ABSTRACT Softwood (pinus silvestris) lignosulfonates from the acidic stage of a three-stage sulfite cook were fractionated and purified by ultrafiltration and ion exclusion chromatography. The fractions were characterized by 13C NMR spectroscopy together with conventional chemical methods. In order to ascertain correct signal assignment of the 13C NMR spectra of lignosulfonate fractions, the chemical shifts of model compounds were studied. It was …