Used as a stable isotope-labeled internal standard in mass spectrometry and gas chromatography for accurate quantification of decanoic acid in biological samples. Enables tracing of metabolic pathways involving medium-chain fatty acids, particularly in studies of lipid metabolism, mitochondrial function, and energy production. Applied in research on ketogenic diets and metabolic disorders due to its role in tracking fatty acid oxidation. Also used in pharmaceutical development to study drug metabolism when decanoic acid is a component or metabolite.