Determination of 3 β-hydroxysterols by the cysteine-sulfuric acid reaction

Abstract A colorimetric method for the determination of 3β-hydroxysterols in bile and tissue has been described. This is based upon the reaction of the purified sterol digitonides with cysteine and sulfuric acid. Spectrophotometric data has been presented, and evidence that the reaction depends upon the presence of hexoses in digitonin. The accuracy of the proposed method has been assessed and close agreement obtained with results for free cholesterol using the Liebermann-Burchard reaction. The sensitivity of the method is such that 10 μg of cholesterol in bile or tissue extracts can be determined.