Used as an intermediate in the synthesis of azo dyes and pigments, particularly for producing water-soluble dyes with strong affinity for paper and textiles. Its sulfonic acid groups enhance solubility and improve binding to polar substrates. Also employed in the formulation of pH indicators due to its ability to undergo reversible color changes in different pH environments. Additionally, it serves as a derivatizing agent in analytical chemistry for detecting amines and phenols through chromogenic reactions.