Abstract: Polyguluronate sulfate(PGS) with a high degree of sulfate substitution was prepared by chemical sulfation with sulfur trioxide pyridine complex(SO₃-Py) on the basis of polyguluronic acid(PG), which was isolated from the hydrolysate of alginate. The optimum sulfation conditions were determined by orthogonal design method and the structure of PGS was confirmed by 2D-NMR spectroscopy. A new environment-friendly degradation method(the so called solid phase acid degradation) was developed to prepare PGS oligosaccharides, in which 732^# resin was used as an acidic degradation medium. The results of degradation show that the weight average relative molecular weight(M_w) of PGS oligosaccharides was lower than 3000, when the ratio of 732^# resin is 200 mg/mL and mass fraction of PGS is 2%, degradation temperature is 100 ℃ and degradation time is 6 h. Thirteen PGS oligosaccharides(F₁—F₁₃) were obtained by Bio-Gel P6 column separation. The polymerization degree of F₁—F₁₃ is from one to thirteen, respectively, demonstrated by ESI-MS analysis. The solid phase acid degradation method was used to solve the problems of environmental pollution, inorganic salts separation and corrosion of reactors, which are universal in traditional acid degradation methods, and it provides a new approach to preparation of oligosaccharides.

Key words: Solid phase degradation, Polyguluronate sulfate, Oligosaccharides, Electrospray tandem mass spectrometry