Sulforhodamine B acid chloride is widely used as a reactive dye in biochemical research, particularly for labeling proteins, peptides, and other biomolecules. Its ability to form stable covalent bonds with amino groups makes it valuable for fluorescence-based studies, enabling the tracking and visualization of molecular interactions in live cells or fixed tissues. It is also employed in the development of fluorescent probes for imaging and diagnostic applications, offering high sensitivity and photostability. Additionally, it serves as a key component in the synthesis of fluorescent conjugates for flow cytometry, microscopy, and other analytical techniques.