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Does the Red Shift in UV-Vis Spectra Really Provide a Sensing Option for Detection of N-nitrosamines Using Metalloporphyrins?

Gallou, Fabrice (2023) Does the Red Shift in UV-Vis Spectra Really Provide a Sensing Option for Detection of N-nitrosamines Using Metalloporphyrins? ACS omega, 8 (1). pp. 1154-1167.


N-nitrosamines are widespread cancerogenic compounds in human environment, including water, tobacco products, food, and medicinal products. Their presence in pharmaceuticals has recently led to several recalls of important medi-cines from the market and now require strict controls and tight limits of N-nitrosamines. Analytical determination of N-nitrosamines is expensive, laborious, and time-inefficient making development of simpler and faster techniques for their detection crucial. Several reports published in the previous decade have demonstrated cobalt porphyrin-based chemosensors selectively bind N-nitrosamines, which produces a red shift of characteristic Soret band in UV-Vis spec-tra. In this manuscript thorough re-evaluation of metalloporphyrin:N-nitrosamine adducts was performed using vari-ous characterization methods. Herein, we demonstrate that while N-nitrosamines can interact directly with cobalt-based porphyrin complexes, the red shift in UV-Vis spectra is not selectively assured and might result also from the interaction between impurities in N-nitrosamines and porphyrin skeleton or interaction of other functional groups within the nitrosamine structure and the metal ion within the porphyrin. We show that pyridine nitrogen is the inter-acting atom in tobacco-specific nitrosamines (TSNAs), as pyridine itself is an active ligand and not the cyclic N-nitrosamine fragment. When using Co(II) porphyrins as chemosensors, acidic and basic impurities in dialkylnitrosa-mines (e.g. formic acid, dimethylamine) are also UV-Vis spectra red shift producing species. Treatment of these ni-trosamines with solid bases prevents the observed UV-Vis phenomena. These results imply that cobalt based metal-loporphyrins cannot be considered as selective chemosensors for UV-Vis detection of N-nitrosamine moiety contain-ing species. Therefore, special caution in interpretation of UV-Vis red shift for chemical sensors is suggested.

Item Type: Article
Date Deposited: 07 Mar 2023 00:45
Last Modified: 07 Mar 2023 00:45


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