Short answer? Yes, some of your concentrates contain ethyl alcohol (aka. EA, alcohol, PGA/pure grain alcohol). Which ones? That is going to take some research, and that is still kind of sketchy.
EA is used often, because of it's ability to carry (or suspend) certain molecules/compounds better than water, PG, or VG. So it is there for a purpose, and why you don't try to get rid of it in your concentrates. Once it is diluted into a mix/recipe, its importance goes away; and many will "breathe" (allow the fresh mix to sit uncovered (no cap, or drip tip) for a time.
How much time is another question all together. While breathing a fresh mix helps to allow unwanted elements (mainly EA) to escape; it also allows some wanted elements to escape, that can be beneficial to the overall flavor and aroma. These volatile compounds are often responsible for the more aromatic "fresh" notes it a mix. (side note: heating a mix also "cooks" these aromatic notes off faster) Generally speaking; flavors like lemon, and strawberry are often very susceptible to this kind of flavor loss.
To make matters worse; even though EA may not be used as a general carrier, for the overall concentrate (and sometimes included on the label's ingredients list); it may still be present as a carrier for individual compounds making up the concentrate. Here is just one example from TFA (Bavarian Cream):
View attachment 761741
Note that both the vanillin, and Maltol, are using an Ethyl carrier.
So, practically, what can be done? Well, one could air out/breathe everything and just accept any associated flavor loss. Or, vape a small amount of a untried fresh mix, and look for tell-tales.
Alcohol will give a kind of harsh "boozy," almost chemically, note to a mix. Think of what a sip of cheap liquor tastes like. If I get that, then (depending on the batch size); I might breathe it for 3(ish) hours, or longer as needed.
Rarely, do I find a mix needing more than 6-8 hours.
Truthfully, the majority of recipes I like, will naturally dissipate any EA after a week or two,
without any actual breathing. This can vary from mixer, to mixer; based on personal sensitivity; and bottle composition. If you are mixing and aging in glass; it is harder for the EA to escape, than if you were aging in a plastic bottle. Likewise; a bottle filled to the brim, will "hold on to" the EA longer, than a bottle that has a few mLs worth of air left at the top.
You haven't missed it. I am not aware of any
thorough listing for EA presence. TFA is probably one of the most transparent manufacturers, that I am aware of; and even on their site, one would have to have a significant chemistry background, or be willing to do a lot of cross referencing... which I am just not willing to do.
So, for
me, I like to vape just a small amount of any new (to me) recipe (often 5 or 6 drops is all that is needed), to get an idea of the mix's starting point, and then put it away for a day or 3. Then, I will vape a small amount again, and if it still has that boozy harshness; give it an hour or two, with the cap and dropper tip off. Then, I will cap it, shake it, and put it away again for at least a day. As my new "tester" mixes are only 10-15mL; that has always been long enough. Larger batch sizes may likely require longer.
Side Note: This is purely anecdotal, and only my personal opinion, but...
A lot of what I see blamed on the presence of EA, is more often, caused by the use of too much flavoring. Taste any one of your concentrates (the smallest drop on a fingertip is plenty); and see if you don't get a rather unpleasant chemical-like taste and even harshness. Why, would too much flavoring in an e-liquid, not provide similar results?
Excessively breathing an over-flavored mix,
can help soften a poorly formulated recipe, and make it taste better. But, why not just use a more appropriate amount of concentrate to begin with? It is more cost effective; and just plain tastes better... to me, anyway.