Used as a deuterated internal standard in analytical chemistry, particularly in mass spectrometry and gas chromatography, to accurately quantify dioctyl phthalate (DOP) levels in environmental and biological samples. Its stable isotopic labeling allows for precise tracking and differentiation from non-labeled compounds, improving measurement accuracy in studies related to plasticizer migration, exposure assessment, and contamination analysis. Commonly applied in monitoring phthalate metabolites in urine, blood, and wastewater to assess human and environmental exposure.