title: Colorimetric determination of tocopheryl acetate (vitamin E) in pure form and in multi-vitamin capsules.
abstract: A simple, accurate and sensitive method for the determination of micro amounts of vitamin E (V(E)) in pure form and in multi-vitamin capsules is described. The method is based on the reduction of tetrazolium blue in slightly alkaline medium by vitamin E after extraction from aqueous EDTA medium with petroleum ether and transesterification. The oxidation reduction reaction occurs after 10 min of heating in a water bath at 90+/-2 degrees C, leading to the formation of a highly coloured formazan derivative. Different variables affecting the colour development were investigated and optimized. Absorbance measurements were made at 526 nm and the calibration graph was linear for 0.2-11.0 microg/ml of (V(E)) with relative precision of about 0.7-1.5% when the standard additions method is used.
authors.affiliation: Chemistry Department, Benha University, Egypt.
authors.forename: A S
authors.initials: AS
authors.lastname: Amin
mesh_terms: D000975:Antioxidants / Q000032:analysis; D002214:Capsules / Q000737:chemistry*; D003124:Colorimetry / Q000379:methods*; D007501:Iron / Q000737:chemistry; D013778:Tetrazolium Salts / Q000737:chemistry; D024505:Tocopherols; D014810:Vitamin E / Q000031:analogs & derivatives / Q000032:analysis*; D024502:alpha-Tocopherol / Q000031:analogs & derivatives*
chemical_list: D000975:Antioxidants; D002214:Capsules; D013778:Tetrazolium Salts; C042207:4-anisyltetrazolium blue; D014810:Vitamin E; D007501:Iron; D024502:alpha-Tocopherol; D024505:Tocopherols