ScreeningTests for UrinaryVanilmandelicAcid

The most common metabolite of neural crest tumors is vanilmandelic acid. There have recently been several screening tests for this substance in urine, in which diazotized aromatic amines couple with it to produce colored azo dyes. The general opinion has been that these tests are very nonspecific, yet little has been written concerning the exact chemical basis of the reaction with respect to biological compounds. We have examined this reaction in some detail, using p-nitroaniline as the diazotized amine, and found it to be surprisingly selective with respect to the chemical configuration of the compounds with which it couples to produce the characteristic violet color interpreted as a positive result. The important structural feature of most of these compounds is that they contain a hydroxymethyl group attached to the guaiacol nucleus, as seen in 3-methoxy4-hydroxybenzylalcohol. Addftlonal Keyphrases: neural crest tumors #{149} pheochromocytoma #{149} neuroblastoma #{149} screening #{149} diag