Bismuthiol II is primarily used as a chelating agent in analytical chemistry for the detection and quantification of heavy metals, particularly bismuth and lead. It forms stable complexes with these metals, allowing for precise measurement in various samples. In environmental testing, it aids in monitoring metal contamination in water and soil. Additionally, Bismuthiol II is employed in biochemical research to study metal-protein interactions and metal ion transport mechanisms. Its ability to selectively bind to specific metals makes it valuable in industrial processes for metal recovery and purification.