Afatinib impurity 11 is primarily used in the pharmaceutical industry as a reference standard in the quality control and analytical testing of Afatinib, a medication used to treat certain types of non-small cell lung cancer. It helps in identifying and quantifying impurities during the manufacturing process, ensuring the drug's purity, safety, and efficacy. This impurity is crucial for developing and validating analytical methods, such as HPLC or LC-MS, to monitor the presence of unwanted by-products in Afatinib formulations. Its role is essential in complying with regulatory standards and maintaining the high quality of the final pharmaceutical product.