Abstract: The present invention relates to the field of affinity purification and provides for means and methods applying protein binding agents competing for a target protein for use as capture and elution tool, wherein the elution agent comprises an immunoglobulin single variable domain (ISVD), and is capable of displacing the capturing binding agent. More specifically, the displacement efficiency of the ISVD-containing protein binding agent is driven by its dissociation kinetics, with a rate constant of dissociation (koff) equal or lower as compared to the capturing agent. Furthermore, said protein binding agents are deployable in high-throughput purification from complex mixtures, or for capturing protein-complexes, thereby facilitating structural, biochemical and physicochemical analysis of said target proteins.