The present invention concerns a method of purifying a biological liquid comprising antibodies corresponding to whole human or animal blood or to a product obtained from human or animal blood, by bringing a biological liquid into contact with at least one substrate comprising a solid phase onto which molecules of at least one oligosaccharide are grafted by covalent bonding, the molecules of the at least one oligosaccharide being capable of binding to one or more of said antibodies present in said biological liquid, in a manner such as to capture at least a portion of said antibodies present in said biological liquid by binding with at least certain of the molecules of oligosaccharide(s) grafted onto said solid phase, characterized in that said solid phase carries free aldehyde functions —CHO.
