Used as a deuterated internal standard in analytical chemistry, particularly in mass spectrometry and nuclear magnetic resonance (NMR) studies, to accurately quantify and track the behavior of triphenyl phosphate in environmental, biological, and industrial samples. Its deuterated structure allows for clear differentiation from non-labeled compounds, improving measurement precision. Commonly applied in studies assessing flame retardant degradation, metabolite formation, and environmental persistence due to its stability and detectability.