Used as a stable isotope-labeled internal standard in mass spectrometry and chromatography for accurate quantification of indoleacetic acid (IAA) in plant tissues and biological samples. Enables precise tracking of IAA metabolism, transport, and distribution in plant physiology studies. Helps distinguish endogenous IAA from exogenous sources in metabolic labeling experiments. Supports research in plant growth regulation, hormone signaling, and environmental stress responses by providing reliable analytical measurements.