You guys are both right, what I am saying however, is that something other than oxidation is responsible for the change in color.
I am guessing if you mixed up some flavorings in a base with no nic involved, the mix will change color anyway. I may to try to do this just to see. Heck, I got nothing else to do anyway![]()
You are correct there is also a chemical reaction between the flavor and nicotine molecules that add to the color. Such as chocolates turn very dark brown, Vanillas turn pink Etc. it's not all oxidation.