Measurement of Plasma Free Metanephrine and Normetanephrine by Liquid Chromatography–Tandem Mass Spectrometry for Diagnosis of Pheochromocytoma

Abstract
Background: Quantification of plasma free metanephrines is usually accomplished by HPLC with electrochemical detection, but sample preparation is labor-intensive and time-consuming, run times are long, and interfering substances sometimes obscure the relevant peaks. The aim of this study was to develop a sensitive and specific LC-MS/MS method for plasma free metanephrines.