Facile preparation of reduced graphene oxide/ZnFe₂O₄ nanocomposite as magnetic sorbents for enrichment of estrogens

Reduced graphene oxide/ZnFe₂O₄ (rGO/ZnFe₂O₄) nanocomposite was facile prepared and applied as magnetic sorbent for the extraction of estrogens including 17β-estradiol, 17α-estradiol, estrone and hexestrol from water, soil, and fish samples prior to HPLC analysis. The rGO/ZnFe₂O₄ nanocomposite was characterized by scanning electron microscope, Fourier transform-infrared spectroscopy, X-ray diffraction, and vibrating sample magnetometer. The experimental parameters affecting the efficiency of magnetic solid-phase extraction (MSPE) including the amount of material, extraction time, pH, temperature, desorption solvents, desorption time, and desorption solvent volume were investigated respectively. With the developed method, good linearity was observed in the range of 0.05–500 ng/mL with the correlation coefficients (R²) between 0.9978 and 0.9993. The limits of detection (S/N = 3) and limits of quantification (S/N = 10) were achieved at 0.01–0.02 ng/mL and 0.05 ng/mL, respectively. The enrichment factors were calculated as the range of 241–288. Using rGO/ZnFe₂O₄ nanocomposite as the sorbent, the developed MSPE followed by HPLC analysis, was applied to analysis of estrogens in river water, soil and fish samples. The method has the potential application in the extraction and preconcentration ultra trace compounds in complex matrices, such as environmental and biological samples.