Improvement of the FeCl3 test for phenylpyruvic acid.
A simple alternative colorimetric method has been developed for quantitative determination of phenylpyruvic acid in urine based on the improved stability of the ferric complex of enol-phenylpyruvate in water-dimethylsulfoxide 50% vol. mixed solvent. The method can be applied directly to urine or to a dry ether-extract of urine. Operating on the dry ether-extract of urine, detection of phenylpyruvic acid is possible at an amount of as low as 1 mg/100 ml. Whereas, if urine samples are processed, detection is possible for a concentration of as low as 5 mg/100 ml and quantitative determination for a concentration greater than 10 mg/100 ml. The test carried out on a diaper wet with urine retains the same sensitivity and shows instantaneous development of the green colour.
D002712:Chlorides; D003124:Colorimetry / Q000379:methods; D004121:Dimethyl Sulfoxide; D005290:Ferric Compounds; D006801:Humans; D007202:Indicators and Reagents; D010667:Phenylpyruvic Acids / Q000652:urine*
D002712:Chlorides; D005290:Ferric Compounds; D007202:Indicators and Reagents; D010667:Phenylpyruvic Acids; D004121:Dimethyl Sulfoxide