This study concerns the problems encountered in the molecular characte
rization of ultra-high molar mass (UHMM) hyaluronan samples. The deter
mination of the molar mass distribution of UHMM polymers is fairly dif
ficult. Shear degradation and non-newtonian Bow are the main difficult
ies in the fractionation on SEC columns. Considering these difficultie
s, the samples have remained previously characterized by off-line Ligh
t scattering and viscometry. The characterization by means of light sc
attering presents the problem of non linear angular variation of the s
cattering. We present a method to estimate reliable Values for molar m
ass and dimensions of UHMM hyaluronan polymers. To overcome the intrin
sic viscosity shear rate dependence we have used a multi-bulb capillar
y viscometer. The persistence length of the UHMM hyaluronan polymer ha
s been estimated. (C) 1998 Elsevier Science Ltd. All rights reserved.