Two-dimensional TLC with an adsorbent gradient for analysis of saponins inSilene vulgaris Garcke

A saponin mixture obtained from the roots of Silene vulgaris Garcke (Caryop hyllaceae) has been chromatographed by two-dimensional (2D) TLC. In this va liant of 2D TLC the first development was performed on an RP-18W HPTLC plat e and that in the perpendicular direction on a silica gel HPTLC plate. Appl ication of this method enables the use of different types of adsorbent in o ne analysis. With this adsorbent gradient the saponin mixture could be sepa rated into 18 components whereas conventional TLC separated the mixture int o nine components only These results indicate that solid-phase gradient TLC is relatively simple, easy to perform, inexpensive, and suitable for the p reliminary analysis of saponins.