Used primarily in histology and microbiology for fluorescent staining of acid-fast organisms such as Mycobacterium species. It binds to the mycolic acids in the cell walls of these bacteria, allowing them to be visualized under a fluorescence microscope with high sensitivity. Commonly used in combination with other dyes like rhodamine B in the auramine-rhodamine stain method. This technique is especially valuable in diagnosing tuberculosis and other mycobacterial infections due to its rapid detection and higher yield compared to traditional Ziehl-Neelsen staining. Also applied in some industrial settings for quality control in detecting microbial contamination.