Prednisolone, Prednisone and Cortisone are commonly used steroids to treat a range of inflammatory conditions and autoimmune disorders. These synthetic derivatives of hydrocortisone were developed and approved for medicinal use as early as the 1940’s. American chemists first identified Cortisone as having a therapeutic benefit in the treatment of rheumatoid arthritis and it was commercialized by Merck in 1948. The first commercially feasible synthesis of prednisone was carried out in 1955 in the laboratories of the Schering Corporation. A C18 HPLC column can be used for the analysis of these synthetic steroids, but they are not well retained, and resolution is incomplete. This application brief will look at the differences in chromatography between the Quasar C18 and AQ phase chemistries for the analysis prednisolone, prednisone and cortisone.