Simultaneous determination of genotoxic nitrosamine impurities in sitagliptin/metformin combination tablets: comparative evaluation of ionisation techniques coupled with LC-MS/MS and high-resolution mass spectrometry
Hyo‐Jeong Lee, Minki Shim, Seungjin Jung, Sang Beom Han, Dong‐Kyu Lee
Genotoxic nitrosamine impurities have increasingly posed substantial safety concerns for pharmaceutical formulations, particularly sitagliptin/metformin combination tablets. In particular, <i>N</i>-nitrosodimethylamine (NDMA) and 7-<i>N</i>-nitroso-3-(trifluoromethyl)-5,6,7,8-tetrahydro[1,2,4]triazolo[4,3-<i>a</i>]pyrazine (NTTP)-a newly identified nitrosamine drug-substance-related impurity (<i>N</i>-nitroso-sitagliptin or <i>N</i>-nitroso-STG-19)-have been detected in these pharmaceutical formulations. However, there are no established analytical methods addressing the simultaneous quantification of these two distinct classes of nitrosamine impurities in a single analysis. Therefore, we aimed to develop and validate a robust analytical approach utilising liquid chromatography-mass spectrometry (LC-MS) coupled with atmospheric-pressure chemical ionisation (APCI). Comparison of the ionisation modes and mass analysers revealed that LC-APCI-MS significantly outperformed electrospray ionisation for NDMA, whereas both ionisation methods were suitable for NTTP. Furthermore, both high-resolution quadrupole time-of-flight and triple quadrupole mass spectrometry platforms met the regulatory validation criteria, with excellent linearity (<i>R</i><sup>2</sup> > 0.997), recovery (95-102%), and precision (RSD < 5.7%) observed across both instruments. In contrast, GC-MS analysis, one of the major methods for NDMA or nitrosamine detection, was unsuitable for NTTP quantification because of inadequate volatility and chromatographic resolution. As sitagliptin/metformin remains the primary therapy for type 2 diabetes, the proposed method offers a practical solution for quality control monitoring and ensures a safe and stable supply of this widely used combination product.
https://doi.org/10.1039/d5ay01001b
Mass spectrometry
Nitrosamine
Impurity
Analytical Chemistry (journal)
Quadrupole
Ionization
Electrospray
Triple quadrupole mass spectrometer
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