Used as a stable isotope-labeled internal standard in gas chromatography-mass spectrometry (GC-MS) analyses, particularly in environmental and petroleum testing. Its deuterated structure allows for accurate quantification of nonadecane and similar hydrocarbons by distinguishing it from the non-labeled compounds in complex mixtures. Commonly applied in studies involving hydrocarbon degradation, metabolic tracing, and fuel analysis where precise measurement of aliphatic hydrocarbons is required. Its high isotopic purity minimizes interference and enhances detection sensitivity.