title: Quantitative TLC determination of epimeric ratios of 16-methyl 17-ketone oxidation products of dexamethasone and related drugs.
abstract: A TLC system sensitive enough to detect, identify, and allow quantitation of the 16-methyl alpha- and beta-epimers of 9-fluoro-11 beta-hydroxy-16-methylandrosta-1,4-diene-3,17-dione is described. These epimeric 17-ketones may be present as impurities in dexamethasone, betamethasone, or related drugs. A spectrodensitometer with a TLC scanning attachment was used, and results from densitometry compared favorably with quantitation by high-performance liquid chromatography, as was described recently. TLC was convenient in the rapid examination of drug samples for the detection and identification of epimeric 17-ketones and for the determination of the alpha to beta ratio of such epimers. Various applied photographic techniques for documenting TLC data are described.
mesh_terms: D002851:Chromatography, High Pressure Liquid / Q000379:methods; D002855:Chromatography, Thin Layer / Q000379:methods; D003907:Dexamethasone / Q000031:analogs & derivatives* / Q000032:analysis*; D007659:Ketones; D010084:Oxidation-Reduction; D013237:Stereoisomerism
chemical_list: D007659:Ketones; D003907:Dexamethasone