Used primarily in research and development, particularly in analytical chemistry, as an internal standard in mass spectrometry for the quantification of lidocaine and its metabolites. Its deuterated structure allows for precise tracking and differentiation from non-deuterated compounds in complex biological matrices. This is crucial in pharmacokinetic studies, drug metabolism research, and forensic toxicology to ensure accurate and reliable data. Additionally, it aids in the development and validation of analytical methods for detecting lidocaine in various samples, such as blood, urine, or tissue.