Ritonavir-d6 is primarily used in research and development as an internal standard in analytical chemistry. It is especially valuable in mass spectrometry and liquid chromatography-mass spectrometry (LC-MS) studies to ensure accurate quantification and identification of Ritonavir in biological samples. By acting as a stable isotope-labeled reference, it helps in minimizing errors and improving the precision of pharmacokinetic and metabolic studies. This compound is crucial in drug development processes, enabling researchers to track the behavior, absorption, and distribution of Ritonavir in the body with high reliability.