Monitoring cholesterol autoxidation processes using multideuteriated cholesterol

Deuterium-labeled cholesterol is used to monitor for artifactually produced cholesterol oxidation products during analysis. [2H9]Cholesterol, labeled on the side chain, is added to the sample immediately upon isolation, and the ratios of labeled to unlabeled oxides and of labeled to unlabeled cholesterol are monitored by capillary gas chromatography-mass spectrometry. The analytical methodology involves an initial solvent extraction followed by silica gel LC and reversed-phase HPLC to isolate and concentrate the oxide fraction. The feasibility of the technique for analysis of cholesterol oxides in foods and biological samples at the part per million level with an accuracy of better than +/- 5% is demonstrated.