N-Nitrosoanatabine-d3 (N-NAT-d3) is the deuterium labeled N-Nitrosoanatabine (HY-145476). (R,S)-N-Nitrosoanatabine (N-NAT) is a tobacco-specific nitrosamine (TSNA) that has been found in tobacco, tobacco products, and electronic cigarettes. The (S) enantiomer comprises approximately 80% of the N-NAT found in commercial and research cigarettes and smokeless tobacco.3 Unlike other TSNAs, N-NAT is not carcinogenic in rats when administered at doses of 1, 3, and 9 mmol/kg.