DETERMINATION OF FREE URINARY CATECHOLAMINES BY HIGH-PERFORMANCE LIQUID-CHROMATOGRAPHY WITH ELECTROCHEMICAL DETECTION

The present paper compares a manual high-performance liquid chromatographic (HPLC) method with electrochemical detection (ED) with an on-line HPLC-ED method for the determination of free catecholamines (CAs) (norepinephrine, epinephrine, and dopamine) in urine. The manual method involves a two-stage extraction procedure with home-packed columns filled with weakly acidic cation-exchange resin followed by adsorption onto alumina while the on-line method uses a strong cation-exchange polymer as precolumn material which allows the simultaneous determination of free CAs and metanephrines (MNs) in urine. Reference control urine samples analysed with both methods gave levels of CAs within the acceptable reference ranges. Dihydroxybenzylamine was used as an internal standard in both methods and the separation was performed by ion-pairing reversed-phase HPLC.