New Indicator for the Titration of Iron(III) with EDTA

Abstract

New metal indicators, 7 -(2-hydroxy-1-naphthylazo)-8-hydroxy-quinoline-5-sulfonic acids were synthesized. Among them 7-(6-nitro-4-sulfo-2-hydroxy-1-naphthylazo)-8-hydrqxyquinoline-5-sulfonic acid(NH-SNAZOXS) is recommended as an indicator for the titration of iron(III) with EDTA. The sharp color change at the equivalence point from yellow to violet is obtained at pH 2.0 to 3.0 at 50°.