ON LINE FILTRATION OF DIALYSATE STRUCTURAL AND FUNCTIONAL FEATURES OFAN ASYMMETRIC POLYSULFONE HOLLOW-FIBER ULTRAFILTER (DIACLEAN(R))

The endotoxin transfer across dialysis membranes has been investigated using specific in vitro circuits. Backdiffusion and backfiltration ha ve been analyzed and most dialysis membranes have shown to be permeabl e to LAL positive substances Synthetic membranes however display the b etter capacity of retention of these products despite their higher por osity and permeability. For such reason synthetic polysulfone ultrafil ters are used as pyrogen filters to obtain ultrapure dialysate. We hav e investigated the characteristics of a polysulfone ultrafilter named Diaclean and manufactured by Amicon Ireland. The capacity of endotoxin retention has been investigated both in filtration and backfiltration modes on new and used ultrafilters. The capacity of endotoxin adsorpt ion was investigated as well. Used ultrafilters appeared to maintain t he retention capacity and the adsorption capacity up to 4 months of us e. Only slight differences were noted from the baseline values (p = n. s.). The best adsorption capacity is always displayed by the outer lay er of the membrane suggesting ifs best utilization in back filtration mode with tangential flow. No morphological changes were observed in t he used membrane analyzed by scanning electron microscopy.