IDENTIFICATION AND QUANTITATIVE-DETERMINATION OF ORTHO-HYDROXYMANDELIC AND META-HYDROXYMANDELIC ACID IN HUMAN-URINE

o‐Hydroxymandelic acid and m‐hydroxymandelic acid have been identified in human urine by gas chromatography mass spectrometry selected ion monitoring. After solvent extraction the urinary acids were converted to their O‐trifluoroacetoxy methyl ester derivatives which were identified by comparison of the retention times and relative intensities of the characteristic m/z 374 and m/z 315 ions with those from authentic samples. 4,6‐[2H2]‐o‐hydroxymandelic acid and 2,4,6‐[2H3]‐m‐hydroxymandelic acid were synthesized for use as internal standards in the quantitative estimation of the isomeric hydroxymandelic acids excreted in urine. In ten normal adults the following results were obtained: o‐hydroxymandelic acid 4–16 ng mg−1 creatinine and m‐hydroxymandelic acid 11–71 ng mg−1 creatinine. Acid hydrolysis of the urine or ingestion of a diet of known composition did not affect these results, indicating that these compounds are excreted as the free acids and probably arise by metabolism of the corresponding phenylethanolamine(s). Copyright © 1979 Heyden & Son Ltd