Aptamer-based magnetic solid-phase extraction coupled with LC-MS/MS for the determination of recombinant FGF10 in rat plasma.

Establishing sensitive and reliable methods for the quantification of structurally intact recombinant protein therapeutics in biological matrices remains essential for pharmacokinetic studies but continues to be analytically challenging. In this study, we developed an aptamer-based magnetic solid-phase extraction coupled with liquid chromatography-tandem mass spectrometry (Apt-MSPE-LC-MS/MS) method for the quantitative determination of recombinant fibroblast growth factor 10 (rFGF10) in rat plasma. The aptamer-mediated extraction enabled selective enrichment of rFGF10 prior to LC-MS/MS analysis, resulting in a 7.2-fold increase in analytical sensitivity compared with direct LC-MS/MS analysis. The developed method exhibited satisfactory linearity over a concentration range of 1.0-50 μg⋅mL⁻¹ (R² = 0.998), with acceptable precision (6.3-13.6%), accuracy (%Bias, -5.8% to 8.0%), and a limit of detection (LOD) of 0.53 μg⋅mL⁻¹. Matrix effect evaluation demonstrated acceptable and reproducible matrix effects, with coefficient of variation (CV) values below 15%. The validated Apt-MSPE-LC-MS/MS method was successfully applied to the pharmacokinetic analysis of rFGF10 in rats. Overall, this workflow provides a selective and reliable strategy for the quantitative analysis of structurally intact recombinant proteins in complex biological matrices.