal tar , Petroleum
Journal title :
Journal of Chromatography A
Journal title :
Journal of Chromatography A