Optimization of heteroatom doped graphene oxide by deep eutectic solvents and the application for pipette-tip solid-phase extraction of flavonoids.

In order to improve the permeation and adsorption properties of graphene oxide, heteroatoms and deep eutectic solvent were introduced in this study. After being modified, the structural properties of graphene oxide were improved and the materials were applied to the determination of myricetin and rutin in tea sample by pipette-tip solid-phase extraction method. The materials were characterized by scanning electron microscopy, Fourier transform infrared spectroscopy, X-Ray diffractomer, energy dispersive spectroscopy, atomic force microscope, and specific surface area by Brunauer-Emmett-Teller N adsorption desorption analysis. Meanwhile, they were tested by static and dynamic adsorption. The result showed that the materials after modifying had better adsorption amount for myricetin and rutin than graphene oxide. The calibration graphs of myricetin and rutin in MeOH were linear over 0.10-500.00 µg/mL, and the limits of detection and quantification were in the range of 0.00546-0.0182 µg/mL and 0.00741-0.0247 µg/mL, respectively. A reliable analytical method was developed for recognition targets in tea sample by DES modified nitrogen-doped graphene oxide with satisfactory extraction recoveries (myricetin 99.77%, rutin 98.14%). It was potential for the rapid purification of myricetin and rutin in tea sample combined with the pipette-tip solid-phase extraction.