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I just read the reply talking about the distilling process.  I am in fact
a chemistry teacher with a bachelor's and some graduate work in chemistry.

The description of distilling is pretty accurate.  Theoretically a
distilled liqud is pure, but if a chemist needed something ABSOLUTELY
pure, he would distill it several times.  Once the vanilla (which has
probably only been distilled once and therefore probably contains some
gluten) is put in a recipe and cooked, the alcohol will evaporate, but it
should leave anything dissolved in it behind.  Now, chances are it will
take a little with it, but, by the whole principle of distillation (
which is in essence occurring again), most of the solutes (gluten & other
materials) will be left behind in the food.

Melissa
St. Louis, MO