Liquid Chromatography‐Electrospray Mass Spectrometry Determination of Imatinib and Its Main Metabolite, N‐Desmethyl‐Imatinib in Human Plasma

Abstract The aim of this paper was to develop a specific and sensitive liquid chromatography/electrospray ionization mass spectrometry method for the determination of imatinib and its metabolite in human plasma. The method involved a solid phase extraction of the compounds and internal standard (imatinib‐D8) from human plasma. LC separation was performed on a SymmetryShield™ RP8 column with a mobile phase of water:acetonitrile:formic acid. MS data were acquired in single ion monitoring mode at m/z 494.4, m/z 480.4 and m/z 502.4 for imatinib, N‐desmethyl‐imatinib, and imatinib‐D8, respectively. The absence of ion suppression was demonstrated. The drug/internal standard peak area ratios were linked via a quadratic relationship to plasma concentrations (8.35–8350 µg/L for imatinib and N‐desmethyl‐imatinib). Precision was 2.8–10.8% and accuracy was 91.3–111.3%. Extraction recoveries were ≥70%. The lower limit of quantitation was 8.35 µg/L for both imatinib and N‐desmethyl‐imatinib.