Paper-Chromatographic Quantitation of 4-Hydroxy-3-methoxymandelic Acid (VMA) in Urine

We describe a quantitative paper-chromatographic method for assaying 3-methoxy-4-hydroxymandelic acid (VMA) in urine. VMA is extracted from acidified urine into ethyl acetate, separated from interfering amine, acid, and alcoholic metabolites by paper chromatography, and reacted with diazotized p -nitroaniline. The colored derivative is eluted and spectrophotometrically analyzed. Recoveries of replicates of standard and sample solutions on the same chromatogram exceeded 95%.