High-pressure liquid chromatographic determination of 13-cis-retinoic acid and all-trans-retinoic acid in human plasma

A simple and selective method is described for the determination of 13-cis-retinoic acid and all-trans-retinoic acid in plasma. The assay involves lyophilization of the sample, extraction of the residue with methanol, and separation of the retinoids by reverse-phase high-pressure liquid chromatography. The procedure can detect as little as 0.05 μg of either compound. It is capable of being readily modified to determine the amount of retinoic acid in other tissues as well as tissue concentrations of other retinoids. Using this assay, the absorption and disappearance from human plasma of an oral dose of 13-cis-retinoic acid have been followed.