Used as a deuterated internal standard in mass spectrometry for quantifying choline and related metabolites in biological samples. Its stable isotope labeling (deuterium) allows for accurate measurement in metabolic studies, particularly in lipid and neurotransmitter research. Commonly applied in clinical diagnostics and pharmaceutical development where precise tracking of metabolic pathways is required. Also employed in NMR spectroscopy due to deuterium enrichment, enhancing signal resolution in complex mixtures.