Abstract
A procedure is described for separating vanillylmandelic acid (VMA) and homovanillic acid (HVA) from urine so that they can be assayed by chemical means or gas chromatography. The process comprises passing a threefold diluted urine over cation exchange column (AG 50W-X12) to remove catecol amines and amino acids. The VMA and HVA is then adsorbed from the diluted urine to an anion exchange column (AG 2-X8). After washing with water, the HVA and VMA are eluted with an NaCl-K 2CO 3 solution. The VMA can be determined by oxidation to vanillin directly. By extraction with n-pentanone-2, after acidification and evaporation to dryness, the residue may be redissolved for processing or treated with a methylating reagent for gas chromatography. For the latter purpose, 4-methoxy benzophenone is recommended as the internal standard.
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