Rothera's Test
It is highly sensitive for both acetoacetic and acetone. Although it is one of the oldest methods still it is widely used.
Procedure:
- Take about 5ml of urine in a test tube and saturate with ammonium sulphate and add few crystals (or about 0.5ml of 20% aqueous solution) of sodium nitroprusside. If solid crystals are taken, shake well the tube to dissolve the crystals and wait for about 10 minutes.
- Now carefully pour down the side of the test tube about 2 - 3 ml of concentrated ammonia (Liquor ammonia) so that it forms a layer on the top of saturated urine. Formation of a purple ring at the junction indicates positive test.