I have some leftover ethanol containing small amount of ammonia solution (aq.). What would be the proper way to recover the alcohol without having ammonia in it?

My best guess is to neutralize the basic alcohol with some high boiling acid such as sulfuric or acetic and then proceed with fractional distillation.

Can you please confirm this won't produce any nasty side products?

Apart from ammonia and water, the ethanol contains only cactus plant material that came through Soxhlet (so probably mostly fats/oils).

...or maybe just heating the ethanol will do to evaporate the ammonia.

You will make diethyl ether this way. This might blow you up as ether is unstable and has a low autoignition point (Fumes tend to aggregate because its heavier than air and a lamp or basically any electrical device can ignite them). Also it will form peroxides in the air that can ignite the ethanol upon storing and with the friction of opening the bottle.

Use citric acid as it wont boil or other similar weak solid acids. It also is so weak that it wont be able to catalyse the production of diethyl ether.
Amonnium salts are unstable in heat. So dont boil to dryness and keep temp around the boiling point of the ethanol.

Check ph of the distillate.

Acetic acid will form ethylacetate which is similar to diethyl ether.
Acetic acid and ethanol will also form an azeotrope.

Thanks. Surely I don't want to make any ethers or esters in the process...

I will therefore use the citric acid and I guess this will work for methanol as well, right?

As for pH checking - the alcohol is either absolute or 190 proof, so do you think adding small amount of water will enable accurate pH checking?

I am testing different soxhlet teks that sometimes use either basic or acidic alcohol as a solvent, so recovering the solvent is now more complicated than just distilling it.

Fortunately, An1cca's mescaline extraction method requires only a small amount of ammonia (like 2-4 ml of 24% ammonia solution) but still I like to keep the recycled solvents free of contaminants.