Phenylpyruvic acids in the urine is detected by:
Ferric chloride test is a quantitative test for the detection of phenylketonuria; the addition of ferric chloride to urine give rise to a blue green colour in the presence of phenylketonuria. This colour is due to phenylpyruvate.
Guthrie's test
VMA in urine
Gerhas test
Ferric chloride test