Used as a stable isotope-labeled internal standard in mass spectrometry and metabolic studies to accurately quantify octanoic acid and related metabolites in biological samples. Its deuterated structure allows for clear differentiation from non-labeled compounds during analytical testing. Commonly applied in pharmacokinetic research, lipid metabolism studies, and biomarker validation where precise measurement is critical. Also employed in tracing metabolic pathways due to its resistance to isotopic fractionation and high chemical stability.