Determination of amiodarone and desethylamiodarone in human plasma by high-performance liquid chromatography–electrospray ionization tandem mass spectrometry with an ion trap detector

A sensitive and specific high-performance liquid chromatography–electrospray ionization-tandem mass spectrometry (HPLC–ESI-MS–MS) method has been developed for the simultaneous determination of amiodarone and desethylamiodarone in human plasma. After the addition of the internal standard tamoxifen, plasma samples were extracted using Oasis® MCX solid-phase extraction cartridges. The compounds were separated on a 5 μm Symmetry C18 (Waters) column (150×3.0 mm, internal diameter) with a mobile phase of acetonitrile–0.1% formic acid (46:54, v/v) at a flow-rate of 0.5 ml/min. The overall extraction efficiency was more than 89% for both compounds. The assay was sensitive down to 1 μg/l for amiodarone and down to 0.5 μg/l for desethylamiodarone. Within-run accuracies for quality-control samples were between 95 and 108% of the target concentration, with coefficients of variation <8%. The proposed method enables the unambiguous identification and quantitation of amiodarone and desethylamiodarone in both clinical and forensic specimens.