A method for the manufacture of a solid porous separation material based
on a polysaccharide, said method comprising the steps of: (a) providing
an aqueous solution (I) of a polysaccharide, (b) solidifying the
solution, preferably by transforming the solution to a gel, and (c)
optionally cross-linking the polysaccharide, with the proviso that, if
step (c) is present, steps (b) and (c) may be carried out simultaneously.
The method is characterised in that the polysaccharide provided in step
(a) is modified by being inter-molecularly cross-linked to an extent such
that the viscosity of solution (I) is at least 110%, preferably at least
200%, of the viscosity of an aqueous solution (II) of the corresponding
polysaccharide which has not been inter-molecularly cross-linked and
which is present in the same concentration as the inter-molecularly
cross-linked polysaccharide is in solution (I).