[Determination of urine catecholamines and metanephrines by reversed-phase liquid chromatography-tandem mass spectrometry].

The measurement of urine catecholamine and metanephrine concentrations is important for biochemical screening and diagnosis of pheochromocytoma. The goal of this work was to develop a simple liquid chromatography-tandem mass spectrometry (LC-MS/MS) method for determining catecholamines and metanephrines in urine to replace an existing liquid chromatographic method using electrochemical detection. Urine samples were prepared using Oasis weak-cation-exchange cartridges. The eluate was analyzed on an Agilent ZORBAX Eclipse Plus Phenyl-Hexyl column in 3 min. Adrenaline, noradrenaline, dopamine, metanephrine, normetanephrine, and their deuterated internal standards were monitored in positive electrospray ionization mode by multiple reaction monitoring (MRM). No evidence of ion suppression was observed. The assay was linear up to 5µmol/L for adrenaline, 5µmol/L for noradrenaline, 6.1µmol/L for dopamine, 5.6µmol/L for metanephrine, and 34.6µmol/L for normetanephrine, with lower limits of quantification of 5, 5, 12, 6 and 7 nmol/L, respectively. The intra-day and inter-day precisions for all analytes ranged from 0.59% to 4.64% and 1.98% to 4.80%, respectively. External quality assurance samples were assayed and showed excellent agreement with the target values. This simple method provides an improved assay for determining urine catecholamines and metanephrines.