Identification of Vitamin D3 in Human Skin

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 D3. Further, the iodine trichloride and trimethylsilyl derivatives of isolated vitamin D3 had chromatographic properties indistinguishable from the derivatives formed from the authentic compound. The pyro and isopyro products of authentic vitamin D3-trimethylsilylate yielded almost identical mass spectra. Radioisotope studies indicated an average 38% recovery of tritiated vitamin D3 through the isolation procedure prior to gas-liquid chromatography. Preliminary quantitation of vitamin D3 in abdominal skin was approximately 3.2 µg/gm of skin.