Synthesis of a graphitic carbon nitride nanocomposite with magnetite as a sorbent for solid phase extraction of phenolic acids

We have developed a facile in-situ growth method for the deposition of magnetite (Fe₃O₄) particles on the surface of a graphitic carbon nitride (g-C₃N₄) nanosheet. The material was characterized by X-ray diffraction, transmission electron microscopy, Fourier transform infrared spectroscopy, and thermogravimetric analysis. The high affinity of g-C₃N₄ for phenolic acids in combination with the magnetism of Fe₃O₄ provides an efficient means for magnetic solid phase extraction. The adsorption, desorption and recoveries were examined. Under optimized conditions, the method has limits of detection in the range from 17.5–42.6 ng mL⁻¹ (at an S/N of 3), and precisions from 2.8–3.8 % (for n = 5). The method was successfully applied to the determination of protocatechuic, caffeic, and ferulic acids in Salicornia herbacea L. plant extracts. Recoveries ranged from 92.4–99.5 %. (author)