Molecular weight spectra of ultrafilter rejection. II. Measurements on highly rejecting filters

A mixture of maltodextrins (10,000-80,000 daltons) has been used to follow the response of rejection by membranes to molecular weight. Two ultrafilters and a reverse osmosis membrane having rejection values greater than 0.999 for the high molecular weight fractions were tested. The procedure described permits determination of sieving values (1-R) as low as 1 x 10^?5. The results indicate that only the reverse osmosis membrane was sufficiently retentive to assure the absence of significant levels of endotoxins in the product streams.