title: Simultaneous quantification of various retinoids by high performance liquid chromatography: its relevance to alcohol research.
abstract: BACKGROUND
  We established a high performance liquid chromatography system that allowed simultaneous quantification of various retinoids.
  
  
  METHODS
  We applied the retinoids to a high performance liquid chromatography system with a silica gel absorption column. Samples were separated by the system with a binary multistep gradient with two kinds of solvent that contained n-Hexan, 2-propanol, and glacial acetic acid in different ratios. Each retinoid was detected at a wavelength of 350 nm.
  
  
  RESULTS
  This condition allowed separation of 13-cis-retinoic acid, 9-cis-retinoic acid, all-trans-retinoic acid, 13-cis-retinol, all-trans-retinol, all-trans-4-oxo-retinoic acid, and 13-cis-4-oxo-retinoic acid as distinct single peaks. Each retinoid was also analyzed separately and its retention time determined. To ascertain the reliability of this system for retinoid quantification, retinoids at various concentrations were applied to the system. We observed the linearities between the concentration and area under the curve of the peak for each retinoid by linear least-squares regression analysis up to 2.5 ng/ml for all retinoic acids and up to 5 ng/ml for all retinols. There was no significant scattering in tests of within-day reproducibility or day-to-day reproducibility. Using this system, we examined effects of light exposure on isomerization of retinoids. When retinoids were exposed to room light for 2 hr, the amounts of all but 13-cis-retinol changed significantly. In particular, the amounts of all-trans-retinoic acid and 9-cis-retinoic acid were reduced by 40% and 60%, respectively.
  
  
  CONCLUSIONS
  The HPLC system established in this study should be useful for studying the oxidation pathway of retinol to retinoic acid. A light-shielded condition is required when particular retinoic acids are analyzed.
authors.affiliation: Department of Internal Medicine, School of Medicine, Keio University, Tokyo, Japan. yokoyama@mc.med.keio.ac.jp
authors.forename: H
authors.initials: H
authors.lastname: Yokoyama
authors.forename: M
authors.initials: M
authors.lastname: Matsumoto
authors.forename: H
authors.initials: H
authors.lastname: Shiraishi
authors.forename: H
authors.initials: H
authors.lastname: Ishii
mesh_terms: D000077556:Alitretinoin; D002851:Chromatography, High Pressure Liquid; D000431:Ethanol / Q000378:metabolism*; D015474:Isotretinoin / Q000032:analysis; D015203:Reproducibility of Results; D012176:Retinoids / Q000032:analysis*; D014212:Tretinoin / Q000032:analysis; D014801:Vitamin A / Q000032:analysis
chemical_list: D012176:Retinoids; D014801:Vitamin A; D000077556:Alitretinoin; D000431:Ethanol; D014212:Tretinoin; D015474:Isotretinoin