Aniline-d7 is primarily used as a deuterated internal standard in analytical chemistry, especially in mass spectrometry and nuclear magnetic resonance (NMR) spectroscopy. Its key application lies in quantitative analysis where it serves as a reference compound to accurately measure the concentration of non-deuterated aniline and related aromatic amines in complex mixtures. Due to its identical chemical properties but distinct mass or NMR signal, it enables precise tracking and differentiation from the analyte of interest.

It is widely employed in environmental testing, pharmaceutical research, and metabolic studies to monitor aniline derivatives and assess reaction pathways. The deuterium labeling enhances detection sensitivity and reduces background interference, making it valuable in high-precision analytical methods. Additionally, it is used in kinetic isotope effect studies to investigate reaction mechanisms involving aniline compounds.