AN IMPROVED STATISTICAL PARAMETER ALLOWING ELABORATE COMPARISON OF POLYMER MOLECULAR-WEIGHT DISTRIBUTION BY GEL-FILTRATION CHROMATOGRAPHY -APPLICATION TO CHITOSAN

Chitosan is a natural polymer which presents variable chemical charact eristics, especially with respect to molecular weight. For this determ ination, many techniques have been employed, and among these, gel filt ration chromatography is the only one that provides the molecular weig ht distribution. This method allows us to obtain different average mol ecular weights, and also to calculate the indices of polydispersity I- 1 and I-2 and the statistical skewing factor g (the Fisher factor whic h we have applied to gel filtration chromatography). With the help of all these data, we set up a methodology which enables us to compare th e molecular weight distributions of four chitosans. This study shows t hat the introduction of I-1, I-2 and g makes molecular weight comparis ons very easy. It also appears that the skewing factor g is a reliable indicator of the effects of hydrolysis on molecule size.