Ferric Chloride-Impregnated Silica Gel for Thin-Layer Chromatography of Steroids

Abstract

Silica gel G is mixed with an aqueous solution of ferric chloride, and the resulting slurry spread onto glass plates. After spotting, development, and drying, the plates are sprayed with sulfuric acid. Cholesterol, ergosterol, and Δ5-pregnen-3β-ol-20-one produce colored spots (pink-violet, greenish black, and pink-violet, respectively) without further treatment, but some other steroids require heating at 70 °C for full color development. Other colors generated are: estrone, orange; Δ4-androsten-3,17-dione, blue-green; androsterone, light brown; and 5α-androstan-17β-ol-3-one, tan. After prolonged heating at 70 °C, 6-keto-cholestanol produces an orange-brown spot. Color reactions are more reproducible than they are when the ferric chloride is sprayed on the plate.