Quantitative Determination of Ivabradine and N-Desmethylivabradine in Human Plasma by HPLC-MS/MS

Ivabradine and N-desmethylivabradine in human plasma was determined by high performance liquid chromatography coupled with tandem mass spectrometry (HPLC-MS/MS)．Diazepam was used as internal standard．Ivabradine and N-desmethylivabradine was separated on a Diamosil C₁₈ column (150 mm×4.6 mm×5 μm)．Electrospray ionization(ESI) source was applied，and multiple reaction monitoring(MRM) mode was operated in the positive mode with the monitor ions at m/z 469.2→177.1 for ivabradine, m/z 455.2→177.1 for N-desmethylivabradine and m/z 285.1→193.1 for the interna1 standard, respectively. The linear calibration curve are obtained over the concentration range of 0.101 3—101.3 μg/L for ivabradine and 0.085—25.5 μg/L for N-desmethylivabradine．The limit of quantitation are 0.101 3 μg/L and 0.085 μg/L for ivabradine and N-desmethylivabradine, respectively. The inter-day and intra-day precision (RSD) is less than 15%. The average recoveries are above 75%.