[Fluorescence quenching method for the determination of p-hydroxyphenylpyruvic acid]

A fluorescence quenching method for the determination of p-hydroxyphenylpyruvic acid with trytophan in the medium pH 11.01 NH3-NH4Cl is studied. The calibration curve is linear for p-hydroxyphenylpyruvic acid from 0 to 15 micrograms.mL-1 with lambda ex/lambda em = 285/356 nm. The detection limit is 0.37 microgram.mL-1. Twenty replicate determinations of solutions containing 10 micrograms.mL-1 p-hydroxyphenylpyruvic acid show a relative standard deviation of 1.2%. This method can be applied to the determination of p-hydroxyphenylpyruvic acid in serum with satisfactory results.