Used as a stable isotope-labeled internal standard in analytical chemistry, particularly in mass spectrometry and gas chromatography. Its deuterated methyl group allows for accurate quantification of acetophenone and related compounds in complex matrices such as environmental samples, biological fluids, and pharmaceutical formulations. Due to its chemical similarity to non-labeled acetophenone, it closely matches the analyte’s behavior during extraction and analysis, improving measurement precision and reliability. Also employed in metabolic studies to trace reaction pathways without altering the chemical properties of the parent compound.