Used as an internal standard in analytical chemistry for the quantification of atenolol in biological samples, ensuring accurate measurement in pharmacokinetic studies. It aids in the development of sensitive and specific methods for drug monitoring in plasma or urine. This labeled compound is particularly valuable in mass spectrometry, where its deuterium atoms provide a distinct mass signature, reducing interference and enhancing precision. It is also employed in metabolic studies to track the distribution and transformation of atenolol in the body, supporting research on its efficacy and safety.