High-pressure liquid chromatography: separation of the metabolites of vitamins D2 and D3 on small-particle silica columns.

The high-pressure liquid chromatographic separation of all of the known metabolites of vitamin D(2) and vitamin D(3) found in biological fluids has been achieved. This technique has been successfully applied to the analysis of vitamin D mixtures, purification of vitamin D metabolites, and identification of radioactive peaks. Some theoretical bases for the observed resolutions are suggested.