CALCIUM ALGINATE DRESSINGS - I - PHYSICOCHEMICAL CHARACTERIZATION ANDEFFECT OF STERILIZATION

In order to analyze the alginate components of alginate dressings and the fractions which are released when the dressing is in contact with model biological fluids, the use of various analytical methods was con sidered. The first step was the conversion of a calcium alginate batch to pure sodium alginate. The recovery of the latter from either insol uble or soluble mixed sodium/calcium alginates was performed by comple xation of calcium ions with sodium citrate followed by ultrafiltration . Comparisons were made between sugar analysis, H-1 NMR and circular d ichroism (CD) data to determinate the contents in guluronic and mannur onic acids of sodium alginate chains. It was shown that CD measurement s afford a rapid and nondestructive method for determination of %G whe n one takes the ratio theta(200)/theta(220) into account. Fractionatio n of crude alginate (generally ranging from 30 to 70% G) was achieved by the triangle dissolution/precipitation method in order to increase the range of alginate in sugar composition. The various validated proc edures were applied to investigate the effects of irradiation steriliz ation on alginate dressings. It was shown that sugar composition is re tained whereas molecular weight decreased dramatically due to chain sc ission.