Mass spectra of retinol and related compounds

The mass spectra of the all- trans-isomers of retinol (vitamin A), anhydroretinol, retinyl acetate, retinal, retinoic acid and methyl retinoate, and 9- cis-retinal were investigated. Upon electron impact, each compound gave its molecular ion, m e = M + , and peaks representing the loss of its functional group, thereby providing a quick and unambiguous method of identification. Other modes of fragmentation for these compounds are discussed. Less than 1 μg of pure compound is required for positive identification.