Preparative isolation of vitamin D2 from previtamin D2 by recycle high-performance liquid chromatography.

A preparative high-performance liquid chromatographic method, based on recycle chromatography, to separate vitamin D2 (ergocalciferol) from previtamin D is described. The method provides efficient separation by means of a mixture of methanol, acetonitrile and hexane as eluent on a reversed-phase C18 column. Scale-up to a 2-in. diameter column resulted in the collection of 100% pure fractions based on UV detection at 265 nm. The total throughput and the economics of the purification were also optimized.