Electrostatic Assembly of Graphene@SiO₂ Composite for Enhanced Dispersive Solid-Phase Extraction: Targeting Eight Pesticide Residues

As a new carbon nanomaterial, graphene (Gr) has attracted wide attention in the field of separation and analysis because of its large specific surface area and strong hydrophobicity. A highly efficient and selective graphene/SiO₂ (Gr/SiO₂) dispersive solid-phase extraction (d-SPE) material was prepared through electrostatic assembly. This process involved the combination of negatively charged poly (sodium 4-styrenesulfonate) (PSS) mediated GS (denoted as PSS-GS) and positively-charged SiO₂, modified with triethoxy silane amino. The precursor material was characterized using FESEM, FTIR and so on. We evaluated the extraction performance of this new sorbent with eight pesticide residues, using the HPLC–MS method. The sorbent demonstrated excellent recovery rates for the pesticide residues under various frequency of use conditions and pH levels. It showed that the SiO₂ and Gr have synergistic extraction effect, and the composite material has good stability and reusable, Ultimately, this newly developed d-SPE material was successfully applied in the analysis of fruit juice samples, yielding good recovery rates in the range of 82.18 to 117.49%.