Determination of mirfentanil hydrochloride (A-3508.HCl) in human plasma by liquid chromatography-mass spectrometry

A method for the quantitation of mirfentanil hydrochloride (A-3508.HCl) in human plasma is presented for the first time, using LC-MS with single ion monitoring. The drug is extracted with a C-18 solid-phase cartridge and the extract is analysed using a 3 cm C-18 column connected to the ion source of a mass spectrometer via a thermospray interface. The intense ion produced by the protonated molecular ion at m/z 377 is detected by the mass spectrometer in positive-ion mode. The range of quantitation is 0.4-100 ng ml-1 from a 0.5 ml plasma sample. Results of assay validation are given. The method was used to analyse samples from a human pharmacokinetic study following intravenous administration of mirfentanil hydrochloride.