A study of the parameters affecting flow gradient analysis of catecholamines, DOPA and DOPAC by ion pair liquid chromatography with electrochemical detection.

A general method for the determination of norepinephrine, epinephrine, dopamine, 3,4-dihydroxyphenylalanine and 3,4-dihydroxyphenylacetic acid is described. It employs the generation of a flow gradient during the analysis by ion-pair reversed phase liquid chromatography. The method allows a reduction of the analysis time maintaining high resolution of the peaks close to the solvent front. The effect of the flow gradient on column efficiency, detector response and retention are evaluated. The application to specimens of amniotic fluid, urine, human plasma and rat brain tissue is shown.