Nanofluids in analytical chemistry

Nanofluids are stable colloidal dispersions of two basic components. A nano-sized particle which can be ceramic nanoparticles, metallic nanoparticles, or carbon nonmaterials and a base fluid such as water, toluene, ethylene glycol and engine oil. Recently, nanofluids have been used in different fields of analytical chemistry because they can improve mass transfer coefficient[1-4].In recent years, there has been numerous efforts to change the conventional hazardous carriers with environmentally friendly compounds such as ionic liquids (ILs) or deep eutectic solvents in order to make new nanofluids with favorable properties. ILs have unique special properties such as high viscosity, good solubility, good electric conductivity and compatibility with other chemical materials.Due to the specifications listed above, ILs are promising candidates to replace previous dispersant fluids[5]. Bucky gels and ferrofluids are types of nanofluids which were used in our laboratory in order to develop dispersive solid phase microextraction method.If we use nanocarbons (such as carbon nanotube (CNTs), graphene (G) and fullerene) as the nano-sized particle and ionic liquid (IL) as the base fluid, the mixture is called ‘Bucky gel’. By using Fe3O4 magnetic nanoparticles as the nano-sized particle and the coating in a carrier fluid the resulting material will be ferrofluid. Ferrofluids characteristically have both magnetic and fluid properties and due to their unique physical and chemical properties, they have been finding more and more applications in a variety of fields. For the first time in 2013, application of dispersive-solid phase extraction (D-SPE) based on a ferrofluid has been reported by our group.In this review, the most recent developments in preparation of new ferrofluids and bucky gels with the aid of different nanoparticles and base fluids are summarized. Furthermore, recent reports on the applications of these nanofluids for developing different microextraction methods for the analysis of various environmental pollutants are reviewed.