Used as a stable isotope-labeled internal standard in mass spectrometry for quantifying catechol and its metabolites in biological samples. Its deuterated structure allows for accurate differentiation from non-labeled compounds during analytical testing. Commonly applied in pharmacokinetic studies, environmental monitoring, and metabolic research where precise measurement of aromatic diols is required. Also utilized in tracer studies to track chemical transformations and degradation pathways without altering the chemical behavior of the parent compound.