Identification of vitamin D3 in human skin.

Abstract Human skin obtained shortly post mortem was hydrolyzed and extracted with iso-octane. The lipid fraction was chromatographed on thin-layer to separate various sterols. The 7-dehydrocholesterol area was isolated and found to have ultraviolet and infrared spectra identical with authentic 7-dehydrocholesterol. The vitamin D area was isolated and shown to have thin-layer and gas chromatographic properties similar to authentic vitamin D 3 . Further, the iodine trichloride and trimethylsilyl derivatives of isolated vitamin D 3 had chromatographic properties indistinguishable from the derivatives formed from the authentic compound. The pyro and isopyro products of authentic vitamin D 3 -trimethylsilylate yielded almost identical mass spectra. Radioisotope studies indicated an average 38% recovery of tritiated vitamin D 3 through the isolation procedure prior to gas-liquid chromatography. Preliminary quantitation of vitamin D 3 in abdominal skin was approximately 3.2 µg/gm of skin.