Nitroprusside Tube Test (Modified Rothera's Test) for ketone bodies

Nitroprusside Tube Test (Modified Rothera's Test)-This test is sensitive for ketones in urine. This is the original nitroprusside method for ketone bodies. The same principle is applied in this test as in the above tests: Nitroprusside in alkaline solution reacts with a ketone body to form purple colour.

Reagent:Mix and grind together 100 g ammonium sulphate, 3 g sodium nitroprusside and 50 g sodium carbonate (anhydrous).

Note::Sodium nitroprusside is toxic and should be handled with care.

Procedure

1. Add about 0.5-1.0 g sodium nitroprusside mixture to the bottom of a small test tube.

2. Add 1 drop of fresh urine (enough to moisten the dry reagent).

3. Observe the colour change within 1-2minutes.