Used as a deuterated internal standard in mass spectrometry and NMR spectroscopy for accurate quantification and structural analysis of xylidine derivatives in complex mixtures. Its stable isotope labeling (deuterium) allows clear differentiation from non-labeled compounds during analytical testing, improving precision in environmental, pharmaceutical, and metabolic studies. Commonly applied in pesticide degradation research and industrial chemical monitoring due to its structural similarity to aromatic amines found in agrochemicals and dyes.