Fast determination of retinol and alpha-tocopherol in plasma by LC

A fast, selective and economical method for the determination of retinol and alpha-tocopherol is presented. Both vitamins are separated by high-performance liquid chromatography (HPLC) in less than 4 min using an isocratic elution with methanol. The robustness of the method was checked in real samples, obtaining relative standard deviation lower than 3%. The described method was satisfactorily applied to serum samples proceeding of patients enrolled in a METHADONE maintenance treatment program. The retinol concentrations in the serum of these patients fell into the normal interval of concentrations; however, the serum alpha-tocopherol contents were higher than the normal values.