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.