Magnetic nanomaterials have been applied in fields such as ferrofluids, medical imaging, drug targeting and delivery, cancer therapy, separations, and catalysis.Especially, in the area of analytical chemistry, magnetic nanomaterials have obtained broad attentions.In 1973, magnetic carrier technology was first reported by Robinson, who immobilized enzyme on the surface of magnetic materials.Fe3O4 was the commonly used carrier of magnetic nanomaterials.Magnetic nanoparticles (MNPs), as one type of magnetic materials, have been attracting increasing attention due to the special features that they confer to the extraction process.First, MNPs are readily dispersed in sample solutions, which may increase the contact area between solid and liquid to improve the mass transfer process and improve extraction efficiency.Second, MNPs can be easily collected from the sample matrix after enrichment by employing an external magnetic field; this obviates time-consuming steps such as centrifugation and filtration, and thus greatly simplifies the separation process.Finally, MNPs can be recovered for reuse.These advantages demonstrate that the technology based on MNPs is convenient, economic, and efficient.