Nessler reagent is widely used in analytical chemistry for the detection and quantification of ammonia and ammonium ions in various samples. It is particularly valuable in water quality testing, where it helps determine the presence of ammonia in drinking water, wastewater, and environmental samples. The reagent reacts with ammonia to form a yellow to brownish-colored complex, allowing for both qualitative and quantitative analysis through colorimetric methods. In environmental monitoring, it aids in assessing pollution levels and the effectiveness of water treatment processes. Additionally, it is employed in biological and biochemical research to measure ammonia produced in enzymatic reactions or metabolic processes. Its sensitivity and specificity make it a crucial tool in laboratories for ensuring safety and compliance with environmental regulations.