A nanocomposite consisting of graphene oxide, zeolite imidazolate framework 8, and a molecularly imprinted polymer for (multiple) fiber solid phase microextraction of sterol and steroid hormones prior to their quantitation by HPLC

A method is described for multiple monolithic fiber solid-phase microextraction of five sterol and steroid hormones from complex food samples. A composite was prepared from graphene oxide, a metal-organic framework (ZIF-8) and a molecularly imprinted polymers was deposited on a single thin fiber. Four thin fibers were combined to obtain a fiber bundle. The nanocomposite was characterized by Fourier transform infrared spectroscopy, powder X-ray diffraction, scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy. The parameters affecting the extraction were optimized by Box-Behnken design. Following elution with methanol, the analytes progesterone, testosterone, β-sitosterol, cholesterol and campesterol were quantified via HPLC. Response is linear in the 0.01–1000 μg L⁻¹ concentration range, and limits of detection range from 3 to 5 ng L⁻¹. The method was successfully applied to the determination of the five analytes in spiked samples of white meat, egg yolks and vegetables. The relative mean recoveries ranged from 95.0% to 101.0%.

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