Capillary Gas-Chromatographic Retention Behavior and Physico-Chemical Properties of Underivatized Equine Estrogens

Abstract

The capillary gas-chromatographic retention behavior of six underivatized equine estrogens (estrone, equilin, equilenin and their corresponding 17α-diols) on a mixed stationary phase (non-polar CP-Sil 5 CB and slightly polar CP-Sil 19 CB capillary columns coupled in series) was characterized by their Kovats retention indices and steroid numbers. In order to find whether a correlation exists between the chromatographic retention and some physico-chemical properties of the compounds, their octanol-water partition coefficients and dipole moments were measured. No straightforward correlation was observed between the physico-chemical properties and the retention behavior, which suggests that the GC separation of equine estrogens is governed by some specific electron donor-electron acceptor interactions of a chemical nature.