G-MNPs were used as the adsorbent in the whole extraction
procedure and the extraction procedure was illustrated in Fig. 1.
7 mg of G-MNPs was dispersed into a 10 mL sample solution and
then the mixture was shaken for 20 min to reach the adsorption
equilibrium. Subsequently, a strong magnet was deposited at the outside of the sample vial to
isolate the adsorbents, which had already captured the targets, from the sample solution. Then,
the supernatant was decanted, and the concentrated targets were desorbed from the isolated
adsorbents with 200 mL of a mixture of acetone and acetic acid (9:1, v/v) by vigorously
vortexing. The same desorption procedure was repeated two more times. The resulting desorption
solution was collected and transferred to a
1.5 mL Eppendorf tube, and then evaporated to dryness under a gentle stream of nitrogen gas.
Finally, the residue was recon-
stituted with 20 μL of methanol, and 8 μL of which was injected
into the HPLC system for analysis.