Selective Entrapment of Organic Molecules by Ultrafiltration

Abstract

A UM-2 ultrafilter of Diaflo Membrane (Amicon Co.; nominal molecular weight cut off, 1, 000) entrapped amino acids and monosaccharides with molecular weights less than the nominal cut off level. The degree of entrapment of amino acids changed with the change in pH of the solution : neutral amino acids slightly increased (66.4→74.0%) and basic AA increased (6.0→56.0%), whereas acidic AA decreased (86.7→32.3%) with increasing pH from 4 to 10, and that of glucose remained practically unchanged with pH.
The present results suggest that, even when the molecular weights of organic molecules in natural waters are sufficiently below the nominal cut off level of the UM series filters, they will be selectively entrapped by the UM series filters, if they have ionic sites or highly polar molecules. The degree of entrapment may change with the change in pH of the water.