Process for extraction of biological material

In a process for extraction of biological material, in particular of proteins or peptides, from a first aqueous solution ( 1 ) to a second aqueous solution ( 2 ), a porous membrane ( 3 ) is arranged between the aqueous solutions ( 1, 2 ). At least one of the aqueous solutions ( 1 ) is now modified by addition of a biocompatible and surface-active agent in such a way that the wetting behaviour of the two liquid phases on the membrane and in the pores of the latter differs significantly. In this way, membrane extraction of biological material from a first aqueous solution ( 1 ) to a second aqueous solution ( 2 ) is made possible in a simple and efficient manner. The process is easy to carry out and can be used on an industrial scale.