LC–ESI–MS Determination of Flupentixol in Human Plasma

Flupentixol and an internal standard, loperamide were extracted from human plasma by liquid–liquid extraction and analyzed on a Thermo Hypersil HyPURITY C18 column, with 10 mM ammonium acetate–acetonitrile–methanol (26:62:12, v/v/v) as mobile phase, coupled with electrospray ionization mass spectrometry (ESI–MS). The protonated analyte was quantified by selected-ion monitoring (SIM) with a quadrupole mass spectrometer in a positive-ion mode. The calibration curve was linear (r = 0.9990) over the concentration range: 0.039–2.5 ng mL−1. Intra-day and inter-day precision (RSD%) were less than 13.05%. The established method was successfully applied for the determination of pharmacokinetics of flupentixol in human plasma.