Surfactant-mediated cloud point extractions: An environmentally benign alternative separation approach

Aqueous solutions of certain surfactant micelles exhibit phase separation behavior upon temperature alteration. This phenomenon can be exploited in separation science for the development of extraction, purification, and preconcentration schemes for desired analytes. Since the addition of just a small amount of an appropriate nonionic or zwitterionic surfactant to the aqueous sample solution is required, this approach is convenient and fairly benign, eliminating the need for the use of organic solvents as in conventional liquid-liquid or solid-liquid extraction. The basic features, experimental protocols, and selected recent applications of this alternative extraction approach, termed cloud point extraction (CPE) or micelle-mediated extraction (ME), are briefly reviewed. In addition, the advantages, limitations, and anticipated future directions of this methodology are discussed.