Gradient separation of pharmaceuticals employing supercritical CO2 and modifiers

Sub‐ and Supercritical Fluid Chromatography (SFC) were used to separate seven purine and pyrimidine‐based drugs. A two‐pump system was used, where one pump delivered the carbon dioxide, and the other pump delivered modifier. The modifiers used in this work were methanol, and methanol containing 0.001 M tetrabutylammonium hydroxide. Two of the compounds studied were hydrochloride salts. These compounds were analyzed by a Supercritical Fluid Extraction (SFE)/SFC method.