Urinary vanilmandelic acid determination using column chromatography.
A simple method for determination of urinary vanilmandelic acid, VMA, using column chromatography was described. The interfering substances in the urine were eliminated by passing the urine through a Dowex-1 x 2, 50-100 mesh, column and washing the column with distilled water. The VMA was eluted from the resin using K2CO3-containing 3.0 mol/l NaCl solution and determined spectrophotometrically after periodate oxidation reaction. This method yielded a standard curve which was linear up to 50 mg/l. The recoveries of the method as determined by addition technique ranged from 92.1 to 100.4 per cent with an average of 97.3 per cent. The method yielded satisfactory precisions with the coefficients of variation (C.V.) of less than 5.50 and 6.95 per cent for within-run and between-run experiments respectively. The method was sensitive to the concentrations of 1.2 mg/l with recovery of 92.5 per cent and 2.6 mg/l with the recovery of 109.9 per cent for the standard and urinary VMA respectively. No interfering effects were found from epinephrine and norepinephrine (up to 2,000 micrograms/l), acetylsalicylic acid (up to 50 mg/l) and homovanillic acid (up to 10 mg/l) added to the pooled urine. The correlation coefficients (r) of 0.909 (n = 100) and 0.905 (n = 100) were obtained when the urinary VMA values determined by the proposed and Pisano's methods and expressed as mg/l and mg/g creatinine were compared respectively. The column could be reused at least 5 times. The technique is suitable for any routine clinical laboratory.