Studies of Vitamin A in Nutrition and Cancer

This thesis describes the development of specific assays for separation and extraction of vitamin A (retinol) and its metabolites, retinal, retinoic acid, retinol acetate, retinol palmitate and its pro-vitamin carotene. The assay employed a liquid/liquid extraction procedure which gave reproducible recoveries for retinol and its metabolites. This was followed by a high pressure liquid chromatography (HPLC) procedure using a silica column with hexane:tetrahydrofuran:formic acid as mobile phase. This gave excellent chromatographic efficiency and resolution of metabolites and resulted in a highly sensitive and specific assay for all the compounds analysed. The assay was used for serum, and was modified to be applicable also for liver and nutritional solutions. A major benefit of this assay compared with previous methods is that all retinol metabolites can be separated on a single column without requirement for expensive gradient systems