Quantitation of homogentisic acid in normal human plasma.

A new stable isotope dilution gas chromatograph-mass spectrometric method of analysis of homogentisic acid is described. Using this method, homogentisic acid is measured for the first time in normal human plasma. The assay of sera from nine normal individuals yielded a range of values from 2.4 to 12 ng/ml. The method appears to be very sensitive and may be useful in the characterization of heterozygotes for alkaptonuria and other disorders of tyrosine degradation.