Three-dimensional chitosan/graphene oxide aerogel for high-efficiency solid-phase extraction of acidic herbicides in vegetables

A simple, facile method was adopted to synthesize three-dimensional chitosan grafted graphene oxide aerogel modified silica (3D CS/GOA@Sil) as an eco-friendly, sustainable extraction material for the preconcentration of phenoxy acid herbicides. An amidation reaction realized the immobilization of CS and GO on the surface of silica, which was followed by a freeze-drying technique to yield the CS/GOA@Sil with 3D architecture structure. The successful synthesis and properties of 3D CS/GOA@Sil were characterized and confirmed by using scanning electron microscopy, infrared spectroscopy, BET adsorption-desorption analysis, and thermogravimetric analysis. The surface area of 3D CS/GOA@Sil was twice that of the individual GO@Sil. Besides, the adsorption and extraction times were also shorter due to the ordered porous structure and rapid mass transfer. Under the optimal conditions, coupled with a high-performance liquid chromatography-ultraviolet detector, this as-established method presented wide linearities with desirable correlation coefficients (>= 0.9936) and low limits of detection (<= 1.5 mu g L-1). Finally, it was applied in the analysis of phenoxy acid herbicides in vegetables, and satisfactory relative recoveries of 62.38-102.92% of spiked standard solutions with different concentrations were obtained.