Stereospecific Response of E/Z-isomers of N-Nitrososarcosine in LC–ESI–MS/MS

Abstract The carcinogenic compound N-nitrososarcosine (NSAR) is found in foods and tobacco products, and its quantification is of great interest. Although the presence of two stereoisomers, E- and Z-NSAR, is well-known, individual investigation of the isomers has not been reported so far. The presen...

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Published in:Journal of chromatographic science 2021-10, Vol.59 (9), p.813-822
Main Authors: Werneth, Madeleine, Pani, Jutta, Hofbauer, Ludwig, Pummer, Stefan, Weber, Maria-Theres, Pour, Georg, Kählig, Hanspeter, Mayer-Helm, Bernhard, Stepan, Herwig
Format: Article
Language:English
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Summary:Abstract The carcinogenic compound N-nitrososarcosine (NSAR) is found in foods and tobacco products, and its quantification is of great interest. Although the presence of two stereoisomers, E- and Z-NSAR, is well-known, individual investigation of the isomers has not been reported so far. The present study by liquid chromatography–electrospray ionization–tandem mass spectrometry (LC–ESI–MS/MS) reveals that (i) the mass spectrometric responses of the isomers differ by a factor of approximately two and (ii) the isomer ratio is unstable in freshly prepared standard solutions. As a consequence, NSAR concentrations determined by LC–ESI–MS/MS are biased if those facts are not taken into account. The method described here overcomes the difficulty of stereospecific response by adjusting the isomer ratio and was applied to 100 tobacco products and fully validated for moist and dry snuff reference materials showing expanded measurement uncertainties of ~20% and limits of quantification of ~20 ng/g.
ISSN:0021-9665
1945-239X
DOI:10.1093/chromsci/bmab013