Magnetic molecularly imprinted polymer-assisted charge-transfer spectrophotometric determination of levofloxacin in biological samples.

Levofloxacin (LVX) is a broad-spectrum fluoroquinolone antibiotic whose therapeutic efficacy and safety are highly dependent on maintaining appropriate drug concentrations in biological fluids. An analytical approach exhibiting high selectivity and sensitivity for LVX quantification in biological matrices was established through the integration of magnetic molecularly imprinted polymers (MMIPs) with charge-transfer (CT) complex-based UV-vis spectrophotometry. MMIPs were synthesized via surface-initiated free-radical polymerization on vinyltrimethoxysilane-functionalized Fe3O4 nanoparticles, generating well-defined recognition sites complementary to LVX. The resulting sorbent exhibited rapid binding kinetics, high adsorption capacity (58.8 mg/g), and excellent selectivity toward LVX over structurally related fluoroquinolones. Following magnetic solid-phase extraction, LVX was derivatized through CT complex formation with p-chloranilic acid, producing an intense absorption band at 522 nm and significantly enhancing spectrophotometric sensitivity. Under optimized conditions, the proposed method showed linearity over the range of 5-500 μg/L, with limits of detection of 1.52 μg/L for serum and 1.49 μg/L for urine. High enrichment efficiency (EF = 19.8), good precision (RSD <4.7%), and excellent recoveries (94.6-100.8%) were achieved in real samples. The method demonstrated good agreement with HPLC-UV analysis. Owing to its simplicity, cost-effectiveness, and high selectivity, the developed MMIP-assisted CT spectrophotometric approach represents a practical alternative for therapeutic drug monitoring of LVX in complex biological fluids.