Used primarily as an internal standard in mass spectrometry and liquid chromatography-tandem mass spectrometry (LC-MS/MS) for the accurate quantification of clonazepam in biological samples. Its deuterated acetamido group enhances detection specificity and reduces interference from matrix effects, making it ideal for forensic toxicology, clinical drug monitoring, and pharmacokinetic studies. The compound enables precise measurement of clonazepam and its metabolites in urine, blood, and plasma by providing a stable isotopic reference that closely mimics the behavior of the non-labeled drug during sample processing and analysis.