Overview of mixed-mode ion-exchange materials in the extraction of organic compounds

Mixed-mode ion-exchange materials, including silica-based, polymer-based and other supports, have been applied in sample treatment with different techniques, mainly solid-phase extraction, but also other microextraction techniques such as solid-phase microextraction, stir bar sorptive extraction and microextraction by packed sorbent. These materials are widespread because they conveniently combine capacity (through the reversed-phase interactions in the material backbone) and selectivity (through the specific ion-exchange interactions). This review provides an overview of the advances and applications of mixed-mode ion-exchange materials for the extraction of organic compounds from complex matrices in environmental, food and biological samples. We summarise the different approaches used to prepare these materials and discuss the extraction protocols applied and the types of compounds and samples analysed based on different selected examples.