Enhancing Quantitative Analysis of Xenobiotics in Blood Plasma through Cross-Matrix Calibration and Bayesian Hierarchical Modeling.

This study addresses the challenges of matrix effects and interspecies plasma protein binding (PPB) on measurement variability during method validation across diverse plasma types (human, rat, rabbit, and bovine). Accurate measurements of small molecules in plasma samples often require matrix-matched calibration approaches with the use of specific plasma types, which may have limited availability or affordability. To mitigate the costs associated with human plasma measurements, we explore in this work the potential of cross-matrix-matched calibration using Bayesian hierarchical modeling (BHM) to correct for matrix effects associated with PPB. We initially developed a targeted quantitative approach utilizing biocompatible solid-phase microextraction coupled with liquid chromatography-mass spectrometry for xenobiotic analysis in plasma. The method was evaluated for absolute matrix effects across human, bovine, rat, and rabbit plasma comparing pre- and postmatrix extraction standards. Absolute matrix effects from 96 to 108% for most analytes across plasma sources indicate that the biocompatibility of the extraction phase minimizes interference coextraction. However, the extent of PPB in different media can still affect the accuracy of the measurement when the extraction of small molecules is carried out via free concentration, as in the case of microextraction techniques. In fact, while matrix-matched calibration revealed high accuracy, cross-matrix calibration (e.g., using a calibration curve generated from bovine plasma) proved inadequate for precise measurements in human plasma. A BHM was used to calculate correction factors for each analyte within each plasma type, successfully mitigating the measurement bias resulting from diverse calibration curve types used to quantify human plasma samples. This work contributes to the development of cost-effective, efficient calibration strategies for biofluids. Leveraging easily accessible plasma sources, like bovine plasma, for method optimization and validation prior to analyzing costly plasma (e.g., human plasma) holds substantial advantages applicable to biomonitoring and pharmacokinetic studies.