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

Aqueous solutions of certain surfactant micelles exhibit phase separation b ehavior upon temperature alteration. This phenomenon can be exploited in se paration science for the development of extraction, purification, and preco ncentration schemes for desired analytes. Since the addition of just a smal l amount of an appropriate nonionic or zwitterionic surfactant to the aqueo us sample solution is required, this approach is convenient and fairly beni gn, 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 extracti on (ME), are briefly reviewed. In addition, the advantages, limitations, an d anticipated future directions of this methodology are discussed.