Gas-liquid chromatographic determination of diethylstilbestrol at low levels in mixed feeds.

A gas-liquid chromatographic method for the determination of diethylstilbestrol (DES) at 2 ppb in mixed feeds and ingredients is presented. The DES is extracted into ethanol, the solvent is evaporated, and the residue is redissolved in chloroform. The extract is purified by washing the chloroform solution with carbonate buffer and transferring the DES to sodium hydroxide. The sodium hydroxide is washed with chloroform, the pH is adjusted to 10.3, and the DES is transferred to chloroform. The extract is derivatized with hepatafluorobutyric anhydride, chromatographed on an SE-30 glass column, and measured with a 3H electron capture detector. The method has been used for routine testing of a wide variety of feeds and ingredients.