A newborn develops severe vomiting and symptoms of metabolic acidosis. Urinalysis results are positive for ketones and negative for glucose and other reducing substances. Which of the following screening tests would be positive in this patient?
a. Clinitest
b. Ehrilch test
c. DNPH
d. Ferric chloride tube test

This is a chemical compound used for quantitative identification of Ketones and Aldehydes in a sample.Since the urine analysis shows positive results for ketone and aldehydes,this is the test for the this. It is usually marked with yellow/orange precipitate(ppt) (dinitrophenylhydrazone).The latter is formed as a results of condensation reaction.

DNPH is a solid compound whose color changes from red to orange, when used to test for the carbonyl groups.Red when pure.

To conduct the test 1-2drops of the sample is dissolved in 2 ml of ethanol.

This should be added to about 3ml of DNPH,and shake severely for the solute and solvents to mixed up.

Usually, a precipitate should formed afterwards.However,if this did not appear, 15 minutes intervals should be observed for the precipitate( yellow or orange ppt) to appear.

The color of the precipitate depends nature of the carbon molecule or hydrocarbons in the sample. Thus, if the sample is aromatic that is unsaturated hydrocarbon e.g benzene red ppt appears, However, if straight hydrocarbon molecules (aliphatic) Orange ppt appears.