Used primarily as a reagent in analytical chemistry for the detection and quantification of various substances, including nitrites in water and environmental samples (via colorimetric assays forming a red azo dye) and hydrogen peroxide and other peroxides. It plays a crucial role in enzymatic assays and biochemical research. Additionally, it serves as a key intermediate in the synthesis of dyes and pigments, contributing to the production of vibrant and stable colorants for industrial applications. Its utility extends to the field of photography, where it acts as a developing agent in certain photographic processes, aiding in the creation of high-quality images.