Ammonium chloride-15N is primarily used as a labeled compound in research and analytical applications, particularly in studies involving nitrogen metabolism and tracing. It serves as a stable isotope tracer in environmental science, agriculture, and biological research to understand nitrogen cycling, fertilizer uptake, and nutrient dynamics in ecosystems. In biochemistry, it is employed to study protein synthesis, amino acid metabolism, and other nitrogen-based processes in living organisms. Additionally, it is utilized in nuclear magnetic resonance (NMR) spectroscopy as a nitrogen-15 source for labeling molecules, enabling detailed structural and mechanistic investigations. Its role in isotopic labeling makes it a valuable tool for advancing scientific understanding of nitrogen-related pathways and processes.