Magnetic N-doped 3D graphene-like framework carbon for extraction of cephalexin monohydrate and ceftiofur hydrochloride

Magnetic N-doped 3D graphene-like framework carbon (Fe3O4@N-3DFC) was prepared via direct pyrolysis of sodium citrate and further hydrothermal reaction, and employed in the extraction of two cephalosporin antibiotics including cephalexin monohydrate and ceftiofur hydrochloride. The scanning electron microscopy, transmission electron microscopy, Fourier transform infrared spectrometry, X-ray photoelectron spectroscopy and X-ray diffraction were employed to confirm the successful synthesis of 3DFC-based adsorbents (3DFCs) including 3DFC, Fe3O4@3DFC and Fe3O4@N-3DFC. Fe3O4@N-3DFC sorbent with 3D graphene-like honeycomb architecture combined magnetic and N doping shows the attractive features including graphene carbon sheets, hierarchical porous structure, good wettability and higher surface affinity for cephalosporin antibiotics. Furthermore, the comparison of extraction efficiency with raw 3DFC and Fe3O4@3DFC sorbent also confirmed the superiority of Fe3O4@3DFC sorbent. Under optimized conditions, good linearity lines were obtained with the determination coefficients from 0.9953 to 0.9995. The limit of detections were in the range of 0.20-0.45 mu g L-1 and 0.03-0.10 pg L-1 for cephalexin and ceftiofur, respectively. The spiked extraction recoveries were between 81.59% and 98.35% with the relative standard deviation values less than 6.98%. Combined with high performance liquid chromatography, Fe3O4@3DFC based magnetic solid-phase extraction was successfully applied in river water and zebrafish samples analysis.