Liquid chromatographic determination of desoxycorticosterone acetate in oil injections

To determine desoxycorticosterone acetate in oil injections, reverse phase partition chromatography on silanized, purified siliceous earth was used to separate the corticosteroid ester from the bulk of the oil vehicle. The latter was retained on the column while the steroid and the sterol and triterpenoid fractions of the oil were eluted. An internal standard was added to this eluate, which was then subjected to reverse phase high performance liquid chromatography (HPLC). The desoxycorticosterone acetate was quantitatively separated in the HPLC procedure from any free desoxycorticosterone, preservatives, and minor components of the oil. The suitability of the HPLC procedure was verified with a number of C18 packing materials, both pellicular and microparticular. The desoxycorticosterone acetate was adequately resolved from the internal standard, progesterone, with most C18 packing materials evaluated. The proposed procedure provides a suitable stability-indicating assay for desoxycorticosterone acetate in oil injections.