Magnetic Solid Phase Extraction of Paeonol and Paeonoflorin from Moutan Bark with Magnetic Graphene Oxide

Herbal medicine plays an important role in modern medicine and separation of the active ingredients from herbal medicine is vital for convenient and safe usage. Paeonol and paeonoflorin are the active ingredients in the widely used herbal medicine of moutan bark. In this study, the composite of graphene oxide-Fe3O4 nanoparticles (GO-Fe3O4) was synthesized and used as a magnetic absorbent to extract paeonol and paeonoflorin from the herbal medicine of moutan bark. The adsorption of paeonol and paeoniflorin on GO-Fe3O4 rapidly reached equilibrium (within 10 min) due to the high absorption capability of GO. Thermodynamics and kinetics for the absorption process were studied. The optimal condition for the elution of the target compound from GO-Fe3O4 was the use of 2 mL of a mixed solvent (methanol and dichloromethane, 1:1 by volume) with 0.2% formic acid for 5 min. The GO-Fe3O4 adsorbent possesses the advantages of rapid adsorption and convenient separation. GO-Fe3O4 can be used over 6 times without losing absorbing capacity. This method is efficient, convenient and rapid, thus possesses a high potential for the separation of active ingredients from herbal medicine.