Correlation between Chemical Structure and Physical Properties of Alginates.

Abstract

Alginic acid from Ascophyllum nodosum and Laminaria hyperborea stipes was subjected to partial acid hydrolysis, and the products were examined by free boundary electrophoresis. The various alginate fragments were isolated by fractional precipitation and analysed.The same types of building elements as previously found in L. digitata alginate were present, and the differences between the three alginates were caused by the building elements occurring in different proportions. The solubility of the alginate fragments in acidic solutions and the presence of calcium ions was examined and correlated with the properties and composition of the alginates. The higher solubility of A. nodosum alginates in acidic solutions was caused by a smaller propotion of the homopolymer blocks in this alginate than in alginates from the Laminaria species. A fraction of the A. nodosum alginate, with a particularly low content of homopolymer blocks, was found to be completely soluble in acidic solutions at low ionic strength.