Used primarily as a labeled internal standard in mass spectrometry and gas chromatography for the detection and quantification of benzyl chloride and related compounds. Its deuterated structure allows for clear differentiation from non-labeled analytes, improving accuracy in analytical measurements. Also employed in metabolic studies to track reaction pathways and degradation products in environmental and biological systems. Serves as a reagent in organic synthesis where isotopic labeling is required to study reaction mechanisms or to prepare deuterated derivatives of pharmaceuticals and agrochemicals.