Biotage has produced an application note describing a mixed-mode weak cation exchange SPE protocol for extraction of three catecholamines and three metanephrine metabolites from plasma prior to LC-MS/MS detection.
Introduction
The method described in this application achieves high reproducible recoveries for a number of common catecholamine analytes in plasma. The application demonstrates how EVOLUTE® EXPRESS SPE products dramatically improve flow characteristics and enhance sample preparation productivity. By truly eliminating the need for column conditioning and equilibration, samples can be prepared using a simple, fast load-wash-elute procedure.
Analytes
Epinephrine, Norepinephrine, Dopamine, Metanephrine, Normetanephrine and 3-Methoxytyramine (Sigma Aldrich Chemical Co, Poole, UK).
Internal Standards
D6-Epinephrine, D6-Norepinephrine, D4-Dopamine, D3-Metanephrine, D3-Normetanephrine (Sigma Aldrich Chemical Co, Poole, UK).
Method
The solid-phase extraction procedure, UHPLC and MS conditions are given in the application note.
Results
Extraction recoveries were calculated at a concentration of 5 ng/mL. Data is summarized from the results of n ≥ 7 extracted samples compared to n ≥ 4 blank samples fortified with an amount of analytes equivalent to 100% after extraction. Linearity was determined between 0.04 and 1.28 ng/mL for norepinephrine and dopamine and between 0.02 and 1.28 ng/mL for epinephrine, normetanephrine, metanephrine and 3-methoxytyramine. Example calibration lines using a manual full extraction can be found within the application note for each component.
