Used as a stable isotope-labeled internal standard in mass spectrometry and nuclear magnetic resonance (NMR) studies to accurately quantify xanthine derivatives in biological samples. Its isotopic enrichment allows for precise tracking of metabolic pathways involving purine metabolism, particularly in pharmacokinetic and metabolic profiling research. Commonly applied in drug development and clinical diagnostics to distinguish endogenous compounds from exogenous analogs, enhancing measurement accuracy in complex matrices such as plasma, urine, and tissue extracts.