Used in water quality testing to detect and measure chlorine, bromine, ozone, and other oxidizing agents in swimming pools, drinking water, and wastewater. The reagent reacts with these disinfectants to produce a pink color, the intensity of which corresponds to the concentration of the oxidizer. Commonly used in colorimetric tests with test kits or photometers for quick, on-site analysis. Helps maintain proper sanitation levels and ensures compliance with health standards.