N-Nitrosamine Quantitation in Pharmaceticals by Tandem Mass Spectrometry

N Nitrosamines, potent mutagenic contaminants, have triggered multiple pharmaceutical recalls since 2018, underscoring the need for rapid and confident detection tools. Current analytical methods include HPLC-based separation followed by quantitation by mass spectrometry (MS), a relatively slow process. In a previous study, we introduced a rapid and straightforward method of multiple reaction monitoring (MRM) based nano electrospray ionization (nESI) MS for selective quantitation of sixteen N nitrosamines across diverse pharmaceutical matrices. That approach leveraged lithium adduct formation to enhance ionization efficiency and produce diagnostic fragmentations, achieving limits of detection below 10 ng/mg with high precision and sub minute analysis time.
Building upon this foundation, we extend our methodology through use of an automated desorption electrospray ionization two dimensional tandem mass spectrometry (DESI 2D MS/MS) platform. Lithium adducted N nitrosamines exhibit a universal 30 Da (NO) neutral loss under collision induced dissociation, which DESI 2D-MS/MS continuously captures without prior precursor ion selection. Integrated with a motorized XY stage, the system enables untargeted surface analysis and acquires comprehensive fragmentation data in <10 s per sample. Applied to several pharmaceutical matrices, we show confident detection of sixteen N-nitrosamines at the 10ng/mg level. This advance establishes DESI-2D MS/MS as a fast, autonomous screening platform capable of flagging nitrosamine contaminants in pharmaceuticals or environmental samples with high confidence, guided by their characteristic neutral loss signature. The 2D MS/MS method exemplifies the evolution of mass spectrometry toward compact, intelligent, and field deployable chemical sensing.