A Modified Spot Test for Urinary 4-Hydroxy-3-methoxymandelic Acid (VMA)

Abstract

An aliquot of urine was spotted on an anion-exchange paper (ECTEOLA-cellulose) to avoid diffusion of VMA, and a solution of diazotized p-nitroaniline in 0.1N hydrochloric acid was sprayed on the paper. The wet paper was immersed in 0.5N ammonia solution to make the coupling reaction proceed and to remove the reagent. VMA yielded a violet colour. All of the urine specimens of patients with pheochromocytoma or neuroblastoma tested gave positivereaction.