In general, to remove/extract one material from another. In blood bank world, the term refers to removing (or “dissociating”) an antibody that is attached to the surface of a red blood cell. This procedure is most commonly used in identification of complicated antibodies, sometimes in the workup of transfusion reactions or hemolytic disease of the newborn, as well as in the workup of warm autoantibodies. Most commonly, a solvent like acidic glycine is used to dissociate the antibodies from the red cells (though heat or cold can also be used, somewhat less effectively). The resulting suspension is then centrifuged and the supernatant fluid (the “eluate“) removed. The eluate may then be tested to identify the antibody. Elution is often used in association with adsorption.