Improved method of determining retinol and retinyl palmitate in rat liver and serum by high-performance liquid chromatography.

In this study, we examined the effect of certain analytical procedures to determine the best method of recovering the ingested retinoids, specifically retinol and retinyl palmitate, from rat liver and serum. In this experiment, the best extraction solvent for retinol was n-hexane and that for retinyl palmitate was ethyl acetate. The best results were obtained using a mobile phase (n-hexane-diethyl ether, 76:24, v/v) as the sample solvent in the assay for liver retinol, similarly, chloroform as the sample solvent in the assay for serum retinol, and for liver retinyl palmitate, the best sample solvent was methanol-toluene (5: 5, v/v). The assayed values of retinol and retinyl palmitate measured in ethanol (0.125% BHT added) and extraction solvent (0.025% BHT added) were significantly higher than those when no BHT was added to the ethanol and extraction solvent. The determination methods for extracting retinol and retinyl palmitate from the liver varied according to the conditions layed out above. Simultaneous determination of retinol and retinyl palmitate has been illustrated in previous papers by various authors: however, we found that the individual determination of retinol and retinyl palmitate was necessary to accurately assay each retinoid.