The Rapid and Simple Determination of Urinary 3-Methoxy-4-Hydroxymandelic Acid Eliminated the Interference of Exogenous Vanillin

Abstract

Methods for a determination of 3-methoxy-4-hydroxy-mandelic acid (VMA) based on the Pisanos' method are complicated and time consuming, so the convenal method is modified to simplify and increase speed of an analysis. The procedure can eliminate interfering substances (for example, vanillin) from urine by the pre-extraction using ethyl acetate, and the treatment for oxidation with periodic acid to convert VMA to vanillin is performed at the room tempareture. Vanillin which formed is extracted with toluene, followed by the extraction with 1M potassium carbonate solution, and then absorbance of the potassium carbonate layer is determined spectrophotometrically.
The coefficient of variation between the Pisano's method and the proposed method was 0.95, and mean recovery of standerd added to urine was 99.8 per cent (n=21).
The determination of VMA, the end-product of catecholamine metabolism, is important for diagnosis of patients with pheochromocytoma, ganglioneuroma, neuroblastoma, metastatic carcinoid, and familial dysautonomia, etc, so this modified simple method is useful for the clinical test.