本文叙述一种检测地塞米松,倍它米松(Betame-thasone)或有关药物中所含17-酮差向异构体杂质的薄层层析法。本法适用于17-酮差向异构体α和β比例的测定。使用附有薄层层析扫描附件的分光光密度计,激发波长240nm,并应用各种摄影术记录薄层色谱。本法对α,β差向异构体的分离以及差向异构体比例的测定均与高速液相层析法所得结果一致。 This article describes a method for the determination of impurities in 17-keto epimers contained in dexamethasone, betamethasone or related drugs. This method is applicable to the determination of the 17-keto epimers α and β. A spectrodensitometer with a thin-layer tomography attachment was used with an excitation wavelength of 240 nm and various photographic recordings of the thin-layer chromatography. The separation of α, β epimers and the determination of the ratio of epimers by this method are consistent with those obtained by high performance liquid chromatography.