Ethylbenzene-d10 is primarily used as a labeled internal standard in analytical chemistry, particularly in gas chromatography-mass spectrometry (GC-MS) studies. Its deuterated structure allows for precise quantification and identification of non-deuterated ethylbenzene in complex mixtures, such as environmental samples or petroleum products. This compound is also employed in research involving isotope labeling to trace chemical reactions or metabolic pathways, providing insights into reaction mechanisms or biological processes. Additionally, it serves as a reference material in nuclear magnetic resonance (NMR) spectroscopy for structural analysis and molecular characterization.