Separation of intermediates of iron-catalyzed dopamine oxidation reactions using reversed-phase ion-pairing chromatography coupled in tandem with UV-visible and ESI-MS detections

► Intermediates of iron-catalyzed dopamine oxidation were identified by IPC-ESI-MS. ► The short-lived intermediate, 6-hydroxydopamine, was detected and quantified. ► Regenerable anion exchange column is used for on-line ion-pairing reagent removal. ► Mechanism and kinetics of complex reactions can be studied with IPC-ESI-MS.