title: High-performance liquid chromatographic analysis of retinal and retinol isomers.
abstract: Normal-phase chromatograms of retinal- and retinol isomers using various mobile phrases are presented, showing that in n-hexane--tert.-butyl methyl ether and also in n-heptane--tert.-butyl methyl ether the elution order for retinol is 13-cis-, 11-cis-, 9-cis- and all trans-retinol, whereas in n-hexane-1,4-dioxane 11-cis- elutes before 13-cis-retinol. Assignment of these main retinal and retinol peaks was performed using pure crystals of isomers, measurement of absorbance spectra and analysis of NMR spectra. The new mobile phase n-heptane-tert.-butyl methyl ether allows best baseline separation of the commonly occurring isomeric forms in reasonably short analysis time. In addition, eight di-cis- and tri-cis-retinol isomers were tentatively identified. The chromatograms show that former identifications in the literature are inconsistent or wrong.
authors.affiliation: Physiologisches Institut, Justus-Liebig-Universität, Giessen, Germany.
authors.forename: G N
authors.initials: GN
authors.lastname: Nöll
mesh_terms: D002851:Chromatography, High Pressure Liquid / Q000379:methods* / Q000706:statistics & numerical data; D003460:Crystallization; D004146:Dioxanes; D006536:Heptanes; D006586:Hexanes; D007202:Indicators and Reagents; D009682:Magnetic Resonance Spectroscopy; D008738:Methyl Ethers; D012172:Retinaldehyde / Q000032:analysis* / Q000737:chemistry; D013237:Stereoisomerism; D014801:Vitamin A / Q000032:analysis* / Q000737:chemistry
chemical_list: D004146:Dioxanes; D006536:Heptanes; D006586:Hexanes; D007202:Indicators and Reagents; D008738:Methyl Ethers; D014801:Vitamin A; C043243:methyl tert-butyl ether; C026385:n-hexane; C028618:n-heptane; C025223:1,4-dioxane; D012172:Retinaldehyde