Determination of urinary 3-methoxy-4-hydroxy-mandelic acid (vanillylmandelic acid) by paper electrophoresis

A procedure is presented for the determination of 3-methoxy-4-hydroxymandelic acid (or vanillylmandelic acid) in urine. For separation from other phenolic acids, paper electrophoresis at low constant current is employed. Data are presented to show that this method is useful as a confirmatory test for pheochromocytoma, in which elevated urinary levels of vanillylmandelic acid are found. rrHE DETERMINATION of 3-methoxy-4-hydroxymandelic acid, also called vanillylmandelic acid (VMA), in urine has recently come into use as a confirmatory test for pheochromocytoma (1-6). Armstrong and his associates (1, 2, 7) discovered that this phenolic acid oc-curred in small amounts in normal human urine and in elevated con-centrations in pheochromocytoma. As a result of their observations (1, 2) and especially of those by others in related investigations (8-11), VMA was shown to be one of the major metabolites in body tissues of epinephrine and norepinephrine. Thus, urinary VMA level is a good index of catecholamine production in the body. Other investigators (3-6) have confirmed the findings of Arm-strong and his group (1, 2). For the measurement of VMA, Gitlow et at. (6) and Robinson and associates (5) modified the Armstrong two-dimensional paper chromatographic method (1, 2, 7). Studnitz and Hanson (3, 4) based their separation on the use of high-voltage paper electrophoresis. We were interested in measuring this phenolic acid by combining Gitlow ‘s (6) conditions for hydrolysis and extraction of urine with a modification of the Studnitz-Hanson (4) electrophoresis and elutio