Method for substance separation using a cellulose hydrate membrane in size exclusion chromatography

A method for separating a mixture of materials comprising at least two components of different average molecular weight Mw in a range from 4000 to 4 000 000, comprising the steps:

• A) contacting the mixture of materials in a first liquid medium with at least one flat adsorbent and adsorptively depleting the at least one component having a lower average molecular weight from the first liquid medium through the at least one flat adsorbent, and
• B) separating the at least one flat adsorbent from step A) from the first liquid medium, which comprises the at least one component having a higher average molecular weight,
• wherein the at least one flat adsorbent is a membrane having a porous double structure consisting of:
• micropores having a diameter in the range from >100 nm to 20 μm, and
• ultrapores which have a diameter of <100 nm and which are not accessible to Blue Dextran having an average molecular weight Mw of 2 000 000, and
• wherein a fraction of the volume of the ultrapores is more than 15% of an entire pore volume accessible to water, and
• wherein the membrane is obtained by a method comprising:
• providing a cellulose ester membrane as a starting material for the membrane;
• and
• sequentially hydrolyzing said cellulose ester membrane in a swelling medium and crosslinking said cellulose ester membrane with an at least bifunctional agent, wherein the duration of hydrolysis is in the range of 5 to 45 minutes.