nicotine oxidation?

[Rossum]

Thanks very much, Rossum. Your experiment and pics are excellent. It's really helpful to be able to visualize what you're talking about — I wouldn't have imagined just how dark brown the nicotine could get.
So, the nicotine I have really is just barely tinted (I guess that's due also to the much lower strength which is 36mg/ml — 3.6%) .

Keep in mind that the base in my pics is all 100 mg/ml, so ~3x as strong as yours.

I think this means that an equivalent percentage of oxidation would make it ~3x as dark as your 36 mg base.

 

[Cool_Breeze]

Keep in mind that the base in my pics is all 100 mg/ml, so ~3x as strong as yours.

I think this means that an equivalent percentage of oxidation would make it ~3x as dark as your 36 mg base.

Is it certain that all darkening is due to nicotine and oxidation thereof?

 

[Rossum]

Is it certain that all darkening is due to nicotine and oxidation thereof?

Due to nicotine? Almost certainly. I have kept bottles of PG, VG, and PG/VG mixtures at room temperature for years and have observed zero visible changes to them. But 100 mg/ml nic base kept at room temperature inevitably darkens.

Due to oxidation of nicotine? I'm not sure what other reaction would explain it.

 

[Diver9543]

It's mostly recommended to keep nic in a freezer if storing for long periods and a fridge with whatever opened amount you are using.

Well, since I keep a small amount (200ml) of nic at room temperature I should move around some of the gunpowder in my garage fridge to make room for an opened bottle of nic.

 

[Cool_Breeze]

I'll rank it right up there with watching paint dry.