RETENTION BEHAVIOR OF SYNTHETIC CORTICOSTEROIDS IN PACKED-COLUMN SUPERCRITICAL-FLUID CHROMATOGRAPHY

The retention behavior of the synthetic corticosteroids used in a ther apy was investigated using packed-column supercritical fluid chromatog raphy (SFC) modified from a commercial liquid chromatographic system. The influence of the stationary phase, modifiers, column pressure and temperature was studied systematically. An aminopropyl-bound silica co lumn and carbon dioxide modified with methanol were selected. The sele ctivity and separation efficiency in the packed-column SFC were superi or to those in the existing normal- and reversed-phase liquid chromato graphic conditions. Seven polar corticosteroids, possessing 1 to 4 hyd roxyl groups, showed baseline separation within 6.5 min on a modifier gradient.