Determination of Plasma Epinephrine, Norepinephrine and Dopamine by LC/MS/MS Using Isobaric Amine Reactive Tags

摘要

Low fmole concentrations of the main endogenous catecholamines (Epinephrine, Norepinephrine and Dopamine) can be labeled with iTRAQ~R reagents with high recovery yields, reproducibility and good linearity. The labeled catecholamines can be detected in ESI/MS, MRM mode with high specificity and sensitivity from high amole to low fmole concentrations. The signal intensity is enhanced by a factor of up to approx100. In addition, upon labeling the catecholamines improve retention on RP C18 column. Quantitation is achieved using isobaric internal calibration standard for every catecholamine which corrects for any variations in the analysis. The method has a good potential to reliably quantify catecholamines in plasma extracts (specific to catechol function). A challenge that remains to be solved is improving recovery and reproducibility values of trace amounts of plasma extracts after its drying step.