| Abstract: | An improved protocol has been developed to isolate homovanillic acid (HVA) and vanilmandelic acid (VMA) from urine with strong anion-exchange resin. The sample is diluted with acetate buffer and passed through a disposable column. HVA, uric acid, and many hydrophobic organic acids are removed with 1.0 M acetic acid—ethanol, Then VMA is eluted with 0.5 M phosphoric acid. Two isocratic mobile phases allow rapid high-performance liquid chromatographic measurement of VMA (5 min) and HVA (8 mins) on a 5-μm ODS column. Selective conditions were developed with dual-electrode coulometric detection to permit specific measurement of VMA, HVA, and internal standards, with less than 5% between-run variation. |
