Weight Cut-off and Pore Size

What we mean by the molecular weight cut-off of a diffuse cut-off membrane must be clearly defined. The convention established by AMICON and adopted by most UF membrane manufacturers is based on the retention of globular proteins (spherical macromolecules). The retention R (in percent) maybe defined as follows  

The convention states that the molecular weight cut-off of the membrane is equal to the molecular weight of globular proteins which are 90% retained by the membrane. 

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The spim hoUow fibers were characterized with regard to cross-sectional membrane morphology, membrane surface chemistry, mechanical properties, water permeation, molecular weight cut-off, and pore size distribution. It was observed that the water permeation and molecular weight cut-off of the as-spim hoUow fibers are dependent on the structure of the additives. 

TABLE 1. Molecular Weight Cut-Offs and Pore Size Ranges... 

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