Used as a deuterated internal standard in analytical chemistry, particularly in mass spectrometry and gas chromatography, to accurately quantify nonylphenol levels in environmental samples. Its primary application is in monitoring pollution in water, soil, and wastewater due to nonylphenol’s endocrine-disrupting properties. The deuterated structure allows for clear differentiation from non-deuterated compounds during analysis, improving measurement precision and reliability. Commonly employed in environmental testing labs and regulatory studies assessing the impact of industrial surfactant degradation.