HIGH-PERFORMANCE LIQUID-CHROMATOGRAPHIC DETERMINATION OF CATECHOLAMINE METABOLITES AND 5-HYDROXYINDOLEACETIC ACID IN HUMAN URINE USING A MIXED-MODE COLUMN AND AN 8-CHANNEL ELECTRODE ELECTROCHEMICAL DETECTOR

An HPLC system for the simultaneous determination of acidic catecholam ine metabolites, related compounds and 5-hydroxyindoleacetic acid (5-H IAA) in human urine was developed. A mixed-mode (C-18/anion-exchange) column with isocratic elution using citrate buffer and an eight-channe l electrochemical detector were used. Vanilmandelic acid (VMA), 3,4-di hydroxyphenylacetic acid (DOPAC), 4-hydroxy-3-methoxyphenyllactic acid (vanillactic acid, VLA), homovanillic acid (HVA), vanillic acid (VA) and 5-HIAA in urine were determined simultaneously. Detection limits a nd inter (n = 5) and intra-assay (n = 5) coefficients of variation wer e satisfactory. The mean of analytical recoveries (n=3, +/-C.V. (%)) w ere between 97+/-3.2 (VMA) and 105+/-4.8 (VA). Correlations between th e analytical results for VMA, HVA and 5-HIAA obtained by an establishe d method and the present method were satisfactory. The mean +/-2 S.D. of the excretion rates of VMA, DOPAC, VLA, HVA, 5-HIAA and VA in urine from healthy adult volunteers were 0.61-4.36, 0.13-1.02, 0-0.35, 0.67 -6.55, 0.50-5.14 and 0-0.55 mg/g creatinine, respectively.