Spectrophotometric analysis of vitamin E using Cu(I)-bathocuproine or/and Fe(Il)-2,4,6-tris-(2′-pyridyl)-s-triazine complexes

Vitamin E (tocopherols and tocotrienols) antioxidants are determined by reducing Cu(II) to Cu(I) or Fe(III) to Fe(II) in presence of vitamin E and subsequent complexation of Cu(I) with bathocuproine and/or Fe(II) with 2,4,6-tris-(2'-pyridyl)-s-triazine (TPTZ). Both the reactions are monitored separately, Cu(I)-bathocuproine at 479 nm where as, Fe(II)(TPTZ) at 595 nm spectrophotometrically. Linear calibration curves are achieved for both complexes between 1 to 5mug ml(-1) for vitamin E. The methods were applied for the determination of vitamin E in pharmaceutical preparations and edible oils. Vitamin E, from edible oils, was solvent extracted into n-hexane prior to saponification. Furthermore, a single lined flow injection manifold was also examined. A large excess of Cu(II) or Fe(III) with different concentrations of vitamin E in buffer pH 4 was run on the line and constant amounts of reagent bathocuproine or TPTZ in each case was injected through the injector. The peak height shows a linear relationship for vitamin E between 0.5 to 2.5 mug ml(-1) for both complexes.