title: Two-step separation of xanthine derivatives on Dowex-50 utilizing an eluant effect.
mesh_terms: D002852:Chromatography, Ion Exchange; D008722:Methods; D008745:Methylation; D010636:Phenols / Q000302:isolation & purification; D014970:Xanthines / Q000302:isolation & purification*
chemical_list: D010636:Phenols; D014970:Xanthines