Abstract Objectives Voriconazole is an antifungal agent measured in serum and plasma for therapeutic drug monitoring. This study aimed to develop a robust isotope-dilution liquid chromatography-tandem mass spectrometry (ID-LC-MS/MS) reference measurement procedure (RMP) to ensure accurate and reliable quantification in compliance with metrological standards. Methods A commercially available voriconazole material, traceable to the International System of Units (SI), characterized by quantitative nuclear magnetic resonance spectroscopy (qNMR), served as the primary reference material. Chromatographic separation was achieved using a Raptor Biphenyl column, and isotope-labeled voriconazole was utilized as the internal standard. The candidate RMP was validated for selectivity, matrix effects, linearity, precision, accuracy, sample stability, and measurement uncertainty. Results The method’s selectivity was successfully demonstrated, with no interfering signals observed at the retention time of voriconazole. Assessment of matrix effects revealed no significant differences in slopes across native serum, analyte-free human serum, and Li-hep plasma, confirming the absence of matrix-derived interferences. Intermediate precision was ≤3.7 %, repeatability was ≤2.3 %, and accuracy showed a mean bias ranging from −0.7 to 2.7 % across all matrices and concentration levels. Relative bias for the lower limit of the measuring interval (LLMI) was 1.7 %, with a coefficient of variation (CV) for intermediate precision of 4.3 %. Expanded measurement uncertainties (k=2) for target value assignment (n=6) ranged from 1.4 to 3.4 %. Conclusions This validated ID-LC-MS/MS-based RMP proved to be selective, precise, accurate, and reliable for the quantification of voriconazole in human serum and plasma. The RMP demonstrated high accuracy and precision, along with suitable measurement uncertainty, meeting all relevant requirements for an RMP. These findings support the method’s suitability for use in establishing target values and ensuring accuracy in clinical laboratories.
Kubicova et al. (Fri,) studied this question.