Measurement of urinary catecholamines and their catechol metabolites and precursor by liquid chromatography with column-switching and on-line fluorimetric and electrochemical detection.

A new method is described for the determination of catecholamines and their precursor (3,4-dihydroxyphenylalanine), and separately of their catechol metabolites (3,4-dihydroxymandelic acid, 3,4-dihydroxyphenylacetic acid, 3,4-dihydroxyphenylethylene glycol and 3,4-dihydroxyphenylethanol) in urine. After a two-step pretreatment involving ethyl acetate extraction and adsorption onto alumina, the separation is performed by ion-pair reversed-phase high-performance liquid chromatography. A column-switching system enables complete separation of the most polar compounds without increase in the total analysis time. The column eluates are monitored with both fluorimetric and amperometric detectors, the relative responses of which are used as an index of peak purity. Reference values for twelve healthy adults are given.