This chemical, known as INT (Iodonitrotetrazolium sodium salt), is primarily used as a redox indicator in biochemical, microbiological, and histochemical assays, particularly for detecting dehydrogenase activity, cell viability, and microbial metabolism. It is commonly employed in tetrazolium reduction assays (such as the INT assay), where it is reduced by metabolically active cells, bacteria, or enzymes like NADH dehydrogenase to form a colored, insoluble formazan product, allowing for the quantification of cell proliferation, viability, cytotoxicity, and enzymatic activity. Its high sensitivity and stability make it suitable for high-throughput screening in drug discovery, cancer research, environmental microbiology, and pathology. Additionally, it is utilized in enzyme activity assays and histochemical staining to visualize metabolic processes in tissues and cells. Its water-soluble nature ensures compatibility with various biological systems, making it a versatile tool in biomedical, microbiological, and diagnostic research.