Recent advances on graphene and graphene oxide as extraction materials in solid-phase (micro)extraction

Sample pretreatment plays a vital role in determining and analyzing targets in complex samples like food, biological, and environmental samples. Particularly, graphene and graphene oxide have been widely explored as sorbents in sample preparation. More recently, their composites with magnetic materials, molecularly imprinted polymers, metal-organic frameworks, covalent organic frameworks, aerogels, and other materials have also been developed for sample preparation. Interestingly, these composites enhanced enrichment and selectivity towards different types of analytes by multiple mechanisms including hydrogen bonding, pi-stacking, electrostatic, hydrophobic, and hydrophilic effects. Primarily, this review focuses on the recent development of graphene/graphene oxide-based sorbents in solid-phase extraction (SPE) and solid-phase microextraction (SPME) from 2017 to 2022. The main extraction techniques in this paper include column SPE, dispersive SPE, magnetic SPE, pipettetip SPE, fiber SPME, in-tube SPME, etc. Meanwhile, the current problems and prospects are summarized and described.