Abstract: The invention concerns a process for removing inorganic salts from a liquid medium having a solids content of from about 25 to about 65 mg/ml and containing active organic peptide substances of a molecular weight of from about 500 to about 10,000 and up to 70% by weight inorganic salts based on the solids content of the liquid medium, which comprises the steps of transferring said liquid medium onto a filtration gel layer carried on a perforated centrifuge drum at a liquid medium: gel volume ratio of from about 1:2.5 to about 1:4.5, said filtration gel layer being higher cross-linked and having a particle size of from about 40 to 120 .mu., centrifuging at a centrifugal force of from about 800 to about 1500 g, and collecting the liquid centrifugate containing the active organic peptide substances and a low amount of salt.The substance recovered by the process possesses growth regulating properties and can be recovered from mammalian blood or serum.