Fractionation of a wood tar pitch by planar chromatography for the characterisation of large molecular mass materials

A commercial tar pitch derived from pine wood - Massen Pine (Pinus Massonia) and sold as Stockholm tar has been fractionated by planar chromatography with examination of the fractions by size exclusion chromatography in NMP eluent, by UV-fluorescence and by matrix assisted laser desorption mass spectrometry. The relatively small molecules, mobile in planar chromatography, are shown to be non-polar. Large molecules were found in each fraction, corresponding in SEC elution times up to polystyrenes of molecular mass of at least 1.8 million. Size exclusion chromatography profiles by UV light absorbance showed differences in relative absorbance of different wavelengths for large and small molecules, implying differences in structures. MALDI mass spectra indicated molecules of mass of several thousand mass units with the upper limit of mass not defined. Planar chromatography provides a fast, cheap method of isolating large molecular mass fractions of this biomass tar. (C) 1999 Elsevier Science B.V. All rights reserved.