Isotope dilution LC-orbitrap-HRMS with automated sample preparation for the simultaneous quantification of 11 antimycotics in human serum

Introduction: The aim of this project was to develop and validate an isotope-dilution liquid chromatography high resolution mass spectrometry (LC-HRMS) method for the quantification of the 11 most widely used systemic antimycotics and to study whether HRMS is a feasible alternative for therapeutic drug monitoring (TDM) when compared to tandem MS (MS/MS) technology. Methods: After protein precipitation, followed by automated online sample clean-up the analytes were separated within 4 min on a C18 column using an acetonitrile-water gradient. Eleven antimycotics, namely 5-flucytosine, amphotericin B, anidulafungin, fluconazole, isavuconazole, itraconazole, ketoconazole, micafungin, OH-itraconazole, posaconazole and voriconazole were finally quantified in full MS scan mode using positive electrospray ionization (ESI +) with a mass range fromm/z 110-1300 using HRMS. The method was comprehensively validated on the basis of the European Medicines Agengy (EMA) method validation protocol using commercially available IVD kit components. Results: Good linear relationship between peak area responses and drug concentrations (R-2 > 0.995) and excellent selectivity were observed for all antimycotics in this study. Inaccuracy and imprecision of all quality controls were consistently below +/- 12.6% and +/- 8.1%, respectively. Quantification results were in agreement with an IVD LC-MS/MS method. Conclusion: HRMS was shown to be suitable for TDM of small molecules when compared to tandem mass spectrometry. The novel HRMS method is quickly installed and may be a robust and reliable tool for routine TDM of antimycotics in clinical laboratories. (C) 2019 Elsevier B.V. All rights reserved.