Used as a stable isotope-labeled internal standard in mass spectrometry and metabolic studies, particularly in quantifying succinic acid and related metabolites in biological samples. Its deuterated structure allows for accurate differentiation from non-labeled compounds during analytical testing. Commonly applied in metabolomics, pharmacokinetics, and biomarker discovery to trace metabolic pathways such as the citric acid cycle. Also employed in pharmaceutical research to study enzyme mechanisms and metabolic flux without altering the chemical behavior of the parent compound.