This has been an issue for some time, and finally there appears to be a study that gives objective information on contaminants in acetone. Ace hardware, kleanstrip, and many other kinds of acetone were examined in this study, and they were all found to have some levels of impurities. The four main impurities were:

diacetone alcohol (2-pentanone,4-hydroxy-4-methyl-)
mesityl oxide (3-penten-2-one,4-methyl-)
phorone (2,5-heptadien-4-one,2,6-dimethyl-)
phenol

although other impurities were found as well.

Can anyone else can comment on how bad they are? I don't think phenol is all that bad, espcially in trace quantities, but I know nothing about the toxicology of the others. Is it possible that any of these will just evaporate away?

Link to Article

Good find.

you googled those contams? they are byproducts from acetne synthesis?

im thinking these are all volatile and will evap?

Looked them up on wikiepdia and didn't find much. I remember diacetone alcohol boils around 166 C... but not sure whether it evaporates off at lower temperatures.

I'll look into the others more when I get a chance.

In the mean time, I was hoping somebody with chemistry knowledge could infer from the article how concentrated these contaminants are? Like, are we talking a few mg, micrograms, or nanograms per liter of acetone? In the words of Paracelsus, "the dose makes the poison"

Water boils at 100 C, still it evaporates even at 10 C.

All the impurities mentioned in this article is volatile and will therefore evaporate, just as acetone. Taken from the conclusion: "Moreover this work addresses only those compounds that are stable and volatile for the gas chromatographic system and does not address those components more labile or nonvolatile that may also be present in a solvent to alter or affect results."

So none of these contaminants is of any real interest when using acetone as a solvent and evaporating it. Some other trace impurities that are non-volatile might be though.