Thanks for your reply, very helpful.
We have been told by the authorities to test our product for N-nitrosomelatonin, but during development we see that the standard impurity, N-nitroso melatonin, is very unstable as we assumed based on literature. But we have tried with literature to argue that this N-nitrosomelatonin is not a regular nitrosamine and therefore should not be considered as one. This has not been accepted and therefore we are trying to develop a method.
In order to further support our findings, does anyone know whether it could work to perform an AMES test in an aprotic suspension if we see that the nitrosamine impurity is unstable in an aqueous solution?