Abstract
Liquid chromatography-mass spectrometry (LC-MS) is the standard instrumental procedure for quantitating nitrosamine drug substance-related impurities (NDSRIs) due to its superior specificity and sensitivity. Electrospray (ESI) is the most used ionization source in LC-MS. However, analytes can undergo fragmentation directly within the ESI source before reaching the collision cell. This phenomenon is known as in source fragmentation (ISF). To our knowledge, the impact of ISF on analytical procedure performance for NDSRI measurements has not been explored. Thus, here, we present a case study on an NDSRI (nitroso-bumetanide) to illustrate how efforts can be taken during analytical procedure development to minimize ISF while still achieving the analytical target profile (ATP) measurement goals. In addition, we share some thoughts about incorporating risk assessment and leveraging prior knowledge for analytical procedure development for NDSRI LC-MS technology-based testing purposes.