A graphene oxide surface-molecularly imprinted polymer as a dispersive solid-phase extraction adsorbent for the determination of cefadroxil in water samples

In this work, a graphene oxide (GO)-functionalized molecularly imprinted polymer (MIP) (GO-MIPs) was prepared using a non-covalent molecular imprinting approach and applied to dispersive solid-phase extraction (DSPE) coupled with ultra-high-performance liquid chromatography with photodiode array detection (UPLC-PDA) to sensitively detect cefadroxil (FAD) in aqueous solution. FAD was used as a template to synthesize GO-MIPs, with 2-(trifluoromethyl) acrylic acid (TFMAA) and ethylene glycol dimethacrylate (EGDMA) as the monomer and cross-linker, respectively, in methanol. The GO-MIPs was eluted with acetic acid-methanol (20/80, v/v) and then characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), thermal gravimetric analysis (TGA) and Raman spectroscopy. The selectivity of the GO-MIPs versus a graphene oxide-functionalized non-imprinted polymer (GO-NIPs) was confirmed based on the selectivity factors (SFs) using cefixime, cefoxitin sodium and ceftiofur hydrochloride as structural analogues of FAD. The efficiency of the synthesized GO-MIPs was evaluated through application of the proposed DSPE procedure. The influencing factors of DSPE, such as the sample pH, extraction time, desorption reagents and desorption time, were optimized, and the analytical performance of the developed DSPE-UPLC-PDA method was evaluated under the optimized conditions. Good linearity was obtained over 0.04-6.0 mg mL(-1) (R-2 = 0.9979), with a detection limit (S/N-3) of 0.01 mu g mL(-1). Finally, the developed method was applied to determine the concentration of FAD in water samples, and the spiked average recoveries ranged between 72.5% and 104.8%. The GO-MIPs served as good carriers for the selective adsorption of FAD and showed promise for the preconcentration of FAD in complex samples.