Used as a stable isotope-labeled internal standard in mass spectrometry for the quantification of methyl diethyldithiocarbamate in biological and environmental samples. Its deuterated structure allows for accurate differentiation from the non-labeled compound during analytical testing. Commonly applied in metabolism studies, pesticide residue analysis, and biomonitoring to assess exposure to dithiocarbamate fungicides. The labeled compound improves precision in detection by compensating for matrix effects and instrument variability.