Separation and quantitation of cholesterol oxides by HPLC with an evaporative light scattering detector in a model system

A method to analyze cholesterol and 10 of its oxidation products, ranging from the weakly polar cholest-4-ene-3,6-dione to moderately polar cholest-5-ene-3 beta,7 alpha-diol, in a single run is described, The separation was achieved by normal-phase gradient high-performance liquid chromatography with an evaporative light-scattering detector. This universal mass detector does not detect changes in solvent composition; this makes it possible to employ gradients, an essential technique whenever a wide range of compounds with diverse characteristics is to be separated. Standards at Concentrations from 0.1-1.0 mu g were separated within 37 min on an alumina/silica column with a gradient elution system that contained dichloromethane, acetonitrile, and water.