Abstract
N-(4-methoxyphenyl)-1,4-phenylenediamine, abbreviated MPPD, also known as Variamine Blue B, is a p-phenylenediamine used as visual indicator in the complexometric titration of Fe(III) with EDTA (pH 2.0).It has been observed the colorless MPPD can be oxidized to its respective free radical MPPD*+ (purple) in buffered acid medium (pH 4,0; acetate).In presence of reducing agents (e.g. ascorb…