I dig, but I think it's a little of both. Do you see the difference in filter masks?
Pure nicotine is
extreeeeemly poisonous. A small amount absorbed through the skin can kill you. Accidentally inhaled?

Don't want to know.
I also don't know in what concentrations it's purchased or what solution it comes in to the suppliers but my guess is that it comes to these labs FDA certified pure. (98.9% or something)
The better production labs shoot for never letting any of the basic ingredients come into contact with the ambient atmosphere
or humans.
Everything is handled within a closed system. I don't know if that includes flavoring.