FLUOROMETRIC-DETERMINATION OF URINARY VANILMANDELIC ACID AND HOMOVANILLIC-ACID BY HIGH-PERFORMANCE LIQUID-CHROMATOGRAPHY AFTER ELECTROCHEMICAL OXIDATION

A postcolumn derivatization method using electrochemical oxidation was developed for the determination of vanilmandelic (VMA) and homovanillic (HVA) acids in human urine. Both acids were extracted with ethyl acetate from urine under acidic conditions and separated by ion-exchange chromatography on a Hitachi-gel #3011-N column. They were derivatized to fluorescent products by electrochemical oxidation and their fluorescence intensities were measured (Ex 315 nm, Em 420 nm). The calibration curves were linear in the range from 5 to 120 ng. The detection limits (S/ N=3) for VMA and HVA were 24 and 12 ng per ml of urine, respectively. The relative standard deviations (n=5) for VMA and HVA were 7.5 and 5.5% at mean concentrations of 1.0 and 2.2 µg ml-1, respectively. The method was successfully applied to a simultaneous determination of VMA and HVA in the urine of patients with neuroblastoma and of healthy volunteers. © 1990, The Japan Society for Analytical Chemistry. All rights reserved.