How long can N theoretically last?

[KlMeNw]

Is it at all possible to get N now? If so, what's the longest you could store it before it goes bad?

 

[Praestat_Mori]

There's a thread where the stability of SN and N is being discussed: https://sanctioned-suicide.net/threads/stability-of-sn-and-n.151639/

Afaik it's still possible in South America but it seems to become harder to acquire it.