A nanocomposite consisting of graphene oxide and Fe₃O₄ magnetic nanoparticles for the extraction of flavonoids from tea, wine and urine samples

We describe a single-step solvothermal method for the preparation of nanocomposites consisting of graphene oxide and Fe₃O₄ nanoparticles (GO/Fe₃O₄). This material is shown to be useful as a magnetic sorbent for the extraction of flavonoids from green tea, red wine, and urine samples. The nanocomposite is taking advantage of the high surface area of GO and the magnetic phase separation feature of the magnetic sorbent. The nanocomposite is recyclable and was applied to the extraction of flavonoids prior to their determination by HPLC. The effects of amount of surfactant, pH value of the sample solution, extraction time, and desorption condition on the extraction efficiency, and the regeneration conditions were optimized. The limits of detection for luteolin, quercetin and kaempferol range from 0.2 to 0.5 ng∙ mL⁻¹ in urine, from 3.0 to 6.0 ng∙mL⁻¹ in green tea, and from 1.0 to 2.5 ng∙mL⁻¹ in red wine. The recoveries are between 82.0 and 101.4 %, with relative standard deviations of <9.3 %. (author)