<i>N</i>-Nitrosamine Quantitation in Pharmaceuticals by Tandem Mass Spectrometry

The mutagenic potential of <i>N</i>-nitrosamines has heightened regulatory scrutiny and prompted numerous drug recalls due to their formation as impurities during pharmaceutical manufacturing. However, the simultaneous and rapid analysis of multiple <i>N</i>-nitrosamines remains challenging. In this study, we show a rapid (<1 min) and robust multiple reaction monitoring (MRM) approach for the trace-level quantitation of <i>N</i>-nitrosamines across a wide concentration range (10 ng/mg to 500 μg/mg) in diverse pharmaceutical matrices. Lithium cation (Li⁺) adduct formation during ionization is utilized to enable diagnostic fragmentation in tandem mass spectrometry (MS/MS), yielding a limit of detection of 5 ng/mg with high quantitative accuracy and precision. This method is also applied to trace analysis of <i>N</i>-nitrosated drug impurities within their parent pharmaceutical matrices. With minimal sample preparation, rapid analysis times, and broad applicability to complex pharmaceutical formulations, this MRM method offers a practical and powerful tool for the identification and quantitation of <i>N</i>-nitrosamines and its potential adoption in pharmaceutical quality control and industrial settings.