Isotope labelled N-Nitrosodiphenylamine (N525775), which is the N-nitroso analogue of diphenylamine that was once used as a rubber additive but is no longer due to undesirable carcinogenic effects (1). N-Nitrosodiphenylamine may have potential carcinogenic activity and is currently classified as a probable carcinogen by EPA with genetic toxicity (2,3).Drinking water contaminant candidate list 3 (CCL 3) compound as per United States Environmental Protection Agency (EPA), environmental, and food contaminants.