Analysis of catecholamines in urine by positive-ion electrospray tandem mass spectrometry.
BACKGROUND
Determination of urinary catecholamines (CATs) is considered important for clinical diagnosis of pheochromocytoma, paraganglioma, and neuroblastoma. The major disadvantages of existing tests include relatively long instrumental analysis time and potential interference from drugs and drug metabolites that are structurally similar to CATs.


METHODS
CATs were extracted from a 300-microL aliquot of urine by a two-step liquid-liquid extraction method specific for compounds containing a catechol group. Chromatographic separation did not require the use of ion-pairing reagents, which typically hinder MS detection but are frequently used in HPLC analysis of CATs. Instrumental analysis was performed by electrospray ionization tandem mass spectrometry (ESI-MS/MS) in the multiple-reaction monitoring mode. Stable-isotope-labeled CATs were used as internal standards.


RESULTS
Epinephrine (E), norepinephrine (NE), and dopamine (D) were measured within 3.5 min instrumental run time. Quantification limits were 2.5 microg/L for E and D and 10 microg/L for NE. The total imprecision (CV) was < or =9.6%; extraction recoveries were 71% +/- 12%.


CONCLUSIONS
HPLC with ESI-MS/MS in combination with sample preparation specific to catechol group-containing compounds allows rapid testing for disorders associated with increased CAT concentrations. The method is free of interferences from drugs and drug metabolites, which commonly interfere with HPLC methods.
Kushnir
Mark M
MM
ARUP Institute for Clinical and Experimental Pathology, 500 Chipeta Way, Salt Lake City, UT 84108, USA. kushnmm@aruplab.com
Urry
Francis M
FM
Frank
Elizabeth L
EL
Roberts
William L
WL
Shushan
Bori
B
D002395:Catecholamines / Q000652:urine*; D002851:Chromatography, High Pressure Liquid; D004298:Dopamine / Q000652:urine; D004837:Epinephrine / Q000652:urine; D006801:Humans; D009638:Norepinephrine / Q000652:urine; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D021241:Spectrometry, Mass, Electrospray Ionization
D002395:Catecholamines; D004298:Dopamine; D009638:Norepinephrine; D004837:Epinephrine