Separation and Identification of Cholesterol Oxidation Products in Dried Egg Preparations

Abstract

A technique is described for the simultaneous determination of a wide range of angiotoxic sterols in foods produced by the oxidation of cholesterol. Gas chromatography using on‐column injection onto a bonded phase fused silica capillary column gave excellent separation of the oxides examined. Combined gas chromatography‐ mass spectrometry was used to confirm the identities of the trimethylsilyl ether derivatives of the various sterols and 6‐ketocholestanol was found to be an acceptable internal standard for determination. Analysis of powdered scrambled egg mix showed the presence of several cholesterol oxides, with cholesterol‐5α,6α‐epoxide, cholesterol‐5β,6β‐epoxide and 7‐ketocholesterol predominating. Other atherogenic sterols identified included 25‐hydroxycholesterol, 7α‐hydroxycholesterol, 7β‐hydroxycholesterol and 5α‐cholestane‐3β,5,6β‐triol.