Analysis of cholesterol, cholesterol-5,6-epoxides and cholestane-3β,5α,6β-triol in nipple aspirates of human breast fluid by gas chromatography/mass spectrometry

Abstract
A method has been developed for the quantitative determination of cholesterol and three of its major oxidative metabolites (the 5α,6α-epoxide, the 3β,5α,6β-triol, and the 5β,6β-epoxide) in a single sample of human breast fluid (2–50 μl), using gas chromatography/mass spectrometry with selected ion monitoring. High specificity and reliable quantification is achieved by the use of the inverse stable isotope dilution method, employing deuterium-labeled variants of the compounds as internal standards.