Automated Extraction of Catecholamines and Metanephrines in UrineCarmen Adamson
The catecholamines are bioamines that play an integral role as neurotransmitters in the central and peripheral nervous system. Screening for catecholamines and their O-methylated metabolites is a widely accepted approach for diagnosis of catecholamine-secreting tumors. Generally, these tumors are benign, but the potent effects on the cardiovascular system caused by excess catecholamines can have potentially fatal outcomes. Correct, timely diagnosis is crucial. Unlike plasma, it is recommended that both metanephrines and catecholamines be measured in urine. Urine analysis is non-invasive and exhibits sufficiently high levels of target compounds.
The proposed method uses diphenylborinic acid (DPBA) as a complexing agent to stabilize and increase lipophilicity for reversed phase retention. Dispersive pipette extraction (DPX) takes place within a pipette tip, which facilitates an easily automated alternative to traditional SPE requiring less sample and solvent volume. The objective of this study was to develop an automated sample preparation method utilizing DPBA complexing agent with DPX extraction for minimized sample preparation time and high sensitivity analysis of epinephrine, norepinephrine, dopamine, metanephrine, and normetanephrine in urine with LC-MS/MS.
All sample preparation was performed on a Hamilton NIMBUS96 platform.
The automated DPX extraction is a fast 5 step process of aspiration and dispense cycles. The elution solution reverses the complexation of the analytes and selectively elutes them. The elution is then ready for injection.