Magnetic solid-phase extraction using metal-organic frameworks (MOFs) and their derived carbons

Magnetic solid-phase extraction (MSPE) is a useful sample preparation technique, enabling the dispersion of solid sorbents in liquid sample matrices followed by the magnetic retrieval of the sorbent. MSPE can be implemented using any kind of magnetic materials independently of their size and shape, and is a powerful tool for the application of micro/nanomaterials for analytical sample preparation. Metal-organic frameworks (MOFs) have emerged recently as highly valuable sorbents for solid-phase extraction (SPE) due to their large surface area, chemical selectivity, and versatility for tuning their chemical composition and pore size. For MSPE applications, MOFs can be magnetized, or used as precursors for the preparation of MOF-derived magnetic porous carbons (MPCs). In this review, we outline and discuss the different approaches for the preparation of magnetic MOFs and their conversion to MPCs. The applications of magnetic MOFs and MPCs as sorbents for MSPE are critically discussed and oriented to the type of MOF used and the extracted analytes. Recent efforts on the automation of MSPE procedures using magnetic MOFs and MPCs are also described.