Used as a redox dye in biochemical assays, particularly in the measurement of ascorbic acid (vitamin C) concentration. It acts as an electron acceptor and changes color from blue to colorless when reduced, allowing visual or spectrophotometric monitoring of redox reactions. Commonly employed in photosynthesis research to study electron transport chain activity in chloroplasts. Also utilized in microbiology for rapid screening of bacterial metabolism and in enzyme activity tests involving dehydrogenases.