High performance liquid chromatography–electrospray ionization mass spectrometric determination of isosorbide 5-mononitrate in human plasma

A novel, selective and sensitive high performance liquid chromatography–mass spectrometric (HPLC–MS) method has been developed for the determination of isosorbide 5-mononitrate (5-ISMN) in human plasma. With acetaminophen as internal standard, sample pretreatment involved one-step extraction with diethyl ether of 0.5 mL plasma. Analysis was performed on an ACQUITY UPLC™ BEH C18 column (100 mm × 2.1 mm, 1.7 μm) with mobile phase consisting of acetonitrile–water (20:80, v/v). The detection was carried out by means of electrospray ionization mass spectrometry in negative ion mode with selected ion recording (SIR). Standard curves were linear (r2 ≥ 0.99) over the concentration range of 1.04–1040 ng/mL. The lower limit of quantification (LLOQ) was 1.04 ng/mL. The intra- and inter-day precisions (RSDs) were less than 8.6% and 13.4%, respectively, and the accuracy (RE) was within ±0.45%. The method herein described was fully validated and successfully applied to the pharmacokinetic study of 5-ISMN in compound extended-release tablets in 18 healthy male volunteers after oral administration.