Impurities in pharmaceuticals are the unwanted chemicals that remain with the active pharmaceutical ingredients (APIs). They may also develop during formulation or upon aging of both API and formulated APIs to medicines or other chemicals. The presence of these unwanted chemicals even in small amounts may influence the efficacy and safety of the pharmaceutical products. Impurity profiling (i.e., the identity as well as the quantity of impurity in the pharmaceuticals), is now receiving important critical attention from regulatory authorities. The different pharmacopoeias, such as the British Pharmacopoeia (BP) and the United States Pharmacopoeia (USP), are slowly incorporating limits to allowable levels of impurities present in the APIs or formulations. Below is the impurity test for NicSelect liquid nicotine, it is important for us and our manufacturer to be thorough, consistent, and transparent.