Separation of valtrate and isovaltrate by means of preparative liquid chromatography

In this study valtrate and isovaltrate, two isomeric valepotriates present in various Valeriana species, were separated on a preparative scale with a Waters preparative Liquid Chromatography/500 A system. A rapid separation was achieved with the solvent methylene chloride-n-propanol-acetone (99 + 0.5 + 0.5). Extensive use of the recycle mode of the instrument resulted in a considerable reduction of the amount of solvent used, without affecting the purity and the recovery (greater than 90%) of the separated components. With the method presented in this communication 1 gram of a mixture of valtrate and isovaltrate was separated in 20 minutes using 2.1 liters of solvent.