Chlorpyrifos-(diethyl-d10) is primarily used as an internal standard in analytical chemistry, particularly in mass spectrometry and chromatography. Its deuterated structure allows for precise quantification and detection of chlorpyrifos and its metabolites in environmental and biological samples. This chemical is essential in residue analysis for monitoring pesticide levels in food, water, and soil, ensuring compliance with safety regulations. It also aids in toxicological studies to understand the metabolism and environmental impact of chlorpyrifos. Its stability and distinct isotopic signature make it a reliable tool for accurate and sensitive measurements in complex matrices.