Spectrophotometric Titration of Resorufin and Resazurin with Iron(II) in Strong Phosphoric Acid Medium and Resorufin as a New Redox Indicator in the Reductimetric Titration of Some Metal Ions

摘要

Spectrophotometric titration methods have been developed for the determination of micro-gram quantities of resazurin and resorufin and the analysis of their binary mixture using iron(II) as a reductant in high concentration of orthophosphoric acid (10.5 M) medium.Both resazurin and resorufin are reduced to a blue-green semiquinone (lambda_(mzx) 640 nm) with iron(II) in three electrons and one electron reduction steps respectively.Resorufin has been proposed as a new advantageous redox indicator in the determination of V(V),V(IV),Mo(VI),Cr(Vl),Cu(II),Sb(V),As(V),Os(VIII) and Ir(IV) in phosphoric acid medium using the same reductant