Urinary free catecholamines determined by liquid chromatography--fluorometry

Free norepinephrine, epinephrine, and dopamine are determined in urine after purification on a small ion-exchange column and concentration on alumina. The catecholamines are separated by reversed-phase ion-pair chromatography and are quantitated by measuring their native fluorescence (lambda ex 285 nm, lambda em 305 nm). The internal standard is dihydroxybenzylamine. Within-day CVs for the compounds ranged from 1.6 to 5.6%; between-day CVs were 6.6 to 9.8%.