A novel ferrofluid based on hydrophobic deep eutectic solvent and Fe3O4@NH2-graphene oxide for the analysis of estrogens from various samples

A new ferrofluid based on hydrophobic deep eutectic solvent and Fe 3 O 4 @NH 2 -graphene oxide was designed, and then used as extraction medium for the extraction and analysis of estrogens in water by coupled with vortex-assisted liquid-liquid micoextraction and high performance liquid chromatography. The morphology, structure, thermal stability and magnetic property of the material were studied by scanning electron microscope (SEM), Fourier Transform-Infrared Spectroscopy (FT-IR), X-ray diffraction (XRD), thermogravimetric analysis (TGA) and vibrating sample magnetometer (VSM). Four estrogens, including estradiol (E2), ethinyl estradiol (EE2), bisphenol AP (BPAP) and hexestrol (HEX), were used as the model analytes. Key parameters related to the ferrofluid preparation and extraction conditions were optimized by single-factor and response surface method. Under the optimal conditions, good linearity (R 2  > 0.99) in the concentration ranges of 0.1–200, 0.2–200, 0.007–200 and 0.15–200 μg/L were obtained for E2, EE2, BPAP and HEX, respectively. The limits of detection for E2, EE2, BPAP and HEX were 0.030, 0.070, 0.002 and 0.05 μg/L, respectively. The established method was successfully applied for the quantification of E2, EE2, BPAP and HEX in urine, environmental water, beverage and package samples. The method was simple, rapid, sensitive and producible.