title: A new procedure for the formation of isotachysterol derivatives of subnanomole quantities of ergocalciferol, cholecalciferol and its metabolites prior to gas liquid chromatography.
mesh_terms: D002762:Cholecalciferol / Q000378:metabolism*; D002849:Chromatography, Gas; D004872:Ergocalciferols / Q000378:metabolism*; D004875:Ergosterol / Q000031:analogs & derivatives* / Q000138:chemical synthesis; D008722:Methods; D012632:Secosteroids / Q000138:chemical synthesis*
chemical_list: D004872:Ergocalciferols; D012632:Secosteroids; D002762:Cholecalciferol; C002960:isotachysterol; D004875:Ergosterol