title: Analysis of fat-soluble vitamins. XV. Confirmation of isotachysterol in vitamin D concentrates.
abstract: The reaction with maleic anhydride yielding Diels-Alder adducts is used to distinguish vitamin D isomers. Treatment at 100 degrees C for 3 hr eliminates the fast-reacting (tachysterol and trans-vitamin D) and slow-reacting (cis-vitamin D and previtamin D) isomers. However, isotachysterol is not eliminated. The procedure has been incorporated as a confirmation test for isotachysterol in the official final action method for the determination of vitamin D in concentrates, 43.B14-43.B24.
mesh_terms: D004875:Ergosterol / Q000031:analogs & derivatives; D005223:Fats; D007536:Isomerism; D008722:Methods; D008968:Molecular Conformation; D012632:Secosteroids / Q000032:analysis*; D012995:Solubility; D013053:Spectrophotometry; D013261:Sterols / Q000032:analysis*; D014807:Vitamin D / Q000032:analysis*
chemical_list: D005223:Fats; D012632:Secosteroids; D013261:Sterols; D014807:Vitamin D; C002960:isotachysterol; D004875:Ergosterol