Used as an internal standard in analytical chemistry for the quantification of acetaminophen in various samples, including biological fluids like blood and urine. It is particularly valuable in mass spectrometry and chromatography techniques due to its isotopic labeling, which ensures accurate and reliable measurements. Additionally, it aids in pharmacokinetic studies to understand drug metabolism and distribution in the body. Its application extends to quality control in pharmaceutical manufacturing to verify the consistency and purity of acetaminophen-containing products.