Capillary electrochromatography of cholesterol and its ester derivatives

Separation of cholesterol and its ester derivatives using micellar electrok inetic chromatography is a challenge due to the extreme hydrophobicity of t hese compounds. In this work, an isocratic capillary electrochromatography (CEC) method has been developed to separate a complex mixture of cholestero l and its 12-ester derivatives. The proportions of mobile phase (tetrahydro furan, acetonitrile, water), as well as the effects of acid modifiers, buff er concentrations, voltage, and temperature on the separation of cholestero l derivatives were investigated. Addition of a polymeric surfactant, poly(s odium N-undecanoyl-L-glycinate), to the mobile phase reduced migration time and improved resolution of the analytes. The CEC method developed allows b aseline separation of a complex mixture of cholesterol and 12 ester derivat ives in less than 40 min. Finally, the method is applied to the characteriz ation of cholesterol, cholesterol linoleate, and cholesterol oleate extract ed from atherosclerotic plaque deposits in the arterial walls of a human ao rta.