HPLC-ED DETERMINATION OF CATECHOLAMINES AND THEIR METABOLITES IN URINE

High performance liquid chromatography (HPLC) with electrochemical det ection (ED) was applied for the monitoring of catecholamines (epinephr ine - E, norepinephrine - NE, dopamine - DA) and their main metabolite s (homovanillic acid - HVA, vanillylmandelic acid - VMA) in urine samp les of patients with the pheochromcytoma diagnosis. Both amperometric and colorimetric detectors were tested for the clinical applications a nd the results were compared. The optimization of separation condition s was worked out, especially the effects of mobile phase compositions (pH, ionic strength, organic modifier and ion-pair agent concentration s). Dependences of capacity ratio values k' on all optimized component s of the mobile phases were evaluated. Chromatographic conditions were optimized for the suitable chromatographic resolution (Rij> 1.25). Ex traction recoveries for liquid-liquid and solid-phase extractions have been worked-out. Detection limits for catecholamines in urine were in the range of 0.3-0.6 ng/nl and 10-20 ng/ml for HVA, VMA using coulome tric detector.