Application of a New Iron Reagent, 3-(2-Pyridyl)-5, 6-diphenyl-1, 2, 4-triazine, to Spectrophotometric Determination of Tocopherols

Abstract

Tsen's modification of Emmerie-Engel method was further improved by applying 3-(2-pyridyl)-5, 6-diphenyl-1, 2, 4-triazine (PDT) in place of bathophenanthroline as iron reagent. The reaction mixture of PDT, ferric chloride and tocopherol gave a spectrum with the maximum absorption at 554 nm. The sensitivity of PDT was about 1.2-fold of bathophenanthroline for each tocopherol. The rate of color development of PDT was fast similarly to bathophenanthroline. The calibration curves obtained for α-, β-, γ- and δ-tocopherols by the method using PDT followed Beer's law. The present method was much more economical than the bathophenanthroline method.