Electrospun nanofibrous scaffold for immobilizing natural hydrophobic deep eutectic solvent in liquid-phase microextraction of propranolol and metoprolol from human plasma

The development of practical and efficient sample-preparation strategies for pharmaceutical analysis in complex biological matrices remains challenging. Herein, a novel liquid-phase microextraction approach using an electrospun nanofiber-immobilized natural hydrophobic deep eutectic solvent (LPME-ENF-iNHDES) was developed for the simultaneous extraction of propranolol and metoprolol in human plasma. Polyacrylonitrile nanofibers were fabricated by electrospinning and used as a porous scaffold to retain an NHDES composed of decanoic acid and dodecanoic acid at a 2:1 molar ratio. In this configuration, the NHDES serves as the primary liquid extraction phase, while the nanofibrous scaffold facilitates its retention and handling during microextraction. The extraction procedure was systematically optimized using a central composite design, yielding optimum conditions of pH 11.9, 6.7 mg nanofiber, 4.1% (w/v) NaCl, and 8.8 min extraction time. The method showed linear ranges of 10-1000 ng/mL for propranolol and 20-1000 ng/mL for metoprolol, with R² values of 0.9972 and 0.9966, respectively. Satisfactory intra-day and inter-day precision and extraction recoveries were obtained. The PAN nanofiber scaffold was reusable for at least seven consecutive cycles, with NHDES reloaded before each cycle; only 200 μL of desorption solvent and 1 min of desorption time were required. The method showed no appreciable interference from endogenous matrix components. Comparison with previously reported methods indicated that the proposed configuration provides satisfactory analytical performance together with practical advantages for the simultaneous plasma analysis of these β-blockers.