Gas chromatographic-mass spectrometric assay for low levels of retinoic acid in human blood.

A rapid and sensitive method of analysis for retinoic acid in human blood has been developed using gas chromatography-mass spectrometry for separation and detection. The retinoic acid is isolated by solvent extraction into petroleum ether, and converted to methyl retinoate by reacting with dimethylformamide dimethylacetal. The method has been applied to the study of retinoic acid in human blood after subtotal inunction, total inunction and intravenous injection of retinoic acid. The sensitivity limit of 1 ng/ml blood is realized with a 10-ml blood sample.