Used as a stable isotope-labeled internal standard in environmental and agricultural research to accurately quantify atrazine and its metabolites in soil, water, and plant samples using mass spectrometry. Enables precise tracking of atrazine degradation pathways and helps assess environmental persistence and contamination levels without interference from matrix effects. Commonly applied in residue analysis, metabolic studies, and regulatory testing due to its identical chemical behavior to non-labeled atrazine while being distinguishable by analytical instruments.