OXIDATION OF N-NITROSAMINES AT A RUTHENIUM-BASED MODIFIED ELECTRODE IN AQUEOUS-SOLUTIONS

A modified electrode comprising a film of mixed-valent ruthenium oxides with cyano cross-links on glassy carbon mediates the oxidation of N-nitrosamines. The oxidations are two-electron processes that are complicated by neither coupled chemical reactions in the solution phase nor heterogeneous kinetics during cyclic voltammetry at pH 0.3 with scan rates of 4-144 mV s(-1) Over the pH 0.3-3.0 range, the current is limited by diffusional mass transport to the electrode\solution interface. Using N-nitrosodi-n-propylamine as a model compound, the mechanism of the oxidation was shown to involve a coupled protonation of the oxidized form of the mediating film; the pK(a) of this material was estimated as 2.9. Bulk-scale controlled-potential electrolysis of N-nitrosamines yielded the corresponding N-nitramine; gas chromatography-mass spectrometry did not show any evidence of side reactions. The efficiency of this process, together with the known stability of this modified electrode, makes electrochemical oxidation an alternative to the chemical oxidation of N-nitrosamines by hydrogen peroxide.