The present invention relates to a process for purification of a target biomolecule, comprising the steps: (a) contacting (i) a target biomolecule, (ii) a dual affinity polypeptide, and (iii) a solid support comprising a catching ligand, wherein the ratio between the equilibrium dissociation constants of the dual affinity polypeptide, [KD,t/KD,s], is at least 100 at standard conditions; and (b) recovering the target biomolecule by elution.