react 1ml of yourketone with 15-20mls of ice cold saturated aqueous sodium metabisulfite, in a test tube. shake like hell for 2minutes, return to freezer for a couple then repeat a couple more times, at end all of(or some) the yellow ketone that floated on top will have reacted and become a white suspension; your ketone/bisulfite adduct, proof that you ineed have created ketone.
this technioque can also be used on a preparative scale instead of distilling (for the lazy) and then the ketone is released by reacting you bisulfite adduct with an excess of Na2HCO3 solution.