Hydroxyapatite (HA) has a long and successful history in the field of antibody purification, and it has worked well for immunoglobulin M (IgM) monoclonal antibodies (MAbs) (1,2,3,4,5,6,7,8). Applications range from initial capture to intermediate purification to final polishing. HA is best known for its superior ability to reduce antibody aggregates, but it also supports excellent reduction of DNA, viruses, and endotoxins. As IgM MAbs exhibit increasing potential in the fields of cancer and infectious disease and in stem-cell therapies, HA’s…