Phenylpyruvic acids in the urine is detected by:: (A) Guthrie's test, (B) VMA in urine, (C) Gerhas test, (D) Ferric chloride test
Answer is D. 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.