Development of levulinic Acid/L-Proline DES-functionalized Fe3O4 nanoparticles for high-performance extraction of flavonoids from Scutellaria Radix

Flavonoids in Scutellaria Radix ( SR ) exhibit significant pharmacological activities, yet conventional extraction methods often suffer from low efficiency and poor selectivity. Here, a green and effective strategy was developed using deep eutectic solvent (DES)-functionalized magnetic nanoparticles for selective flavonoid enrichment. Forty-eight DESs were screened, and levulinic acid/L-proline (2:1) was identified as the optimal system. The selected DES was employed to synthesize Fe 3 O 4 @SiO 2 @DES, which demonstrated high specificity and adsorption performance in magnetic solid-phase extraction. Under optimized conditions, adsorption efficiencies for four representative flavonoids ranged from 0.770 ± 0.01 to 0.983 ± 0.002, with desorption recoveries of 0.551 ± 0.003 to 0.919 ± 0.019. The method showed excellent linearity (R 2  ≥ 0.9998) and low limits of detection and quantification (0.01-0.35 μg mL −1 and 0.03-0.98 μg mL −1 , respectively). Moreover, the adsorbent retained high adsorption efficiency after six reuse cycles, demonstrating stability and reusability. This work provides a sustainable and selective approach for flavonoid enrichment from SR and highlights the potential of DES-functionalized magnetic nanomaterials as an eco-friendly alternative to conventional organic solvent-based extraction.