This review, with more than 170 references, presents a general overview of the use of magnetic nanoparticles (MNPs) to perform sample preparation. In this way, the main types of MNPs used for this purpose, such as magnetic molecularly imprinted polymer (MMIP), noble metal coated MNPs, carbon nanotubes (CNTs), quantum dots (QDs), silica, and surfactant are described in terms of their composition, properties, and synergetic potential. Finally, some examples of their analytical applications are reported, as well as pointing out possible future applications of MNPs in the analytical field.

A simple and rapid methodology to separate and characterize gold nanoparticles (AuNPs) in aqueous medium by capillary electrophoresis–evaporative light scattering detection (CE–ELSD) is presented.