Ferrofluids based analytical extractions and evaluation of their greenness

Ferrofluids are stable dispersions of magnetic nanoparticles in a carrier liquid. They have attracted considerable attention in analytical extractions as they combine fluid-like properties with magnetic character, providing magnetic control over the extraction process. The synthesis of ferrofluids is very straightforward, and it generally involves the preparation of magnetic nanoparticles, their coating, and then mixing in a suitable carrier solvent. This review provides an overview of the synthesis of ferrofluids and some considerations that should be taken into account when synthesizing ferrofluids for analytical extractions. This review also provides insights into the role of coating/composite materials and carrier liquids and how they can contribute toward the extraction of analytes. The applications of ferrofluids-based microextractions have been covered briefly. Finally, the green index of ferrofluids-based analytical methodologies has been evaluated using Eco-Scale, GAPI, and AGREE metrics. The factors that can induce further greenness in such methods have been critically appraised.