Determination of Fentanyl in Canine Plasma using HPLC-MS Detection

A simple, easy, and accurate high-performance liquid chromatographic method for the determination of fentanyl concentrations in plasma samples has been developed and validated. Following a liquid extraction with acetonitrile, samples were separated by reversed-phase high-performance liquid chromatography (HPLC) on an XBridge C18 column (2.1 x 50 mm, 3.5μm) and detected by mass spectroscopy. The mobile phase was a mixture of water with 0.1% formic acid, and acetonitrile with 0.1% formic acid (90:10), with a flow rate of 0.6 ml/min. The procedure produced a linear curve over the concentration range of 0.1-25 ng/ml for fentanyl in canine plasma with a LOQ of 0.1 ng/ml. Intra- and inter-assay variability ranged from 2.6%-8.2% and the average recovery for fentanyl was 100%.