Sofosbuvir Impurity K is primarily used in the pharmaceutical industry as a reference standard during the quality control and analytical testing of Sofosbuvir, an antiviral medication. It helps in identifying and quantifying impurities in Sofosbuvir drug substances and formulations, ensuring the drug's safety, efficacy, and compliance with regulatory standards. Its application is critical in research and development processes to maintain the purity and consistency of the active pharmaceutical ingredient (API). Additionally, it aids in the validation of analytical methods used for impurity profiling, contributing to the overall quality assurance of the drug product.