6 CHANNEL ELECTROCHEMICAL HPLC DETECTOR USING GRAPHITE REINFORCEMENT CARBON ELECTRODE FOR DETERMINATION OF CATECHOLAMINE METABOLITES

A six channel electrochemical HPLC detector was constructed and applied to the determination of catecholamine metabolites. Using graphite reinforcement carbon (GRC), available as the lead of mechanical pencils, an hexadic-electrode system was fabricated with an Ag reference electrode and a stainless steel counter electrode in an electrochemical flow cell of wall-jet geometry. Then relative standard deviation of the amperometric response of catecholamines measured at 6 electrodes was less than 4%. The use of the detector facilitated the measurement of hydrodynamic voltammograms of samples containing complex components such as catecholamine metabolites. Satisfactory determinations of some catecholamine metabolites, such as 4-hydroxy-3-methoxyphenylglycol, 3,4-dihydroxyphenylacetic acid, vanillylmandelic acid and homovanilic acid in human urine were made.