Rapid determination of fenoldopam in human plasma by UPLC-MS/MS for pharmacokinetic analysis in patients.

Abstract We developed and validated a rapid, selective, and sensitive ultra-performance liquid-chromatography mass-spectrometry (UPLC–MS/MS) method for quantifying fenoldopam in human plasma for pharmacokinetic studies. Fenoldopam and the internal-standard (IS), oxazepam, were isolated from human plasma by liquid–liquid extraction using ethyl acetate after alkalization, and were separated on a 2.1 × 100 mm Acquity UPLC HSS T3 C18 column (inside diameter, 1.8 μm) using a mobile phase of water (0.05% formic acid) and acetonitrile gradient elution. The fenoldopam and IS were eluted at 1.07 and 2.32 min, respectively. Quantification was performed using positive-ion electrospray-ionization (ESI), and the fenoldopam and IS responses were optimized at the m / z 306.16 → 107.10 and m / z 287.1 → 241.01 transitions, respectively. The assay was validated over the linear range of 0.1–40 ng/mL fenoldopam with intra- and interassay precision