Co-solvent enhanced adsorption with magnetic velvet-like carbon nitride for high efficiency solid phase extraction.

Magnetic velvet-like graphitic carbon nitride (V-g-C3N4/Fe3O4) was used for rapid 1 min extraction of flavonoids from different tea extracts by co-solvent enhanced adsorptive magnetic solid phase extraction. The nanocomposite can interact with flavonoids, in which Fe3O4 provide hydrogen bond and V-g-C3N4 has hydrophobic and π-π interaction to promote adsorption. The enhanced adsorptive magnetic solid phase extraction method is developed with the addition of a co-solvent (water) to dramatically change the solvent environment, which enhanced the speed of movement of target compounds from the solvent to the sorbent and increase the adsorption capacity. The synergistic effects improved the extraction rate of flavonoids with excellent reproducibility (88.2-107.2%), sensitivity (limits of detection (S/N = 3): 0.075-0.1 μg/mL) and recoveries (88.2-107.2%). This study demonstrated the potential to apply this method for various target analytes from complex sample matrices.