N,N-Diethyl-p-phenylenediamine sulfate salt

N,N-Diethyl-p-phenylenediamine sulfate (DPD) is used as a chromogenic indicator or reagent in analytical chemistry and in water quality testing. It is commonly used in a test called the DPD method, primarily for the measurement of free and total chlorine by titrimetric, colorimetric and spectroscopic methods in water. DPD reacts with free chlorine (hypochlorous acid and hypochlorite ions) to form a pink or magenta-colored compound. The intensity of the color is directly proportional to the concentration of chlorine, making it a convenient method for chlorine quantification. In general, it is used for spectrophotometric determination KIO4 levels, drugs (containing phenolic groups or aromatic amino groups) and as a peroxidase substrate. DPD has been developed as a color developing agent in photgraphy.