Used as a stable isotope-labeled internal standard in mass spectrometry-based bioanalytical assays. Its primary application is in quantitative analysis of metabolites, peptides, and small molecules, where it helps correct for matrix effects and instrument variability. Due to the deuterium labeling, it provides excellent differentiation from the non-labeled compound in LC-MS/MS, ensuring accurate and precise measurement in pharmacokinetic and metabolic studies. Commonly applied in drug development and biomarker validation workflows.