Rapid extraction of free fatty acids from edible oil after accelerated storage based on amino-modified magnetic silica nanospheres

Abstract

In this study, magnetic amino-modified silica nanospheres (Fe₃O₄@SiO₂@NH₂) were prepared via coating 3-aminopropyltriethoxysilane on the surface of Fe₃O₄ magnetite and used for the extraction of free fatty acids (FFAs) from edible oil samples for the first time. Fourier transform infrared spectroscopy and vibrating sample magnetometer analysis indicated that Fe₃O₄@SiO₂@NH₂ was successfully synthesized and exhibited superparamagnetism. The static and dynamic adsorption experiments showed that Fe₃O₄@SiO₂@NH₂ exhibited rapid adsorption equilibrium and satisfactory adsorption capacity towards FFAs. Under optimized adsorption and analytical conditions, Fe₃O₄@SiO₂@NH₂ could effectively extract FFAs from edible oil samples with excellent linearities (0.2–1000 nmol g⁻¹), extremely low limits of detection (0.09–0.46 nmol g⁻¹), and satisfactory recoveries (77.4–101.8%) and precisions (3.1–9.6%). Moreover, compared to classic solid phase extraction using a commercial cartridge, the current magnetic solid phase microextraction method has many advantages including easier preparation of adsorbents, a simpler sample handling procedure and lower cost. Therefore, this method provides a promising alternative to the traditional method for the analysis of FFAs to ensure the sanitation and quality of oils.