Used as a stable isotope-labeled internal standard in analytical chemistry for the accurate quantification of 2,4-D (2,4-dichlorophenoxyacetic acid) residues in environmental and biological samples. Its primary application is in mass spectrometry and chromatography workflows, where it helps distinguish between natural 2,4-D and the labeled compound due to the mass shift from 13C6. This allows precise measurement of 2,4-D levels in soil, water, food, and plant tissues, supporting environmental monitoring, pesticide metabolism studies, and regulatory compliance testing.