HPTLC chromatography of androstene derivates. Application of normal phase thin-layer chromatographic retention data...

The chromatographic behavior of seven 16-oximino derivatives of 3beta-hydropxy-5-androstene have been investigated using the normal-phase (NP) HPTLC chromatographic mode of the type silica-non-polar diluent (benzene)-polar modifier (acetonitrile, ethyl acetate, or dioxane). The linear relationship between the retention constants (R(M)) and the logarithm of the organic modifier content in the mobile phase allowed for the calculation of R(M)0 values. The influence of substituent in the molecule on extrapolated retention data is discussed. To better understand the retention mechanism in the separation of androstene compounds, the functional group contributions (tauX) were compared with Hansch substituent constants (pi). An attempt to quantitate the lipophilicity of the investigated compounds using normal phase thin-layer chromatographic R(M)0 value was made. Also, the relative lipophilicity values determined previously by RPC as well as activity were compared with NPC data.