if all else fails, evaporate the entire liquid off. This may take a while but at least you will be sure that there is no acetone left...
Then re-liquify or... since then you've already got a dry mass ... you could pull with IPA or acetone, filter, evaporate, re-X... spice. I suppose this would work...
Be careful though since the dry mass will be highly basic - breathing in any dust or powder from this can cause damage to your lungs...
As for orion's suggestion, I suppose you could try smelling whether the acetone has evapped yet or not.