Used as a stable isotope-labeled internal standard in analytical chemistry, particularly in mass spectrometry and gas chromatography, to accurately quantify 2,6-dimethylaniline and related compounds in complex matrices. Its deuterated structure allows for clear differentiation from non-labeled analytes, improving measurement precision in environmental, pharmaceutical, and toxicological studies. Also employed in metabolic research to trace reaction pathways without altering the chemical behavior of the parent compound.