Improved solid-phase extraction and liquid chromatography with electrochemical detection of urinary catecholamines and 5-S-L-cysteinyl-L-dopa.
We describe a rapid, precise, accurate liquid chromatographic procedure for determining urinary catecholamines and 5-S-L-cysteinyl-L-dopa. The catecholamines (norepinephrine, epinephrine, and dopamine) and 5-S-L-cysteinyl-L-dopa are extracted from 1.0 ml of urine together with internal standards, by using a Bond-Elut strong cation-exchange (SCX) and an affinity phenylboronic acid (PBA) extraction column in series. The eluate obtained from PBA column is then chromatographed on a reversed-phase C18 column with a mobile phase containing pentane- and heptanesulfonate as ion-pair reagents. The detection is achieved with an amperometric detector set at an oxidation potential of +0.55 V. The chromatography is complete is less than 8 min for catecholamines and less than 5 min for cysteinyldopa. The method can measure less than 2 micrograms/l for catecholamines and 5 micrograms/l for cysteinyldopa. Analytical recoveries of catecholamines and cysteinyldopa added to urine pool ranged from 90-107%. Between run coefficient of variation ranged from 4.7 to 8%. None of the drugs and catecholamines metabolites tested interfered with the assay.
Huang
T H
TH
Department of Laboratory Medicine, University of California, San Francisco 94143.
Wall
J
J
Kabra
P
P
D002395:Catecholamines / Q000652:urine*; D002853:Chromatography, Liquid; D003548:Cysteinyldopa / Q000652:urine*; D004295:Dihydroxyphenylalanine / Q000031:analogs & derivatives*; D004563:Electrochemistry; D004837:Epinephrine / Q000652:urine; D006801:Humans; D007202:Indicators and Reagents; D009638:Norepinephrine / Q000652:urine
D002395:Catecholamines; D007202:Indicators and Reagents; D003548:Cysteinyldopa; D004295:Dihydroxyphenylalanine; D009638:Norepinephrine; D004837:Epinephrine