Abstract
The separation of ecdysteroids by high-performace liquid chromatography (HPLC) on reversed-phase (C18 and APS-Hypersil (aminopropyl) microparticulate columns and by thin-layer chromatography has been evaluated. Reversed-phase columns with solvent gradient elution are particularly suitable for analysis of ecdysteroids of widely differing polarities since the re-equilibration time is shorter than with adsorption columns. Clear separation of ecdysteroids from the corresponding 3-dehydro and 3-epi derivatives can be achieved on a 25 cm long APS-Hypersil column, but 3-epiecdysone and 20-hydroxyecdysone are incompletely resolved in this system. However, the separation of the latter pair of compounds can be readily achieved on a longer APS-Hypersil column or on a reversed-phase HPLC column or by thin-layer chromatography. APS-Hypersil has advantages over silica gel as column packing material for separation of polar compounds such as ecdysteroids. The mechanism of retention on APS-Hypersil is discussed.
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