Steroid structure and retention in normal- and reversed-phase thin-layer chromatography

The chromatographic behavior of a series of estradiol and estrone derivativ es has been studied on silica gel with binary nonaqueous mobile phases and on C-8- and C-18-modified silica gel layers with binary aqueous mobile phas es. The slopes and intercepts of the linear relationships between the reten tion constant, R-M, and the logarithm of the volume fraction of the polar c omponent of the nonaqueous mobile phase, and of the volume fraction of orga nic component of the aqueous-organic mobile phase, have been calculated and are discussed in relation to the properties of the solute and of the mobil e and stationary phases. The retention and relative retention of compounds depend largely on the retention behavior of their substituents.