Simultaneous effect of organic modifier and physicochemical parameters of some steroidal drugs on their retention on a narrow-bore C1 column

The retention time of 16 steroidal drugs was measured on a narrow-bore C1 column using water–methanol mixtures as mobile phases and the retention factor (k) was calculated for each mobile phase and drug. The relationships between retention factor, mobile phase composition and physicochemical parameters of solutes were elucidated by principal component analysis (PCA) followed by two-dimensional non-linear mapping and varimax rotation around two axes. Calculations indicated that the binding of steroidal drugs to the surface of the stationary phase is of mixed character electrostatic and polar interactive forces are equally involved. Sterical correspondence between the surface of the stationary phase and the solutes also exert a considerable influence on the retention behaviour.