Simplified kinetic calibration of solid-phase microextraction for in vivo pharmacokinetics.

Solid-phase microextraction (SPME) has been demonstrated to be useful for in vivo sampling in pharmacokinetic studies. In this study, a single time-point kinetic calibration for in vivo dynamic monitoring was developed by simplification of the laborious multiple time-point kinetic calibration, based on the independent desorption kinetics of the preloaded standards from SPME fibers with the changing analyte concentrations. The theoretical foundation and practical application conditions, such as the replicate numbers, the optimal time-point for desorption, and the sampling time, were systematically investigated. Furthermore, the feasibility of using regular standards rather than deuterated ones for the kinetic calibration was justified by comparing to the data obtained using the deuterated standards. All the methods were verified by in vitro and in vivo experiments. The results from in vivo SPME were validated by the blood drawing and chemical assay. These simplified calibration methods improved the quantitative applications of SPME for dynamic monitoring and in vivo sampling, enhance the multiplexing capability and automatic potentials for high throughput analysis, and decrease expenses on reagents and instruments.