Used as a standard solution in chemical oxygen demand (COD) testing to determine the amount of organic pollutants in water and wastewater. It helps in assessing the efficiency of wastewater treatment processes by measuring the oxygen equivalent of the organic matter present. Commonly used in environmental laboratories and industrial water quality control to ensure regulatory compliance and monitor pollution levels. The solution provides a known concentration for calibration and validation of COD measurement methods, ensuring accuracy and reliability in test results.