Facile fabrication of reduced graphene oxide-encapsulated silica: A sorbent for solid-phase extraction

• A facile hydrothermal strategy was developed for the synthesis of SiO2@rGO.
• The SiO2@rGO has large rGO immobilized amount.
• The SiO2@rGO shows remarkable adsorption capacity toward CPs and peptides.
• A superior recovery could be obtained compared to C18, GCB and CNTs.
• The SiO2@rGO was used to determine CPs in water samples.

In this study, a facile hydrothermal reduction strategy was developed for the preparation of reduced graphene oxide-encapsulated silica (SiO2@rGO). Compared with other conventional methods for the synthesis of SiO2@rGO, the proposed strategy endowed the obtained SiO2@rGO with larger amount of immobilized rGO. The prepared functionalized silica shows remarkable adsorption capacity toward chlorophenols (CPs) and peptides. When it was used as solid-phase extraction (SPE) sorbent, a superior recovery could be obtained compared to commercial sorbents, such as C18 silica, graphitized carbon black and carbon nanotubes. Based on these, the prepared material was used as SPE sorbent for the enrichment of CPs, and a method for the analysis of CPs in water samples was established by coupling SPE with high performance liquid chromatography–ultra violet detection (SPE-HPLC/UV). In addition, the obtained SiO2@rGO was further successfully extended to the enrichment of peptides in bovine serum albumin (BSA) digests.