Study on binding of REEs with water-soluble polysaccharides in fern

The binding of rare earth elements (REEs) with water-soluble polysaccharide s of nondeproteinization and deproteinization in the leaves of the fern Dic ranopteris dichotoma was studied by molecular activation analysis (MAA). Tw o cold-water-soluble polysaccharides (extracted by 75% ethanol and 90% etha nol, respectively) and one hot-water-soluble polysaccharide (extracted by 9 0% ethanol) were separated using biochemical separation techniques. The eig ht rare earth elements (La, Ce, Nd, Sm, Eu, Tb, Yb, and Lu) in these polysa ccharides were determined by instrumental neutron activation analysis. Our new results showed that the REEs were bound firmly with the water-soluble p olysaccharides in the plant, regardless of whether nondeproteinization or d eproteinization was used. The molecular-weight (MW) measurement demonstrate d that REEs were mainly bound with low-MW (10,000-20,000) polysaccharides.