Widely used in biochemistry and analytical chemistry for labeling primary and secondary amines due to its high fluorescence and sensitivity. Commonly employed to derivatize amino acids, peptides, and proteins, enabling their detection and quantification in techniques like HPLC and capillary electrophoresis. Frequently used in the synthesis of fluorescent probes and sensors, especially for monitoring enzymatic activity or studying molecular interactions. Its sulfonyl chloride group readily reacts with amine groups, forming stable sulfonamide bonds, making it ideal for covalent tagging in biological systems. Also utilized in the preparation of environment-sensitive dyes, where fluorescence properties change in response to polarity or binding events.