Evaluation of GC and GC–MS methods for the analysis of cholesterol oxidation products

Various methods are used to analyse cholesterol oxidation products (COP) due to the unavailability of a standard method. In order to select a suitable method for the enrichment of COP, three methods of saponification (A–C), and transesterification (D) of tallow with three levels (5, 10 and 20 μg) of spiked COP, were evaluated. Further enrichment of COP was done by solid phase extraction, quantified by GC, and confirmed by GC–MS. The in-house method A, and method D showed,the best results among the four methods evaluated. The recoveries at all levels of spiked COP were generally higher than 60% in method A. The recoveries of all spiked COP at 5 μg level were consistently lower in method D compared with method A. From the results of this study it can be concluded that method A may be more suitable for the analysis of very low levels of COP in foods.